Enhancement of Adsorption Capacity of Chitosan by Chemical Modification

$20.00

Enhancement of Adsorption Capacity of Chitosan by Chemical Modification

Olalekan C. Olatunde, Chidinma G. Ugwuja, Emmanuel I. Unuabonah

Chitosan is a natural biopolymer which has found wide application in fields like medicine, drug delivery and water purification due to its unique chemical and physical properties. Being the second most abundant natural polysaccharide on earth, application of Chitosan for adsorption of pollutants is gaining wide acceptance due to many possible derivatives and properties of Chitosan that can be explored. However, despite its excellent properties, the use of chitosan for adsorption purposes is limited by its poor mechanical property and solubility especially in acidic medium. These limitations could, however, be offset by modifying Chitosan via various chemical routes like the grafting of – sulfur (S), oxygen (O), nitrogen (N) and phosphorus (P) – containing functional moieties and crosslinking reagents. Studies into the mechanism of adsorption of these modified Chitosan materials showed great dependence on pH and on the nature of the incorporated functional group, with chelate formation and electrostatic interaction being the most prominent adsorbent-adsorbate interaction. This chapter seeks to provide an in-depth review on some of these chemical modifications as well as current trends in the engineering of Chitosan for efficient water treatment.

Keywords
Chitosan, Adsorption, Grafting, Crosslinking, Chelate Formation, Electrostatic Interation

Published online 7/1/2018, 42 pages

DOI: http://dx.doi.org/10.21741/9781945291753-8

Part of the book on Chitosan-Based Adsorbents for Wastewater Treatment

References
[1] R.P. Schwarzenbach, T. Egli, T.B. Hofstetter, U. Von Gunten, B. Wehrli, Global water pollution and human health, Annual Review of Environment and Resources 35 (2010) 109-136. https://doi.org/10.1146/annurev-environ-100809-125342
[2] M. Mende, D. Schwarz, S. Schwarz, Chitosan–A Natural Adsorbent for Copper Ions, Proceedings of the World Congress on Civil, Structural, and Environmental Engineering (CSEE’16), 2016.
[3] M. Ilayaraja, S. Sharmilaparveen, R. Sayeekannan, Synthesis and adsorption properties of Chitosan cross linked with phenol–formaldehyde resin for the removal of heavy metals and dyes from water, IOSR-J. Appl. Chem. 7 (2014) 16-26. https://doi.org/10.9790/5736-07211626
[4] M. Wang, Y. Ma, Y. Sun, S.Y. Hong, S.K. Lee, B. Yoon, L. Chen, L. Ci, J.-D. Nam, X. Chen, Hierarchical Porous Chitosan Sponges as Robust and Recyclable Adsorbents for Anionic Dye Adsorption, Scientific Reports 7(1) (2017) 18054. https://doi.org/10.1038/s41598-017-18302-0
[5] S. Xie, S. Huang, W. Wei, X. Yang, Y. Liu, X. Lu, Y. Tong, Chitosan Waste‐Derived Co and N Co‐doped Carbon Electrocatalyst for Efficient Oxygen Reduction Reaction, ChemElectroChem 2(11) (2015) 1806-1812. https://doi.org/10.1002/celc.201500199
[6] G. Crini, P.-M. Badot, Application of chitosan, a natural aminopolysaccharide, for dye removal from aqueous solutions by adsorption processes using batch studies: A review of recent literature, Progress in Polymer Science 33(4) (2008) 399-447. https://doi.org/10.1016/j.progpolymsci.2007.11.001
[7] J. Wang, C. Chen, Chitosan-based biosorbents: modification and application for biosorption of heavy metals and radionuclides, Bioresource Technology 160 (2014) 129-141. https://doi.org/10.1016/j.biortech.2013.12.110
[8] G.Z. Kyzas, D.N. Bikiaris, Recent modifications of chitosan for adsorption applications: a critical and systematic review, Marine Drugs 13(1) (2015) 312-337. https://doi.org/10.3390/md13010312
[9] E. Guibal, E. Touraud, J. Roussy, Chitosan interactions with metal ions and dyes: dissolved-state vs. solid-state application, World Journal of Microbiology and Biotechnology 21(6-7) (2005) 913-920. https://doi.org/10.1007/s11274-004-6559-5
[10] R.C. Goy, D.d. Britto, O.B. Assis, A review of the antimicrobial activity of chitosan, Polímeros 19(3) (2009) 241-247. https://doi.org/10.1590/S0104-14282009000300013
[11] M.R. Hussain, M. Iman, T.K. Maji, Determination of degree of deacetylation of chitosan and their effect on the release behavior of essential oil from chitosan and chitosan-gelatin complex microcapsules, International Journal of Advanced Engineering Applications 6(4) (2013) 4-12.
[12] M.A. Elgadir, M.S. Uddin, S. Ferdosh, A. Adam, A.J.K. Chowdhury, M.Z.I. Sarker, Impact of chitosan composites and chitosan nanoparticle composites on various drug delivery systems: A review, journal of Food and Drug Analysis 23(4) (2015) 619-629.
[13] Y. Yuan, B.M. Chesnutt, W.O. Haggard, J.D. Bumgardner, Deacetylation of chitosan: material characterization and in vitro evaluation via albumin adsorption and pre-osteoblastic cell cultures, Materials 4(8) (2011) 1399-1416. https://doi.org/10.3390/ma4081399
[14] N. Kubota, Y. Eguchi, Facile preparation of water-soluble N-acetylated chitosan and molecular weight dependence of its water-solubility, Polymer Journal 29(2) (1997) 123. https://doi.org/10.1295/polymj.29.123
[15] M.H. Ottey, K.M. Vårum, O. Smidsrød, Compositional heterogeneity of heterogeneously deacetylated chitosans, Carbohydrate Polymers 29(1) (1996) 17-24. https://doi.org/10.1016/0144-8617(95)00154-9
[16] M. Duarte, M. Ferreira, M. Marvao, J. Rocha, An optimised method to determine the degree of acetylation of chitin and chitosan by FTIR spectroscopy, International Journal of Biological Macromolecules 31(1-3) (2002) 1-8. https://doi.org/10.1016/S0141-8130(02)00039-9
[17] E. El-Nesr, A. Raafat, S.M. Nasef, E. Soliman, E. Hegazy, Chitin and chitosan extracted from irradiated and non-irradiated shrimp wastes (Comparative Analysis Study), Arab Journal of Nuclear Science and Applications 46(1) (2013) 53-66.
[18] J.S. Piccin, M. Vieira, J. Gonçalves, G. Dotto, L.A.d.A. Pinto, Adsorption of FD&C Red No. 40 by chitosan: Isotherms analysis, Journal of Food Engineering 95(1) (2009) 16-20. https://doi.org/10.1016/j.jfoodeng.2009.03.017
[19] J. Unagolla, S. Adikary, Adsorption characteristics of cadmium and lead heavy metals into locally synthesized Chitosan Biopolymer, Tropical Agricultural Research 26(2) (2015).
[20] Q. Li, E. Dunn, E. Grandmaison, M.F. Goosen, Applications and properties of chitosan, Journal of Bioactive and Compatible Polymers 7(4) (1992) 370-397. https://doi.org/10.1177/088391159200700406
[21] S. Jana, A. Saha, A.K. Nayak, K.K. Sen, S.K. Basu, Aceclofenac-loaded chitosan-tamarind seed polysaccharide interpenetrating polymeric network microparticles, Colloids and Surfaces B: Biointerfaces 105 (2013) 303-309. https://doi.org/10.1016/j.colsurfb.2013.01.013
[22] X. He, K. Li, R. Xing, S. Liu, L. Hu, P. Li, The production of fully deacetylated chitosan by compression method, The Egyptian Journal of Aquatic Research 42(1) (2016) 75-81. https://doi.org/10.1016/j.ejar.2015.09.003
[23] A.N. Hernandez-Lauzardo, S. Bautista-Baños, M.G. Velazquez-Del Valle, M. Méndez-Montealvo, M. Sánchez-Rivera, L.A. Bello-Perez, Antifungal effects of chitosan with different molecular weights on in vitro development of Rhizopus stolonifer (Ehrenb.: Fr.) Vuill, Carbohydrate polymers 73(4) (2008) 541-547. https://doi.org/10.1016/j.carbpol.2007.12.020
[24] H. Zhang, S.H. Neau, In vitro degradation of chitosan by a commercial enzyme preparation: effect of molecular weight and degree of deacetylation, Biomaterials 22(12) (2001) 1653-1658. https://doi.org/10.1016/S0142-9612(00)00326-4
[25] M. Vakili, M. Rafatullah, B. Salamatinia, A.Z. Abdullah, M.H. Ibrahim, K.B. Tan, Z. Gholami, P. Amouzgar, Application of chitosan and its derivatives as adsorbents for dye removal from water and wastewater: A review, Carbohydrate Polymers 113 (2014) 115-130. https://doi.org/10.1016/j.carbpol.2014.07.007
[26] E. Guibal, Interactions of metal ions with chitosan-based sorbents: a review, Separation and Purification Technology 38(1) (2004) 43-74. https://doi.org/10.1016/j.seppur.2003.10.004
[27] I. Aranaz, M. Mengíbar, R. Harris, I. Paños, B. Miralles, N. Acosta, G. Galed, Á. Heras, Functional characterization of chitin and chitosan, Current Chemical Biology 3(2) (2009) 203-230.
[28] T.K. Saha, N.C. Bhoumik, S. Karmaker, M.G. Ahmed, H. Ichikawa, Y. Fukumori, Adsorption of methyl orange onto chitosan from aqueous solution, Journal of Water Resource and Protection 2(10) (2010) 898. https://doi.org/10.4236/jwarp.2010.210107
[29] J. Barron-Zambrano, A. Szygula, M. Ruiz, A.M. Sastre, E. Guibal, Biosorption of Reactive Black 5 from aqueous solutions by chitosan: column studies, Journal of Environmental Management 91(12) (2010) 2669-2675. https://doi.org/10.1016/j.jenvman.2010.07.033
[30] A.G. Hadi, Dye removal from colored textile wastewater using synthesized chitosan, Int. J. Sci. Technol. 2(4) (2013) 359-364.
[31] J. Iqbal, F.H. Wattoo, M.H.S. Wattoo, R. Malik, S.A. Tirmizi, M. Imran, A.B. Ghangro, Adsorption of acid yellow dye on flakes of chitosan prepared from fishery wastes, Arabian Journal of Chemistry 4(4) (2011) 389-395. https://doi.org/10.1016/j.arabjc.2010.07.007
[32] M.-E. Ignat, V. Dulman, T. Onofrei, Reactive Red 3 and Direct Brown 95 dyes adsorption onto chitosan, Cellulose Chemistry and Technology 46(5-6) (2012) 357-367.
[33] G. Dotto, L. Pinto, Adsorption of food dyes acid blue 9 and food yellow 3 onto chitosan: Stirring rate effect in kinetics and mechanism, Journal of Hazardous Materials 187(1-3) (2011) 164-170. https://doi.org/10.1016/j.jhazmat.2011.01.016
[34] H. Zhang, S. Schiewer, Arsenic (V) sorption on crab shell based chitosan, Impacts of Global Climate Change2005, pp. 1-7.
[35] G. Ratnamala, K. Brajesh, Biosorption of remazol navy blue dye from an aqueous solution using Pseudomonas putida, International Journal of Science, Environment and Technology 2(1) (2013) 80-89.
[36] P. Miretzky, A.F. Cirelli, Hg (II) removal from water by chitosan and chitosan derivatives: a review, Journal of Hazardous Materials 167(1-3) (2009) 10-23. https://doi.org/10.1016/j.jhazmat.2009.01.060
[37] F.-C. Wu, R.-L. Tseng, R.-S. Juang, Comparative adsorption of metal and dye on flake-and bead-types of chitosans prepared from fishery wastes, Journal of Hazardous Materials 73(1) (2000) 63-75. https://doi.org/10.1016/S0304-3894(99)00168-5
[38] E.A. El-hefian, M.M. Nasef, A.H. Yahaya, Chitosan physical forms: a short review, Australian Journal of Basic and Applied Sciences 5(5) (2011) 670-677.
[39] N. Shah, R. Mewada, T. Mehta, Chitosan: Development of Nanoparticles, Other Physical Forms and Solubility with Acids, Journal of Nano Research, Trans Tech Publ, 2013, pp. 107-122.
[40] C. Peniche, W. Argüelles‐Monal, H. Peniche, N. Acosta, Chitosan: an attractive biocompatible polymer for microencapsulation, Macromolecular Bioscience 3(10) (2003) 511-520. https://doi.org/10.1002/mabi.200300019
[41] E. Guibal, C. Milot, J.M. Tobin, Metal-anion sorption by chitosan beads: equilibrium and kinetic studies, Industrial & Engineering Chemistry Research 37(4) (1998) 1454-1463. https://doi.org/10.1021/ie9703954
[42] J. Berger, M. Reist, J.M. Mayer, O. Felt, R. Gurny, Structure and interactions in chitosan hydrogels formed by complexation or aggregation for biomedical applications, European journal of Pharmaceutics and Biopharmaceutics 57(1) (2004) 35-52. https://doi.org/10.1016/S0939-6411(03)00160-7
[43] S. Kumbar, A. Kulkarni, T. Aminabhavi, Crosslinked chitosan microspheres for encapsulation of diclofenac sodium: effect of crosslinking agent, Journal of Microencapsulation 19(2) (2002) 173-180. https://doi.org/10.1080/02652040110065422
[44] N. Li, R. Bai, Copper adsorption on chitosan–cellulose hydrogel beads: behaviors and mechanisms, Separation and Purification Technology 42(3) (2005) 237-247. https://doi.org/10.1016/j.seppur.2004.08.002
[45] L. Lim, L.S. Wan, The effect of plasticizers on the properties of polyvinyl alcohol films, Drug Development and Industrial Pharmacy 20(6) (1994) 1007-1020. https://doi.org/10.3109/03639049409038347
[46] T.S. Trung, W.W. Thein-Han, N.T. Qui, C.-H. Ng, W.F. Stevens, Functional characteristics of shrimp chitosan and its membranes as affected by the degree of deacetylation, Bioresource technology 97(4) (2006) 659-663. https://doi.org/10.1016/j.biortech.2005.03.023
[47] C.R. Huei, H.-D. Hwa, Effect of molecular weight of chitosan with the same degree of deacetylation on the thermal, mechanical, and permeability properties of the prepared membrane, Carbohydrate polymers 29(4) (1996) 353-358. https://doi.org/10.1016/S0144-8617(96)00007-0
[48] N. Bhattarai, D. Edmondson, O. Veiseh, F.A. Matsen, M. Zhang, Electrospun chitosan-based nanofibers and their cellular compatibility, Biomaterials 26(31) (2005) 6176-6184. https://doi.org/10.1016/j.biomaterials.2005.03.027
[49] Z. Chen, X. Mo, C. He, H. Wang, Intermolecular interactions in electrospun collagen–chitosan complex nanofibers, Carbohydrate Polymers 72(3) (2008) 410-418. https://doi.org/10.1016/j.carbpol.2007.09.018
[50] Y.-T. Jia, J. Gong, X.-H. Gu, H.-Y. Kim, J. Dong, X.-Y. Shen, Fabrication and characterization of poly (vinyl alcohol)/chitosan blend nanofibers produced by electrospinning method, Carbohydrate Polymers 67(3) (2007) 403-409. https://doi.org/10.1016/j.carbpol.2006.06.010
[51] I.-C. Liao, A.C. Wan, E.K. Yim, K.W. Leong, Controlled release from fibers of polyelectrolyte complexes, Journal of Controlled Release 104(2) (2005) 347-358. https://doi.org/10.1016/j.jconrel.2005.02.013
[52] Q. Wang, N. Zhang, X. Hu, J. Yang, Y. Du, Chitosan/starch fibers and their properties for drug controlled release, European Journal of Pharmaceutics and Biopharmaceutics 66(3) (2007) 398-404. https://doi.org/10.1016/j.ejpb.2006.11.011
[53] S. Poole, The foam‐enhancing properties of basic biopolymers, International Journal of Food Science & Technology 24(2) (1989) 121-137. https://doi.org/10.1111/j.1365-2621.1989.tb00626.x
[54] D. Thacharodi, K.P. Rao, Collagen-chitosan composite membranes for controlled release of propranolol hydrochloride, International Journal of Pharmaceutics 120(1) (1995) 115-118. https://doi.org/10.1016/0378-5173(94)00423-3
[55] K. Oungbho, B.W. Müller, Chitosan sponges as sustained release drug carriers, International Journal of Pharmaceutics 156(2) (1997) 229-237. https://doi.org/10.1016/S0378-5173(97)00201-9
[56] J. Tong, L. Chen, Review: Preparation and Application of Magnetic Chitosan Derivatives in Separation Processes, Analytical Letters 46(17) (2013) 2635-2656. https://doi.org/10.1080/00032719.2013.807815
[57] A.A. Alhwaige, T. Agag, H. Ishida, S. Qutubuddin, Biobased chitosan hybrid aerogels with superior adsorption: Role of graphene oxide in CO2 capture, RSC Advances 3(36) (2013) 16011-16020. https://doi.org/10.1039/c3ra42022a
[58] M. Vakili, M. Rafatullah, B. Salamatinia, A.Z. Abdullah, M.H. Ibrahim, K.B. Tan, Z. Gholami, P. Amouzgar, Application of chitosan and its derivatives as adsorbents for dye removal from water and wastewater: a review, Carbohydr Polym 113 (2014) 115-30. https://doi.org/10.1016/j.carbpol.2014.07.007
[59] J. Ji, L. Wang, H. Yu, Y. Chen, Y. Zhao, H. Zhang, W.A. Amer, Y. Sun, L. Huang, M. Saleem, Chemical Modifications of Chitosan and Its Applications, Polymer-Plastics Technology and Engineering 53(14) (2014) 1494-1505. https://doi.org/10.1080/03602559.2014.909486
[60] J. Ma, Y. Sahai, Chitosan biopolymer for fuel cell applications, Carbohydrate Polymers 92(2) (2013) 955-975. https://doi.org/10.1016/j.carbpol.2012.10.015
[61] S.K. Shukla, A.K. Mishra, O.A. Arotiba, B.B. Mamba, Chitosan-based nanomaterials: a state-of-the-art review, International Journal of Biological Macromolecules 59 (2013) 46-58. https://doi.org/10.1016/j.ijbiomac.2013.04.043
[62] V.K. Mourya, N.N. Inamdar, Chitosan-modifications and applications: Opportunities galore, Reactive and Functional Polymers 68(6) (2008) 1013-1051. https://doi.org/10.1016/j.reactfunctpolym.2008.03.002
[63] L. Pontoni, M. Fabbricino, Use of chitosan and chitosan-derivatives to remove arsenic from aqueous solutions–a mini review, Carbohydrate Research 356 (2012) 86-92. https://doi.org/10.1016/j.carres.2012.03.042
[64] P. Miretzky, A.F. Cirelli, Hg(II) removal from water by chitosan and chitosan derivatives: a review, Journal of Hazardous Materials 167(1-3) (2009) 10-23. https://doi.org/10.1016/j.jhazmat.2009.01.060
[65] L. Zhang, Y. Zeng, Z. Cheng, Removal of heavy metal ions using chitosan and modified chitosan: A review, Journal of Molecular Liquids 214 (2016) 175-191. https://doi.org/10.1016/j.molliq.2015.12.013
[66] J. Wang, L. Wang, H. Yu, A. Zain Ul, Y. Chen, Q. Chen, W. Zhou, H. Zhang, X. Chen, Recent progress on synthesis, property and application of modified chitosan: An overview, International Journal of Biological Macromolecules 88 (2016) 333-44. https://doi.org/10.1016/j.ijbiomac.2016.04.002
[67] K.H. Prashanth, R. Tharanathan, Chitin/chitosan: modifications and their unlimited application potential—an overview, Trends in Food Science & Technology 18(3) (2007) 117-131. https://doi.org/10.1016/j.tifs.2006.10.022
[68] J. Wang, L. Wang, H. Yu, A. Zain ul, Y. Chen, Q. Chen, W. Zhou, H. Zhang, X. Chen, Recent progress on synthesis, property and application of modified chitosan: An overview, International Journal of Biological Macromolecules 88 (2016) 333-344. https://doi.org/10.1016/j.ijbiomac.2016.04.002
[69] R. Jayakumar, M. Prabaharan, R.L. Reis, J.F. Mano, Graft copolymerized chitosan—present status and applications, Carbohydrate Polymers 62(2) (2005) 142-158. https://doi.org/10.1016/j.carbpol.2005.07.017
[70] W. Xie, P. Xu, Q. Liu, Antioxidant activity of water-soluble chitosan derivatives, Bioorganic & Medicinal Chemistry Letters 11(13) (2001) 1699-1701. https://doi.org/10.1016/S0960-894X(01)00285-2
[71] W. Xie, P. Xu, W. Wang, Q. Liu, Preparation and antibacterial activity of a water-soluble chitosan derivative, Carbohydrate Polymers 50(1) (2002) 35-40. https://doi.org/10.1016/S0144-8617(01)00370-8
[72] R. Jayakumar, M. Prabaharan, R. Reis, J. Mano, Graft copolymerized chitosan—present status and applications, Carbohydrate Polymers 62(2) (2005) 142-158. https://doi.org/10.1016/j.carbpol.2005.07.017
[73] S.K. Yong, N.S. Bolan, E. Lombi, W. Skinner, E. Guibal, Sulfur-Containing Chitin and Chitosan Derivatives as Trace Metal Adsorbents: A Review, Critical Reviews in Environmental Science and Technology 43(16) (2013) 1741-1794. https://doi.org/10.1080/10643389.2012.671734
[74] G. Cardenas, P. Orlando, T. Edelio, Synthesis and applications of chitosan mercaptanes as heavy metal retention agent, International Journal of Biological Macromolecules 28(2) (2001) 167-174. https://doi.org/10.1016/S0141-8130(00)00156-2
[75] Q. Song, C. Wang, Z. Zhang, J. Gao, Adsorption of lead using a novel xanthated carboxymethyl chitosan, Water science and technology : a Journal of the International Association on Water Pollution Research 69(2) (2014) 298-304.
[76] S.K. Yong, W.M. Skinner, N.S. Bolan, E. Lombi, A. Kunhikrishnan, Y.S. Ok, Sulfur crosslinks from thermal degradation of chitosan dithiocarbamate derivatives and thermodynamic study for sorption of copper and cadmium from aqueous system, Environmental Science and Pollution Research 23(2) (2016) 1050-1059. https://doi.org/10.1007/s11356-015-5654-5
[77] F. Li, C. Bao, J. Zhang, Q. Sun, W. Kong, X. Han, Y. Wang, Synthesis of chemically modified chitosan with 2, 5‐dimercapto‐1, 3, 4‐thiodiazole and its adsorption abilities for Au (III), Pd (II), and Pt (IV), Journal of Applied Polymer Science 113(3) (2009) 1604-1610. https://doi.org/10.1002/app.30068
[78] M. Ruiz, A. Sastre, E. Guibal, Pd and Pt recovery using chitosan gel beads. II. Influence of chemical modifications on sorption properties, Separation Science and Technology 37(10) (2002) 2385-2403. https://doi.org/10.1081/SS-120003519
[79] B. Kannamba, K.L. Reddy, B.V. AppaRao, Removal of Cu(II) from aqueous solutions using chemically modified chitosan, Journal of Hazardous Materials 175(1-3) (2010) 939-48. https://doi.org/10.1016/j.jhazmat.2009.10.098
[80] M. Ahmad, K. Manzoor, P. Venkatachalam, S. Ikram, Kinetic and thermodynamic evaluation of adsorption of Cu(II) by thiosemicarbazide chitosan, (1879-0003 (Electronic)).
[81] E. Metwally, S.S. Elkholy, H.A.M. Salem, M.Z. Elsabee, Sorption behavior of 60Co and 152+154Eu radionuclides onto chitosan derivatives, Carbohydrate Polymers 76(4) (2009) 622-631. https://doi.org/10.1016/j.carbpol.2008.11.032
[82] Y. Zhu, Z.-S. Bai, H.-L. Wang, Microfluidic synthesis of thiourea modified chitosan microsphere of high specific surface area for heavy metal wastewater treatment, Chinese Chemical Letters 28(3) (2017) 633-641. https://doi.org/10.1016/j.cclet.2016.10.031
[83] M. Li, Z. Zhang, R. Li, J.J. Wang, A. Ali, Removal of Pb(II) and Cd(II) ions from aqueous solution by thiosemicarbazide modified chitosan, International Journal of Biological Macromolecules 86 (2016) 876-84. https://doi.org/10.1016/j.ijbiomac.2016.02.027
[84] Y.-C. Lin, H.-P. Wang, F. Gohar, M.H. Ullah, X. Zhang, D.-F. Xie, H. Fang, J. Huang, J.-X. Yang, Preparation and copper ions adsorption properties of thiosemicarbazide chitosan from squid pens, International Journal of Biological Macromolecules 95 (2017) 476-483. https://doi.org/10.1016/j.ijbiomac.2016.11.085
[85] L. Zhou, J. Liu, Z. Liu, Adsorption of platinum(IV) and palladium(II) from aqueous solution by thiourea-modified chitosan microspheres, Journal of Hazardous Materials 172(1) (2009) 439-446. https://doi.org/10.1016/j.jhazmat.2009.07.030
[86] E.C. da Silva Filho, P.D.R. Monteiro, K.S. Sousa, C. Airoldi, Ethylenesulfide as a useful agent for incorporation on the biopolymer chitosan in a solvent-free reaction for use in lead and cadmium removal, Journal of Thermal Analysis and Calorimetry 106(2) (2011) 369-373. https://doi.org/10.1007/s10973-010-1205-y
[87] A. Khan, S. Badshah, C. Airoldi, Dithiocarbamated chitosan as a potent biopolymer for toxic cation remediation, Colloids and surfaces. B, Biointerfaces 87(1) (2011) 88-95. https://doi.org/10.1016/j.colsurfb.2011.05.006
[88] K.C. Gavilan, A.V. Pestov, H.M. Garcia, Y. Yatluk, J. Roussy, E. Guibal, Mercury sorption on a thiocarbamoyl derivative of chitosan, Journal of Hazardous Materials 165(1-3) (2009) 415-26. https://doi.org/10.1016/j.jhazmat.2008.10.005
[89] L. Wang, R. Xing, S. Liu, H. Yu, Y. Qin, K. Li, J. Feng, R. Li, P. Li, Recovery of silver (I) using a thiourea-modified chitosan resin, Journal of Hazardous Materials 180(1-3) (2010) 577-82. https://doi.org/10.1016/j.jhazmat.2010.04.072
[90] E. Repo, J.K. Warchol, T.A. Kurniawan, M.E.T. Sillanpää, Adsorption of Co(II) and Ni(II) by EDTA- and/or DTPA-modified chitosan: Kinetic and equilibrium modeling, Chemical Engineering Journal 161(1-2) (2010) 73-82. https://doi.org/10.1016/j.cej.2010.04.030
[91] N.K. Lazaridis, G.Z. Kyzas, A.A. vassiliou, D.N. Bikiaris, Chitosan derivatives as biosorbents for basic dyes, Langmuir 23 (2007) 7634-7643. https://doi.org/10.1021/la700423j
[92] Y. Yan, B. Xiang, Y. Li, Q. Jia, Preparation and adsorption properties of diethylenetriamine-modified chitosan beads for acid dyes, Journal of Applied Polymer Science 130(6) (2013) 4090-4098. https://doi.org/10.1002/app.39691
[93] J. Roosen, K. Binnemans, Adsorption and chromatographic separation of rare earths with EDTA- and DTPA-funtionalized chitosan biopolymers, Journal of Materials Chemistry A 2 (2014) 1530-1540. https://doi.org/10.1039/C3TA14622G
[94] H.M. Zalloum, Z. Al-Qodah, M.S. Mubarak, Copper Adsorption on Chitosan-Derived Schiff Bases, Journal of Macromolecular Science, Part A 46(1) (2008) 46-57.
[95] B. Hastuti, D. Siswanta, Mudasir, Triyono, Synthesis and Characterization Pectin-Carboxymethyl Chitosan crosslinked PEGDE as biosorbent of Pb(II) ion, IOP Conference Series: Materials Science and Engineering 299 (2018) 012052. https://doi.org/10.1088/1757-899X/299/1/012052
[96] N.G. Kandile, A.S. Nasr, New hydrogels based on modified chitosan as metal biosorbent agents, International Journal of Biological Macromolecules 64 (2014) 328-33. https://doi.org/10.1016/j.ijbiomac.2013.12.022
[97] H.T.Y. Ly, S. Van Nguyen, in International Conference on Green Technology and Sustainable Development (GTSD). (IEEE, 2016), vol. DOI: 10.1109/GTSD.2016.62, pp. 244-250.
[98] K.S. Manish, Recyclable Crosslinked O-Carboxymethyl Chitosan for Removal of Cationic Dye from Aqueous Solutions, Journal of Waste Water Treatment & Analysis 03(04) (2012). https://doi.org/10.4172/2157-7587.1000138
[99] L. Wang, R. Xing, S. Liu, S. Cai, H. Yu, J. Feng, R. Li, P. Li, Synthesis and evaluation of a thiourea-modified chitosan derivative applied for adsorption of Hg(II) from synthetic wastewater, International Journal of Biological Macromolecules 46(5) (2010) 524-8. https://doi.org/10.1016/j.ijbiomac.2010.03.003
[100] L. Wang, A. Wang, Adsorption properties of congo red from aqueous solution onto N,O-carboxymethyl-chitosan, Bioresource Technology 99(5) (2008) 1403-8. https://doi.org/10.1016/j.biortech.2007.01.063
[101] L. Wang, H. Peng, S. Liu, H. Yu, P. Li, R. Xing, Adsorption properties of gold onto a chitosan derivative, International Journal of Biological Macromolecules 51(5) (2012) 701-4. https://doi.org/10.1016/j.ijbiomac.2012.06.010
[102] L. Wang, Q. Li, A. Wang, Adsorption of cationic dye on N,O-carboxymethyl-chitosan from aqueous solutions: equilibrium, kinetics, and adsorption mechanism, Polymer Bulletin 65(9) (2010) 961-975. https://doi.org/10.1007/s00289-010-0363-1
[103] C. Wang, Q. Song, J. Gao, Investigation of adsorption capacity of N-carboxymethyl chitosan for Pb(II) ions, Water science and technology : a Journal of the International Association on Water Pollution Research 68(8) (2013) 1873-9.
[104] N.V. Suc, H.T.Y. Ly, Lead (II) removal from aqueous solution by chitosan flake modified with citric acid via crosslinking with glutaraldehyde, Journal of Chemical Technology & Biotechnology 88(9) (2013) 1641-1649. https://doi.org/10.1002/jctb.4013
[105] A. Sowmya, S. Meenakshi, Effective removal of nitrate and phosphate anions from aqueous solutions using functionalised chitosan beads, Desalination and Water Treatment 52(13-15) (2013) 2583-2593. https://doi.org/10.1080/19443994.2013.798842
[106] R. Laus, T.G. Costa, B. Szpoganicz, V.T. Favere, Adsorption and desorption of Cu(II), Cd(II) and Pb(II) ions using chitosan crosslinked with epichlorohydrin-triphosphate as the adsorbent, Journal of Hazardous Materials 183(1-3) (2010) 233-41. https://doi.org/10.1016/j.jhazmat.2010.07.016
[107] S.-J. Wu, T.-H. Liou, C.-H. Yeh, F.-L. Mi, T.-K. Lin, Preparation and characterization of porous chitosan–tripolyphosphate beads for copper(II) ion adsorption, Journal of Applied Polymer Science 127(6) (2013) 4573-4580.
[108] M. Ahmad, K. Manzoor, S. Ikram, Versatile nature of hetero-chitosan based derivatives as biodegradable adsorbent for heavy metal ions; a review, International Journal of Biological Macromolecules 105(Pt 1) (2017) 190-203. https://doi.org/10.1016/j.ijbiomac.2017.07.008
[109] S.A. Ali, R.P. Singh, Synthesis and Characterization of a Modified Chitosan, Macromolecular Symposia 277(1) (2009) 1-7. https://doi.org/10.1002/masy.200950301
[110] N. Li, R. Bai, Novel chitosan-cellulose hydrogel adsorbents for lead adsorption, Conference Proceedings, AIChE Annual Meeting, 2004.
[111] S. Rosa, M.C. Laranjeira, H.G. Riela, V.T. Favere, Cross-linked quaternary chitosan as an adsorbent for the removal of the reactive dye from aqueous solutions, Journal of Hazardous Materials 155(1-2) (2008) 253-60. https://doi.org/10.1016/j.jhazmat.2007.11.059
[112] R. Karthik, S. Meenakshi, Removal of Pb(II) and Cd(II) ions from aqueous solution using polyaniline grafted chitosan, Chemical Engineering Journal 263 (2015) 168-177. https://doi.org/10.1016/j.cej.2014.11.015
[113] H. Abdel-Razik, H. Almahy, Recovery of Water from Heavy metals using Chelating Chemcially Modified Chitosan, Int. J. Chem. Sci. 13(4) (2015) 1713-1725.
[114] K. Kondo, R. Eto, M. Matsumoto, Adsorption of Pd and Pt on Chemically Modified Chitosan, Bull Soc Sea Water Sci Jpn 69 (2015) 197-204.
[115] K. Azlan, W.N. Wan Saime, L. Lai Ken, Chitosan and chemically modified chitosan beads for acid dyes sorption, Journal of Environmental Sciences 21(3) (2009) 296-302. https://doi.org/10.1016/S1001-0742(08)62267-6
[116] R. Bhatt, B. Sreedhar, P. Padmaja, Adsorption of chromium from aqueous solutions using crosslinked chitosan-diethylenetriaminepentaacetic acid, Int J Biol Macromol 74 (2015) 458-66. https://doi.org/10.1016/j.ijbiomac.2014.12.041
[117] A. Pestov, S. Bratskaya, Chitosan and Its Derivatives as Highly Efficient Polymer Ligands, Molecules 21(3) (2016) 330. https://doi.org/10.3390/molecules21030330
[118] H. Karaer, İ. Uzun, Adsorption of basic dyestuffs from aqueous solution by modified chitosan, Desalination and Water Treatment 51(10-12) (2013) 2294-2305. https://doi.org/10.1080/19443994.2012.734967
[119] Y. Xing, X. Sun, B. Li, Poly(methacrylic acid)-modified chitosan for enhancement adsorption of water-soluble cationic dyes, Polymer Engineering & Science 49(2) (2009) 272-280. https://doi.org/10.1002/pen.21253
[120] V.K. Konaganti, R. Kota, S. Patil, G. Madras, Adsorption of anionic dyes on chitosan grafted poly(alkyl methacrylate)s, Chemical Engineering Journal 158(3) (2010) 393-401. https://doi.org/10.1016/j.cej.2010.01.003
[121] W.S. Wan Ngah, K.H. Liang, Adsorption of Gold(III) ions intos chitosan and N-carboxymethyl chitosan: Equilibrium studies, Ind. Eng. Chem. Res. 38 (1999) 1411-1414. https://doi.org/10.1021/ie9803164
[122] R. Jayakumar, R.L. Reis, J.F. Mano, Chemisry and Apllications of Phosphorylated Chitin and Chitosan, e-polymers 35 (2006) 1-16.
[123] F. Lebouc, I. Dez, M. Gulea, P.-J. Madec, P.-A. Jaffrès, Synthesis of Phosphorus-Containing Chitosan Derivatives, Phosphorus, Sulfur, and Silicon and the Related Elements 184(4) (2009) 872-889. https://doi.org/10.1080/10426500802715585
[124] R. Jayakumar, N. Selvamurugan, S.V. Nair, S. Tokura, H. Tamura, Preparative methods of phosphorylated chitin and chitosan—An overview, International Journal of Biological Macromolecules 43(3) (2008) 221-225. https://doi.org/10.1016/j.ijbiomac.2008.07.004
[125] A. Zuñiga, A. Debbaudt, L. Albertengo, M.S. Rodríguez, Synthesis and characterization of N-propyl-N-methylene phosphonic chitosan derivative, Carbohydrate Polymers 79(2) (2010) 475-480. https://doi.org/10.1016/j.carbpol.2009.08.011
[126] A. Heras, N.M. Rodríguez, V.M. Ramos, E. Agulló, N-methylene phosphonic chitosan: a novel soluble derivative, Carbohydrate Polymers 44(1) (2001) 1-8. https://doi.org/10.1016/S0144-8617(00)00195-8
[127] V.M. Ramos, Rodrı, x, N.M. guez, Rodrı, x, M.S. guez, A. Heras, E. Agulló, Modified chitosan carrying phosphonic and alkyl groups, Carbohydrate Polymers 51(4) (2003) 425-429. https://doi.org/10.1016/S0144-8617(02)00211-4
[128] D.J. Suchyta, R.J. Soto, M.H. Schoenfisch, Selective monophosphorylation of chitosan via phosphorus oxychloride, Polym Chem 8(16) (2017) 2552-2558. https://doi.org/10.1039/C7PY00123A
[129] A.M.A. Morsy, Adsorptive removal of uranium ions from liquid waste solutions by phosphorylated chitosan, Environmental Technology & Innovation 4 (2015) 299-310. https://doi.org/10.1016/j.eti.2015.10.002
[130] Z.-m. Dong, Y.-f. Qiu, Y. Dai, X.-h. Cao, L. Wang, P.-f. Wang, Z.-j. Lai, W.-l. Zhang, Z.-b. Zhang, Y.-h. Liu, Z.-g. Le, Removal of U(VI) from aqueous media by hydrothermal cross-linking chitosan with phosphate group, Journal of Radioanalytical and Nuclear Chemistry 309(3) (2016) 1217-1226. https://doi.org/10.1007/s10967-016-4722-8
[131] A.M. Elbarbary, M.M. Ghobashy, Phosphorylation of chitosan/HEMA interpenetrating polymer network prepared by gamma-radiation for metal ions removal from aqueous solutions, Carbohydr Polym 162 (2017) 16-27. https://doi.org/10.1016/j.carbpol.2017.01.013
[132] J. Wang, S. Zhuang, Removal of various pollutants from water and wastewater by modified chitosan adsorbents, Critical Reviews in Environmental Science and Technology 47(23) (2017) 2331-2386. https://doi.org/10.1080/10643389.2017.1421845
[133] X. Tang, C. Wang, Adsorption of Ni(II) from Aqueous Solution by Polyaminated Crosslinked Ni(II)-Imprinted Chitosan Derivative Beads, Environmental Engineering Science 30(10) (2013) 646-652. https://doi.org/10.1089/ees.2013.0099
[134] S. Sun, A. Wang, Adsorption properties of carboxymethyl-chitosan and cross-linked carboxymethyl-chitosan resin with Cu(II) as template, Separation and Purification Technology 49(3) (2006) 197-204. https://doi.org/10.1016/j.seppur.2005.09.013
[135] S. Sun, L. Wang, A. Wang, Adsorption properties of crosslinked carboxymethyl-chitosan resin with Pb(II) as template ions, Journal of Hazardous Materials 136(3) (2006) 930-7. https://doi.org/10.1016/j.jhazmat.2006.01.033
[136] Y. Baba, O. kaoru, T. Ohshima, R. Dhakal, Preparation of palladium(II)-imprinted chitosan derivatives and its adsorption properties of precious metals, J. Ion Exchange 18(4) (2007) 226-230. https://doi.org/10.5182/jaie.18.226
[137] D. Yang, L. Qiu, Y. Yang, Efficient Adsorption of Methyl Orange Using a Modified Chitosan Magnetic Composite Adsorbent, Journal of Chemical & Engineering Data 61(11) (2016) 3933-3940. https://doi.org/10.1021/acs.jced.6b00706
[138] L. Jia, J.S. Wang, Q.W. Guo, X.L. Zou, L. Xie, Adsorption of Cr (VI) by Cross-Linked Magnetic Hydroxamated Chitosan, Advanced Materials Research 842 (2013) 175-179. https://doi.org/10.4028/www.scientific.net/AMR.842.175
[139] L. Fan, C. Luo, Z. Lv, F. Lu, H. Qiu, Preparation of magnetic modified chitosan and adsorption of Zn(2)(+) from aqueous solutions, Colloids and surfaces. B, Biointerfaces 88(2) (2011) 574-81. https://doi.org/10.1016/j.colsurfb.2011.07.038
[140] T.V.J. Charpentier, A. Neville, J.L. Lanigan, R. Barker, M.J. Smith, T. Richardson, Preparation of Magnetic Carboxymethylchitosan Nanoparticles for Adsorption of Heavy Metal Ions, ACS Omega 1(1) (2016) 77-83. https://doi.org/10.1021/acsomega.6b00035
[141] A. Donia, A. yousif, A. Atia, M. Elsamalehy, Efficient adsorption of Ag(I) and Au(III) on modified magnetic chitosan with amine functionalities, Desalination and Water Treatment 52 (2014) 2537-2547. https://doi.org/10.1080/19443994.2013.794706
[142] N. Tripathi, G. Choppala, R.S. Singh, P. Srivastava, B. Seshadri, Sorption kinetics of zinc and nickel on modified chitosan, Environ Monit Assess 188(9) (2016) 507. https://doi.org/10.1007/s10661-016-5499-5
[143] S.P. Kamble, S. Jagtap, N.K. Labhsetwar, D. Thakare, S. Godfrey, S. Devotta, S.S. Rayalu, Defluoridation of drinking water using chitin, chitosan and lanthanum-modified chitosan, Chemical Engineering Journal 129(1-3) (2007) 173-180. https://doi.org/10.1016/j.cej.2006.10.032
[144] P. Liang, Y. Zhang, D. Wang, Y. Xu, L. Luo, Preparation of mixed rare earths modified chitosan for fluoride adsorption, Journal of Rare Earths 31(8) (2013) 817-822. https://doi.org/10.1016/S1002-0721(12)60364-0
[145] T. Fagundes, E.L. Bernardi, C.A. Rodrigues, PHOSPHATE ADSORPTION ON CHITOSAN-FeIII-CROSSLINKING: BATCH AND COLUMN STUDIES, Journal of Liquid Chromatography & Related Technologies 24(8) (2001) 1189-1198. https://doi.org/10.1081/JLC-100103441
[146] J. Zhang, N. Chen, T. Zheng, Y. Yu, Q. Hu, C. Feng, A study of the mechanism of fluoride adsorption from aqueous solutions onto Fe-impregnated chitosan, Phys.Chem.Chem.Phys 17 (2015) 12041-12040. https://doi.org/10.1039/C5CP00817D
[147] E.I. Unuabonah, A. Adewuyi, M.O. Kolawole, M.O. Omorogie, O.C. Olatunde, S.O. Fayemi, C. Günter, C.P. Okoli, F.O. Agunbiade, A. Taubert, Disinfection of water with new chitosan-modified hybrid clay composite adsorbent, Heliyon 3(8) (2017) e00379. https://doi.org/10.1016/j.heliyon.2017.e00379
[148] N.A. Negm, H.E. Ali, Modification of heavy metal uptake efficiency by modified chitosan/anionic surfactant systems, Engineering in Life Sciences 10(3) (2010) 218-224. https://doi.org/10.1002/elsc.200900110
[149] M.U. Khobragade, A. Pal, Fixed-bed column study on removal of Mn(II), Ni(II) and Cu(II) from aqueous solution by surfactant bilayer supported alumina, Separation Science and Technology 51(8) (2016) 1287-1298. https://doi.org/10.1080/01496395.2016.1156698
[150] A. Adak, M. Bandyopadhyay, A. Pal, Adsorption of Anionic Surfactant on Alumina and Reuse of the Surfactant-Modified Alumina for the Removal of Crystal Violet from Aquatic Environment, Journal of Environmental Science and Health, Part A 40(1) (2005) 167-182.
[151] D. Das, A. Pal, Adsolubilization phenomenon perceived in chitosan beads leading to a fast and enhanced malachite green removal, Chemical Engineering Journal 290 (2016) 371-380. https://doi.org/10.1016/j.cej.2016.01.062
[152] C. Lin, S. Wang, H. Sun, R. Jiang, Adsorption of anionic dye by anionic surfactant modified chitosan beads: Influence of hydrophobic tail and ionic head-group, Journal of Dispersion Science and Technology 39(1) (2017) 106-115. https://doi.org/10.1080/01932691.2017.1298041
[153] M.H. Mahaninia, L.D. Wilson, Cross-linked chitosan beads for phosphate removal from aqueous solution, Journal of Applied Polymer Science (2015) 1-10.
[154] U. Filipkowska, T. Jozwiak, P. Szymczyk, Application of cross-linked chitosan for phosphate removal from aqueous solutions, Progress on Chemistry and Application of Chitin and Its Derivatives XIX (2014) 5-14. https://doi.org/10.15259/PCACD.19.01
[155] M. Ahmad, S. Ahmed, B.L. Swami, S. Ikram, Preparation and characterization of antibacterial thiosemicarbazide chitosan as efficient Cu(II) adsorbent, (1879-1344 (Electronic)).
[156] M.A. Badawi, N.A. Nem, M.T.H. Abou Kana, H.H. Hefni, M.M. Abdel Moneem, Adsorption of aluminum and lead from wastewater by chitosan-tannic acid modified biopolymers Isotherms kinetics thermodynamics and process mechanism, International Journal of Biological Macromolecules 99 (2017) 405-476. https://doi.org/10.1016/j.ijbiomac.2017.03.003
[157] A.V. Pestov, O.V. Koryakova, I.I. Leonidov, Y.G. Yatluk, Gel-synthesis, structure, and properties of sulfur-containing chitosan derivatives, Russian Journal of Applied Chemistry 83(5) (2010) 787-794. https://doi.org/10.1134/S1070427210050058
[158] M. Ruiz, A.M. Sastre, E. Guibal, Palladium sorption on glutaraldehyde-crosslinked chitosan, Reactive and Functional Polymers 45(3) (2000) 155-173. https://doi.org/10.1016/S1381-5148(00)00019-5
[159] P. Chassary, T. Vincent, J. Sanchez Marcano, L.E. Macaskie, E. Guibal, Palladium and platinum recovery from bicomponent mixtures using chitosan derivatives, Hydrometallurgy 76(1) (2005) 131-147. https://doi.org/10.1016/j.hydromet.2004.10.004
[160] C. Gerente, V.K.C. Lee, P.L. Cloirec, G. McKay, Application of Chitosan for the Removal of Metals From Wastewaters by Adsorption—Mechanisms and Models Review, Critical Reviews in Environmental Science and Technology 37(1) (2007) 41-127. https://doi.org/10.1080/10643380600729089
[161] N. Sakkayawong, P. Thiravetyan, W. Nakbanpote, Adsorption mechanism of synthetic reactive dye wastewater by chitosan, Journal of colloid and interface science 286(1) (2005) 36-42. https://doi.org/10.1016/j.jcis.2005.01.020
[162] G.Z. Kyzas, D.N. Bikiaris, Recent modifications of chitosan for adsorption applications: a critical and systematic review, Marine drugs 13(1) (2015) 312-37. https://doi.org/10.3390/md13010312
[163] S.S. Silva, J.F. Mano, R.L. Reis, Ionic liquids in the processing and chemical modification of chitin and chitosan for biomedical applications, Green Chemistry 19(5) (2017) 1208-1220. https://doi.org/10.1039/C6GC02827F
[164] K. Ghandi, A Review of Ionic Liquids, Their Limits and Applications, Green and Sustainable Chemistry 04(01) (2014) 44-53. https://doi.org/10.4236/gsc.2014.41008
[165] Y. Liu, Y. Liu, T. Huo, X. Wu, J. Wei, P. Dong, D. Di, J. Wang, Y. Sun, Effect of the ionic liquid group in novel interpenetrating polymer networks on the adsorption properties for oleuropein from aqueous solutions, New Journal of Chemistry 39(12) (2015) 9181-9190. https://doi.org/10.1039/C5NJ01475A
[166] K.P. Eliodorio, V.S. Andolfatto, M.R.G. Martins, B.P. de Sá, E.R. Umeki, A. de Araújo Morandim-Giannetti, Treatment of chromium effluent by adsorption on chitosan activated with ionic liquids, Cellulose 24(6) (2017) 2559-2570. https://doi.org/10.1007/s10570-017-1264-3
[167] Y. Wei, W. Huang, Y. Zhou, S. Zhang, D. Hua, X. Zhu, Modification of chitosan with carboxyl-functionalized ionic liquid for anion adsorption, International Journal of Biological Macromolecules 62 (2013) 365-9. https://doi.org/10.1016/j.ijbiomac.2013.09.020
[168] A.S. Kumar, S. Sharma, R.S. Reddy, M. Barathi, N. Rajesh, Comprehending the interaction between chitosan and ionic liquid for the adsorption of Palladium, International Journal of Biological Macromolecules 72 (2015) 633-9. https://doi.org/10.1016/j.ijbiomac.2014.09.002
[169] L. Lupa, R. Voda, A. Popa, Adsorption behavior of cesium and strontium onto chitosan impregnated with ionic liquid, Separation Science and Technology 53(7) (2017) 1107-1115. https://doi.org/10.1080/01496395.2017.1313274
[170] F. Naseeruteen, N.S.A. Hamid, F.B.M. Suah, W.S.W. Ngah, F.S. Mehamod, Adsorption of malachite green from aqueous solution by using novel chitosan ionic liquid beads, International Journal of Biological Macromolecules 107(Pt A) (2018) 1270-1277.
[171] D. Ishii, C. Ohashi, H. Hayashi, Facile enhancement of the deacetylation degree of chitosan by hydrothermal treatment in an imidazolium-based ionic liquid, Green Chemistry 16(4) (2014) 1764-1767. https://doi.org/10.1039/c3gc41852a