Chitosan-montmorillonite biocomposites as sorbents for anionic and cationic dyes

Full text: Currently, the synthesis of biocomposites has presented a novel approach for modifying several properties of polysaccharides, such as swelling/absorption of water and mechanical/thermal behavior [1]. In addition, the composite materials had a higher specific strength, lower specific gravity and higher chemical resistance [2]. Some materials have been used to form composites with chitosan such as mineral clays, which have been investigated due to their high disponibility and their promising chemical and physical properties [1-3]. Among them, montmorillonite has been highlighted because of its high cationic exchange capacity and the possibility of lamellar expansion, which provides greater versatility in the interaction and intercalation of bulky molecules such as chitosan. In this study, chitosan-clay beads in the proportions of 5, 15 and 25% were prepared by crosslinking with pentasodium tripolyphosphate to form new selective sorbent materials for both anionic and cationic dyes as methylene blue and remazol blue from aqueous solutions. The prepared biocomposites were characterized by XRD, FTIR, thermogravimetry, ¹³C NMR and TEM. The effects of the pH, the contact time and the initial dye concentration were investigated. Both kinetic and equilibrium parameters of the sorption process were obtained. The results were highly promising and suggest that these adsorbents can be applied as alternative for dye removal in wastewater stream. References: [1] S.F. Wang, L. Shen, Y.J. Tong, L. Chen, I.Y. Phang, P.Q. Lim, T.X. Liu, Polymer Degradation and Stability, 90 (2005) 123-131. [2] D. Saravanan, T. Gomathi, P.N. Sudha, International Journal of Biological Macromolecules, 53 (2013) 67-71. [3] A.R. Nesic, S.J. Velickovic, D.G. Antonovic, Journal of Hazardous Materials, 209-210 (2012) 256-263. (author)