Advances in chemical modifications of starches and their applications

Carbohydrate Research 476 (2019) 12–35

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Advances in chemical modifications of starches and their applications a

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a

Fazal Haq , Haojie Yu , Li Wang , Lisong Teng , Muhammad Haroon , Rizwan Ullah Khan , Sahid Mehmooda, Bilal-Ul-Amina, Raja Summe Ullaha, Amin Khana, Ahsan Nazira a b

T

State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, People’s Republic of China Oncological Surgery and Cancer Center, The First Affiliated Hospital, Zhejiang University, 310003, People's Republic of China

ARTICLE INFO

ABSTRACT

Keywords: Starch Chemical modification Ammonia Phenol Heavy metals Dyes

Starch is a homopolysaccharide made up of glucose units which are linked together via a glycosidic linkage. This biopolymer is well known for its low cost, biodegradability, renewability and easy availability. In spite of all these beauties, starch has some problems with their solubility in water, retrogradation, loss of viscosity due to rupturing of glucosidic bond when subjected to treatment and absence of some groups of primary importance like different functional groups especially carboxylic group, ester group, ether group and amino group. In order to overcome these shortcomings and enhance its applications, starch must be modified. The modification can be done chemically, physically and enzymatically, but noteworthy one is the chemical modification. In this review article, we focused on the recently used ways of chemical modification such as acid hydrolysis, cross-linking, acetylation/esterification, dual modification, oxidation and grafting of starch, and their properties. This review article highlighted the application of modified starch as an adsorbent for the removal of ammonia, phenol, heavy metals, and dyes.

1. Introduction Starch is the homopolysaccharide, which is stored as a food material in plants. It is the polymeric form of anhydrous glucose units, which are generally setup in the unique and autonomous granules. The granules of the starch have different sizes, shapes, structures and chemical penning [1]. The complex body of the starch is comprised of two different types of structures i.e. amylose and amylopectin [2,3]. Amylose structure is almost long, and narrow having glucose units comprised of around 99% (1–4) and 1% (1–6)-α-linkages, whereas the structure of amylopectin is branched containing approximately 95% (1–4) and 5% (1–6)-α-linkages [4]. Amylose covers a range of degrees of polymerization depending upon the source. The amylose molecule of potato starch has high degree of polymerization ranging from 840 to 22000 glucose unit. Amylopectin is one of the largest molecules in nature with an average degree of polymerization of about 2 million (corresponding with an average molecular weight of about 400 million). The molecular weight of amylopectin is about 1000 times as high as the molecular weight of amylose [5,6]. Starch is well known for its biocompatibility, biodegradability, low cost and nontoxicity [7–9]. However, native starch has limited applications due to its insolubility in water even at 25 °C and gentle regress

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so, starch is modified either chemically, physically or genetically [1] in order to make it more useful and to enhance its application. In the recent past years, starch has been chemically modified in different ways by replacing the hydroxyl groups with different functional groups [10–13]. The beauty of the modified starches is they are low in cost as compared to other materials. The price of starch in 2012 was about $ 0.55 kg−1 which accounts for the lower cost of starch-based biopolymers compared to the other biopolymers such as poly (lactic acid) PLA, polyhydroxyalkanoates PHA or polyester [14]. The modified starches are expensive [15] as compared to native starches because of high cost of the reactants used. In chemically modified starches like starch xanthate, carboxymethyl starch, starch sulfate, starch phosphate and starch carbamate, starch phosphate is easy to prepare and low in cost. The reason for the inexpensiveness is the low cost of the reactants used [16]. In this review article, we have riveted on the chemical modifications of starches, and their application as an adsorbent material for the removal of ammonia, phenol and other materials like dyes and heavy metals from waste matter. Ammonia (NH3) is a colorless gas with a pungent smell, which acts as a precursor to food and fertilizers for mundane organisms. But, if it is inhaled then ammonia is the most harmful chemical on the earth [17]. Most of the harmful effects of ammonia lead to in irritation of nasal

Corresponding author. Corresponding author. E-mail addresses: [email protected] (H. Yu), [email protected] (L. Wang).

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https://doi.org/10.1016/j.carres.2019.02.007 Received 25 November 2018; Received in revised form 10 February 2019; Accepted 25 February 2019 Available online 02 March 2019 0008-6215/ © 2019 Elsevier Ltd. All rights reserved.

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Scheme 1. Proposed mechanism for modified hydrolyzed starch [55].

adsorption of ammonia [33–36]. Similarly, the modified starches were also used as an adsorbent for the removal of phenols [37–39], heavy metals [40,41] and dyes [42–44]. The vast majority of starch is industrially produced in the world either for sale as starch or for conversion to other products [45]. The modified starches have been used in drug delivery [46], for oral delivery of vitamin E to small intestine [47], in food industry [48], in biotechnology [49] and in sensitized solar cell [50]. In spite of their vast application in different fields, still the preparation of these modified starches are practiced in laboratory due to use of expensive reagents. Many companies have regulations for chemically modified starches approved for food applications [51]. It is expected that in near future these modified starches would be synthesizing on large scale in industries on special demand for specific function. This article highlighted modification of starch and their use as an adsorbent for the removal of ammonia, phenol, heavy metals and dyes. This paper, first time pointed the adsorption behavior of starch for ammonia and phenol and also describe recent literature about the adsorption of heavy metals and dyes.

Fig. 1. The proposed acid hydrolysis process of C. auriculatum starch [59]. Copy right, 2017, Elsevier.

cavities and tracheobronchitis, chemical pneumonitis, dyspnea, laryngospasm, noncardiogenic pulmonary edema, irritation of eyes, headache and respiratory failure [18–22]. Phenol and phenolic compounds have become environmental trouble due to the manmadeeffect on the natural world [23]. Phenol makes an easy approach to the human body through inhaling the smoke of cigarette, cigar and pipe [24]. The most common problems caused by the phenol are irritation in eyes and skin, and damages to kidneys and liver [25]. Heavy metals seriously affect humans as well as aquatic life. The most drastic diseases caused by the heavy metals in human beings are cancer, hyperkeratosis, nephritic tubular damage, anxiousness, and depression [26]. The well-known diseases induced by the heavy metals in fishes are gangrene, growth retardation, hypocalcaemia and skin wound [27]. In the textile and so many other industries, dyes are used to color goods [28]. There are so many sources of dyes like anthropogenic, cosmetic, paper, textile and plastic industries [29–31]. The dyes severely affect living organisms and also cause environmental pollution. The serious diseases i.e. imbalance of the central nerve system (CNS), and hepatic disorder are caused by the dyes in human beings [32]. Recently, the modified starches were used for the

2. Chemical modifications In the early 1940s, the studies of chemical modification got popularity in the world of modern science and research. Actually, the normal starch has a problem with insolubility in water and easy retrogation, so to overcome this problem and upgrade their properties starch is chemically modified. Chemical modification is the insertion of a new functional group on the starch backbone to give characteristic properties to the starch. Uptill now, different researchers have replaced the hydroxyl group of starch by different groups like carboxyl, acetyletc. [34,52]. There are numerous methods for chemical modification of starch, but some crucial methods are acid hydrolysis, cross-linking, acetylation/esterification, dual modification, oxidation, and grafting. 2.1. Acid hydrolysis of starch Generally, acid hydrolysis is the process in which proticacidis used to break the chemical bond through nucleophilic substitution reaction with the addition of water molecule. The acid-modified starches have vast applications in food, pharmaceutical, textile, paper and many other

Table 1 Hydrolyzed starches by different acids with their characteristic properties. Starch

Acid

Properties of the modified starch

Ref

Waxy corn starch Potato starch Potato starch CyananchumauriculatumRoyleex-wight starch Corn starch Moth bean Amaranth and waxy maize starch

HCl HCl HCl HCl HCl HCl H2SO4

No change in crystallinity decreased viscosity and increased solubility. Increased crystallinity, extended thermal transition, and enhanced enthalpies. Increased solubility, decreased paste viscosity, swelling power, and crystallinity. Changed crystal type from CB-type to A-type. Enhanced the viscosity stability, bonding ability, and constancy of starch-based wood adhesive. Decreased amylose contents, swelling power and pasting property. Crystallinity type (A-type) not changed.

[63] [57] [64] [59] [61] [65] [66]

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Fig. 2. Reactions of some commonly used cross-linking reagents [72] Copyright,2015, Royal Society of Chemistry.

which acts as Lewis acid so it readily reacts with water (step D) to regenerate the hydroxyl group (step E) [55]. M. jianget al. recently treated starch with the aqueous hydrochloric acid to synthesize the waxy corn hydrolyzed starch. This acid hydrolyzed starch showed no change incrystal structure but decreased viscosity. So by adjusting the conditions of acid hydrolysis, the stability and food quality enhancing properties of the starch should be heightened [56]. Recently, three varieties of potato starch yellow, red and purple were reacted with 2.2 N HClsolution at 35 °C for 40 days. The acid hydrolyzed starch showed the significant change in the crystallinity, degrading of the starch granule and broadening of the thermal-transitions [57]. D. Li et al. performed the induced electric field aided hydrochloric acid (IEF-HCl) hydrolysis of potato starch in the fluidic system. The IEFHCl-modified starches showed an increase in solubility, while a decrease in crystallinity, paste viscosity and swelling power as compared to the native starch [58]. Acid hydrolysis affected the structural makeup of starch. CyananchumauriculatumRoyleex-wight starch (2%, w/ v) was treated with 2.2 M HCl solution at 35 °C for 1–9 days. All the structural changes during this period are shown in Fig. 1. As a result of acid hydrolysis crystal type also altered fromCB-type to A-type as well as the proportion of single helix, amorphous components, and amylose contents decreased [59]. Recently, amaranth and waxy maize starches were acid hydrolyzed with 100 mL of 3.16 M H2SO4, to produce nanocrystals. The obtained results showed that in the crystalline lamella, the establishment of the starch component depends upon the starch granule size responsible for the production of nanocrystals with a different structure. Small granule size favored rapid hydrolysis rate because it increased the approach of a proton to the inner regions [60]. All the hydrolyzed starches by different acids with their characteristics properties are summarized in Table 1. Y. Wang et al. prepared the acid hydrolyzed starch by treating the cornstarch with 120 mL of HCl (0.5 M). The obtained acid hydrolyzed starch amended the bonding performance, viscosity, stability, and water resistance of the starch-based wood adhesive [61]. The starch obtained from the seeds of moth bean was treated with 2.2N HCl for durations ranging from 0 to 120 h. The results showed aprogressive decrease in amylose content (18.3%) and swelling power (8.8 g/g) during acid hydrolysis treatment [62].

Fig. 3. Mechanistic pathway for sorption of acetophenone and 1-phenylethanol on the exterior of porous cross-linked starch polymer along with their adsorption energies [75]. Copyright, 2018, Elsevier.

Scheme 2. Synthetic pathway of starch-based hydrogels [76].

different industries [53–55]. The mechanism for the acid modification is shown in Scheme 1. First, the hydronium ion (H3O+) which acts as an electrophile attacks on the oxygen atom of the starch having the lone pair of electrons (step A), the oxygen intern attract the electrons of the carbon-oxygen to fill its deficiency (step B), and produce carbonium ion intermediate (step C). The carbonium ion is electron deficient species

2.2. Cross-linking of starch In a polymer, the production of chemical side bonds in different chains is called as cross-linking. There are so many well-known crosslinking reagents such as phosphorus oxychloride [67], epichlorohydrin 14

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Fig. 4. Native and octenyl succinic anhydride starches with labeled particle size [80] Copyright, 2018, Elsevier.

Scheme 3. Mechanistic pathway for the synthesis of esterified starch [83].

[68], sodium tripolyphosphate [69] and sodium trimetaphosphate. The below Fig. 2 shows the reactions of some cross-linking reagents [70]. H Kim et al. treated native potato starch with sodium trimetaphosphate or sodium tripolyphosphate to prepare the cross-linked amorphous granular potato starches (CLAPGS). Due to cross-linking, the solubility, pasting and swelling properties of CLAGPS were confined and showed totally different characteristics compared to amorphous granular potato starches [71]. Recently, cross-linked starch xynthate was synthesized by grafting co-polymerization of acryl amide and sodium acrylate. The reaction was done in the presence of initiator potassiumpersulfate and sodium hydrogen sulfite and cross-linker N-N mehtyl bisacrylamide. This crosslinked starch xanthatelost its crystallinity [73]. By treating potato starch with sodium trimetaphosphate/sodium tripolyphosphate, the cross-linking happened at the amorphous area and does not change the crystalline area in potato starch granules. The cross-linked starch increased the contents of resistant starch (RS) and should be employed in the food industry as an alternate nutritional fiber [74]. The novel crossed-linked starch polymer was prepared by cross-linking starch with bitolylenediisocyanate (TODI)and used as an adsorbent for the adsorption of acetophenone (AP) and 1-phenylethanol (PE) from the petrochemical effluent [75]. The adsorption mechanism is shown in Fig. 3. T Sun et al. prepared starch-based hydrogels by using diselenide crosslinker as shown in Scheme 2. Rhodamine B was selected as a model drug to investigate the drug loading and release behavior of this crossed linked starch-based hydrogels.

Fig. 5. Acylated starches against carbon-chain lengths with DS-values [85] Copyright, 2004, Elsevier. 15

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native arenga starch with acetic anhydride in an aqueous slurry at pH 7, 8, 9 and 10. Due to acetylation, the crystallinity of the starch molecule decreased but it enhanced the swelling power, solubility, water, and oil holding capacity [52].Pre-treated-microwave acetylated starch was prepared by pre-treating potato starch with 600 W microwaves and then acetylated with acetic anhydride and glacial acetic acid (1:1 in volume). After acetylation, the crystal structure also changed from Btype to C-type. Due to modification, the solubility was remarkably increased, while the swelling power was decreased [78]. The acetylated modified starch was prepared by treating banana starch with acetic anhydride and for the production of nanoparticles of both, the acetylated and native starch were treated with acetone. Both the starches were used for the synthesis of curcumin-loaded starch nanoparticles. The results showed higher encapsulation efficiency and controlled release for acetylated banana starch nanoparticles because acetylation offers stronger hydrogen bonding interaction between the curcumin and the modified starch [79]. Recently, sago and gelose 80 starches were treated with octenyl succinic anhydride (OSA). The modified starches decreased the amylose contents. The original amylose contentforOSA sago starch and OSA gelose 80 were 25.27%and 70.70% respectively. After modification due to structural changes, there was a remarkable increase in particle size for both OSA sago starch and OSA gelose(80 29.89 μm and 20.37 μm) respectively [80]. The results are depicted in Fig. 4. Recently Rasana Colussi and colleagues prepared biodegradable films from acetylated starches with different amylose content. They treated acetic anhydride with high and low medium amylose starches to amend the properties of the films. Acetylation reduced the tensile strength, increased the water solubility and rapid degradation of films [81]. Bao Zhang et al. synthesized octenyl succinylated cassava starch (OSCS) by reacting cassava starch with octenyl succinic anhydride. The results showed that this method is very efficacious for enhancing slowly digestible starch (SDS) 23.59% and resistant starch contents (RS) 53.13% in starch samples [82]. Recently, tapioca starch was esterified by treating with imidazolide of 3-carboxypropyl-trimethylammonium chloride (CPTMACl) in the presence of solvent dimethyl sulfoxide (DMSO). The synthetic route for the reaction is shown in Scheme 3. The novel modified starch, (starch-4-(N, N, N-trimethylammonium) butyrate chloride), showed a significant effect against two bacterial strains Staphylococcusaureus and Klebsiellapneumonia [83]. D. Lin et al. have prepared the corn starch acetate by providing the reaction conditions like amount of acetic anhydride at 12%, time of microwave radiations at 11 min, and power of the radiations at 100 W. The modified acetate starch showed much better solubility, expansion force, water separation and water absorption than native corn starch [84]. The starch molecule has a large number of hydroxyl groups which can be esterified by an acid and its derivatives. Starches with four different types and variant ratio of amylopectin and amylose contents were esterified by Fang with an acid chloride of various chain lengths.

Fig. 6. Native and citrate starches with variant DS-values (A) swelling power and (B) solubility [87] Copyright, 2015, Elsevier.

So, in the presence of the external redox agent, enzyme stimuli and the combination of both showed controlled multi-responsive release behavior of rhodamine B [76].Acha starch was parted and cross-linked using citric acid. The modified starch just increased the emulsion capacity while decreased the solubility, oil absorption capacity, water absorption capacity, bulk density, foam capacity as compared to the native acha starch [77]. 2.3. Acetylation/esterification of starch The introduction of an acetyl group to the compound simply by the removal of hydrogen of the hydroxyl group to form the ester is called acetylation. Abdul Rahim et al.synthesized acetylated starch by treating

Fig. 7. (A) tensile strength and (B) bending strength of degraded composites [89] Copyright, 2015, Elsevier. 16

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Scheme 4. Schematic summary of esterification [85–92].

The acid chloride having the chain length between 6 and 8 carbon atoms are perfectly esterified because in such a case the esterification reaction is dominant, but if the chain length is shorter than 6 or more than 8 carbon atoms, the reverse reaction (hydrolysis) is dominant which decreases the rate of esterification. The maximum degree of substitution (DS) was found to be 3 [85]. Acylated starches against carbon-chain lengths with different DS-values are shown in Fig. 5. Chi et al. under different conditions of temperature (50 °C, 65 °C and 75 °C) acetylated corn starch with acetic anhydride and got a different degree of substitution (DS) (0.85, 1.78 and 2.89) [86]. Mei et al. found that increasing the concentration of citric acid from 10% to 30% during esterification of cassava starch, the degree of substitution (DS) also increased from 0.058 to 0.178. But if the concentration is exceeded to 40%, the degree of substitution is decreased to 0.129. The below Fig. 6 shows the relationship among temperature, swelling power, and solubility. Up to 65 °C, there is no substantial change in solubility and swelling power but as the temperature increases both the properties also increased. However, the esterified starch have low solubility and swelling power as compared to the native starch because of the increase in DS value [87]. The potato starch oleate ester was synthesized by reacting potato starch with 1-butyl-3-methylimidazolium chloride in the presence of catalyst immobilized lipase. The results obtained showed a maximum degree of substitution (DS) (0.22) if the reaction performed at 60 °C for 4 h. The obtained product might be used as a bearer for bioactive agents and biodegradable packaging [88]. The esterified corn starch with maleic anhydride and its composite with polylactic acid showed higher bending and tensile strength than the native starch (NS)/PLA composite, the results depicted in the below Fig. 7 [89]. Lipase-coupling esterification of octenyl succinic anhydride with waxy corn starch was found that the reaction efficiency of 84.05 ± 2.07% could be obtained in 30 min with a degree of substitution (DS) equal to 0.0195. For the production of product on large scale in industries, the decreased

reaction time is favored [90]. The starch betainet was synthesized by reacting starch with betainyl chloride. This esterified starch is widely used in the paper industry for increasing the strength of paper [91]. The schematic summary of esterification is given in Scheme 4. 2.4. Dual modification of starch The combination of physical and chemical modification methods or chemical and enzymatic modification methods for the improvement of properties and utilization of starches is called dualmodification. The most frequently used technique is dual chemical modification like cross-linking/acetylation or cross-linking/hydroxypropylation and acetylation/oxidation [93–96]. The dual modification of cross-linking and heat-moisture treatment of the waxy maize starch had a remarkable effect on the physiochemical and in vitro digestibility. The modified starch lowers the past clarity, swelling power, and ΔH, but increases the melting temperature and crystallinity [97]. Dual enzyme modification of oat starch with β-amylase and transglucosidase was performed. Due to this dual enzymatic modification granules changed to a fibrous structure having cracks on the surface. The type of crystallinity changed from A-type to A + V type pattern. Moreover, the resistant starch contents increased to 17.14–23.9% from 35.81 to 48.88% [98]. S. Pietrzyk et al. oxidized the corn and corn waxy starches by treating with NaClO and acetylated by using acetic anhydride. The modified starches showed the better water solubility, greater rheological stability and less susceptibility to retrogradation [99]. The acid modification of sorghum starch with lactic acid (3%) was pursued by oxidation with active chlorine (1.5%) introducing carbonyl and carboxyl group in the modified starch. The films produced from oxidized and dual modified starches were responsible for changing the stiffness, increasing tensile strength, but decreased the elongation [100]. The dually modified starch also increased the swelling property and solubility due to interruption of inter and intra molecular hydrogen bonding. 17

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Fig. 8. Chemical reaction (A) sodium phytate cross-linking of starch. (B) hydrogen peroxide (H2O2) of oxidation starch R:Starch polymer [102] Copyright, 2017, Elsevier.

The raw potato starch was acid hydrolyzed with HCl solution, which is further treated with propylene oxide to obtain acid-hydrolyzed-hydroxypropylated potato starch (AHP). The rheological properties like flow behavior and sol-gel transition of the dually modified starch depended on the molecular structure. So, any increase in the degree of hydrolysis or content of propylene oxide would increase the flow behavior index and decrease the consistency coefficient of the modified starch [101]. F. Sun et al. synthesize the oxidized wheat starch (OWS) and cross-linked wheat starch (CLWS). Then, they dually modified the wheat starches by treating with 12% hydrogen peroxide (H2O2) and 2% sodium phytate to obtain the cross-linked oxidized wheat starch (COWS) and oxidized cross-linked wheat starch (OCWS) [102]. The synthetic reaction is shown below in Fig. 8. Due to dual modification the properties like peak viscosity and swelling power were increased, while past clarity, solubility, and water binding capacity were lowered. The most suitable schematic sketch of cross-linked oxidized wheat starch (COWS) is shown in Fig. 9. Recently the physicochemical and functional properties of lentil starch were investigated. Sonication did not affect these properties substantially but the combined action of sonication and irradiation changed the physicochemical and functional properties significantly by increasing water absorption capacity, oil absorption capacity, solubility and transmittance [103]. Recently, the dual modification of potato starch by annealing and ultra-high pressure has greatly increased the pasting viscosity [104]. The elephant foot yam starch was dually modified to check out the change in physio-chemical properties. The modification was done by two different methods and got two different types of modified starches, oxidized cross-linked starch, and crosslinked oxidized starch. For the preparation of oxidized cross-linked starch, they oxidized the starch with sodium hypochlorite and then

cross-linked with sodium trimetaphosphate (STMP). In case of oxidized cross-linked starch, they first cross-linked starch with STMP and then oxidized with sodium hypochlorite. Synthetic scheme is shown in Scheme 5. The obtained result showed that oxidized cross-linked starch has bettered solubility, thermal characteristics and paste clarity than crosslinked oxidized starch. The information related to solubility are shown in Fig. 10 [105]. 2.5. Oxidation of starch Ozone is a very strong oxidizing agent and it is rapidly decomposed into oxygen. In the recent research, the potato starch was modified effectively by oxidation with ozone in aqueous solution. The systematic setup used for ozonation is shown in Fig. 11 [106]. This ozonation did not affect the crystallinity of the starch, but enhanced the different properties like paste clarity, pasting and gel texture. The proposed mechanism of action of ozone in the starch molecule is shown in Fig. 12. The oxidized maize starch was prepared by treating with sodium hypochlorite and active chlorine. The solubility of the films of oxidized starch was lowered, and it is because oxidation produced carbonyl and carboxyl groups which affected the intra-molecular bonding and interaction between the amylose molecules which is responsible for the reduction of water absorbance of the modified starch [108]. Y. Yu et al. synthesized highly oxidized corn starch in the presence of H2O2 using copper-iron catalyst at different temperatures (70–98 °C) and duration (1–4 h). This highly oxidized starch with a reasonable degree of oxidation and molecular weight would be able to coordinate with zirconium and amended the tanning process. By increasing the degree of 18

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Fig. 9. Schematic sketch of cross-linked oxidized wheat starch (COWS) [102] Copyright, 2017, Elsevier.

biocompatible nanogold (AuNPs). The synthetic mechanism for nanogold particles is shown in Fig. 13 [110]. The produced AuNPs were used as an active catalyst to reduce p-nitroaniline and increase the reduction rate from 12.1%–39.2% justin2 hours. AuNPs showed antibacterial efficacy for different bacterial species(especially against S. aureus). P. Naknaen et al. oxidized the jack fruit seed starch with NaOCl having different active chlorine concentration (1–5%). The results showed that the properties of the modified starch depend on the active chlorine concentration. At a high level of active chlorine (4–5%) and incubation temperature the swelling power increased [111]. Recently potato starch was oxidized by sodium hypochlorite with different chlorine concentrations (0, 0.1, 0.2, 1.0, 2.0, 3.0 and 4.0 g for 100 g of starch). The properties of potato starch depend on the concentration of sodium hypochlorite. High concentration of sodium hypochlorite increased the carboxyl and carbonyl contents, pasting temperature and solubility, while decreased the gel strength, swelling power and relative crystallinity [112]. Oxidized starches have the ability to enhance physio-chemical properties like film formation and adhesion in some pattern which is

Scheme 5. Synthetic pathway of modified starches via (a) oxidation and (b) cross-linking [105].

oxidation the molecular weight and particle size decreased [109]. The native maize starch with different weight was oxidized with H2O2, followed by dropwise addition of gold chloride solution and sodium hydroxide or sodium carbonate at 25 °C. By adding base, the color of the reaction mixture turned blue which indicated the production of 19

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et al. synthesizedcarboxymethyl starch-g-lactic acid-co-glycolic acid (CMS-g-PLGA) and magnetite (Fe3O4) nanocomposite by grafting with L-lactic acid and glycolic acid in the presence of catalyst Sn(Oct)2, and proposed mechanism is shown in Scheme 7. The composites were achieved by a double emulsion method. The size, saturation magnetization and zeta potential of CMS-gPLGA/Fe3O4 were 773 nm, 41.96 emu g−1and -20.00 mV respectively. So it is assumed that CMS-g-PLGA/Fe3O4nanocomposite can play a significant role in the field of biomedical and pharmaceutics [120]. Cassava starch-graft-poly (acrylonitrile) was synthesized by treating cassava starch with acrylonitrile (AN) in the presence of ceric ammonium nitrate (CAN) and N,N-methylenebis(acrylamide) (MBA) as free radical initiator and cross-linking agent [121]. The results showed that this coated urea sustained the release of nitrogen to the soil. It was investigated that nitrogen released from starch graft coated urea after 180 days, while from the uncoated urea it took one month. The water retention capacity decreases by increasing the percentage of grafting. The water retention capacity for coated urea ranged from 74.2% to 426.6%. The starch-g-poly (butyl acrylate) (starch-g-PBA) was prepared by reacting butyl acrylate with starch in the presence of a biocatalyst, horseradish peroxidase (HRP) and hydrogen peroxide plus acetophenone [122]. The synthetic route is shown in Fig. 14. Recently thermoplastic starch was prepared by treating starch with sorbitol and water. Their composite films were formed on a chillrole system, which was modified by grafting acrylonitrile on starch. The modified films showed excellent antibacterial activity against the two bacterial strains like gram staphylococcus aureus and Pseudomonasaeruginosa [123]. The novel modified Caffeic acid-g-starch was prepared by grafting of caffeic acid onto a starch in DMSO by using N, N-carbonyl diimidazole (CDI) [101]. Mechanistic pathway for the synthesis of modified starch is given in Fig. 15. The production of poly(butyl acrylate) chains on the starch improved the thermal stability of starch, and also showed better elastic behavior. Further, it was also investigated that the addition of ethanol gelatinization enhanced the grafting efficiency and grafting percentage. The grafting increased thermal stability and the modified starch showed amorphous crystallinity. Furthermore, after grafting the free radical scavenging action and reducing the power of modified starch increased to the highest degree, which suggested the characteristics of starch-gcaffeic acid as an innovative antioxidant agent. D V. Ludin et al. introduced a new way of synthesis of starch-graft-poly (methyl acrylate) copolymer. This method was comprised of two stages. Stage one is borylation of hydroxyl groups of starch and stage second is the graft-copolymerization, which involved polymerization of methyl acrylate stamped down by 1, 4-benzoquinone and SH2-substitution at the boron atom. Due to

Fig. 10. The consequence of temperature on the solubility of dually modified elephant foot yam starches [105]Copyright, 2016, Elsevier.

useful in drug delivery system for boosting a controlled release of active agents [113]. Most of the starch-based derivatives are produced by treating an oxidizing agent with a starch slurry at the particular pH and temperature [114]. The oxidized starch derivative depends upon the two basic starch things i.e. reagent used and oxidative method applied, which improves the physicochemical properties of the indigent starch particles. The change in the physicochemical properties, i.e. decrease in viscosity, low-temperature stability and high clarity of the oxidized starch derivatives play a vital role in the field of food biotechnology and pharmaceutical industries [115]. As the starch has a bunch of hydroxyl groups in their structure which were oxidized to carboxyl or carbonyl groups followed by depolarization responsible to cleaved the links present between the glucopyranose units [116,117]. Starch oxidized by the sodium periodate is very useful for cross-linking, polymer compatibility, strength and barrier capacity of the biodegradable active films [118]. The oxidized starch (OS) almost showed better stability, film forming, lower molecular size, and viscosity. The most important oxidized starch dialdehyde synthesis is shown in Scheme 6. The most favorable oxidant used for this synthesis is a periodic acid which oxidizes the adjacent hydroxyl to aldehyde and then to carboxylic functional group [10]. 2.6. Grafting on starch The process of covalent attachment of monomers on the main chain of the polymer and their further polymerization on the same main chain is called grafting. Process time for this phenomenon is inconsistent and may be accomplished in minutes, hours or days [119].N. Tudorachi

Fig. 11. Assembly used for starch ozonation system [106] Copyright 2017, Elsevier. 20

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Fig. 12. A pictorial illustration of the projected mechanism of ozone action in starch molecule [107] Copyright, 2017, Elsevier.

Fig. 13. Mechanistic pathway for the preparation of colloidal solution by using oxidized starch under a basic environment at 25 °C [110] Copyright, 2017, Elsevier.

homogeneity and selectivity, of this route of graft-copolymerization has priority over other methods [124]. The synthetic route is shown in Scheme 8. Recently corn starch grafted polyacrylic acid was prepared through a new approach by means of oxy-catalyst as an originator and aluminum triflate [Al(OTf)3] as co-catalyst [125]. The synthetic route is shown in Scheme 9. This new approach proved that in free radical polymerization catalyst could serve well as an alternate for ferrous ammonium sulfate as an initiator catalyst. S. Li et al. prepared starch-grafted acrylamide by grafting acrylamide onto mung bean starch in the presence of ceric ammonium nitrate (CAN) and 3-Chloro-2-hydroxypropyltrimethylammoniumchloride (CHPTAC) as an etherification agent. The modified starch is

environment-friendly, biodegradable and has flocculation effect [126]. The whole synthetic route and mechanism are shown in Fig. 16. The sago starch grafted poly (methyl methacrylate) was prepared in the presence of variant initiators system under an inert atmosphere in an aqueous medium. The synthetic Scheme 10 is shown below. By using initiator ceric ammonium nitrate the utmost grafting percentage (%G) was assured 246% at the most favorable conditions like 141 mmol of methyl-methacrylicacid, 0.4 mmol of nitric acid, 2.0 mmol of the CAN, 70 °C reaction temperature and 2-h reaction period. Similarly, for potassium persulfate (PPS), the maximum (%G) was 90%. The most favorable conditions were assumed to be; methyl-methacrylic acid 47 mmol, PPS 1.82 mmol, reaction temperature of 50 °C and reaction period 1.5-h. 21

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acid) (AS-g-PAA) has been synthesized by acryloylation followed by grafting. First, the slurry was produced by dissolving starch in water at 80 °C, and then N, N-dimethylacetamide, LiCl, dry pyridine and acryloyl chloride were added to obtain the acryloylated starch. Finally, the acryloylated starch in the presence of Fenton's initiation system (Fe2/ H2O2) was treated with acrylic acid. The whole reaction pathway is shown in Scheme 12 [129]. The product showed improved properties like adhesion and film forming. Furthermore, the product showed slow but surely enhanced absorbency by means of the extent of neutralization and retention. In short, absorbency showed dependency on the monomer, initiator, and degree of neutralization. Details regarding absorbency are shown in Fig. 18. 3. Applications Starch can be used in different fields, but the most important is their use as an adsorbent. Here are some of the vital uses of starch as an adsorbent for the removal of ammonia, phenol, heavy metals and dyes.

Scheme 6. The mechanism for starch oxidation [10].

3.1. Ammonia adsorption

This modified starch may have functioned as a biodegradable plastic [127]. Starch grafted polyacrylamide (St-g-PAM) was prepared by reacting maize starch with acrylamide in water. The mixture was charged with ceric ammonium nitrate (CAN), and microwave radiation of power 800 W was passed. After the microwave irradiation, the mixture was cooled and starch grafted polyacrylamide (St-g-PAM) was obtained. The synthetic route is shown in Scheme 11 [128]. The intrinsic viscosity and algal flocculation showed direct proportionality with the grafting percentage of the graft copolymer. The ‘Jar test’ process was employed for the study of algal flocculation efficacy of modified starch and the obtained results are shown in Fig. 17. The results demonstrated that the biomass obtained from the algal harvesting might be utilized for biodiesel production, food supplements for human and animals [128]. A superabsorbent polymer acryloylated starch-grafted-poly (acrylic

Gaseous ammonia (NH3) has a distinctive pungent smell and is an important basic component because it is the precursor for derived aerosol formation in the environment [130–134]. Most of the harmful effects of ammonia cause irritation of nasal cavities and tracheobronchitis, chemical pneumonitis, dyspnea, laryngospasm, noncardiogenic pulmonary edema, irritation of eyes, headache and respiratory failure [18–22] so, it is necessary to remove ammonia.M. Haroon et al. used carboxymethyl starch-g-polyvinylpyrrolidone (CMS-g-PVP) as a sorbent for the removal of ammonia and rhodamine 6G. The synthetic Scheme 13 shows the synthesis of this modified starch [33]. The presence of the hydroxyl and carboxyl groups on the carboxymethyl starch and the insertion of pyrrolidone, on the backbone of the modified starch were responsible to adsorb ammonia by forming hydrogen bonding. Scheme 14and Fig. 19below shows the adsorption

Scheme 7. Synthetic route of CMS-g-PLGA [120].

Fig. 14. Schematic illustration of the grafting reaction of BA onto the starch catalyzed by HRP [122] Copyright, 2017, Elsevier. 22

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Fig. 15. Synthesis of starch-g-caffeic acid [101] Copyright, 2017, John Wiley and Sons.

Scheme 8. Showed stage one and stage second [124].

Scheme 9. Synthesis of starch grafted polyacrylic acid [125].

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Scheme 10. The synthetic mechanism for sago starch grafted poly methyl methacrylate [127].

Fig. 16. A general illustration of (a) synthesis and (b) mechanism for MBSgrafted AM [104] Copyright, 2017, Springer Nature.

mechanism for ammonia and graph for adsorption of ammonia respectively. The graph shows a direct relationship between the concentration of CMS-g-PVPs and adsorption capacity [135]. Q. Chen et al.grafted acrylic acid on amylose backbone to synthesize amylose grafted poly- (acrylic acid). This modified starch was tested as a sorbent for the removal of ammonia. The synthetic route for the reaction is shown in Scheme 15. The obtained results showed that by increasing the carboxylic functional groups on amylose structure, their adsorption capacity for the ammonia adsorption is also increased. The reason for this adsorption is as the carboxylic groups provided by the acrylic acid are acidic in nature and ammonia is basic in nature so it grabs the ammonia via Lewis acid-base concept [34]. The results for ammonia adsorption in the form of graphs are depicted in Fig. 20. The cigarette smoke contains so many toxic compounds like hydrocyanic acid, crotonaldehyde, tar, ammonia and total particulate matter. Recently, corn porous starch (PS) and cross-linked porous starch (PPS) were tested as a sorbent for the removal of these toxic materials. The obtained results showed that PS reduced ammonia 8.91–11.72% while the percentage for PPS was 28.08–35.93% [36]. Recently, the experiment was conducted in which amylose and

Scheme 11. The synthetic route for the synthesis of starch grafted polyacrylamide (St-g-PAM) [128].

amylopectin were pyrolized at 400 °C. After this, the pyrolized amylose and amylopectin were oxidized by oxidizing agents like HNO3 and H2SO4. The main aim of this oxidation was to change the surface morphology by producing carboxylic, lactonic and phenolic groups. These modified starches were used for the adsorption of ammonia and carbon disulfide. The results showed that as the modified amylose and amylopectin have the acidic groups, ammonia made direct interaction with carboxylic, lactonic and phenolic groups [35,136,137]. B. Shahrooie et al. prepared starch-basedhydrogelnanocomposite by dispersing starch in deionized water and cross-linking agents like maleic anhydride and fumarate-alumoxane (Fum-A). This new starchbasedhydrogelnanocomposite was employed as asorbent for the

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adsorption of ammonium ion from the aqueous medium. NH4+ions interacted with the functional groups present on the hydrogel nanocomposite via hydrogen bonding, and these interactions were responsible for the chemical adsorption of NH4+ [138]. The proposed mechanism for the adsorption of NH4+ by starch-basedhydrogelnanocomposite is shown in Fig. 21. 3.2. Phenol adsorption Phenol is regarded as a distinctive organic contaminant since it is unsafe for animals, human and plants so, it is necessary to adopt some methods to remove phenol from different sources. From the sources like water, adsorption is the best technique to remove phenol [139]. C. Qiu et al. used the worm-shaped amylopectin nanoparticles (APNPs) and spherical shape amylose nanoparticles (AMNPs) for the removal of polyphenol. The amylose nanoparticles exhibited a spherical shape with 20–50 nm particle size, while the amylopectin nanoparticles displayed worm-like shape having a length of 200–500 nm and width of 10–20 nm. The results showed that both the nanoparticles have a higher binding affinity to grab polyphenols [38]. Recently, from ginko seed starch carbon spherules were prepared. The ginko seed starch spherules were tested for the adsorption of phenol, p-nitrophenol, and p-chlorophenol. From the result, it was found that phenol has greater adsorption affinity from the others. It was also found that phenol is physically adsorbed and the process isexothermic [39]. Q. Zhang et al. prepared two types of cross-linked polymer by usingcross-linking agents like hexamethylenediisocyanate (HMDI) and 4, 4′-methylene-bis-phenyldiisocyanate (MDI). Polymer 1 represented the starch polymer prepared by MDI and polymer 2 by HMDI. These two synthesized polymers were used for the sorption of polyphenols such as 2,4-dinitrophenol, onitrophenol, p-nitrophenol, and 2-s-butyl-4,6-dinitrophenol from the aqueous medium. The obtained results showed a higher sorption efficacy for polymer 1 as compared to polymer 2. It is because of the stiff structure of polymer 1 due to higher cross-linking as compared to polymer 2, that showed a greater affinity for the phenolic compounds [140].

Fig. 17. Starch grafted polyacrylamide flocculation efficacy study via standard ‘Jar test’ procedure [128] Copyright, 2012, Elsevier.

3.3. Heavy metals adsorption Nowadays, pollution caused by heavy metals is one of the most rapidly growing problems in the environmental problems [141,142] so it must be eradicated urgently.

Scheme 12. Synthetic steps involved in the synthesis of (a) acryloylchloride, (b) acryloylated starch (c) acryloylated starch-poly acrylic acid [129].

Fig. 18. Variation of contents (a) monomer, (b) initiator, (c) extent of neutralization and their effect on the absorbency [129] Copyright, 2014, John Wiley and Sons. 25

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Scheme 13. Synthesis of CMS-g-PVP [33].

Q. Liu et al. recently used oxidized starch nanoparticles (SNPs) to investigate their adsorption efficacy for heavy metals like Cu2+ and Pb2+. The starch nanoparticles due to small size, large surface area, and negative charge showed higher adsorption capacity for heavy metals. The heavy metals linked with the starch nanoparticles via electrostatic interactions [41]. The starch-functionalized graphene oxide composite (GO-starch) was prepared by suspending graphene oxide and starch in anhydrous dimethyl sulfoxide. This GO-starch was successfully used for the uptake of Cd (II) ions from the aqueous medium. Thermodynamic studies favored that the adsorption of Cd (II) under optimized condition was spontaneous and endothermic [143]. The contaminated water has many heavy metals like Pb, Co, Cu, Cd, and Ni. Starch coated titanium

Scheme 14. Proposed mechanism for the sorption of ammonia on carboxymethyl starch-g-polyvinylpyrrolidones [33].

Fig. 19. (a) Variations in pH of HCl solution with respect to change in concentration of CMS-g-PVP-5 (b) variations in ammonia adsorption with respect to change in concentration of CMS-g-PVP-5 (c) variation in pH of HCl solution with time using carboxymethyl starch and carboxymethyl starch-g-polyvinylpyrrolidones [33] Copyright, 2018, Elsevier.

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spontaneous. At optimized condition, the maximum sorption capacities for Pb, Cu, and Cd were found to be 93.5%, 88.4% and 85.5% respectively [146]. For the removal of toxic heavy metals like Cu(II), Fe(III), Zn(II), or Ni(II) ions from the aqueous solution, cationic depolymerized barley starch, sulfonylated starch and cationized depolymerized potato peel waste were used as binding agents. The results showed that the maximum binding capacities of cationized depolymerized starches (sulfonylated starch and waste starch) for Fe(III), Zn(II), and Cu(II) ions were85–95%and 78–94%respectively [147]. The magnetic crosslinked starch-graft-poly-(acrylamide)-co-sodium xanthate was used as a flocculant and an adsorbent for the removal of heavy metals. It was observed that magnetic crosslinked starch-graft-poly (acrylamide)-co-sodium xanthate adsorb 78.3% of Pb2+ and 63% of Cu2+ from their respective salt solution. The decontamination mechanism is shown in Fig. 23 [148]. Cadmium is highly toxic heavy metal. This contaminates the water which severely affects the human life. Cassava starch-based superabsorbent polymers (CST- SAPs) were used as sorbents to adsorb Cd2+ ions. The maximum adsorption value of 347.46 mg/g for Cd2+ was obtained by providing the optimized conditions like the initial concentration of 200 mg/L, pH 6.0, contact temperature and time of 323 K and 6 h, and 0.1 g adsorbent content [149]. The adsorption is due to the formation of complexation between Cd2+ and carboxylic groups. X. Ma et al. used porous starch xanthate (PSX) and porous starch citrate (PSC) for the adsorption of Cd2+. The maximum sorption capacity for PSX and PSC were found to be 109.1 and 57.6 mg/g. The porous structure of both these two starches has xanthate and carboxylate groups which grab the Cd2+ via chelation and electrostatic interaction [150]. The linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organomontmorillonite hydrogel composite was prepared through emulsion polymerization method by mixing waste linear low-density polyethylene, starch-acrylicacid, and organo-montmorillonite. This hydrogel composite was used as an adsorbent for the removal of Pb (II) ion. The maximum adsorption capacity of the hydrogel composite for

Scheme 15. Mechanistic pathway for the synthesis of amylose grafted poly (acrylic acid) [34].

dioxide nanoparticles were used for the removal of Pb, Co, Cu, Cd, and Ni. Synthetic and adsorption mechanism for starch coated titanium dioxide nanoparticles is shown inFig. 22 [40]. L. Ekebafe et al. used hydrolyzed starch graft poly-(acrylic acid) and starch graft poly(acrylonitrile) copolymers as adsorbents for the deletion of Pb2+ from aqueous solution. The adsorption capacity for starch graft poly (acrylic) acid was 118.61 mg/g, while for starch graft poly (acrylonitrile) was 115.83 mg/g. Thermodynamic results displayed that the adsorption phenomenon was endothermic and spontaneous [144]. Similarly, Z. Pour et al. used novel magnetic nanocomposite hydrogel (m-CVP) beads for removal of Pb (II), Cu (II) and Cd (II) and crystal violet (CV) and congo red (CR) dye from water. It was prepared by direct gelation of poly (vinyl alcohol) (PVA), carboxymethyl starch-g-polyvinyl imidazole (CMS-g-PVI) and Fe3O4 blend in the solution of boric acid followed by crosslinking with glutaraldehyde (GA). The obtained results show the highest absorbance values for Pb (II), Cu (II) and Cd (II) which are found to be 65.00, 83.60, 53.20 mg/g respectively. This chemisorption process was endothermic and spontaneous [145]. S. Basri et al. introduced carboxymethyl sago starch-acid hydrogel and tested for the sorption of heavy metals especially Pb, Cu and Cd from their respective aqueous solution. During sorption, the negative value of ΔH and ΔG showed that the process was exothermic and

Fig. 20. (a) and (b) the technique of filling filter tips (c) and (d) pH value and ammonia adsorption in 8 min [34] Copyright, 2016, Elsevier.

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Fig. 21. The proposed chemical adsorption mechanism for ammonium ion [138] Copyright, 2015, Elsevier.

Fig. 22. Procedure for synthesis and adsorption mechanism [40] Copyright, 2018, Taylor & Francis. 28

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Fig. 23. Sanitization mechanism of M-CSAX [148] Copyright, 2017, Taylor & Francis.

Pb (II) ion was found to be 430 mg/g. The adsorption mechanism is shown in Fig. 24 [151]. Recently, starch-stabilized Fe/Cu nanoparticles were successfully used for the adsorption of As (III) and As (V) from the synthetic arseniccontaminated water. The experimental results showed highest adsorption capacity for As (III) and As (V) at 90.1 mg/g and 126.58 mg/g respectively at pH 7. The surface of the nanoparticles have oxygencontaining functional groups which form complexation with As (III) and As (V) and adsorb these heavy metals [126]. M. Naushad et al. also prepared more efficient adsorbent for the removal of the toxic Hg2+ metal ion. They used the starch/SnO2nanocomposite for the removal of Hg2+. The results showed the highest adsorption value of 192 mg g −1. The thermodynamic study showed that the process was spontaneous,

endothermic and chemisorptions. This adsorbent is easily desorbed [152]. The complete adsorption and desorption mechanism is shown in Fig. 25. 3.4. Dyes adsorption Dyes are extremely toxic, mutagenic and carcinogenic and cause different types of diseases in human beings and to aquatic life. Almost approximately 1 × 104 tons of dyes are consumed in textile industries all over the world every year. The survey analysis showed that every

Fig. 25. The mechanism for the adsorption and desorption of Hg2+ ion using starch/SnO2nanocomposite [152] Copyright, 2016, Elsevier.

Fig. 24. Proposed mechanisms for the adsorption of Pb(II) ion [151] Copyright, 2015, Elsevier.

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Scheme 16. The projected mechanism for the synthesis of St-AgNPs and adsorption of Malachite Green (MG) [156] Copyright, 2018, Elsevier.

year 100 tons of dyes contaminate water [153–155], which affect the human and aquatic life in different aspects so; this is very important to remove dyes from the wastewater. S. Muzaffar et al. synthesized the starch silver nanoparticles (StAgNPs) by mixing 5 mL of 0.2% starch solution and 2.5 mL of 0.1 M L−1 AgNO3 solution by fast shaking at 60 °C. After that, 5 mL of an aqueous extract containing Malus domestica-Green Delicious (MD-GD) and Lagenariasiceraria (LS) was added drop-wise. The change in color from yellow to black confirmed the formation of starch silver nanoparticles (St-AgNPs). The starch silver nanoparticles were used for the adsorption of industrial dye Malachite Green (MG). The obtained results showed that % removal efficiency (%RE) of St-AgNPs-LS and St-AgNPs-MD-GD was found to be 95.90% and 85.01% respectively [156]. The proposed mechanism for synthesis and adsorption is shown below in Scheme 16. Similarly, the malachite green (MG) dye from aqueous solution was also removed by polysaccharide-based nanocomposite hydrogel adsorbent (NHA). The results showed that the sorption process was physical, endothermic and spontaneous. For MG dye the maximum adsorption capacity was found to be 297 mg/g [42]. M. Zubair et al. synthesized the starch-NiFe-layered double hydroxide (S/NiFe-LDH) composite by co-precipitation method and was employed for the adsorption of methyl orange (MO) dye. They also prepared the two hybrids S/NiFe-LDH (1:1) and S/NiFe-LDH (1:2) with different ratios of NiFe-LDH and starch. The S/NiFe-LDH composite was found to be a good adsorbent for the removal MO.

The maximum adsorption capacities from Langmuir isotherm were found to be 246.91 mg/g, 358.42 mg/g, and 387.59 mg/g for NiFe-LDH, S/NiFe-LDH (1:2) and S/NiFe-LDH (1:1) respectively [157]. Recently chitosan starch-based composites were used for the adsorption of congo red dye. This carcinogenic dye was removed via flocculation method and their interaction with polysaccharide starch [43]. S. Mallakpour et al. modified the surface of multiwalled carbon nanotubes (MWCNT)s by ascorbic acid (AA) to enhance the dispersion in the starch matrix. By ultrasonication method, the starch-based nanocomposites (NCs) containing 3, 6 and 9 wt% of AA modified MWCNTs (AA-MWCNT)s were fabricated. The starch/AA-MWCNTs NCs were used for the adsorption of methyl orange dye. The results showed that starch/AA-MWCNTs NCs effectively removed the methyl orange dye via electrostatic interaction produced between sites present on the composite surface and dye molecules [158]. The chitosan/oxidized starch/silica (CS/OSR/Silica) hybrid membrane was also used for the removal of direct dyes Blue 71 and Red 31. The CS/OSR/Silica hybrid membrane was formed by using cross-linking agent 3-aminopropyltriethoxysilane (APTES) and oxidized starch. The results showed that CS/OSR/Silica hybrid membrane has optimized adsorption efficiency at pH 9.82 and 60 °C for direct dyes Red 31 and Blue 71 [159]. F. Ngwabebhoh et al. used a semi-interpenetrating network (IPN) superabsorbent chitosan-starch (ChS) hydrogel for the sorption of Direct Red 80 (DR80) dye. The findings of the experiment showed maximum sorption capacity was 312.77 mg/g for the hydrogel. The mean sorption energy for the Direct Red 80 (DR80)

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Scheme 17. Adsorption of Direct Red 80 (DR80) dye on the surface of chitosan-starch (ChS) hydrogel [160] Copyright, 2016, Elsevier.

dye was E = 11.34–14.9 kJ/mol which showed that the sorption process was chemisorptions, temperature dependent, endothermic and spontaneous [160]. Below is the mechanism for adsorption of Direct Red 80 (DR80) dye on the surface of chitosan-starch (ChS) hydrogel in Scheme 17. Recently, a novel magnetic nano-adsorbent (MNP@St-g-PVS) was used for the removal of malachite green (MG) and methylene blue (MB). The megnative nano-adsorbent was prepared in the presence of magnetic nanoparticles via graft copolymerization of vinyl acetate onto starch. Due to graft copolymerization acetate groups were transformed into hydroxyl groups proceeded by sulfation of the hydroxyl groups. Later this was used for the sorption of methylene blue (MB) and malachite green (MG). The adsorbent (MNP@St-g-PVS) showed maximum sorption capacity of 621 mg/g and 567 mg g−1for methylene blue (MB) and malachite green (MG) [161]. Similarly X. Yang et al. prepared activated hierarchical porous carbon spheres (AHPCS) from corn starch. To obtained fabricate, magnetic AHPCS, activated hierarchical porous carbon spheres (AHPCS) were loaded with CoFe2O4. The results showed that sorbent had well-developed pore size surface area and magnetic properties. It could adsorb more than 97% methylene blue in just 5 min [162]. The starch-g-PAAc/CNWs nanocomposites were synthesized and used for the sorption of dye methylene blue.

The investigation showed the highest methylene blue sorption capacity≈2050 mg/g of the dried hydrogel at pH 5 with the composite at 5 wt% (cellulose nanowhiskers). Almost 90% of methylene blue was removed by starch-g-PAAc/CNWs nanocomposites. The optimized conditions were achieved at pH 5. At this pH the negatively charged groups (eCOO-) on the sorbent interacted with the positive charge of methylene blue [163]. The adsorption mechanism is given below in Fig. 26. For the removal of methylene blue, G. Gong et al. used to fabricate magnetic carboxymethyl starch/poly(vinyl-alcohol)(mCMS/ PVA) composite gel. The mCMS/PVA showed outstanding sorption ability for methylene blue and appropriate magnetic separation ability. The adsorption ability of the adsorbent could be increased by adjusted the pH range from 4 to 9. This adsorbent was reusable and could be used for cleanup environment [164]. The starch incorporated acrylic gels were also reported for the adsorption of dyes named Safranine T (ST) and Brilliant Cresyl Blue (BCB) from the water. This starch incorporated acrylic gel was prepared via free radical polymerization of acrylic acid, AA/hydroxy ethyl methacrylate (HEMA), and sodium acrylate (SA) with starch in water. The results exhibited that amongst all the three types of gels the starch incorporated sodium polyacrylate gel displayed the maximum sorption of 9.7–85.3 mg/L (97–61% removal) and 9.1–83 mg/L (91–60% removal) for Safranine T (ST) and Brilliant

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Fig. 26. Adsorption mechanism of methylene onto Starch-g-PAAc/CNWs hydrogel nanocomposite [163] Copyright, 2015, Elsevier.

Cresyl Blue (BCB) respectively [165]. The synthetic route and adsorption mechanism showed in Scheme 18. Mercaptosuccinic acid (MSA) modified porous starch xerogel (PSX/ MSA) were used for there moval of gardenia yellow (GY), a natural colorant. The experimental results showed that the introduction of the carboxylic group from the mercaptosuccinic acid and porous structure from the starch xerogel enhanced their adsorption capacity as compared to the unmodified starch xerogel and potato starch [166]. The synthetic scheme and adsorption mechanism showed in Fig. 27. Currently, M. Haroon et al. synthesized the carboxymethyl starch-gpolyvinylpyrrolidone (CMS-g-PVP), which was used for the adsorption of Rhodamine 6G (dye). The results obtained showed that carboxymethyl starch-g-polyvinylpyrrolidone (CMS-g-PVPs) had a great affinity to adsorb the Rhodamine 6G via ionic interaction and hydrogen bonding [135]. The proposed mechanism for the sorption of Rhodamine 6G by CMS-g-PVPs is given in Scheme 19.

units linked through glycosidic linkage. Starch is well known for its biocompatibility, biodegradability, low cost and nontoxicity. In spite of all these beauties starch has some problem with their solubility in water, retrogradation, loss of viscosity and some groups of primary importance, so in order to overcome these short comings and to vast its application starch must be modified. In literature, starch is modified by many researchers in different ways. They introduced many functional groups on the starch backbone to give characteristics properties to the starch and used these starches for a different purpose. There are different techniques for modification starch such as chemical modification, physical modification, and enzymatic modification, but the most significant one is the chemical modification which comprises acid hydrolysis, cross-linking, acetylation/esterification, dual modification, oxidation and grafting. Amongst the other applications of modified starch, the most important one is its use as a sorbent for the removal of ammonia, phenol, heavy metals, and dyes. In literature, there is very little work published on starch as an adsorbent for the removal of ammonia and phenol. Now the time needs to explore some new ways to modify the starch and introduce such functional groups onto starch backbone which have good affinity to grab these toxic compounds (ammonia, phenol, heavy metals and dyes).

4. Conclusion Starch is the most abundant carbohydrate in nature, present as a food material in plants. It is the polymeric form of anhydrous glucose

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Scheme 18. Formation of PAS, SPS (starch incorporated acrylic or acrylate) or CPS (starch incorporated copolymer) gel and its interaction with Safranine T (ST) or Brilliant Cresyl Blue (BCB) dye [165] Copyright, 2015, Elsevier.

Fig. 27. A synthetic scheme of PSX/MSA and gardenia yellow (GY) sorption by the adsorbents [166] Copyright, 2016, Elsevier. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Scheme 19. Projected adsorption mechanism of Rhodamine 6G on CMS-g-PVP5 [135]. 33

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Conflicts of interest

pp. 541–568. [52] A. Rahim, S. Kadir, International Food Research Journal 24 (2017) 102. [53] N. Atichokudom-chai, S. Shobsngob, P. Chinachoti, S. Varavinit, Starch - Stärke 53 (2001) 577–581. [54] X. Kong, S. Kasapis, J. Bao, H. Corke, J. Sci. Food Agric. 92 (2012) 1800–1807. [55] R. Hoover, Food Rev. Int. 16 (2000) 369–392. [56] M. Jiang, Y. Hong, Z. Gu, L. Cheng, Z. Li, C. Li, Int. J. Biol. Macromol. 106 (2018) 320–329. [57] L. Yang, Y. Xia, Y. Tao, H. Geng, Y. Ding, Y. Zhou, Carbohydr. Polym. 188 (2018) 228–235. [58] P. Li, B. Gao, A. Li, H. Yang, Microporous Mesoporous Mater. 263 (2017) 210–219. [59] X. Wang, F. Wen, S. Zhang, R. Shen, W. Jiang, J. Liu, Int. J. Biol. Macromol. 96 (2017) 807–816. [60] B.B. Sanchez de la Concha, E. Agama-Acevedo, M.C. Nuñez-Santiago, L.A. BelloPerez, H.S. Garcia, J. Alvarez-Ramirez, J. Cereal Sci. 79 (2018) 193–200. [61] Y. Wang, H. Xiong, Z. Wang, L. Chen, Int. J. Biol. Macromol. 103 (2017) 819–828. [62] H. Singh, S. Thakur, J. Mukhrjee, T. Nayak, S. Kumar, B. Kaur, Starch Staerke 69 (2017). [63] M. Jiang, Y. Hong, Z. Gu, L. Cheng, Z. Li, C. Li, Int. J. Biol. Macromol. 106 (2018) 320–329. [64] D. Li, N. Yang, Y. Jin, L. Guo, Y. Zhou, Z. Xie, Z. Jin, X. Xu, Food Chem. 229 (2017) 57–65. [65] H. Singh, S. Thakur, J. Mukhrjee, T. Nayak, S. Kumar, B. Kaur, Starch Staerke 69 (2017) 1–10. [66] B.B. Sanchez de la Concha, E. Agama-Acevedo, M.C. Nuñez-Santiago, L.A. BelloPerez, H.S. Garcia, J. Alvarez-Ramirez, J. Cereal Sci. 79 (2018) 193–200. [67] H.-S. Kim, D.-K. Hwang, B.-Y. Kim, M.-Y. Baik, Food Chem. 130 (2012) 977–980. [68] Đ. Ačkar, J. Babić, D. Šubarić, M. Kopjar, B. Miličević, Carbohydr. Polym. 81 (2010) 76–82. [69] S. Lack, V. Dulong, L. Picton, D.L. Cerf, E. Condamine, Carbohydr. Res. 342 (2007) 943–953. [70] M. Gui-Jie, W. Peng, M. Xiang-Sheng, Z. Xing, Z. Tong, J. Appl. Polym. Sci. 102 (2006) 5854–5860. [71] H.-y. Kim, S.-M. Oh, J.-E. Bae, J.-H. Yeom, B.-Y. Kim, H.-S. Kim, M.-Y. Baik, Carbohydr. Polym. 178 (2017) 41–47. [72] Q. Chen, H. Yu, L. Wang, Z. ul Abdin, Y. Chen, J. Wang, W. Zhou, X. Yang, R.U. Khan, H. Zhang, RSC Adv. 5 (2015) 67459–67474. [73] K. Feng, G. Wen, Int. J. Polym. Sci. 9 (2017). [74] H. Heo, Y.-K. Lee, Y.H. Chang, Emir. J. Food Agric. 29 (2017) 463. [75] K. Chai, K. Lu, Z. Xu, Z. Tong, H. Ji, J. Hazard Mater. 348 (2018) 20–28. [76] T. Sun, C. Zhu, J. Xu, Soft Matter 14 (2018) 921–926. [77] S. Isah, A. Oshodi, V. Atasie, Chem. Int. 3 (2017) 150–157. [78] K. Zhao, B. Li, M. Xu, L. Jing, M. Gou, Z. Yu, J. Zheng, W. Li, Lebensm. Wiss. Technol. 90 (2018) 116–123. [79] L. Acevedo-Guevara, L. Nieto-Suaza, L.T. Sanchez, M.I. Pinzon, C.C. Villa, Int. J. Biol. Macromol. 111 (2018) 498–504. [80] N.Z. Abiddin, A. Yusoff, N. Ahmad, Food Hydrocolloids 75 (2018) 138–146. [81] R. Colussi, V.Z. Pinto, S.L.M. El Halal, B. Biduski, L. Prietto, D.D. Castilhos, E.d.R. Zavareze, A.R.G. Dias, Food Chem. 221 (2017) 1614–1620. [82] B. Zhang, J.-Q. Mei, B. Chen, H.-Q. Chen, Food Chem. 229 (2017) 136–141. [83] A. Pfeifer, R. Hampe, T. Heinze, Starch Staerke 69 (2017) 1–8. [84] D. Lin, W. Zhou, J. Zhao, W. Lan, R. Chen, Y. Li, B. Xing, Z. Li, M. Xiao, Z. Wu, Int. J. Biol. Macromol. 103 (2017) 316–326. [85] J. Fang, P. Fowler, C. Sayers, P. Williams, Carbohydr. Polym. 55 (2004) 283–289. [86] H. Chi, K. Xu, X. Wu, Q. Chen, D. Xue, C. Song, W. Zhang, P. Wang, Food Chem. 106 (2008) 923–928. [87] J.Q. Mei, D.N. Zhou, Z.Y. Jin, X.M. Xu, H.Q. Chen, Food Chem. 187 (2015) 378–384. [88] A. Zarski, S. Ptak, P. Siemion, J. Kapusniak, Carbohydr. Polym. 137 (2016) 657–663. [89] Y.f. Zuo, J. Gu, Z. Qiao, H. Tan, J. Cao, Y. Zhang, Int. J. Biol. Macromol. 72 (2015) 391–402. [90] J. Xu, C.-w. Zhou, R.-z. Wang, L. Yang, S.-s. Du, F.-p. Wang, H. Ruan, G.-q. He, Carbohydr. Polym. 87 (2012) 2137–2144. [91] H. Granö, J. Yli-Kauhaluoma, T. Suortti, J. Käki, K. Nurmi, Carbohydr. Polym. 41 (2000) 277–283. [92] M. Haroon, L. Wang, H. Yu, N.M. Abbasi, M. Saleem, R.U. Khan, R.S. Ullah, Q. Chen, J. Wu, RSC Adv. 6 (2016) 78264–78285. [93] C.S. Raina, S. Singh, A. Bawa, D. Saxena, Eur. Food Res. Technol. 223 (2006) 561–570. [94] K.O. Adebowale, T.A. Afolabi, B.I. Olu-Owolabi, Carbohydr. Polym. 65 (2006) 93–101. [95] P.B. Zamudio-Flores, A.V. Torres, R. Salgado-Delgado, L.A. Bello-Pérez, J. Appl. Polym. Sci. 115 (2010) 991–998. [96] J. Huang, H.A. Schols, Z. Jin, E. Sulmann, A.G.J. Voragen, Carbohydr. Polym. 68 (2007) 397–406. [97] E.Y. Park, J.-G. Ma, J. Kim, D.H. Lee, S.Y. Kim, D.-J. Kwon, J.-Y. Kim, Food Hydrocolloids 75 (2018) 33–40. [98] A. Shah, F. Masoodi, A. Gani, B. Ashwar, Int. J. Biol. Macromol. 106 (2018) 140–147. [99] S. Pietrzyk, T. Fortuna, M. Łabanowska, L. Juszczak, D. Gałkowska, M. Bączkowicz, M. Kurdziel, Food Chem. 240 (2018) 259–267. [100] B. Biduski, F.T. da Silva, W.M. da Silva, S.L.d.M. El Halal, V.Z. Pinto, A.R.G. Dias, E. da Rosa Zavareze, Food Chem. 214 (2017) 53–60. [101] J. Liu, X. Wang, R. Bai, N. Zhang, J. Kan, C. Jin, Starch Staerke 70 (2017) 1–7. [102] F. Sun, J. Liu, X. Liu, Y. Wang, K. Li, J. Chang, G. Yang, G. He, Food Res. Int. 100

There are no conflicts to declare. Appendix A. Supplementary data Supplementary data to this article can be found online at https:// doi.org/10.1016/j.carres.2019.02.007. References [1] A.M. Smith, Biomacromolecules 2 (2001) 335–341. [2] R.F. Tester, J. Karkalas, X. Qi, J. Cereal Sci. 39 (2004) 151–165. [3] P. Ambigaipalan, R. Hoover, E. Donner, Q. Liu, S. Jaiswal, R. Chibbar, K.K.M. Nantanga, K. Seetharaman, Food Res. Int. 44 (2011) 2962–2974. [4] F. Xie, E. Pollet, P.J. Halley, L. Avérous, Prog. Polym. Sci. 38 (2013) 1590–1628. [5] M. Koller, Recent advances in biotechnology, Microbial Biopolyester Production, Performance and Processing Microbiology, Feedstocks, and Metabolism, vol. 1, Bentham Science Publishers, 2016. [6] M.S. Madihah, A.B. Ariff, K.M. Sahaid, A.A. Suraini, M.I.A. Karim, World J. Microbiol. Biotechnol. 17 (2001) 567–576. [7] C. Qiao, G. Chen, J. Zhang, J. Yao, Food Hydrocolloids 55 (2016) 19–25. [8] X. Liu, P.R. Chang, P. Zheng, D.P. Anderson, X. Ma, Cellulose 22 (2015) 709–715. [9] S. Mahmoudian, M.U. Wahit, A.F. Ismail, A.A. Yussuf, Carbohydr. Polym. 88 (2012) 1251–1257. [10] G. Moad, Prog. Polym. Sci. 36 (2011) 218–237. [11] A.O. Ashogbon, American Journal of Food and Nutrition 5 (2017) 62–68. [12] P. Tomasik, C.H. Schilling, Adv. Carbohydr. Chem. Biochem. 59 (2004) 175–403. [13] R.N. Tharanathan, Crit Rev Food Sci 45 (2005) 371–384. [14] R. Belhassen, F. Vilaseca, P. Mutjé, S. Boufi, Ind. Crops Prod. 53 (2014) 261–267. [15] A. Buettner, Springer Handbook of Odor, Springer, 2017. [16] R.L. Shogren, Carbohydr. Polym. 76 (2009) 639–644. [17] A. Sapek, Crops 2 (2013) 5.9. [18] R. Ali, G. Mittal, S. Sultana, A. Bhatnagar, Exp. Lung Res. 38 (2012) 435–444. [19] A. Akbarzadeh, E. Abasi, M. Ghanei, A. Hasanzadeh, Y. Panahi, Toxin Rev. 35 (2016) 187–195. [20] Q. Li, J. Jiang, S. Cai, W. Zhou, S. Wang, L. Duan, J. Hao, Environ. Sci. Technol. Lett. 3 (2016) 98–103. [21] C.V. Watson, J. Feng, L. Valentin-Blasini, R. Stanelle, C.H. Watson, PLoS One 11 (2016) e0159126. [22] R. Geetha, V. Gayathri, Int. J. Nanosci. (2017) 1750003. [23] M.S. Zaki, O. Fawzi, S. Shalaby, Life Sci. J. 8 (2011) 244–248. [24] M. Ahmaruzzaman, Adv. Colloid Interface Sci. 143 (2008) 48–67. [25] J. Michałowicz, W. Duda, Pol. J. Environ. Stud. 16 (2007). [26] L. Järup, Br. Med. Bull. 68 (2003) 167–182. [27] M.M. Authman, M.S. Zaki, E.A. Khallaf, H.H. Abbas, J. Aquac. Res. Dev. 6 (2015) 1–13. [28] E.Y. Ozmen, M. Sezgin, A. Yilmaz, M. Yilmaz, Bioresour. Technol. 99 (2008) 526–531. [29] E.S. Dragan, D.F. Apopei Loghin, Chem. Eng. J. 234 (2013) 211–222. [30] G. Crini, Bioresour. Technol. 97 (2006) 1061–1085. [31] M.S. Zafar, M. Tausif, M. Mohsin, S.W. Ahmad, M. Zia-ul-Haq, Water, Air, Soil Pollut. 226 (2015) 244. [32] V.V. Panić, S.I. Šešlija, A.R. Nešić, S.J. Veličković, Hem. Ind. 67 (2013) 881–900. [33] M. Haroon, L. Wang, H. Yu, R. Ullah, R. Khan, Q. Chen, J. Liu, Carbohydr. Polym. 186 (2018) 150–158. [34] Q. Chen, H. Yu, L. Wang, Z.-u. Abdin, X. Yang, J. Wang, W. Zhou, H. Zhang, X. Chen, Carbohydr. Polym. 153 (2016) 429–434. [35] W. Shen, S. Zhang, P. Jiang, Y. Liu, Colloids Surf., A 356 (2010) 16–20. [36] L. Guo, Y. Zhu, X. Du, Starch Staerke 64 (2012) 552–562. [37] D. Jin, X. Yang, M. Zhang, B. Hong, H. Jin, X. Peng, J. Li, H. Ge, X. Wang, Z. Wang, Mater. Lett. 139 (2015) 262–264. [38] C. Qiu, Y. Qin, S. Zhang, L. Xiong, Q. Sun, Food Chem. 213 (2016) 579–587. [39] H. Chen, C. Wang, J. Ye, H. Zhou, R. Tao, W. Li, Molecules 23 (2018) 96. [40] A. Baysal, C. Kuznek, M. Ozcan, Int J Environ An Ch (2018) 1–11. [41] Q. Liu, F. Li, H. Lu, M. Li, J. Liu, S. Zhang, Q. Sun, L. Xiong, Food Chem. 242 (2018) 256–263. [42] H. Hosseinzadeh, S. Ramin, Int. J. Biol. Macromol. 106 (2018) 101–115. [43] A.J. Sami, M. Khalid, S. Iqbal, M. Afzal, A. Shakoori, Pakistan J. Zool. 49 (2017). [44] P. Li, B. Gao, A. Li, H. Yang, Microporous Mesoporous Mater. 263 (2017) 210–219. [45] J.N. BeMiller, R.L. Whistler, Starch: Chemistry and Technology, Academic Press, 2009. [46] J. Chen, L. Chen, F. Xie, X. Li, Drug Delivery Applications of Starch Biopolymer Derivatives, Springer, 2019, pp. 133–137. [47] M. Jiang, Y. Hong, Z. Gu, L. Cheng, Z. Li, C. Li, Food Hydrocolloids 106 (2019) 320–329. [48] E. Agama-Acevedo, P.C. Flores-Silva, L.A. Bello-Perez, Starches for Food Application, Elsevier, 2019, pp. 71–102. [49] R. Ashraf, H.S. Sofi, A. Malik, M.A. Beigh, R. Hamid, F.A. Sheikh, Appl. Biochem. Biotechnol. 187 (2019) 47–74. [50] M.O.S. Lobregas, D.H. Camacho, Electrochim. Acta 298 (2019) 219–228. [51] W.F. Breuninger, K. Piyachomkwan, K. Sriroth, Starch, third ed., Elsevier, 2009,

34

Carbohydrate Research 476 (2019) 12–35

F. Haq, et al.

[135] W.L. Muhammad Haroon, Haoji Yu, Raja Summe Ullah, Carbohydr. Polym. 186 c (2018) 150–158. [136] S.-J. Park, B.-J. Kim, J. Colloid Interface Sci. 291 (2005) 597–599. [137] C.L. Mangun, K.R. Benak, M.A. Daley, J. Economy, Chem. Mater. 11 (1999) 3476–3483. [138] B. Shahrooie, L. Rajabi, A.A. Derakhshan, M. Keyhani, Journal of the Taiwan Institute of Chemical Engineers 51 (2015) 201–215. [139] D. Mohan, A. Sarswat, Y.S. Ok, C.U. Pittman Jr., Bioresour. Technol. 160 (2014) 191–202. [140] Q. Zhang, C. Peter Okoli, L. Wang, T. Liang, Disalin Water Treat 55 (2015) 1575–1585. [141] X.-H. Zhao, F.-P. Jiao, J.-G. Yu, Y. Xi, X.-Y. Jiang, X.-Q. Chen, Colloids Surf., A 476 (2015) 35–41. [142] J.-G. Yu, B.-Y. Yue, X.-W. Wu, Q. Liu, F.-P. Jiao, X.-Y. Jiang, X.-Q. Chen, Environ. Sci. Pollut. Res. 23 (2016) 5056–5076. [143] Z. Wang, X. Zhang, X. Wu, J.-G. Yu, X.-Y. Jiang, Z.-L. Wu, X. Hao, J Sol-gel Sci Techn 82 (2017) 440–449. [144] L.O. Ekebafe, D.E. Ogbeifun, F.E. Okieimen, J. Polym. Environ. (2017) 1–12. [145] Z.S. Pour, M. Ghaemy, RSC Adv. 5 (2015) 64106–64118. [146] S.N. Basri, N. Zainuddin, K. Hashim, N.A. Yusof, Carbohydr. Polym. 138 (2016) 34–40. [147] K. Lappalainen, J. Kärkkäinen, A. Rusanen, T.R. Wik, M. Niemelä, A.G. Madariaga, S. Komulainen, R.L. Keiski, M. Lajunen, Starch Staerke 68 (2016) 900–908. [148] S. Wang, C. Zhang, Q. Chang, J. Exp. Nanosci. 12 (2017) 270–284. [149] W. Bai, L. Fan, Y. Zhou, Y. Zhang, J. Shi, G. Lv, Y. Wu, Q. Liu, J. Song, J. Appl. Polym. Sci. 134 (2017). [150] X. Ma, X. Liu, D.P. Anderson, P.R. Chang, Food Chem. 181 (2015) 133–139. [151] M. Irani, H. Ismail, Z. Ahmad, M. Fan, J. Environ. Sci. 27 (2015) 9–20. [152] M. Naushad, T. Ahamad, G. Sharma, H. Ala’a, A.B. Albadarin, M.M. Alam, Z.A. ALOthman, S.M. Alshehri, A.A. Ghfar, Chem. Eng. J. 300 (2016) 306–316. [153] W. Yao, S. Yu, J. Wang, Y. Zou, S. Lu, Y. Ai, N.S. Alharbi, A. Alsaedi, T. Hayat, X. Wang, Chem. Eng. J. 307 (2017) 476–486. [154] T. Robinson, G. McMullan, R. Marchant, P. Nigam, Bioresour. Technol. 77 (2001) 247–255. [155] M.T. Yagub, T.K. Sen, S. Afroze, H.M. Ang, Adv Colloid Interfac 209 (2014) 172–184. [156] S. Muzaffar, H. Tahir, J. Mol. Liq. 252 (2018) 368–382. [157] M. Zubair, N. Jarrah, A. Khalid, M.S. Manzar, T.S. Kazeem, M.A. Al-Harthi, J. Mol. Liq. 249 (2018) 254–264. [158] S. Mallakpour, S. Rashidimoghadam, Carbohydr. Polym. 169 (2017) 23–32. [159] X. He, M. Du, H. Li, T. Zhou, Int. J. Biol. Macromol. 82 (2016) 174–181. [160] F.A. Ngwabebhoh, M. Gazi, A.A. Oladipo, Chem. Eng. Res. Des. 112 (2016) 274–288. [161] A. Pourjavadi, A. Abedin-Moghanaki, A. Tavakoli, RSC Adv. 6 (2016) 38042–38051. [162] X. Yang, D. Jin, M. Zhang, P. Wu, H. Jin, J. Li, X. Wang, H. Ge, Z. Wang, H. Lou, Mater. Chem. Phys. 174 (2016) 179–186. [163] R.F. Gomes, A.C.N. de Azevedo, A.G. Pereira, E.C. Muniz, A.R. Fajardo, F.H. Rodrigues, J. Colloid Interface Sci. 454 (2015) 200–209. [164] G. Gong, F. Zhang, Z. Cheng, L. Zhou, Int. J. Biol. Macromol. 81 (2015) 205–211. [165] B. Mandal, S.K. Ray, Int. J. Biol. Macromol. 81 (2015) 847–857. [166] L. Bao, X. Zhu, H. Dai, Y. Tao, X. Zhou, W. Liu, Y. Kong, Int. J. Biol. Macromol. 89 (2016) 389–395.

(2017) 180–192. [103] T. Majeed, I.A. Wani, P.R. Hussain, Int. J. Biol. Macromol. 101 (2017) 358–365. [104] S. Li, L. Zheng, Y. Wang, X. Han, W. Sun, Y. Yue, D. Li, J. Yang, Y. Zou, Polym. Bull. 74 (2017) 4371–4392. [105] S. Sukhija, S. Singh, C.S. Riar, Food Hydrocolloids 55 (2016) 56–64. [106] N. Castanha, M.D. da Matta Junior, P.E.D. Augusto, Food Hydrocolloids 66 (2017) 343–356. [107] N. Castanha, M.D.d. Matta Junior, P.E.D. Augusto, Food Hydrocolloids 66 (2017) 343–356. [108] P.H. Dao, T.T. Nam, M. Van Phuc, N.A. Hiep, T. Van Thanh, Vietnam Journal of Science and Technology 55 (2017) 395. [109] Y. Yu, Y.-n. Wang, W. Ding, J. Zhou, B. Shi, Carbohydr. Polym. 174 (2017) 823–829. [110] H.E. Emam, M. Zahran, H.B. Ahmed, Eur. Polym. J. 90 (2017) 354–367. [111] P. Naknaen, W. Tobkaew, S. Chaichaleom, Int. J. Food Prop. 20 (2017) 979–996. [112] F. Zhou, Q. Liu, H. Zhang, Q. Chen, B. Kong, Int. J. Biol. Macromol. 84 (2016) 410–417. [113] F. Onofre, Y.-J. Wang, A. Mauromoustakos, Carbohydr. Polym. 76 (2009) 541–547. [114] B. Yaacob, A.M.C.I. MOHD, K. Hashim, B.B. ABU, Iran. Polym. J. (Engl. Ed.) 20 (2011) 195–204. [115] J. Singh, L. Kaur, O.J. McCarthy, Food Hydrocolloids 21 (2007) 1–22. [116] M.M. Sánchez-Rivera, F.J.L. García-Suárez, M. Velázquez del Valle, F. GutierrezMeraz, L.A. Bello-Pérez, Carbohydr. Polym. 62 (2005) 50–56. [117] D. Kuakpetoon, Y.-J. Wang, Starch - Stärke 53 (2001) 211–218. [118] O. Moreno, J. Cárdenas, L. Atarés, A. Chiralt, Carbohydr. Polym. 178 (2017) 147–158. [119] B. Tosh, C. Ranjan Routray, Cheml Sci Rev Lett 3 (2014) 74–92. [120] N. Tudorachi, A.P. Chiriac, L.E. Nita, F. Mustata, A. Diaconu, V. Balan, A. Rusu, G. Lisa, J. Therm. Anal. Calorim. 131 (2018) 1867–1880. [121] A.N. Jyothi, S.S. Pillai, M. Aravind, S.A. Salim, S.J. Kuzhivilayil, Adv. Polym. Technol. (2018) 1–8. [122] S. Wang, J. Xu, Q. Wang, X. Fan, Y. Yu, P. Wang, Y. Zhang, J. Yuan, A. CavacoPaulo, Process Biochem. 59 (2017) 104–110. [123] M. Pirooz, A.H. Navarchian, G. Emtiazi, J. Polym. Environ. 26 (2017) 1702–1714. [124] D.V. Ludin, S.D. Zaitsev, Y.L. Kuznetsova, A.V. Markin, A.E. Mochalova, E.V. Salomatina, J. Polym. Res. 24 (2017) 117. [125] A.D. Mohammed, Graft 4 (2017) 320–328. [126] Y. Babaee, C.N. Mulligan, M.S. Rahaman, Environmental Earth Sciences 76 (2017) 650. [127] A. Fakhru, L-Razi, I.Y.M. Qudsieh, W.M.Z.W. Yunus, M.B. Ahmad, M.Z.A. Rahman, J. Appl. Polym. Sci. 82 (2001) 1375–1381. [128] C. Banerjee, P. Gupta, S. Mishra, G. Sen, P. Shukla, R. Bandopadhyay, Int. J. Biol. Macromol. 51 (2012) 456–461. [129] A.D. Mohammed, D.A. Young, H.C.M. Vosloo, Starch - Stärke 66 (2014) 393–399. [130] J. Kirkby, J. Curtius, J. Almeida, E. Dunne, J. Duplissy, S. Ehrhart, A. Franchin, S. Gagné, L. Ickes, A. Kürten, Nature 476 (2011) 429. [131] J. Erisman, M. Schaap, Environ. Pollut. 129 (2004) 159–163. [132] Y. Huang, S.C. Lee, K.F. Ho, S.S.H. Ho, N. Cao, Y. Cheng, Y. Gao, Atmos. Environ. 59 (2012) 224–231. [133] K. Na, C. Song, C. Switzer, D.R. Cocker, Environ. Sci. Technol. 41 (2007) 6096–6102. [134] K. Na, C. Song, D.R. Cocker III, Atmos. Environ. 40 (2006) 1889–1900.

35