- Email: [email protected]
Isolation and characterization of microcrystalline cellulose from roselle fibers
Accepted Manuscript Title: Isolation and Characterization of Microcrystalline Cellulose from Roselle Fibers Authors: Lau Kia Kian, Mohammad Jawaid, Hidayah Ariffin, Othman Y. Alothman PII: DOI: Reference:
S0141-8130(17)31730-0 http://dx.doi.org/doi:10.1016/j.ijbiomac.2017.05.135 BIOMAC 7624
To appear in:
International Journal of Biological Macromolecules
Received date: Accepted date:
14-5-2017 20-5-2017
Please cite this article as: Lau Kia Kian, Mohammad Jawaid, Hidayah Ariffin, Othman Y.Alothman, Isolation and Characterization of Microcrystalline Cellulose from Roselle Fibers, International Journal of Biological Macromoleculeshttp://dx.doi.org/10.1016/j.ijbiomac.2017.05.135 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Isolation and Characterization of Microcrystalline Cellulose from Roselle Fibers
Lau Kia Kian1, Mohammad Jawaid1*,2, Hidayah Ariffin3, Othman Y Alothman2
1
Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia 2
Department of Chemical Engineering, College of Engineering, King Saud University, Riyadh,
Saudi Arabia 3
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular
Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
*
Corresponding author at: Biocomposite Technology Laboratory, INTROP, Universiti Putra
Malaysia, 43400 UPM Serdang, Selangor, Malaysia. Tel.: +603-89466960; Fax: +603-86471896 E-mail: [email protected] [email protected]
Highlights
Roselle fibre-Microcrystalline cellulose (R-MCC) extracted by chemical process R-MCC demonstrates altered and non-uniform shape of micro-sized fibrils The unsymmetrical broad size distribution can be observed for R-pulp and R-MCC. Crystallinity value of R-MCC (78%) is more than Commercial MCC (74%) Obtained R-MCC also has considerably good thermal stability
Abstract In this study, microcrystalline cellulose (MCC) was extracted from roselle fiber through acid hydrolysis treatment and its properties were compared with those of commercially available MCC. The physicochemical and morphological characteristics, elemental composition, size distribution, crystallinity and thermal properties of the obtained MCC were analyzed in this work. Fourier transform infrared spectroscopy (FTIR) analysis provided clear evidence that the characteristic peak of lignin was absent in the spectrum of the MCC prepared from roselle fiber. Rough surface and slight aggregation of MCC were observed by scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) analysis showed that pure MCC with small quantities of residues and impurities was obtained, with a similar elemental composition to that of commercial MCC. A mean diameter of approximately 44.28 µm was measured for MCC by using a particle size analyzer (PSA). X-ray diffraction (XRD) showed the crystallinity increased from 63% in roselle pulp to 78% in roselle MCC, the latter having a slightly higher crystallinity than that of commercial MCC (74%). TGA and DSC results indicated that the roselle MCC had better thermal stability than the roselle pulp, whereas it had poorer thermal stability in comparison with commercial MCC. Thus, the isolated MCC from roselle fibers will be going to use as reinforcing element in green composites and may be a precursor for future roselle derived nanocellulose, and thus a promising subject in nanocomposite research.
Keywords: Roselle fiber; Microcrystalline cellulose; Fourier transform infrared spectroscopy; Scanning electron microscopy; Thermal properties.
1. Introduction Cellulose is a sustainable, abundant and naturally occurring biopolymer derived from biomass [1]. It is a classic example of a renewable and biodegradable structural plant polymer, which can be processed into elementary fibrils [2, 3]. The high mechanical strength and good thermal resistance properties of cellulose, as well as its low cost, which is due to its availability and abundance in nature, make it an excellent bio-filler for polymer matrixes [4]. It can be extracted from natural fibers, such as roselle, cotton, wood, sisal, flax, hemp, jute, ramie, oil palm, kenaf and coir [5]. Roselle is abundantly cultivated in tropical areas, such as Malaysia, Borneo, Indonesia, India, Tanzania, Thailand, Sri Lanka, Sudan, Tanzania, Togo and Guyana [5]. It can be grown to attain a mature height of 2 to 2.5m [6]. The fiber composition of the roselle plant comprises 58.6364.50% cellulose, 16.27-20.82% hemicellulose and 6.21-10.26% lignin [5]. The fruit of roselle is usually employed for applications in food and biomedical industries, while its underutilized stem could be used for the production of bio-based composites. The isolation of roselle fiber can be conducted by retting the plant in water [7]. Roselle fiber belongs to the category of bast fiber, as it has a characteristic lumen structure. Roselle fiber is a potential bio-filler for composites reinforcement. In Malaysia, the roselle plant is harvested annually for its fruit and the remaining parts, such as the stem, are disposed of as agricultural waste [5, 8]. The application of green composites can contribute to the environmental conservation efforts by decreasing waste disposal, reducing dependence on nonrenewable resources and maintaining the carbon dioxide
balance in nature [9, 10]. Chauhan and Kaith [11] made an attempt to develop a phenolformaldehyde composite reinforced with grafted roselle fiber, while Krishnan and Athijayamani [12] reported having obtained a vinyl ester resin composite reinforced with roselle fiber and coconut shell particulates. Roselle composites are eco-friendly natural polymers, which can be degraded by nature [5]. In recent years, the development of nanosized particles from renewable resources as reinforcing materials in nanocomposites has attracted the researchers’ interest due to the low density, high thermal stability, high tensile strength, biocompatibility and biodegradability of natural fibers [13, 14]. The biodegradability of a nanocomposite can be obtained by utilizing both polymeric materials and reinforcing agents derived from renewable resources [15, 16]. Microcrystalline cellulose is a promising natural material extracted from native cellulose and it has been discerned as a potential starting material to develop nanocomposites or polymer composites [17-19]. Microcrystalline cellulose reinforced composites are environmentally friendly materials that can be widely applied in construction, aerospace, food, pharmaceutical and packaging industries [1, 20]. Microcrystalline cellulose (MCC) is acknowledged as a partially hydrolyzed and depolymerized cellulose, which still consists of disordered amorphous regions [21, 22]. The structure and features of MCC vary with the origin of cellulose and the hydrolysis conditions applied, such as temperature, duration and acids concentration [23]. Different methods have been investigated to extract MCC from natural fiber. Haafiz et al. [18] obtained MCC from oil palm empty fruit bunch pulp, using acid hydrolysis reaction with 2.5 N hydrochloric acid. In addition, Loo et al. [24] isolated MCC from oil palm empty fruit bunch, using bleaching with 0.7% (w/v) sodium chlorite and alkali treatment with 17.5% (w/v) sodium hydroxide, followed by acid hydrolysis
with 55% (w/w) sulphuric acid. Besides, Trache et al. [25] have reported the isolation of MCC by employing 1 mol/L sodium hydroxide, 40 wt% sodium hypochlorite and, finally, 2.5 mol/L hydrochloric acid. Furthermore, the extraction of MCC from fodder grass has been conducted by Kalita et al. [26], utilizing 4% sodium hydroxide, followed by bleaching using a 1:1 ratio of sodium hypochlorite and hydrogen peroxide for pretreatment processes. Moreover, Merci et al. [27] have studied the isolation of MCC from soybean hulls by employing sodium hydroxide and sulphuric acid assisted with reactive extrusion. Commercially produced MCC of different grades is extracted from wood and cotton using dilute mineral acids [23]. To the best of our knowledge, there is lack of research on the isolation and characterization of MCC from roselle fiber. In this paper, the isolation of MCC from roselle fibers was conducted using the acid hydrolysis method. The prepared MCC was characterized as to its physicochemical and morphological properties, as well as its elemental composition, size distribution, crystallinity and thermal properties. Also, a comparison was made between the obtained roselle microcrystalline cellulose and commercial microcrystalline cellulose.
2. Materials and methods 2.1. Materials and chemicals Roselle plant stems were collected from Mersing in Johor, Malaysia. The roselle fiber was obtained after extraction by the water retting technique, as described by Razali et al. [5]. The fiber was further washed with tap water to remove impurities and dried in an oven at 60 °C for 24 h. The dried roselle fiber was ground and sieved to an average particle size of approximately 10 mm. Sodium hydroxide, acetic acid, sodium hypochlorite and hydrochloric acid were
purchased from Evergreen, Malaysia. Commercial microcrystalline cellulose (R&M Chemicals, United Kingdom) supplied by Evergreen, Malaysia, was used as reference in the experimental work for comparison.
2.2. Microcrystalline cellulose preparation Bleaching treatment was conducted with a 10.0% (w/v) sodium hypochlorite (NaCIO) solution for 1 h at 70–80°C. A ratio of fiber to NaClO of 1:60 (g/ml−1) was used and the solution was acidified with acetic acid until pH 4 was reached. The bleached fiber was filtered and washed with distilled water. The process was repeated twice to obtain a white-yellowish colour of the fiber. The bleached fiber was then dried in an oven at 60C for 24 h. Then, the bleached fiber was treated with an 8.0% (w/v) sodium hydroxide (NaOH) solution for 30 min at room temperature at a fiber to NaOH solution ratio of 1:50 (g/ml−1). The alkali treated bleached pulp was filtrated, washed and dried in an oven at 60C for 24 h. After that, the pulp thus obtained (denoted as R-pulp) was hydrolyzed with 2.5 mol/L hydrochloric acid at 85°C for 30 min [23, 28] with a solid to liquor ratio of 1:30 (g/ml−1). Hydrolysis was conducted under agitation at constant stirring speed. The hydrolysis product was cooled at ambient temperature. Filtration and washing were then conducted with distilled water until pH 7 was reached. The obtained MCC was dried in a vacuum oven at 70–80°C for 5 h to constant weight. The denotations of samples are shown in Table 1.
Table 1. Denotations of samples
2.3. Characterization
2.3.1. Fourier transform infrared spectroscopy Fourier transform infrared spectroscopy (FT-IR) was performed using a Perkin Elmer 1600 Infrared spectrometer to conduct 32 scans in the wavenumber range of 650–4000 cm−1 with 4 cm−1 resolution, for each sample. The positions of significant transmittance peaks at a particular wavenumber were tracked by using Nicolet software.
2.3.2. Morphological, elemental and particle size analysis The morphology of the samples was observed using a Hitachi S-3400N scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX) under an accelerating voltage of 15 kV. The samples were gold sputtered before observation to avoid the charging effect. The elemental composition of the samples was identified by EDX diffraction. The particle size analysis of the samples was carried out by using a Malvern Mastersizer 2000 particle size analyzer.
2.3.3. X-ray diffraction The crystallinity of the samples was determined with a SIEMENS D5000 X-ray diffractometer (XRD) using Ni-filtered Cu Kα radiation at an angular incidence of 5° to 40° (2θ angle range). The crystallinity index (Crl) of the samples was calculated using the diffraction peak height intensity method, as provided in Eq. (1): CrI (%) =
𝐼002 −𝐼𝑎𝑚 𝐼002
(1)
Where, I002 is the peak intensity corresponding to the crystalline domain at about 2θ = 19.0° and Iam is the peak intensity corresponding to the amorphous domain at about 2θ = 22.6°.
2.3.4. Thermal analysis The thermal stability of the samples was characterized using a TA Instruments Q500 thermogravimetric analyzer, TGA. About 6 mg of sample was scanned from 30°C to 900°C at a heating rate of 20°C min−1 under a nitrogen gas atmosphere. DSC thermograms were recorded using a TA Instruments Q20 differential scanning calorimeter under nitrogen purge at a heating rate of 10 °C/min. Approximately 10 mg of dry sample was heated at 10 °C/min in nitrogen flux from room temperature to 350 °C.
3. Results and discussion 3.1. Infrared spectroscopy analysis Fig. 1 shows the FTIR spectra of R-pulp, R-MCC and C-MCC. All samples displayed similar spectra, which indicated that the extraction process did not modify the chemical composition of the samples. In addition, the spectra revealed similarities in functional groups. Two prominent absorbance regions in the wavenumber ranges from 2800 cm-1 to 3500 cm-1 and from 500 cm-1 to 1700 cm-1 are remarked in the spectra of all samples. The wide absorbance band appearing in the range from 3300 cm-1 to 3500 cm-1 in the spectra of R-pulp, R-MCC and C-MCC is assigned to the stretching of –OH groups. The decrease in the broadening of this band from the spectrum of R-pulp to that of R-MCC implies various free –OH group amounts, which were affected by the hydrolysis and scission of the cellulose chains [29]. The bands located in the range from 2800 cm-1 to 2900 cm-1 (C-H stretching) are attributed to the crystalline order of cellulose [18, 26]. The
absorption peaks at 1632 cm-1 and 1640 cm-1 correspond to the occurrence of water absorption as a result of the presence of strong cellulose-water interaction [30]. Furthermore, the absorption bands located at 1739 cm-1 and 1740 cm-1 are related to the acetyl or uronic ester groups in hemicellulose [31]. The increase in the intensity of this band from the spectrum of R-pulp to that of R-MCC was likely due to hemicellulose traces remaining after the hydrochloric acid hydrolysis process. However, the R-MCC spectrum shows lower peak intensity when compared with the C-MCC spectrum, which indicates a lower residual hemicellulose content in R-MCC. The absorption peaks at 1430 cm-1 and 1431 cm-1 correspond to CH2 bending vibration. These peaks are associated with the crystallinity of the samples. The R-MCC sample shows a higher degree of crystallinity, with its sharper peak intensity than that of C-MCC, through alteration of the crystalline organization from R-pulp [26]. The bands located in the region from 1509 cm-1 to 1609 cm-1 represent lignin features. This region is attributed to the C=C stretching of aromatic skeletal vibrations in lignin. The reduction of the band intensity from the spectrum of R-pulp to that of R-MCC indicates the removal of the residual quantity of lignin due to the disruption of linkage between lignin and cellulose by the acid hydrolysis reaction [32, 33]. The peaks located at 1368 cm-1 and 1369 cm-1 are related to C-H asymmetric deformations. In addition, the peaks observed at 1058 cm-1, 1157 cm-1 and 1159 cm-1 are assigned to the C-O-C pyranose ring skeletal vibration, while the peak located at 895 cm-1 is related to the β-glycosidic linkage vibration, which is noticeable in the R-pulp, R-MCC and CMCC samples. These peaks are associated with the typical characteristics of pure MCC [34, 35].
3.2. Morphology, elements and particle size analysis
Scanning electron micrographs of R-pulp, R-MCC and C-MCC are presented in Fig. 2(a-c). Rpulp shows individualized fibers with regular shape. This is explained by the dissolution of the plant’s components in the fiber bundles during bleaching and alkaline treatments, which led to separation into individual fibrous strands [24, 36]. Meanwhile, the surface of R-pulp was observed to be clear and smooth. This was probably caused by the partial removal of lignin and hemicellulose [18, 27]. In comparison with R-pulp, R-MCC demonstrates altered and nonuniform shape of micro-sized fibrils with rougher surface. This is attributed to the disintegration in the structure of fibrous strands into smaller size microcrystallites during exposure to the HCl treatment, which hydrolytically cleaved the glycosidic bonds of cellulose [29, 37]. According to similar morphological topographies reported in previous studies [18, 25], the rough surface of MCC is affected by the acid hydrolysis, which is favourable for the isolation of nanocrystals. From the observations, R-MCC also revealed a less aggregated and narrower microstructure compared to C-MCC, which exhibited a more disrupted, cracked and aggregated microstructure. This was probably caused by differences in cellulose materials and chemical treatment conditions [38]. The long microfibrillar structure of R-MCC with a presumably high aspect ratio makes it suitable to be used in the production of high tensile strength biocomposite products. The EDX spectra for all samples are presented in Fig. 3. As expected, all EDX spectra exhibit the peaks for carbon and oxygen as the major elements in their compositions, which correlate with the typical characteristics of cellulose [39]. The carbon percentage for R-pulp and R-MCC is 41.96% and 32.15%, respectively (Table 2), whereas the oxygen percentage for R-pulp and RMCC is 58.04% and 67.85%, respectively. It is easy to notice that the oxygen peak for R-MCC becomes more intense after the chemical treatment applied to R-pulp. This was assigned to the delignification process, which exposes the highly purified cellulose filaments with less silica
impurities and lower phosphorus contents [33, 40]. Sodium and chlorine elements could be slightly detected following the chemical treatment processes. Similar spectra have been reported by Kumar et al. [41] during the preparation of cellulose nanocrystals from sugarcane bagasse. In addition, similar values of carbon and oxygen percentages for both R-MCC and C-MCC are observed. This implies identical elemental compositions of R-MCC and C-MCC.
The particle size distribution of the samples is shown in Fig. 4. The results indicate that the volume weighted mean diameters of R-pulp, R-MCC and C-MCC are 231.25 µm, 44.28 µm and 277.27 µm, respectively (Table 2). The particle size of R-pulp was reduced after the vulnerable amorphous region of long cellulose fibrils was hydrolyzed by acid disintegration to generate shorter R-MCC particles [37, 42]. Unsymmetrical broad size distribution can be observed for Rpulp and R-MCC. This might be explained by the influence of the chemical treatment, which led to different effects in size reduction [19].
3.3. X-ray diffraction analysis The XRD patterns of R-pulp, R-MCC and C-MCC are presented in Fig. 5 and the crystallinity index is tabulated in Table 3. All X-ray diffraction spectra show three main reflections at 2θ = 15.8°, 22.6° and 34.5°. The R-pulp and R-MCC spectra display doublet crystalline peaks at around 2θ = 22.6°. This was assigned to the presence of cellulose I and cellulose II polymorphs [43]. The characteristic transformation of the native cellulose lattice from cellulose I to cellulose II was achieved by the exposure of the cellulose to a high concentration of the NaOH solution [1]. Cellulose II is characterized by stronger hydrophobic interaction, which contributes to its more
stable crystalline form, as compared to that of cellulose I [37]. Similar results have been reported by Azubuike and Okhamafe [44], who employed a 17.5% w/v NaOH solution to treat corn cob cellulose. The diffraction peak located at 22.6° becomes sharper for R-MCC, which indicates higher crystallinity in the structure of R-MCC than in that of R-pulp. The crystallinity value of R-pulp is 63%, while that of R-MCC has been found to be 78%. This can be assigned to the penetration of hydronium ions from HCI into the amorphous region of the cellulose, followed by the hydrolytic fragmentation of glycosyl units, which produced the highly ordered crystallites [24, 37]. In addition, the pre-hydrolysis of biomass with mineral acids helped in further elimination of residual lignin, which also led to an increase in crystallinity, owing to the increase in the intra- and intermolecular hydrogen bonding [25, 26, 38]. The crystallinity value of R-MCC is comparable with that of C-MCC (74% crystallinity index). The crystallinity of cellulose is associated with its structural rigidity, which contributes to a high structural integrity of MCC and to high mechanical properties of the final composites [43, 45, 46]. The MCC isolated from roselle fiber in this study had a higher crystallinity degree than the MCC obtained from jute by Jahan et al. [45], which exhibited a crystallinity index of 75%. This work also achieved higher crystallinity MCC in comparison with that of Merci et al. [27], where the extraction of 70% crystallinity MCC from soybean hulls by reactive extrusion was reported. 3.4. Thermal properties The thermal and degradation properties of MCC are critical for its use in the production of biocomposites designed for high temperature applications [2, 45]. The thermogravimetric analysis (TGA) and derivative thermogram (DTG) curves for R-pulp, R-MCC and C-MCC are shown in Fig. 6 and Fig. 7. Table 4 tabulates the thermal analysis data for R-pulp, R-MCC and C-MCC samples. As may be noted, all samples present two-stage thermal degradation patterns.
The first stage, in the range of 60-150°C, is indicative of initial weight loss as a result of the evaporation of water and other volatile compounds within the samples [27, 47, 48]. Cellulose decomposition in R-pulp begins at 298.14°C, while in R-MCC it begins at 315.43°C. R-MCC also presents higher degradation temperature at 10% weight loss, compared to R-pulp. This is attributed to the high degree of molecular ordering of R-MCC, which requires high heat energy for thermal degradation [33]. The degradation peak temperature of R-MCC occurs at 340.12°C and in R-pulp it is noted at 335.15°C. The degradation of cellulosic components starts at 150°C and lasts up to 380°C, when the decarboxylation, depolymerization and decomposition occur in cellulose and hemicellulose fragments. Biomass is subjected to aromatization, decomposition, combustion, lignin pyrolysis and char residue formation beyond the temperature of 380°C [45, 48, 49]. R-MCC demonstrated comparable thermal stability with that of C-MCC in terms of onset decomposition temperature and degradation peak temperature, which might be affected by the different crystal size [50]. The maximum weight loss for R-pulp occurred at a lower temperature than the maximum weight loss for R-MCC. This is indicative of the high purity of the cellulose in R-MCC [25, 43]. Meanwhile, the char residue weight for R-pulp is 12.57%, which is higher than that for R-MCC (8.48%). The high residual weight of R-pulp was likely due to the char formation from flame retardant compounds [5, 51]. The onset degradation temperature of R-MCC (315°C) and its DTG peak temperature (340°C) are greater than those of MCC extracted from oil palm empty fruit bunch, as reported by Haafiz et al. [18], which presented an onset degradation temperature of 275°C and a DTG peak temperature of 326°C. Thus, the obtained R-MCC has good thermal stability, which is comparable to that of MCC obtained from cotton (305°C) and from Halocynthia (325°C), in the investigation by Kim et al. [50].
The DSC thermogram is shown in Fig. 8. The endothermic peaks appearing from 30°C to 150°C are related to the evaporation of the absorbed moisture content [48, 52]. In a close inspection of the DSC curves between 30°C and 150°C, it is interesting to note that R-MCC displays a pronounced peak at 137.55°C, whereas R-pulp displays two prominent peaks at 140.63°C and 146.97°C. This difference can be explained by the prevalence of non-substituted hydroxyl groups in R-pulp binding more water molecules with strong affinity, which required a larger amount of heat energy to evaporate its bound water content as compared to R-MCC, which was less hygroscopic and exhibited smaller water holding capacity [53]. Moreover, the ΔH for R-pulp is 111.20 J/g at 173.89°C, which is higher than that of R-MCC with 84.01 J/g at 182.06°C (Table 4). This was due to the predominant amorphous regions in R-pulp, which made the cellulose more susceptible to initial thermal degradation, when compared with R-MCC, which was more thermally stable [48]. On the other hand, C-MCC shows two pronounced peaks at 139.18°C and 150.62°C, while the ΔH of the endotherm at 184.80°C is 69.62 J/g. This might be due to a distortion of the water-cellulose interaction, as well as to the asymmetric thermal absorption determined by the aggregated structure and non-uniform size distribution of C-MCC [53, 54]. The thermal decompositions found on the DSC thermograms for all samples have the same trend as those on the TGA thermograms. As discussed earlier regarding TGA analysis, the DSC curves for all samples demonstrate endothermic peaks above 200°C, when cellulose volatilization and char formation occur [55]. C-MCC presents its thermal depolymerization at 332.90°C, as a consequence of its larger size, which requires more heat energy absorption for cellulose degradation, in comparison with R-MCC [25, 50]. The DSC curve for R-pulp exhibits a less significant shoulder peak at 293.84°C, which presents dehydration of cellulose, and a large peak at 309.36°C, which presents the depolymerization of cellulose [25, 56]. Both of these
endothermic peaks indicated double thermal decomposition occurring in R-pulp due to the noncellulosic fragments that prevented the degradation of cellulose [57, 58]. An insignificant endothermic peak is noted for R-MCC thermal decomposition at 307.85°C. This can be likely attributed to the pure crystalline structure of R-MCC, which contained less amorphous phase [48, 58]. 4. Conclusions The findings of the present study have revealed that the roselle fiber could be utilized as alternative biomass for the extraction of MCC by using integrated processes of bleaching, alkaline and acid disintegration. FTIR spectra indicated that the chemical structure of cellulosic components had not been changed and a substantial amount of lignin was effectively removed from roselle fiber during chemical treatments. The morphological analysis by SEM indicated that a rougher and less bulky structure of R-MCC was obtained after the acid hydrolysis of R-pulp. The prepared R-MCC also displayed a high crystallinity index, of 78%, which endorses its suitability for application as a load-bearing material in composite structures. Based on the TGA and DSC analyses, R-MCC was found to exhibit great thermal stability, which suggests that it could withstand high temperature in polymeric composites applications. The MCC developed in this research going to utilize for extraction of Cellulose Nanocrystals (CNC) and further CNC/Polylactic acid based nanocomposites for different applications.
Acknowledgements The authors are grateful for the financial support from Universiti Putra Malaysia through Putra grant no. GP-IPS/2017/9519000. The authors also extend their appreciation to the International
Scientific Partnership Program ISPP at King Saud University for funding this research through ISPP#0011.
References [1] M. Zeni, D. Favero, K. Pacheco, A. Grisa, Preparation of microcellulose (mcc) and nanocellulose (ncc) from Eucalyptus Kraft ssp pulp, Polymer Sciences 1 (2015) 1-7. [2] A. Ferrer, C. Salas, O.J. Rojas, Physical thermal, chemical and rheological characterization of cellulosic microfibrils and microparticles produced from soybean hulls, Industrial Crops and Products 84 (2016) 337–343. [3] Y. Habibi, L.A. Lucia, O.J. Rojas, Cellulose nanocrystals: chemistry, selfassembly, and applications, Chemical Reviews 110 (6) (2010) 3479–3500. [4] S. Shankar, J.W. Rhim, Preparation of nanocellulose from micro-crystalline cellulose: the effect on the performance and properties of agar-based compositefilms, Carbohydrate Polymers 135 (2016) 18–26. [5] N. Razali, S.M. Sapuan, M. Jawaid, M.R. Ishak, L. Yusriah, A study on chemical composition, physical, tensile, morphological, and thermal properties roselle fibre: effect of fibre maturity, Bioresources 10 (1) (2015) 1803-1824. [6] D. Chandramohan, K. Marimuthu, Characterization of natural fibers and their application in bone grafting substitutes, Acta of Bioengineering and Biomechanics 13 (1) (2011) 77–84. [7] M. Thiruchitrambalam, A. Athijayamani, S. Sathiyamurthy, A review on the natural fiberReinforced polymer composites for the development of roselle fiber reinforced polyester composite, Journal of Natural Fibers 7 (2010) 307–323.
[8] A. Athijayamani, M. Thiruchitrambalam, U. Natarajan, B. Pazhanivel, Effect of moisture absorption on the mechanical properties of randomly oriented natural fibers/polyester hybrid composite, Materials Science and Engineering: A 517 (12) (2009) 344–353. [9] D. Maria, S. Garcia, J.M. Lagaron, On the use of plant cellulose nanowhiskers to enhance the barrier properties of polylactic acid, Cellulose 17 (5) (2010) 987-1004. [10] L. Suryanegara, A.N. Nakagaito, H. Yano, The effect of crystallization of PLA on the thermal and mechanical properties of microfibrillated cellulose-reinforced PLA composites, Composites Science and Technology 69 (2009) 1187-1192. [11] A. Chauhan, B. Kaith, Accreditation of novel roselle grafted fiber reinforced bio-composites, Journal of Engineered Fibers and Fabrics 7 (2) (2012). [12] S. Navaneetha krishnan, A. Athijayamani, Mechanical properties and absorption behavior of CSP filled roselle fiber reinforced hybrid composites, Journal of Materials and Environmental Science 7 (5) (2016) 1674-1680. [13] I. Capron, O.J. Rojas, R. Bordes, Behavior of nanocelluloses at interfaces, Current Opinion in Colloid & Interface Science 29 (2017) 83–95. [14] O. Nechyporchuk, M.N. Belgacem, J. Bras, Production of cellulose nanofibrils: a review of recent advances, Industrial Crops and Products 93 (2016) 2–25. [15] P.K. Bajpai, I. Singh, J. Madaan, Development and characterization of PLA-based green composites: a review, Journal of Thermoplastic Composite Materials 31 (2012) 5-8. [16] N. Grishkewich, N. Mohammed, J. Tang, K.C. Tam, Recent advances in the application of cellulose nanocrystals, Current Opinion in Colloid & Interface Science 29 (2017) 32–45.
[17] D. Bandera, J. Sapkota, S. Josset, C. Weder, P. Tingaut, X. Gao, E.J. Foster, T. Zimmermann, Influence of mechanical treatments on the properties of cellulose nanofibers isolated from microcrystalline cellulose, Reactive and Functional Polymers 85 (2014) 134–141. [18] M.K.M. Haafiz, S.J. Eichhorn, A. Hassan, M. Jawaid, Isolation and characterization of microcrystalline cellulose from oil palm biomass residue, Carbohydrate Polymers 93 (2) (2013) 628–634. [19] R. Salminen, M. Reza, T. Paakkonen, J. Peyre, E. Kontturi, TEMPO-mediated oxidation of microcrystalline cellulose: limiting factors for cellulose nanocrystal yield, Cellulose 24 (2017) 1657–1667. [20] T.R. Anju, K. Ramamurthy, R. Dhamodharan, Surface modified microcrystalline cellulose from cotton as a potential mineral admixture in cement mortar composite, Cement and Concrete Composites, 74 (2016) 147-153. [21] R. Husgafvel, K. Vanhatalo, L.R. Chiang, L. Linkosalmi, O. Dahl, Comparative global warming potential assessment of eight microcrystalline cellulose manufacturing systems, Journal of Cleaner Production 126 (2016) 620-629. [22] G. Thoorens, F. Krier, B. Leclercq, B. Carlin, B. Evrard, Microcrystalline cellulose, a direct compression binder in a quality by design environment-A review, International Journal of Pharmaceutics 473 (12) (2014) 64–72. [23] S. Chuayjuljit, S. Su-uthai, S. Charuchinda, Poly(vinyl chloride) film filled with microcrystalline cellulose prepared from cotton fabric waste: properties and biodegradability study, Waste Management & Research 28 (2010) 109–117. [24] Y.X. Loo, M. Afandi, P. Mohammed, A.S. Baharuddin, Characterisation of microcrystalline cellulose from oil palm fibres for food applications, Carbohydrate Polymers 148 (2016) 11–20.
[25] D. Trache, A. Donnot, K. Khimeche, R. Benelmir, N. Brosse, Physico-chemical properties and thermal stability of microcrystalline cellulose isolated from Alfa fibers, Carbohydrate Polymers 104 (2014) 223–230. [26] R.D. Kalita, Y. Nath, M.E. Ochubiojo, A.K. Buragohain, Extraction and characterization of microcrystalline cellulose from fodder grass; Setaria glauca (L) P. Beauv, and its potential as a drug delivery vehicle for isoniazid, a first line antituberculosis drug, Colloids and Surfaces B: Biointerfaces 108 (2013) 85–89. [27] A. Merci, A. Urbano, M.V.E. Grossmann, C.A. Tischer, S. Mali, Properties of microcrystalline cellulose extracted from soybean hulls by reactive extrusion, Food Research International 73 (2015) 38–43. [28] P.Y. Chauchan, R.S. Sapkal, V.S. Sapkal, G.S. Zamre, Microcrystalline cellulose from cotton rags (waste from garment and hosiery industries), International Journal of Chemical Sciences 7 (2009) 681–688. [29] S. Elanthikkal, U. Gopalakrishnapanicker, S. Varghese, J.T. Guthrie, Cellulose microfibres produced from banana plant wastes: isolation and characterization, Carbohydrate Polymers 80 (2010) 852–859. [30] E. Abraham, B. Deepa, L.A. Pothan, M. Jacob, S. Thomas, U. Cvelbar, R. Anandjiwala, Extraction of nanocellulose fibrils from lignocellulosic fibres: a novel approach, Carbohydrate Polymers 86 (2011) 1468–1475.
[31] M. Nuruddin, A. Chowdhury, S.A. Haque, M. Rahman, S.F. Farhad, M. S. Jahan, Extraction and characterization of cellulose microfibrils from agricultural wastes in an integrated biorefinery initiative, Cellulose Chemical and Technology 45 (2011) 347–354. [32] H. Nadji, P.N. Diouf, A. Benaboura, Y. Bedard, B. Riedl, Comparative study of lignins isolated from Alfa grass (Stipa tenacissima L.), Bioresource Technology 100 (2009) 3585–3592. [33] D. Trache, M.H. Hussin, C.T.H. Chuin, S. Sabar, M.R.N. Fazita, O.F.A. Taiwo, T.M. Hassan, M.K.M. Haafiz, Microcrystalline cellulose: isolation, characterization and biocomposites application – A review, International Journal of Biological Macromolecules 93 (2016) 789–804. [34] A. Alemdar, M. Sain, Isolation and characterization of nanofibers from agricultural residues-wheat strawand soy hulls, Bioresource Technology 99 (2008) 1664–1671. [35] D. Ciolacu, F. Ciolacu, V.I. Popa, Amorphous cellulose — Structure and characterization, Celullose Chemistry and Technology 45 (2011) 13–21. [36] N. Johar, I. Ahmad, A. Dufresne, Extraction, preparation and characterization of cellulose fibres and nanocrystals from rice husk, Industrial Crops and Products 37 (2012) 93–99. [37] A.F. Owolabi, M.K.M. Haafiz, Md.S. Hossain, M.H. Hussin, M.R.N. Fazita, Influence of alkaline hydrogen peroxide pre-hydrolysis on the isolation of microcrystalline cellulose from oil palm fronds, International Journal of Biological Macromolecules, 95 (2017) 1228–1234. [38] A.M. Adel, Z.H.A. El-Wahab, A.A. Ibrahim, M. Al-Shemy, Characterization of microcrystalline cellulose prepared form lignocellulisic material. Part I. Acid catalyzed hydrolysis, Bioresource Technology 101 (2010) 4446–4455.
[39] V.N. Krishnan, A. Ramesh, Synthesis and characterization of cellulose nanofibers from coconut coir fibers, Journal of Applied Chemistry 6 (3) (2013) 18-23. [40] M.R.K. Sofla, R.J. Brown, T. Tsuzuki, T.J. Rainey, A comparison of cellulose nanocrystals and cellulose nanofibres extracted from bagasse using acid and ball milling methods, Journal of Nanoscience and Nanotechnology 7 (2016) 1-9. [41] A. Kumar, Y.S. Negi, V. Choudhary, N.K. Bhardwaj, Characterization of Cellulose Nanocrystals Produced by Acid-Hydrolysis from Sugarcane Bagasse as Agro-Waste, Journal of Materials Physics and Chemistry 2 (1) (2014) 1-8. [42] W.T. Wulandari, A. Rochliadi, I.M. Arcana, Nanocellulose prepared by acid hydrolysis of isolated cellulose from sugarcane bagasse, Materials Science and Engineering, 107 (2016). [43] M.H. Hussin, N.A. Pohan, Z.N. Garba, M.J. Kassim, A.A. Rahim, N. Brosse, M. Yemloul, M.R.N. Fazita, M.K.M. Haafiz, Physicochemical of microcrystalline cellulose from oil palm fronds as potential methylene blue adsorbents, International Journal of Biological Macromolecules 92 (2016) 11–19. [44] C.P. Azubuike, A.O. Okhamafe, Physicochemical, spectroscopic and thermal properties of microcrystalline cellulose derived from corn cobs, International Journal of Recycling of Organic Waste in Agriculture 1(1) (2012) 9. [45] M.S. Jahan, A. Saeed, Z. He, Y. Ni, Jute as raw material for the preparation of microcrystalline cellulose, Cellulose 18 (2011) 451–459.
[46] S.M.L. Rosa, N. Rehman, M.I.G. De Miranda, S.M.B. Nachtigall, C.I.D. Bica, Chlorine-free extraction of cellulose from rice husk and whisker isolation, Carbohydrate Polymers 87 (2012) 1131–1138. [47] M. Chowdhury, M. Beg, M.R. Khan, M. Mina, Modification of oil palm empty fruit bunch fibers by nanoparticle impregnation and alkali treatment, Cellulose 20 (3) (2013) 1477–1490. [48] A. Sonia, K.P. Dasan, Chemical, morphology and thermal evaluation of cellulose microfibers obtained from Hibiscus Sabdariffa, Carbohydrate Polymers 92 (2013) 668– 674. [49] M. Jonoobi, A. Khazaeian, P. Md Tahir, S.S. Azry, K. Oksman, Characteristics of cellulose nanofibers isolated from rubberwood and empty fruit bunches of oil palm using chemomechanical process, Cellulose 18 (2011) 1085–1095. [50] U.J. Kim, S.H. Eom, M. Wada, Thermal decomposition of native cellulose: influence on crystallite size, Polymer Degradation and Stability 95 (2010) 778–781. [51] W.P.F. Neto, H.A. Silverio, N.O. Dantas, D. Pasquini, Extraction and characterization of cellulose nanocrystals from agro-industrial residue – Soy hulls, Industrial Crops and Products 42 (2013) 480–488. [52] P. Lu, Y.L. Hsieh, Cellulose isolation and core–shell nanostructures of cellulose nanocrystals from chardonnay grape skins, Carbohydrate Polymers 87 (2012) 2546–2553. [53] W.D. Wanrosli, R. Rohaizu, A. Ghazali, Synthesis and characterization of cellulose phosphate from oil palm empty fruit bunches microcrystalline cellulose, Carbohydrate Polymers 84 (2011) 262–267.
[54] M. Luddee, S. Pivsa-Art, S. Sirisansaneeyakul, C. Pechyen, Particle size of ground bacterial cellulose affecting mechanical, thermal, and moisture barrier properties of PLA/BC biocomposites, Energy Procedia 56 (2014) 211 – 218. [55] A.L. Sullivan, R. Ball, Thermal decomposition and combustion chemistry of cellulosic biomass, Atmospheric Environment 47 (2012) 133–141. [56] K. Das, D. Ray, N.R. Bandyopadhyay, T. Ghosh, A.K. Mohanty, M. Misra, A study of the mechanical, thermal and morphological properties of microcrystalline cellulose particles prepared from cotton slivers using different acid concentrations, Cellulose, 16 (2009) 783–793. [57] A.M. Adel, N.A. El-Shinnawy, Hypolipidemic applications of microcrystalline cellulose composite synthesized from different agricultural residues, International Journal of Biological Macromolecules 51 (5) (2012) 1091-1102. [58] B.A. Simmons, D. Loque, J. Ralph, Advances in modifying lignin for enhanced biofuel production, Journal of Current Opinion in Plant Biology 13 (2010) 313–320.
Figures and Tables Captions Figures Fig. 1. FTIR spectra of R-Pulp, R-MCC, and C-MCC samples
Fig. 2. SEM micrographs of (a) R-pulp, (b) R-MCC and (c) C-MCC at (i) 100×, (ii) 1000× and (iii) 6000× magnifications.
Fig. 3. Energy-dispersive X-ray diffraction (EDX) spectra of (a) R-pulp, (b) R-MCC and (c) CMCC.
Fig. 4. Particle size distribution of R-Pulp, R-MCC, and C-MCC samples
Fig. 5. X-ray diffactograms of R-Pulp, R-MCC, and C-MCC samples
Fig. 6. TGA curves of R-Pulp, R-MCC, and C-MCC samples
Fig. 7. DTG curves of R-Pulp, R-MCC, and C-MCC samples
Fig. 8. DSC curves of R-Pulp, R-MCC, and C-MCC samples
Table 1. Denotations of samples Samples
Denotations
Alkali treated bleached pulp
R-pulp
Roselle microcrystalline cellulose
R-MCC
Commercial microcrystalline cellulose
C-MCC
Table 2. Elemental and particle size analysis data of R-pulp, R-MCC, and C-MCC Samples
Elemental analysis
Particle size analysis
Carbon (%)
Surface
Volume
weighted mean
weighted mean
diameter (µm)
diameter (µm)
Oxygen (%)
R-pulp
41.96
58.04
28.41
231.25
R-MCC
32.15
67.85
11.53
44.28
C-MCC
33.05
66.95
119.13
277.27
Table 3. XRD analysis data of R-pulp, R-MCC, and C-MCC
a
Samples
CrI (%)a
R-pulp
63
R-MCC
78
C-MCC
74
crystalinity index.
Table 4. Thermal analysis data of R-pulp, R-MCC, and C-MCC Samples
TGA analysis
DSC analysis
Tinitial
T10
Tpeak
Wloss
Wresidue
Tinitial
Tpeak
ΔH
(°C)a
(°C)b
(°C)c
(%)d
(%)e
(°C)f
(°C)g
(J/g)h
R-pulp
298.14
245.06
335.15
78.93
12.57
173.89
293.84 111.20
R-MCC
315.43
269.85
340.12
81.23
8.48
182.06
307.85 84.01
C-MCC
326.08
325.17
344.95
90.32
3.85
184.80
332.90
a
69.62
TGA initial decomposition temperature; b TGA degradation temperature at which 10% weight
loss; c DTG peak temperature; d TGA maximum weight loss; e TGA char residue weight; f DSC initial decomposition temperature; g DSC peak temperature; h Heat of decomposition.
S0141-8130(17)31730-0 http://dx.doi.org/doi:10.1016/j.ijbiomac.2017.05.135 BIOMAC 7624
To appear in:
International Journal of Biological Macromolecules
Received date: Accepted date:
14-5-2017 20-5-2017
Please cite this article as: Lau Kia Kian, Mohammad Jawaid, Hidayah Ariffin, Othman Y.Alothman, Isolation and Characterization of Microcrystalline Cellulose from Roselle Fibers, International Journal of Biological Macromoleculeshttp://dx.doi.org/10.1016/j.ijbiomac.2017.05.135 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Isolation and Characterization of Microcrystalline Cellulose from Roselle Fibers
Lau Kia Kian1, Mohammad Jawaid1*,2, Hidayah Ariffin3, Othman Y Alothman2
1
Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia 2
Department of Chemical Engineering, College of Engineering, King Saud University, Riyadh,
Saudi Arabia 3
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular
Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
*
Corresponding author at: Biocomposite Technology Laboratory, INTROP, Universiti Putra
Malaysia, 43400 UPM Serdang, Selangor, Malaysia. Tel.: +603-89466960; Fax: +603-86471896 E-mail: [email protected] [email protected]
Highlights
Roselle fibre-Microcrystalline cellulose (R-MCC) extracted by chemical process R-MCC demonstrates altered and non-uniform shape of micro-sized fibrils The unsymmetrical broad size distribution can be observed for R-pulp and R-MCC. Crystallinity value of R-MCC (78%) is more than Commercial MCC (74%) Obtained R-MCC also has considerably good thermal stability
Abstract In this study, microcrystalline cellulose (MCC) was extracted from roselle fiber through acid hydrolysis treatment and its properties were compared with those of commercially available MCC. The physicochemical and morphological characteristics, elemental composition, size distribution, crystallinity and thermal properties of the obtained MCC were analyzed in this work. Fourier transform infrared spectroscopy (FTIR) analysis provided clear evidence that the characteristic peak of lignin was absent in the spectrum of the MCC prepared from roselle fiber. Rough surface and slight aggregation of MCC were observed by scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) analysis showed that pure MCC with small quantities of residues and impurities was obtained, with a similar elemental composition to that of commercial MCC. A mean diameter of approximately 44.28 µm was measured for MCC by using a particle size analyzer (PSA). X-ray diffraction (XRD) showed the crystallinity increased from 63% in roselle pulp to 78% in roselle MCC, the latter having a slightly higher crystallinity than that of commercial MCC (74%). TGA and DSC results indicated that the roselle MCC had better thermal stability than the roselle pulp, whereas it had poorer thermal stability in comparison with commercial MCC. Thus, the isolated MCC from roselle fibers will be going to use as reinforcing element in green composites and may be a precursor for future roselle derived nanocellulose, and thus a promising subject in nanocomposite research.
Keywords: Roselle fiber; Microcrystalline cellulose; Fourier transform infrared spectroscopy; Scanning electron microscopy; Thermal properties.
1. Introduction Cellulose is a sustainable, abundant and naturally occurring biopolymer derived from biomass [1]. It is a classic example of a renewable and biodegradable structural plant polymer, which can be processed into elementary fibrils [2, 3]. The high mechanical strength and good thermal resistance properties of cellulose, as well as its low cost, which is due to its availability and abundance in nature, make it an excellent bio-filler for polymer matrixes [4]. It can be extracted from natural fibers, such as roselle, cotton, wood, sisal, flax, hemp, jute, ramie, oil palm, kenaf and coir [5]. Roselle is abundantly cultivated in tropical areas, such as Malaysia, Borneo, Indonesia, India, Tanzania, Thailand, Sri Lanka, Sudan, Tanzania, Togo and Guyana [5]. It can be grown to attain a mature height of 2 to 2.5m [6]. The fiber composition of the roselle plant comprises 58.6364.50% cellulose, 16.27-20.82% hemicellulose and 6.21-10.26% lignin [5]. The fruit of roselle is usually employed for applications in food and biomedical industries, while its underutilized stem could be used for the production of bio-based composites. The isolation of roselle fiber can be conducted by retting the plant in water [7]. Roselle fiber belongs to the category of bast fiber, as it has a characteristic lumen structure. Roselle fiber is a potential bio-filler for composites reinforcement. In Malaysia, the roselle plant is harvested annually for its fruit and the remaining parts, such as the stem, are disposed of as agricultural waste [5, 8]. The application of green composites can contribute to the environmental conservation efforts by decreasing waste disposal, reducing dependence on nonrenewable resources and maintaining the carbon dioxide
balance in nature [9, 10]. Chauhan and Kaith [11] made an attempt to develop a phenolformaldehyde composite reinforced with grafted roselle fiber, while Krishnan and Athijayamani [12] reported having obtained a vinyl ester resin composite reinforced with roselle fiber and coconut shell particulates. Roselle composites are eco-friendly natural polymers, which can be degraded by nature [5]. In recent years, the development of nanosized particles from renewable resources as reinforcing materials in nanocomposites has attracted the researchers’ interest due to the low density, high thermal stability, high tensile strength, biocompatibility and biodegradability of natural fibers [13, 14]. The biodegradability of a nanocomposite can be obtained by utilizing both polymeric materials and reinforcing agents derived from renewable resources [15, 16]. Microcrystalline cellulose is a promising natural material extracted from native cellulose and it has been discerned as a potential starting material to develop nanocomposites or polymer composites [17-19]. Microcrystalline cellulose reinforced composites are environmentally friendly materials that can be widely applied in construction, aerospace, food, pharmaceutical and packaging industries [1, 20]. Microcrystalline cellulose (MCC) is acknowledged as a partially hydrolyzed and depolymerized cellulose, which still consists of disordered amorphous regions [21, 22]. The structure and features of MCC vary with the origin of cellulose and the hydrolysis conditions applied, such as temperature, duration and acids concentration [23]. Different methods have been investigated to extract MCC from natural fiber. Haafiz et al. [18] obtained MCC from oil palm empty fruit bunch pulp, using acid hydrolysis reaction with 2.5 N hydrochloric acid. In addition, Loo et al. [24] isolated MCC from oil palm empty fruit bunch, using bleaching with 0.7% (w/v) sodium chlorite and alkali treatment with 17.5% (w/v) sodium hydroxide, followed by acid hydrolysis
with 55% (w/w) sulphuric acid. Besides, Trache et al. [25] have reported the isolation of MCC by employing 1 mol/L sodium hydroxide, 40 wt% sodium hypochlorite and, finally, 2.5 mol/L hydrochloric acid. Furthermore, the extraction of MCC from fodder grass has been conducted by Kalita et al. [26], utilizing 4% sodium hydroxide, followed by bleaching using a 1:1 ratio of sodium hypochlorite and hydrogen peroxide for pretreatment processes. Moreover, Merci et al. [27] have studied the isolation of MCC from soybean hulls by employing sodium hydroxide and sulphuric acid assisted with reactive extrusion. Commercially produced MCC of different grades is extracted from wood and cotton using dilute mineral acids [23]. To the best of our knowledge, there is lack of research on the isolation and characterization of MCC from roselle fiber. In this paper, the isolation of MCC from roselle fibers was conducted using the acid hydrolysis method. The prepared MCC was characterized as to its physicochemical and morphological properties, as well as its elemental composition, size distribution, crystallinity and thermal properties. Also, a comparison was made between the obtained roselle microcrystalline cellulose and commercial microcrystalline cellulose.
2. Materials and methods 2.1. Materials and chemicals Roselle plant stems were collected from Mersing in Johor, Malaysia. The roselle fiber was obtained after extraction by the water retting technique, as described by Razali et al. [5]. The fiber was further washed with tap water to remove impurities and dried in an oven at 60 °C for 24 h. The dried roselle fiber was ground and sieved to an average particle size of approximately 10 mm. Sodium hydroxide, acetic acid, sodium hypochlorite and hydrochloric acid were
purchased from Evergreen, Malaysia. Commercial microcrystalline cellulose (R&M Chemicals, United Kingdom) supplied by Evergreen, Malaysia, was used as reference in the experimental work for comparison.
2.2. Microcrystalline cellulose preparation Bleaching treatment was conducted with a 10.0% (w/v) sodium hypochlorite (NaCIO) solution for 1 h at 70–80°C. A ratio of fiber to NaClO of 1:60 (g/ml−1) was used and the solution was acidified with acetic acid until pH 4 was reached. The bleached fiber was filtered and washed with distilled water. The process was repeated twice to obtain a white-yellowish colour of the fiber. The bleached fiber was then dried in an oven at 60C for 24 h. Then, the bleached fiber was treated with an 8.0% (w/v) sodium hydroxide (NaOH) solution for 30 min at room temperature at a fiber to NaOH solution ratio of 1:50 (g/ml−1). The alkali treated bleached pulp was filtrated, washed and dried in an oven at 60C for 24 h. After that, the pulp thus obtained (denoted as R-pulp) was hydrolyzed with 2.5 mol/L hydrochloric acid at 85°C for 30 min [23, 28] with a solid to liquor ratio of 1:30 (g/ml−1). Hydrolysis was conducted under agitation at constant stirring speed. The hydrolysis product was cooled at ambient temperature. Filtration and washing were then conducted with distilled water until pH 7 was reached. The obtained MCC was dried in a vacuum oven at 70–80°C for 5 h to constant weight. The denotations of samples are shown in Table 1.
Table 1. Denotations of samples
2.3. Characterization
2.3.1. Fourier transform infrared spectroscopy Fourier transform infrared spectroscopy (FT-IR) was performed using a Perkin Elmer 1600 Infrared spectrometer to conduct 32 scans in the wavenumber range of 650–4000 cm−1 with 4 cm−1 resolution, for each sample. The positions of significant transmittance peaks at a particular wavenumber were tracked by using Nicolet software.
2.3.2. Morphological, elemental and particle size analysis The morphology of the samples was observed using a Hitachi S-3400N scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX) under an accelerating voltage of 15 kV. The samples were gold sputtered before observation to avoid the charging effect. The elemental composition of the samples was identified by EDX diffraction. The particle size analysis of the samples was carried out by using a Malvern Mastersizer 2000 particle size analyzer.
2.3.3. X-ray diffraction The crystallinity of the samples was determined with a SIEMENS D5000 X-ray diffractometer (XRD) using Ni-filtered Cu Kα radiation at an angular incidence of 5° to 40° (2θ angle range). The crystallinity index (Crl) of the samples was calculated using the diffraction peak height intensity method, as provided in Eq. (1): CrI (%) =
𝐼002 −𝐼𝑎𝑚 𝐼002
(1)
Where, I002 is the peak intensity corresponding to the crystalline domain at about 2θ = 19.0° and Iam is the peak intensity corresponding to the amorphous domain at about 2θ = 22.6°.
2.3.4. Thermal analysis The thermal stability of the samples was characterized using a TA Instruments Q500 thermogravimetric analyzer, TGA. About 6 mg of sample was scanned from 30°C to 900°C at a heating rate of 20°C min−1 under a nitrogen gas atmosphere. DSC thermograms were recorded using a TA Instruments Q20 differential scanning calorimeter under nitrogen purge at a heating rate of 10 °C/min. Approximately 10 mg of dry sample was heated at 10 °C/min in nitrogen flux from room temperature to 350 °C.
3. Results and discussion 3.1. Infrared spectroscopy analysis Fig. 1 shows the FTIR spectra of R-pulp, R-MCC and C-MCC. All samples displayed similar spectra, which indicated that the extraction process did not modify the chemical composition of the samples. In addition, the spectra revealed similarities in functional groups. Two prominent absorbance regions in the wavenumber ranges from 2800 cm-1 to 3500 cm-1 and from 500 cm-1 to 1700 cm-1 are remarked in the spectra of all samples. The wide absorbance band appearing in the range from 3300 cm-1 to 3500 cm-1 in the spectra of R-pulp, R-MCC and C-MCC is assigned to the stretching of –OH groups. The decrease in the broadening of this band from the spectrum of R-pulp to that of R-MCC implies various free –OH group amounts, which were affected by the hydrolysis and scission of the cellulose chains [29]. The bands located in the range from 2800 cm-1 to 2900 cm-1 (C-H stretching) are attributed to the crystalline order of cellulose [18, 26]. The
absorption peaks at 1632 cm-1 and 1640 cm-1 correspond to the occurrence of water absorption as a result of the presence of strong cellulose-water interaction [30]. Furthermore, the absorption bands located at 1739 cm-1 and 1740 cm-1 are related to the acetyl or uronic ester groups in hemicellulose [31]. The increase in the intensity of this band from the spectrum of R-pulp to that of R-MCC was likely due to hemicellulose traces remaining after the hydrochloric acid hydrolysis process. However, the R-MCC spectrum shows lower peak intensity when compared with the C-MCC spectrum, which indicates a lower residual hemicellulose content in R-MCC. The absorption peaks at 1430 cm-1 and 1431 cm-1 correspond to CH2 bending vibration. These peaks are associated with the crystallinity of the samples. The R-MCC sample shows a higher degree of crystallinity, with its sharper peak intensity than that of C-MCC, through alteration of the crystalline organization from R-pulp [26]. The bands located in the region from 1509 cm-1 to 1609 cm-1 represent lignin features. This region is attributed to the C=C stretching of aromatic skeletal vibrations in lignin. The reduction of the band intensity from the spectrum of R-pulp to that of R-MCC indicates the removal of the residual quantity of lignin due to the disruption of linkage between lignin and cellulose by the acid hydrolysis reaction [32, 33]. The peaks located at 1368 cm-1 and 1369 cm-1 are related to C-H asymmetric deformations. In addition, the peaks observed at 1058 cm-1, 1157 cm-1 and 1159 cm-1 are assigned to the C-O-C pyranose ring skeletal vibration, while the peak located at 895 cm-1 is related to the β-glycosidic linkage vibration, which is noticeable in the R-pulp, R-MCC and CMCC samples. These peaks are associated with the typical characteristics of pure MCC [34, 35].
3.2. Morphology, elements and particle size analysis
Scanning electron micrographs of R-pulp, R-MCC and C-MCC are presented in Fig. 2(a-c). Rpulp shows individualized fibers with regular shape. This is explained by the dissolution of the plant’s components in the fiber bundles during bleaching and alkaline treatments, which led to separation into individual fibrous strands [24, 36]. Meanwhile, the surface of R-pulp was observed to be clear and smooth. This was probably caused by the partial removal of lignin and hemicellulose [18, 27]. In comparison with R-pulp, R-MCC demonstrates altered and nonuniform shape of micro-sized fibrils with rougher surface. This is attributed to the disintegration in the structure of fibrous strands into smaller size microcrystallites during exposure to the HCl treatment, which hydrolytically cleaved the glycosidic bonds of cellulose [29, 37]. According to similar morphological topographies reported in previous studies [18, 25], the rough surface of MCC is affected by the acid hydrolysis, which is favourable for the isolation of nanocrystals. From the observations, R-MCC also revealed a less aggregated and narrower microstructure compared to C-MCC, which exhibited a more disrupted, cracked and aggregated microstructure. This was probably caused by differences in cellulose materials and chemical treatment conditions [38]. The long microfibrillar structure of R-MCC with a presumably high aspect ratio makes it suitable to be used in the production of high tensile strength biocomposite products. The EDX spectra for all samples are presented in Fig. 3. As expected, all EDX spectra exhibit the peaks for carbon and oxygen as the major elements in their compositions, which correlate with the typical characteristics of cellulose [39]. The carbon percentage for R-pulp and R-MCC is 41.96% and 32.15%, respectively (Table 2), whereas the oxygen percentage for R-pulp and RMCC is 58.04% and 67.85%, respectively. It is easy to notice that the oxygen peak for R-MCC becomes more intense after the chemical treatment applied to R-pulp. This was assigned to the delignification process, which exposes the highly purified cellulose filaments with less silica
impurities and lower phosphorus contents [33, 40]. Sodium and chlorine elements could be slightly detected following the chemical treatment processes. Similar spectra have been reported by Kumar et al. [41] during the preparation of cellulose nanocrystals from sugarcane bagasse. In addition, similar values of carbon and oxygen percentages for both R-MCC and C-MCC are observed. This implies identical elemental compositions of R-MCC and C-MCC.
The particle size distribution of the samples is shown in Fig. 4. The results indicate that the volume weighted mean diameters of R-pulp, R-MCC and C-MCC are 231.25 µm, 44.28 µm and 277.27 µm, respectively (Table 2). The particle size of R-pulp was reduced after the vulnerable amorphous region of long cellulose fibrils was hydrolyzed by acid disintegration to generate shorter R-MCC particles [37, 42]. Unsymmetrical broad size distribution can be observed for Rpulp and R-MCC. This might be explained by the influence of the chemical treatment, which led to different effects in size reduction [19].
3.3. X-ray diffraction analysis The XRD patterns of R-pulp, R-MCC and C-MCC are presented in Fig. 5 and the crystallinity index is tabulated in Table 3. All X-ray diffraction spectra show three main reflections at 2θ = 15.8°, 22.6° and 34.5°. The R-pulp and R-MCC spectra display doublet crystalline peaks at around 2θ = 22.6°. This was assigned to the presence of cellulose I and cellulose II polymorphs [43]. The characteristic transformation of the native cellulose lattice from cellulose I to cellulose II was achieved by the exposure of the cellulose to a high concentration of the NaOH solution [1]. Cellulose II is characterized by stronger hydrophobic interaction, which contributes to its more
stable crystalline form, as compared to that of cellulose I [37]. Similar results have been reported by Azubuike and Okhamafe [44], who employed a 17.5% w/v NaOH solution to treat corn cob cellulose. The diffraction peak located at 22.6° becomes sharper for R-MCC, which indicates higher crystallinity in the structure of R-MCC than in that of R-pulp. The crystallinity value of R-pulp is 63%, while that of R-MCC has been found to be 78%. This can be assigned to the penetration of hydronium ions from HCI into the amorphous region of the cellulose, followed by the hydrolytic fragmentation of glycosyl units, which produced the highly ordered crystallites [24, 37]. In addition, the pre-hydrolysis of biomass with mineral acids helped in further elimination of residual lignin, which also led to an increase in crystallinity, owing to the increase in the intra- and intermolecular hydrogen bonding [25, 26, 38]. The crystallinity value of R-MCC is comparable with that of C-MCC (74% crystallinity index). The crystallinity of cellulose is associated with its structural rigidity, which contributes to a high structural integrity of MCC and to high mechanical properties of the final composites [43, 45, 46]. The MCC isolated from roselle fiber in this study had a higher crystallinity degree than the MCC obtained from jute by Jahan et al. [45], which exhibited a crystallinity index of 75%. This work also achieved higher crystallinity MCC in comparison with that of Merci et al. [27], where the extraction of 70% crystallinity MCC from soybean hulls by reactive extrusion was reported. 3.4. Thermal properties The thermal and degradation properties of MCC are critical for its use in the production of biocomposites designed for high temperature applications [2, 45]. The thermogravimetric analysis (TGA) and derivative thermogram (DTG) curves for R-pulp, R-MCC and C-MCC are shown in Fig. 6 and Fig. 7. Table 4 tabulates the thermal analysis data for R-pulp, R-MCC and C-MCC samples. As may be noted, all samples present two-stage thermal degradation patterns.
The first stage, in the range of 60-150°C, is indicative of initial weight loss as a result of the evaporation of water and other volatile compounds within the samples [27, 47, 48]. Cellulose decomposition in R-pulp begins at 298.14°C, while in R-MCC it begins at 315.43°C. R-MCC also presents higher degradation temperature at 10% weight loss, compared to R-pulp. This is attributed to the high degree of molecular ordering of R-MCC, which requires high heat energy for thermal degradation [33]. The degradation peak temperature of R-MCC occurs at 340.12°C and in R-pulp it is noted at 335.15°C. The degradation of cellulosic components starts at 150°C and lasts up to 380°C, when the decarboxylation, depolymerization and decomposition occur in cellulose and hemicellulose fragments. Biomass is subjected to aromatization, decomposition, combustion, lignin pyrolysis and char residue formation beyond the temperature of 380°C [45, 48, 49]. R-MCC demonstrated comparable thermal stability with that of C-MCC in terms of onset decomposition temperature and degradation peak temperature, which might be affected by the different crystal size [50]. The maximum weight loss for R-pulp occurred at a lower temperature than the maximum weight loss for R-MCC. This is indicative of the high purity of the cellulose in R-MCC [25, 43]. Meanwhile, the char residue weight for R-pulp is 12.57%, which is higher than that for R-MCC (8.48%). The high residual weight of R-pulp was likely due to the char formation from flame retardant compounds [5, 51]. The onset degradation temperature of R-MCC (315°C) and its DTG peak temperature (340°C) are greater than those of MCC extracted from oil palm empty fruit bunch, as reported by Haafiz et al. [18], which presented an onset degradation temperature of 275°C and a DTG peak temperature of 326°C. Thus, the obtained R-MCC has good thermal stability, which is comparable to that of MCC obtained from cotton (305°C) and from Halocynthia (325°C), in the investigation by Kim et al. [50].
The DSC thermogram is shown in Fig. 8. The endothermic peaks appearing from 30°C to 150°C are related to the evaporation of the absorbed moisture content [48, 52]. In a close inspection of the DSC curves between 30°C and 150°C, it is interesting to note that R-MCC displays a pronounced peak at 137.55°C, whereas R-pulp displays two prominent peaks at 140.63°C and 146.97°C. This difference can be explained by the prevalence of non-substituted hydroxyl groups in R-pulp binding more water molecules with strong affinity, which required a larger amount of heat energy to evaporate its bound water content as compared to R-MCC, which was less hygroscopic and exhibited smaller water holding capacity [53]. Moreover, the ΔH for R-pulp is 111.20 J/g at 173.89°C, which is higher than that of R-MCC with 84.01 J/g at 182.06°C (Table 4). This was due to the predominant amorphous regions in R-pulp, which made the cellulose more susceptible to initial thermal degradation, when compared with R-MCC, which was more thermally stable [48]. On the other hand, C-MCC shows two pronounced peaks at 139.18°C and 150.62°C, while the ΔH of the endotherm at 184.80°C is 69.62 J/g. This might be due to a distortion of the water-cellulose interaction, as well as to the asymmetric thermal absorption determined by the aggregated structure and non-uniform size distribution of C-MCC [53, 54]. The thermal decompositions found on the DSC thermograms for all samples have the same trend as those on the TGA thermograms. As discussed earlier regarding TGA analysis, the DSC curves for all samples demonstrate endothermic peaks above 200°C, when cellulose volatilization and char formation occur [55]. C-MCC presents its thermal depolymerization at 332.90°C, as a consequence of its larger size, which requires more heat energy absorption for cellulose degradation, in comparison with R-MCC [25, 50]. The DSC curve for R-pulp exhibits a less significant shoulder peak at 293.84°C, which presents dehydration of cellulose, and a large peak at 309.36°C, which presents the depolymerization of cellulose [25, 56]. Both of these
endothermic peaks indicated double thermal decomposition occurring in R-pulp due to the noncellulosic fragments that prevented the degradation of cellulose [57, 58]. An insignificant endothermic peak is noted for R-MCC thermal decomposition at 307.85°C. This can be likely attributed to the pure crystalline structure of R-MCC, which contained less amorphous phase [48, 58]. 4. Conclusions The findings of the present study have revealed that the roselle fiber could be utilized as alternative biomass for the extraction of MCC by using integrated processes of bleaching, alkaline and acid disintegration. FTIR spectra indicated that the chemical structure of cellulosic components had not been changed and a substantial amount of lignin was effectively removed from roselle fiber during chemical treatments. The morphological analysis by SEM indicated that a rougher and less bulky structure of R-MCC was obtained after the acid hydrolysis of R-pulp. The prepared R-MCC also displayed a high crystallinity index, of 78%, which endorses its suitability for application as a load-bearing material in composite structures. Based on the TGA and DSC analyses, R-MCC was found to exhibit great thermal stability, which suggests that it could withstand high temperature in polymeric composites applications. The MCC developed in this research going to utilize for extraction of Cellulose Nanocrystals (CNC) and further CNC/Polylactic acid based nanocomposites for different applications.
Acknowledgements The authors are grateful for the financial support from Universiti Putra Malaysia through Putra grant no. GP-IPS/2017/9519000. The authors also extend their appreciation to the International
Scientific Partnership Program ISPP at King Saud University for funding this research through ISPP#0011.
References [1] M. Zeni, D. Favero, K. Pacheco, A. Grisa, Preparation of microcellulose (mcc) and nanocellulose (ncc) from Eucalyptus Kraft ssp pulp, Polymer Sciences 1 (2015) 1-7. [2] A. Ferrer, C. Salas, O.J. Rojas, Physical thermal, chemical and rheological characterization of cellulosic microfibrils and microparticles produced from soybean hulls, Industrial Crops and Products 84 (2016) 337–343. [3] Y. Habibi, L.A. Lucia, O.J. Rojas, Cellulose nanocrystals: chemistry, selfassembly, and applications, Chemical Reviews 110 (6) (2010) 3479–3500. [4] S. Shankar, J.W. Rhim, Preparation of nanocellulose from micro-crystalline cellulose: the effect on the performance and properties of agar-based compositefilms, Carbohydrate Polymers 135 (2016) 18–26. [5] N. Razali, S.M. Sapuan, M. Jawaid, M.R. Ishak, L. Yusriah, A study on chemical composition, physical, tensile, morphological, and thermal properties roselle fibre: effect of fibre maturity, Bioresources 10 (1) (2015) 1803-1824. [6] D. Chandramohan, K. Marimuthu, Characterization of natural fibers and their application in bone grafting substitutes, Acta of Bioengineering and Biomechanics 13 (1) (2011) 77–84. [7] M. Thiruchitrambalam, A. Athijayamani, S. Sathiyamurthy, A review on the natural fiberReinforced polymer composites for the development of roselle fiber reinforced polyester composite, Journal of Natural Fibers 7 (2010) 307–323.
[8] A. Athijayamani, M. Thiruchitrambalam, U. Natarajan, B. Pazhanivel, Effect of moisture absorption on the mechanical properties of randomly oriented natural fibers/polyester hybrid composite, Materials Science and Engineering: A 517 (12) (2009) 344–353. [9] D. Maria, S. Garcia, J.M. Lagaron, On the use of plant cellulose nanowhiskers to enhance the barrier properties of polylactic acid, Cellulose 17 (5) (2010) 987-1004. [10] L. Suryanegara, A.N. Nakagaito, H. Yano, The effect of crystallization of PLA on the thermal and mechanical properties of microfibrillated cellulose-reinforced PLA composites, Composites Science and Technology 69 (2009) 1187-1192. [11] A. Chauhan, B. Kaith, Accreditation of novel roselle grafted fiber reinforced bio-composites, Journal of Engineered Fibers and Fabrics 7 (2) (2012). [12] S. Navaneetha krishnan, A. Athijayamani, Mechanical properties and absorption behavior of CSP filled roselle fiber reinforced hybrid composites, Journal of Materials and Environmental Science 7 (5) (2016) 1674-1680. [13] I. Capron, O.J. Rojas, R. Bordes, Behavior of nanocelluloses at interfaces, Current Opinion in Colloid & Interface Science 29 (2017) 83–95. [14] O. Nechyporchuk, M.N. Belgacem, J. Bras, Production of cellulose nanofibrils: a review of recent advances, Industrial Crops and Products 93 (2016) 2–25. [15] P.K. Bajpai, I. Singh, J. Madaan, Development and characterization of PLA-based green composites: a review, Journal of Thermoplastic Composite Materials 31 (2012) 5-8. [16] N. Grishkewich, N. Mohammed, J. Tang, K.C. Tam, Recent advances in the application of cellulose nanocrystals, Current Opinion in Colloid & Interface Science 29 (2017) 32–45.
[17] D. Bandera, J. Sapkota, S. Josset, C. Weder, P. Tingaut, X. Gao, E.J. Foster, T. Zimmermann, Influence of mechanical treatments on the properties of cellulose nanofibers isolated from microcrystalline cellulose, Reactive and Functional Polymers 85 (2014) 134–141. [18] M.K.M. Haafiz, S.J. Eichhorn, A. Hassan, M. Jawaid, Isolation and characterization of microcrystalline cellulose from oil palm biomass residue, Carbohydrate Polymers 93 (2) (2013) 628–634. [19] R. Salminen, M. Reza, T. Paakkonen, J. Peyre, E. Kontturi, TEMPO-mediated oxidation of microcrystalline cellulose: limiting factors for cellulose nanocrystal yield, Cellulose 24 (2017) 1657–1667. [20] T.R. Anju, K. Ramamurthy, R. Dhamodharan, Surface modified microcrystalline cellulose from cotton as a potential mineral admixture in cement mortar composite, Cement and Concrete Composites, 74 (2016) 147-153. [21] R. Husgafvel, K. Vanhatalo, L.R. Chiang, L. Linkosalmi, O. Dahl, Comparative global warming potential assessment of eight microcrystalline cellulose manufacturing systems, Journal of Cleaner Production 126 (2016) 620-629. [22] G. Thoorens, F. Krier, B. Leclercq, B. Carlin, B. Evrard, Microcrystalline cellulose, a direct compression binder in a quality by design environment-A review, International Journal of Pharmaceutics 473 (12) (2014) 64–72. [23] S. Chuayjuljit, S. Su-uthai, S. Charuchinda, Poly(vinyl chloride) film filled with microcrystalline cellulose prepared from cotton fabric waste: properties and biodegradability study, Waste Management & Research 28 (2010) 109–117. [24] Y.X. Loo, M. Afandi, P. Mohammed, A.S. Baharuddin, Characterisation of microcrystalline cellulose from oil palm fibres for food applications, Carbohydrate Polymers 148 (2016) 11–20.
[25] D. Trache, A. Donnot, K. Khimeche, R. Benelmir, N. Brosse, Physico-chemical properties and thermal stability of microcrystalline cellulose isolated from Alfa fibers, Carbohydrate Polymers 104 (2014) 223–230. [26] R.D. Kalita, Y. Nath, M.E. Ochubiojo, A.K. Buragohain, Extraction and characterization of microcrystalline cellulose from fodder grass; Setaria glauca (L) P. Beauv, and its potential as a drug delivery vehicle for isoniazid, a first line antituberculosis drug, Colloids and Surfaces B: Biointerfaces 108 (2013) 85–89. [27] A. Merci, A. Urbano, M.V.E. Grossmann, C.A. Tischer, S. Mali, Properties of microcrystalline cellulose extracted from soybean hulls by reactive extrusion, Food Research International 73 (2015) 38–43. [28] P.Y. Chauchan, R.S. Sapkal, V.S. Sapkal, G.S. Zamre, Microcrystalline cellulose from cotton rags (waste from garment and hosiery industries), International Journal of Chemical Sciences 7 (2009) 681–688. [29] S. Elanthikkal, U. Gopalakrishnapanicker, S. Varghese, J.T. Guthrie, Cellulose microfibres produced from banana plant wastes: isolation and characterization, Carbohydrate Polymers 80 (2010) 852–859. [30] E. Abraham, B. Deepa, L.A. Pothan, M. Jacob, S. Thomas, U. Cvelbar, R. Anandjiwala, Extraction of nanocellulose fibrils from lignocellulosic fibres: a novel approach, Carbohydrate Polymers 86 (2011) 1468–1475.
[31] M. Nuruddin, A. Chowdhury, S.A. Haque, M. Rahman, S.F. Farhad, M. S. Jahan, Extraction and characterization of cellulose microfibrils from agricultural wastes in an integrated biorefinery initiative, Cellulose Chemical and Technology 45 (2011) 347–354. [32] H. Nadji, P.N. Diouf, A. Benaboura, Y. Bedard, B. Riedl, Comparative study of lignins isolated from Alfa grass (Stipa tenacissima L.), Bioresource Technology 100 (2009) 3585–3592. [33] D. Trache, M.H. Hussin, C.T.H. Chuin, S. Sabar, M.R.N. Fazita, O.F.A. Taiwo, T.M. Hassan, M.K.M. Haafiz, Microcrystalline cellulose: isolation, characterization and biocomposites application – A review, International Journal of Biological Macromolecules 93 (2016) 789–804. [34] A. Alemdar, M. Sain, Isolation and characterization of nanofibers from agricultural residues-wheat strawand soy hulls, Bioresource Technology 99 (2008) 1664–1671. [35] D. Ciolacu, F. Ciolacu, V.I. Popa, Amorphous cellulose — Structure and characterization, Celullose Chemistry and Technology 45 (2011) 13–21. [36] N. Johar, I. Ahmad, A. Dufresne, Extraction, preparation and characterization of cellulose fibres and nanocrystals from rice husk, Industrial Crops and Products 37 (2012) 93–99. [37] A.F. Owolabi, M.K.M. Haafiz, Md.S. Hossain, M.H. Hussin, M.R.N. Fazita, Influence of alkaline hydrogen peroxide pre-hydrolysis on the isolation of microcrystalline cellulose from oil palm fronds, International Journal of Biological Macromolecules, 95 (2017) 1228–1234. [38] A.M. Adel, Z.H.A. El-Wahab, A.A. Ibrahim, M. Al-Shemy, Characterization of microcrystalline cellulose prepared form lignocellulisic material. Part I. Acid catalyzed hydrolysis, Bioresource Technology 101 (2010) 4446–4455.
[39] V.N. Krishnan, A. Ramesh, Synthesis and characterization of cellulose nanofibers from coconut coir fibers, Journal of Applied Chemistry 6 (3) (2013) 18-23. [40] M.R.K. Sofla, R.J. Brown, T. Tsuzuki, T.J. Rainey, A comparison of cellulose nanocrystals and cellulose nanofibres extracted from bagasse using acid and ball milling methods, Journal of Nanoscience and Nanotechnology 7 (2016) 1-9. [41] A. Kumar, Y.S. Negi, V. Choudhary, N.K. Bhardwaj, Characterization of Cellulose Nanocrystals Produced by Acid-Hydrolysis from Sugarcane Bagasse as Agro-Waste, Journal of Materials Physics and Chemistry 2 (1) (2014) 1-8. [42] W.T. Wulandari, A. Rochliadi, I.M. Arcana, Nanocellulose prepared by acid hydrolysis of isolated cellulose from sugarcane bagasse, Materials Science and Engineering, 107 (2016). [43] M.H. Hussin, N.A. Pohan, Z.N. Garba, M.J. Kassim, A.A. Rahim, N. Brosse, M. Yemloul, M.R.N. Fazita, M.K.M. Haafiz, Physicochemical of microcrystalline cellulose from oil palm fronds as potential methylene blue adsorbents, International Journal of Biological Macromolecules 92 (2016) 11–19. [44] C.P. Azubuike, A.O. Okhamafe, Physicochemical, spectroscopic and thermal properties of microcrystalline cellulose derived from corn cobs, International Journal of Recycling of Organic Waste in Agriculture 1(1) (2012) 9. [45] M.S. Jahan, A. Saeed, Z. He, Y. Ni, Jute as raw material for the preparation of microcrystalline cellulose, Cellulose 18 (2011) 451–459.
[46] S.M.L. Rosa, N. Rehman, M.I.G. De Miranda, S.M.B. Nachtigall, C.I.D. Bica, Chlorine-free extraction of cellulose from rice husk and whisker isolation, Carbohydrate Polymers 87 (2012) 1131–1138. [47] M. Chowdhury, M. Beg, M.R. Khan, M. Mina, Modification of oil palm empty fruit bunch fibers by nanoparticle impregnation and alkali treatment, Cellulose 20 (3) (2013) 1477–1490. [48] A. Sonia, K.P. Dasan, Chemical, morphology and thermal evaluation of cellulose microfibers obtained from Hibiscus Sabdariffa, Carbohydrate Polymers 92 (2013) 668– 674. [49] M. Jonoobi, A. Khazaeian, P. Md Tahir, S.S. Azry, K. Oksman, Characteristics of cellulose nanofibers isolated from rubberwood and empty fruit bunches of oil palm using chemomechanical process, Cellulose 18 (2011) 1085–1095. [50] U.J. Kim, S.H. Eom, M. Wada, Thermal decomposition of native cellulose: influence on crystallite size, Polymer Degradation and Stability 95 (2010) 778–781. [51] W.P.F. Neto, H.A. Silverio, N.O. Dantas, D. Pasquini, Extraction and characterization of cellulose nanocrystals from agro-industrial residue – Soy hulls, Industrial Crops and Products 42 (2013) 480–488. [52] P. Lu, Y.L. Hsieh, Cellulose isolation and core–shell nanostructures of cellulose nanocrystals from chardonnay grape skins, Carbohydrate Polymers 87 (2012) 2546–2553. [53] W.D. Wanrosli, R. Rohaizu, A. Ghazali, Synthesis and characterization of cellulose phosphate from oil palm empty fruit bunches microcrystalline cellulose, Carbohydrate Polymers 84 (2011) 262–267.
[54] M. Luddee, S. Pivsa-Art, S. Sirisansaneeyakul, C. Pechyen, Particle size of ground bacterial cellulose affecting mechanical, thermal, and moisture barrier properties of PLA/BC biocomposites, Energy Procedia 56 (2014) 211 – 218. [55] A.L. Sullivan, R. Ball, Thermal decomposition and combustion chemistry of cellulosic biomass, Atmospheric Environment 47 (2012) 133–141. [56] K. Das, D. Ray, N.R. Bandyopadhyay, T. Ghosh, A.K. Mohanty, M. Misra, A study of the mechanical, thermal and morphological properties of microcrystalline cellulose particles prepared from cotton slivers using different acid concentrations, Cellulose, 16 (2009) 783–793. [57] A.M. Adel, N.A. El-Shinnawy, Hypolipidemic applications of microcrystalline cellulose composite synthesized from different agricultural residues, International Journal of Biological Macromolecules 51 (5) (2012) 1091-1102. [58] B.A. Simmons, D. Loque, J. Ralph, Advances in modifying lignin for enhanced biofuel production, Journal of Current Opinion in Plant Biology 13 (2010) 313–320.
Figures and Tables Captions Figures Fig. 1. FTIR spectra of R-Pulp, R-MCC, and C-MCC samples
Fig. 2. SEM micrographs of (a) R-pulp, (b) R-MCC and (c) C-MCC at (i) 100×, (ii) 1000× and (iii) 6000× magnifications.
Fig. 3. Energy-dispersive X-ray diffraction (EDX) spectra of (a) R-pulp, (b) R-MCC and (c) CMCC.
Fig. 4. Particle size distribution of R-Pulp, R-MCC, and C-MCC samples
Fig. 5. X-ray diffactograms of R-Pulp, R-MCC, and C-MCC samples
Fig. 6. TGA curves of R-Pulp, R-MCC, and C-MCC samples
Fig. 7. DTG curves of R-Pulp, R-MCC, and C-MCC samples
Fig. 8. DSC curves of R-Pulp, R-MCC, and C-MCC samples
Table 1. Denotations of samples Samples
Denotations
Alkali treated bleached pulp
R-pulp
Roselle microcrystalline cellulose
R-MCC
Commercial microcrystalline cellulose
C-MCC
Table 2. Elemental and particle size analysis data of R-pulp, R-MCC, and C-MCC Samples
Elemental analysis
Particle size analysis
Carbon (%)
Surface
Volume
weighted mean
weighted mean
diameter (µm)
diameter (µm)
Oxygen (%)
R-pulp
41.96
58.04
28.41
231.25
R-MCC
32.15
67.85
11.53
44.28
C-MCC
33.05
66.95
119.13
277.27
Table 3. XRD analysis data of R-pulp, R-MCC, and C-MCC
a
Samples
CrI (%)a
R-pulp
63
R-MCC
78
C-MCC
74
crystalinity index.
Table 4. Thermal analysis data of R-pulp, R-MCC, and C-MCC Samples
TGA analysis
DSC analysis
Tinitial
T10
Tpeak
Wloss
Wresidue
Tinitial
Tpeak
ΔH
(°C)a
(°C)b
(°C)c
(%)d
(%)e
(°C)f
(°C)g
(J/g)h
R-pulp
298.14
245.06
335.15
78.93
12.57
173.89
293.84 111.20
R-MCC
315.43
269.85
340.12
81.23
8.48
182.06
307.85 84.01
C-MCC
326.08
325.17
344.95
90.32
3.85
184.80
332.90
a
69.62
TGA initial decomposition temperature; b TGA degradation temperature at which 10% weight
loss; c DTG peak temperature; d TGA maximum weight loss; e TGA char residue weight; f DSC initial decomposition temperature; g DSC peak temperature; h Heat of decomposition.