Adsorption of basic dyestuffs from aqueous solution by modified chitosan

The capability of chitosan to adsorb the basic dyestuffs is very low. For this purpose, chitosan was modified to increase its adsorption capability with some cyclic acid anhydrides in dimethyl sulfoxide. Then, chitosan and its derivatives, chitosan modified with maleic anhydride (CMA), chitosan modified with phthalic anhydride (CPA), and chitosan modified with trimellitic anhydride (CTA), were compared according to their capabilities to remove brilliant green (BG) and methylene blue (MB) from aqueous solution. It was determined that CTA adsorbed much more BG and MB. The 70.57% of BG (C-o: 50 ppm) and 71.86% of MB (C-o: 50 ppm) in the samples of 50 mL by 0.1 g CTA were adsorbed at room temperature and at a shaking rate of 140 rpm within 24 h. As a result of this, the adsorption of BG and MB by CTA was kinetically investigated as dependent on temperature and pH. Besides, the adsorption isotherms of each dyestuff by CTA were determined at different temperatures. Then, some kinetical and thermodynamical parametres were calculated by using experimental data.