Chitosan-montmorillonite bionanocomposite as textile dyes adsorbent

Abstract

The removal of color dyes from wastewater before they are released in natural waters is important since some dyes are highly toxic for environment. Although several traditional chemical and biological processes exist for dye removal, application of these techniques has been restricted of low cost adsorbents suitable for dye removal. Since natural clays are ineffective as adsorbents for organic compounds it is necessary to modify their surface. Chitosan-clay nanocomposites are promising materials with organic-inorganic hybrid interfaces. These materials contain a biopolymer chitosan and they represent a green alternative to conventional organoclays in their applications, i.e. as adsorbents. The intercalation of chitosan into smectite clay can result in monolayer and/or bilayer arrangements. When bilayer structures are formed some free –NH3 + groups present in the interlamellar region are making these materials suitable for adsorption of anionic species, i.e. anionic textile dyes. In this work chitosan-clay nanocomposite was synthesized using Na+-enriched smecite clay and characterized using physical-chemical methods. In this manner the bionanocomposite with bilayered intercalation of chitosan chain was obtained and tested as adsorbent. The adsorption of anionic dyes Acid Orange 10 (AO10), Acid Yellow 99 (AY99) and Reactive Black 5 (RB5) has been studied by varying the different adsorbate concentrations, temperature and shaking time. The concentration of commercial textile dyes was analyzed before and after adsorption test using Thermo Electron Nicolet Evolution 500 UV-VIS spectrophotometer in wavelength range from 250 – 800 nm.