Preparation and characterization of microcrystalline cellulose from waste cotton fabrics by using phosphotungstic acid

Accepted Manuscript Preparation and characterization of microcrystalline cellulose from waste cotton fabrics by using phosphotungstic acid

Wensheng Hou, Chen Ling, Sheng Shi, Zhifeng Yan PII: DOI: Reference:

S0141-8130(18)34477-5 https://doi.org/10.1016/j.ijbiomac.2018.11.112 BIOMAC 10989

To appear in:

International Journal of Biological Macromolecules

Received date: Revised date: Accepted date:

25 August 2018 26 October 2018 12 November 2018

Please cite this article as: Wensheng Hou, Chen Ling, Sheng Shi, Zhifeng Yan , Preparation and characterization of microcrystalline cellulose from waste cotton fabrics by using phosphotungstic acid. Biomac (2018), https://doi.org/10.1016/ j.ijbiomac.2018.11.112

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ACCEPTED MANUSCRIPT Preparation

and

characterization

of

microcrystalline

cellulose from waste cotton fabrics by using phosphotungstic acid Wensheng Hou, Chen Ling, Sheng Shi*, Zhifeng Yan

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College of textile engineering, Taiyuan University of technology, Jinzhong Shanxi 030600, China

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*Corresponding authors. Tel. /fax: +8615110309807.

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E-mail address: [email protected] / [email protected]

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ACCEPTED MANUSCRIPT Abstract Recycling of waste cotton fabrics (WCFs) and converting them into high valueadded products have not been developed. In this study, a novel and green process was developed for the preparation of microcrystalline cellulose (MCC) from WCFs by the

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catalytic hydrolysis of phosphotungstic acid (H3PW12O40, HPW). The effects of

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hydrolysis conditions such as HPW concentration, reaction temperature, reaction time,

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and solid/liquid ratio were investigated. The optimum process conditions were determined as follows: HPW concentration of 3.47 mmol/L, a solid/liquid ratio of 1:40,

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reaction temperature of 140 ℃, and reaction time of 6 h. The yield of MCC prepared

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was as high as 83.4% and exhibited better performance than commercial MCC such as a higher crystallinity (85.2%), smaller particle size (20.37 μm), and narrower particle

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size distribution (72.75%, 8.68–31.1 μm). Furthermore, the HPW could be extracted

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and recycled easily with diethyl ether for five times and used to prepare MCC with a high yield and crystallinity index.

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Key words: Waste cotton fabrics, microcrystalline cellulose, phosphotungstic acid,

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hydrolysis, recycle 1. Introduction

With the rapid increase in population and continuous utilization of textiles in the world, the demand for textiles is increasing year by year. Textiles such as apparel, home textiles, and industrial products usually become waste after being damaged or just used for a period of time [1]. Among them, waste cotton fabrics (WCFs) account for the majority of textile waste due to its huge share in the textile market [2]. Approximately 2

ACCEPTED MANUSCRIPT 25 million ton of cotton is produced annually as the raw material of fibers [3]. WCFs accumulate in the dump and become trash. The massive accumulation of WCFs is a huge waste of valuable resources, and more importantly, this would cause severe environmental pollution [4]. If WCFs can be recycled and converted into high value-

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added products, not only the environmental pollution can be substantially eliminated,

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but also enormous economic benefits can be achieved.

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Microcrystalline cellulose (MCC) is a fine, white, and odorless material in the form of crystalline powder. MCC is a promising natural material because of its nontoxicity,

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biodegradability, biocompatibility, high mechanical strength, large surface area, and

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low density [5]. To date, MCC has been widely used in pharmacy, cosmetics, medical industries, food processing, and material fields [6]. During the industrial production,

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MCC is obtained from wood fiber. Recently, some researchers prepared MCC from

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diverse inexpensive and readily available materials such as oil palm empty fruit bunch [7], tea waste [8], pomelo peel [9], bamboo [10], and corn husk fibers [11]. Because

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WCFs contain up to 95–99% cellulose content [12], WCF is a potential raw material

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for MCC manufacturing.

MCC has been prepared from WCFs using dilute inorganic acids [13–15]. However, this process leads to severe equipment corrosion and environmental issues because of the nature of acid. Recently, many researchers have developed various methods to prepare MCC to avoid the above problems. Until now, the methods developed are as follows: gamma irradiation of jute fiber and WCFs [12, 16], microwave irradiation of rice straw [17], combined acid and enzyme mediated hydrolysis of corn cob and cotton 3

ACCEPTED MANUSCRIPT gin waste [18], and ionizing radiation such as electron beam irradiation of pulp [19]. The properties of MCC are also different when the raw materials and preparation methods are different. Most of these methods are still in the experimental stage and more or less inefficient in energy consumption, cost control, and practical applications.

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Thus, it is essential to develop new methods that can replace the traditional methods for

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preparing MCC.

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Phosphotungstic acid (H3PW12O40, HPW) is a new type of multifunctional catalyst with abundant Bronsted acid sites that can break the β-1,4-glycosidic bonds in cellulose

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[20]. The main advantages of HPW are that HPW can be easily recovered from the

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reaction mixture than inorganic acids with less corrosion on the equipment and a relatively safe working environment [21]. Hence, it was expected that HPW can

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catalyze the hydrolysis of WCFs and convert them into MCC.

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Until now, no studies have reported an integrated preparation process and characterization of MCC using the HPW hydrolysis of WCFs, or its comparison with

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commercial MCC (CMCC). In this paper, a sustainable route was developed for the

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preparation of MCC from WCFs using HPW as the catalyst. The effects of HPW concentration, reaction temperature, reaction time, and solid/liquid ratio on the yield and crystallinity index of MCC were investigated. HPW can be recycled for the next round of experiments. The chemical structure, crystallinity, thermal stability, micromorphology, particle size distribution, and hydrophilicity of MCC and CMCC were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy 4

ACCEPTED MANUSCRIPT (SEM), particle size measurement, and contact angle measurement. Additionally, the differences between MCC and CMCC were evaluated. 2. Materials and methods 2.1 Materials

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The WCFs used in this study were obtained from a dyed cotton shirt supplied by a

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local recycling company, Taiyuan, Shanxi. Before the hydrolysis, the samples were cut

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into small pieces (2×2 cm2), cleaned with water, air dried, and preserved in a desiccator for use. HPW, CMCC, ethanol, and diethyl ether were analytically pure

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reagent. They were purchased from Sinopharm Chemical Reagent (Shanghai, China)

was prepared in the laboratory.

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2.2 Preparation of MCC

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and used as received without further purification. Distilled water for the experiments

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MCC from WCFs was prepared in a reactor (volume 100 mL) equipped with a polyphenylene liner. The WCFs were mixed with 50 mL HPW aqueous solution (0.69–

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6.25 mmol/L) and heated to the desired temperature (130–170 ℃) with a solid/liquid

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ratio of 1:50–1:20 for 4–8 h inside the reactor. The reactor was sealed and placed in a muffle furnace to initiate heating. At the end of the reaction, the reactor was taken out and cooled to room temperature with cooling water. After removing the reactants, the obtained solid residues (MCC) were washed with distilled water and ethanol by filtration. The filtrate was collected to recycle HPW. The solid residues were separated using a 10-mesh sieve to ensure that there were no mixed WCFs in the MCC. Finally, the MCC was oven-dried in a vacuum oven at 60 ℃ for 6 h and stored for further 5

ACCEPTED MANUSCRIPT processing. 2.3 Recycling of HPW The filtrate was transferred to a separatory funnel, and then 20 mL diethyl ether was added. A composite that was neither soluble in water nor diethyl ether formed when the

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liquid mixture was shaken. Finally, the bottom composite was separated and placed in

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a fume hood to evaporate the diethyl ether. The recycled HPW was reused to prepare

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MCC when the experiment was repeated as described above. The yield of MCC was

Yield of MCC (%) = W1 ⁄ W2 × 100%

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calculated using Eq. (1).

(1)

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where W1 and W2 are the weights of MCC and WCFs, respectively. 2.4 Characterization

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2.4.1 FTIR

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The sample was ground, mixed with dried potassium bromide powder, and compressed into a tablet before the analysis. Then, FTIR analysis was conducted using

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an FTIR-1730 instrument (PE, USA) in the range of 4000–400 cm−1 and at a resolution

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of 2 cm−1 over 20 scans. 2.4.2 XRD

The XRD patterns were obtained using an X-diffractometer (TD-3700, Dandong, China) equipped with Cu Kα radiation at the operational conditions of 35 kV and 25 mA. The data were collected in the 2θ range 5–60° with a step interval of 0.05 °. The crystallinity index (CI) and crystallite thickness at the (002) plane were calculated using the peak fitting method [22]. 6

ACCEPTED MANUSCRIPT 2.4.3 TGA TGA measurements were carried out using a TGA-4000 instrument (PE, USA) under nitrogen gas atmosphere. The mass of each sample was 10 mg. The samples were dried to constant weight and then heated from 100 ℃ to 650 ℃ at a heating rate of 10 ℃/min.

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Then, TGA and derivative TGA (DTG) were performed on each sample.

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2.4.4 SEM

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The surface morphology of sample was analyzed using a scanning electron microscope (FESEM; JSM-6700F, JEOL, Tokyo, Japan). The surface of dried sample

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was coated with gold and then observed with an accelerating voltage of 7 kV.

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2.4.5 Particle size measurement

MCC and CMCC were suspended in distilled water at 0.01% (w/w). The pH of MCC

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and CMCC was found to be neutral. The particle size of MCC and CMCC was

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measured using a particle size analyzer, MASTERSIZER 3000 (Malvern PANalytical, UK).

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2.4.6 Contact angle measurement

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The contact angle was measured using the sessile drop test method using a contact angle meter (JC-2000C, Shanghai, China). The layers of WCFs, MCC, and CMCC were pressed using a tablet press, and a drop of water was placed on the surface of WCFs, MCC, and CMCC. Images were recorded after the drop was set on the surface of layers. 3. Results and discussion 3.1 Effect of HPW concentration Based on the previous experimental results, in this study, the effect of HPW 7

ACCEPTED MANUSCRIPT concentration on the preparation of MCC was evaluated under the following conditions: 0.69–6.25 mmol/L HPW concentration, a solid/liquid radio of 1:40, reaction temperature of 150 ℃, and reaction time of 6 h. Fig. 1a shows that with the increase in HPW concentration, the yield and crystallinity index of MCC first increased and then

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decreased. The result is related to the degree of hydrolysis of WCFs. The main

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component of WCF is cellulose, and the molecular chains of cellulose consist of

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crystalline and amorphous regions. The crystallites are arranged in an orderly manner and tightly in the crystalline region and relatively loose in the amorphous region [23,

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24]. Therefore, the amorphous region of cellulose can be more easily hydrolyzed than

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the crystalline region of cellulose. HPW can release a large amount of protons (H+) in an aqueous solution, and these protons are freely available to interact with the oxygen

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atoms in the ether linkages of cellulose [25, 26]. As the acid concentration increases,

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the acidity of HPW would increase. Thus, the higher the HPW concentration, the more facile is the hydrolysis of WCFs. When the HPW concentration is too low such as 0.69

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mmol/L, the WCFs cannot be sufficiently hydrolyzed. A lot of residual WCFs were

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present even after the hydrolysis. Under the circumstances, the yield and CI of MCC were relatively low and increased with the increase in HPW concentration. When the HPW concentration reached 3.47 mmol/L, both the yield and CI of MCC reached their maximum values of 81.3% and 85.7%, respectively. However, when it was further increased, the yield and CI of MCC decreased. This is because a high acid concentration not only hydrolyzed the amorphous region of WCFs, but also hydrolyzed its crystalline region. Therefore, the optimum acid concentration is 3.47 mmol/L. 8

ACCEPTED MANUSCRIPT 3.2 Effect of reaction temperature The effect of reaction temperature on the preparation of MCC was evaluated under the following conditions: 3.47 mmol/L of HPW concentration, a solid/liquid ratio of 1:40, reaction temperature of 130–170 ℃, and reaction time of 6 h. As shown in Fig.

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1b, with the increase in reaction temperature, the yield of MCC increased, but when the

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temperature exceeded 140 ℃, the yield of MCC decreased almost linearly. Interestingly,

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the CI of MCC also showed a similar trend. This is because HPW destroyed the crystalline structure of WCFs, and byproducts such as acetylpropionic acid and

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hydroxymethyl furfural were produced when the reaction temperature was too high [27].

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A maximum yield of 83.4% was achieved for MCC at 140 ℃. The CI of MCC reached up to 85.7% at 150 ℃. Considering that the CI of MCC could reach 85.2% at 140 ℃ and

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3.3 Effect of reaction time

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a lower temperature was more energy saving, the optimum temperature was set at 140 ℃.

Reaction time is a non-negligible principal factor for the preparation of MCC from

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WCFs. In this study, the effect of reaction time on the yield and CI of MCC was

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evaluated at 140 ℃, 3.47 mmol/L HPW concentration, a solid/liquid ratio of 1:40, and a reaction time of 4–8 h. The experimental results are shown in Fig. 1c. It was observed that both the yield and CI of MCC increased and reached their maximum values of 83.4% at 6 h and 85.5% at 7 h, respectively. This is because in the early stages of reaction, the fiber morphology of WCFs was destroyed, and a large amount of MCC was produced. With progress in time, the amorphous region of MCC was lost, and the CI of MCC increased. However, as the reaction time continued to increase, they all began to decline. 9

ACCEPTED MANUSCRIPT This is probably because prolonging the reaction time would not only hydrolyze the amorphous area, but also hydrolyze the crystalline area. Because the yield of MCC was lower at 7 h (82.24%) than at 6 h (83.4%) and the CI of MCC (85.2%) is very close to 7 h at 6 h, the reaction time was set at 6 h.

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3.4 Effect of solid/liquid ratio

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The effect of solid/liquid ratio on the preparation of MCC was evaluated under the

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following conditions: 3.47 mmol/L HPW concentration, a solid/liquid radio of 1:50– 1:20, reaction temperature of 140 ℃, and reaction time of 6 h. As shown in Fig. 1d, the

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yield of MCC slowly increased with increasing solid/liquid ratio, and the yield

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increased from 80.1% to 84.12%. This is because the increase in solid/liquid ratio means the increase in the amount of substrate WCFs. The more the WCFs, the more the

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MCC produced. However, the CI of MCC decreased with increasing solid/liquid ratio.

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This is due to the reduction in the degree of hydrolysis of WCFs. Excessive WCFs can cause an incomplete reaction between the WCFs and HPW in the reactor, thus

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preserving more amorphous region. Thus, the yield of MCC increased while its CI

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decreased with the increase in solid/liquid ratio. When the solid/liquid ratio was 1:40, the yield of MCC was close to the maximum yield, and its CI was also high. Hence, 1:40 was selected as the optimum solid/liquid ratio. From the above results, it can be concluded that the yield and CI of MCC are significantly affected by changing the various parameters. Finally, the optimum processing conditions for preparing MCC were determined as follows: 3.47 mmol/L of HPW concentration, a solid/liquid ratio of 1:40, a reaction temperature of 140 ℃, and a 10

ACCEPTED MANUSCRIPT reaction time of 6 h. 3.5. Characterization 3.5.1 Chemical structure The functional groups present in each sample were determined from the FTIR spectra

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to characterize the chemical structure of samples. The FTIR spectra of MCC, WCFs,

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and CMCC are shown in Fig. 2. The absorption band located in 3340 cm−1 can be

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attributed to the adsorbed water and O–H stretching vibration [28]. The absorption bands at 2900 cm−1 and 2853 cm−1 can be assigned to the symmetric stretching vibration

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and antisymmetric stretching vibration of C–H bond of methyl and methylene groups,

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respectively [29]. The absorption band at 1650 cm−1 can be attributed to opened terminal glycopyranose ring or oxidation of C–OH groups [30]. The absorption band at

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1428 cm−1 can be assigned to the bending vibration of symmetric CH2, known as the

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“crystallinity band” [31]. The peak intensity of MCC was higher than WCFs, indicating the increase in CI. The absorption bands of 1383 cm−1 and 1064 cm−1 can be attributed

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to O–H bending vibration and C–O–C ring skeleton vibration, respectively [32].

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Additionally, the absorption band at 894 cm−1 can be ascribed to the β-1,4-glycosidic bonds in cellulose [33]. The intensity of MCC was stronger than those of WCFs and CMCC, indicating that MCC had a higher purity. Because these characteristic peaks of MCC, WCFs, and CMCC were similar, the catalytic hydrolysis of HPW did not change the cellulose structure of WCFs, and MCC and CMCC have the same chemical structure.

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ACCEPTED MANUSCRIPT 3.5.2 Crystalline structure XRD analysis was carried out to investigate the crystalline structure of MCC, and the structure of MCC was compared with those of WCFs and CMCC. Their XRD patterns are shown in Fig. 3. The structures of MCC, WCFs, and CMCC were of

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cellulose I type because they had similar XRD patterns, and they all showed the main

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diffraction peaks at 2θ = 14.8°, 16.5°, 22.8°, and 34.5°. Moreover, this also indicated

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that the cellulose structure of WCFs did not change by hydrolysis, consistent with the FTIR results. The diffraction peak of MCC at 22.8° became narrower and sharper,

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indicating an increase in crystallinity. The CI of WCFs was 64%, whereas that of MCC

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was 85.2%, indicating that the CI of MCC increased after the hydrolysis. This is because the HPW-hydrolysis treatment could remove the amorphous region of WCFs

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partially, leading to the hydrolytic cleavage of β-1,4-glucopyranose bonds and releasing

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individual crystallites [34]. The crystallite thicknesses of (002) plane of WCFs and MCC were 3.86 nm and 5.45 nm, respectively. The increase in crystallite size of MCC

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indicated that the HPW hydrolysis narrows the MCC crystallite size distribution [35].

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In addition, the CI of MCC was even higher than that of CMCC, indicating that the preparation process was satisfactory. 3.5.3 Thermal stability The TG and DTG patterns of MCC, WCFs, and CMCC are shown in Fig. 4. Fig. 4a shows that the main decomposition stages of MCC and CMCC were observed in the range of 240–370 ℃ and 240–385 ℃, respectively, whereas the main decomposition stage of WCFs was in the range of 280–360 ℃. This is due to the decomposition of 12

ACCEPTED MANUSCRIPT cellulose, such as the dehydration, decarboxylation, depolymerization, and decomposition of glycosyl units followed by the formation of a charred residue [36]. It was the process of ash formation of MCC when the temperature was more than 360 ℃. In the DTG curves (Fig. 4b), each sample showed only one peak, indicating that only

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one type of crystal is present in the samples [37]. This is also consistent with the results

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of FTIR and XRD analyses. It was observed that the degradation temperature of MCC

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is lower than that of WCFs. This is because HPW not only hydrolyzed the amorphous region of WCFs, but also hydrolyzed the crystalline region to some extent [38]. The

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result is consistent with previous reports: they also believed that it was the effect of

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hydrolysis. The weight loss of MCC was 76%, and that of CMCC was 70.06%, indicating a higher purity for MCC [39, 40]. These observations collectively showed

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that MCC has a good thermal stability and could be applied to the production of

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biocomposites, food stabilizers, and pharmaceutical compounds [36]. 3.5.4 Micromorphology and particle size

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The SEM micrographs of MCC and CMCC samples are shown in Fig. 5. It could be

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visually observed that the fabric structure of WCFs was destroyed, and the WCFs were hydrolyzed into small irregular MCC (Fig. 5a) in this process. Compared to the CMCC (Fig. 5b), the particle size of MCC was obviously smaller. To further analyze the particle size distribution of samples, a particle size analyzer was used to measure the particle size distribution of MCC and CMCC, as shown in Fig. 5e. It was observed that the particle size of MCC was smaller and more regular than that of CMCC. The particle size of MCC ranged from 0.87 μm to 111 μm with an average particle size of 20.37 μm, 13

ACCEPTED MANUSCRIPT which was smaller than that of CMCC (14.5–144 μm, 49.34 μm). In addition, the particle size of MCC was mainly distributed in the interval of 8.68–31.1 μm, accounting for 72.75%. This was higher than that of CMCC (24.1–86.4 μm, 67.05%). Combined with the results of XRD analysis, it was found that HPW was able to hydrolyze the

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amorphous region of MCC while preserving the crystalline region of MCC to the

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maximum extent. In other words, HPW showed a certain selectivity for cellulose

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hydrolysis, consistent with the previous reports [41]. The results indicate that the preparation process could produce a smaller size and narrower particle size distribution

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of MCC compared with CMCC.

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3.5.5 Hydrophilicity

Fig. 6 shows the images of contact angle of MCC, WCFs, and CMCC. As shown in

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Table 1, the diff erence in the curvature of water droplet was obvious. It was greater for

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the WCFs than MCC and CMCC, indicating that the hydrophilicity of MCC increased. This is because the dissolution of wax in WCFs and exposure of OH groups in cellulose

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structure led to the exclusion of apolar components, and the hydrophilicity of MCC

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increased [42]. Hence, it can be concluded that the hydrophilicity of MCC significantly increased compared to WCFs. 3.6 Recycling of HPW A major disadvantage of the traditional preparation processes of MCC is their pollution problem and high cost; therefore, it is important to recycle HPW. Fig. 7 shows that as the number of HPW recycling increased, the yield of MCC increased, but the CI of MCC decreased. This is because HPW could not be completely extracted with ether 14

ACCEPTED MANUSCRIPT from the reaction mixture. A small amount of HPW remains in the reaction mixture. As shown in Fig. 7, the mass loss of HPW increased with the increase in the number of cycles. However, the yield of MCC remained at 83.4–84.08%, and the CI of MCC was still higher than 80% after five times of HPW recovery. Therefore, it was proved that

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the recycled HPW can maintain a high catalytic activity and efficiency after five times

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of recycling.

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4. Conclusions

In this study, a green and effective method was developed for the preparation of MCC

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from WCFs using HPW under hydrothermal conditions. The yield and CI of MCC were

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83.4%, and 85.2%, respectively under the optimum process conditions of 3.47 mmol/L of HPW, a solid/liquid ratio of 1:40, reaction temperature of 140 ℃, and reaction time

with

a

higher

crystallinity,

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I

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of 6 h. The characterization results showed that the structure of MCC was cellulose type smaller

size,

and

narrower

particle

size

distributioncompared with CMCC. In addition, HPW could be recycled at least five

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times for the preparation of MCC with a high yield and CI.

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According to the observations mentioned above in this study, it was demonstrated that the hydrolysis of WCFs by HPW is an environment-friendly technique to prepare MCC. This study provides an effective method for the recovery and reuse of WCFs. The MCC prepared from WCFs has high practical significance, and it will be the focus of our study in the future.

Acknowledgments This work was supported by the National Natural Science Foundation of China 15

ACCEPTED MANUSCRIPT [No.51703153].

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ACCEPTED MANUSCRIPT in: Z.Y. Jiang, J.T. Han, X.H. Liu (Eds.) New Materials And Advanced Materials, Pts 1 And 2, Trans Tech Publications Ltd, Stafa-Zurich, 2011, pp. 504–507. [38] M.F. Rosa, E.S. Medeiros, J.A. Malmonge, K.S. Gregorski, D.F. Wood, L.H.C. Mattoso, G. Glenn, W.J. Orts, S.H. Imam, Carbohydr. Polym., 81 (2010) 83–92.

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ACCEPTED MANUSCRIPT Figure captions: Fig. 1 Effects of HPW concentration (a), reaction temperature (b), reaction time (c), and solid/liquid ratio (d) on the yield and CI of MCC. Reaction conditions (a: 150 ℃, 6 h, 1:40; b: 3.47 mmol/L, 6 h, 1:40; c: 140 ℃, 3.47 mmol/L, 1:40; d: 140 ℃, 3.47 mmol/L,

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6 h). Fig. 2 FTIR spectra of MCC, WCFs, and CMCC. MCC was prepared under the

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optimum process conditions.

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Fig. 3 XRD patterns of MCC, WCFs, and CMCC. MCC was prepared under the

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optimum process conditions.

Fig. 4 TG (a) and DTG (b) curves of MCC, WCFs, and CMCC. MCC was prepared

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under the optimum process conditions.

Fig. 5 SEM images of MCC (a), CMCC (b), and size distribution images of MCC and

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CMCC (c). MCC was prepared under the optimum process conditions. Fig. 6 Contact angle images of MCC (a), CMCC (b), and WCFs (c). MCC was prepared

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under the optimum process conditions.

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Fig. 7 Recycling of HPW for preparing MCC under the optimum process conditions.

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ACCEPTED MANUSCRIPT Table 1. Contact angle of MCC, CMCC, and WCFs. Contact angle

MCC

54.12 

CMCC

43.5 

WCFs

72.10 

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Sample

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ACCEPTED MANUSCRIPT Highlights MCC was prepared from waste cotton fabrics by using HPW. The effects of hydrolysis conditions such as reaction temperature, reaction time, HPW concentration and solid-liquid ratio on the yield and CI of MCC were investigated.

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The MCC exhibited higher crystallinity, smaller particle size and narrower particle size

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distribution compared with commercial MCC.

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HPW could be recycled at least five times for preparing MCC with high yield and CI.

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