Removal of Methylene Blue from Aqueous Solution by Crosslinked Chitosan-g-Poly(Acrylic Acid)/Bentonite Composite

A new crosslinked chitosan-g-poly (acrylic acid)/bentonite composite (CS-g-PAA/BT) was prepared and used for the removal of methylene blue (MB). CS-g-PAA/BT was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The water absorbency for CS-g-PAA/BT was found to be 93 and 50 g H(2)Og(-1) in distilled water and 0.2% NaCl, respectively. The results showed that the adsorption of the MB on the CS-g-PAA/BT was effected by the initial dye concentration, the initial pH value, as well as the temperature. Both kinetics and thermodynamic parameters of the adsorption process were estimated. These data indicated an endothermic spontaneous adsorption process that kinetically followed the second-order adsorption process. Equilibrium experiments fitted well the Langmuir isotherm model, and the maximum monolayer adsorption capacity for the MB was 2000-2500 mg g(-1) at 298-313 K. The results of this study implied that CS-g-PAA/BT can be used a promising adsorbent for the removal of MB from wastewater.