Preparation of sulfonated chitosan for enhanced adsorption of methylene blue from aqueous solution

In this research, sulfonated chitosan (S-CS) was prepared by hydrothermal grafting reaction using 4-formyl-1,3-benzene disulfonate and glutaraldehyde as a cross-linker reagent. Batch adsorption experiments were performed to demonstrate the adsorptive properties of S-CS with a cationic dye (methylene blue; MB) as a model organic pollutant. The effect of the solution pH (3 -12), initial dye concentration (50-200 mg L-1), contact time (0-24 h) and temperature (30-50 degrees C) on the relative removal of MB were studied. The kinetics of adsorption for MB showed a good correlation with the pseudo-second order kinetic model, while the adsorption isotherm at equilibrium was conformed to the Temkin model (R-2 > 0.99). The maximum adsorption capacity, q(m) was 351.7, 326.1 and 302.4 mg g(-1) at 303, 313 and 323 K, respectively. Owing to the simpler preparation method, relatively high adsorption capacity and regeneration ability, S-CS represents a promising adsorbent for the controlled MB removal and for other related organic dye pollutants from aqueous solution.