Cross-linked chitosan/sepiolite composite for the adsorption of methylene blue and reactive orange 16

Cross-linked chitosan/sepiolite composite was prepared from sepiolite clay and chitosan, and was cross linked using epichlorohydrin. Among the various weight ratio percentage of chitosan and sepiolite clay composites, CS50SP50 was selected as the best adsorbent for both methylene blue (MB) and reactive orange 16 (RO16). At an optimum adsorbent dosage of 0.2 g/100 mL, the effects of initial dye concentration (25-400 mg/L) and pH (3-11) on MB and R016 adsorption onto CS50SP50 composite were studied. Mono layer adsorption capacities of CS50SP50 composite for MB and R016 were 40.986 mg/g and 190.965 mg/g, respectively at 30 degrees C. Freundlich, Langmuir and Temkin isotherms applied on the adsorption data for both the dyes reveal that data fitted best for Freundlich model. For both the dyes pseudo-second-order kinetics were found to describe the adsorption process better than pseudo-first-order kinetics. The adsorption capacity of CS50SP50 composite for both the dyes was found better compared to previous studies thus making it potentially low-cost adsorbent for removal or both cationic and reactive dyes. (C) 2016 Elsevier B.V. All rights reserved.