Chitosan-clay composite as highly effective and low-cost adsorbent for batch and fixed-bed adsorption of methylene blue

Modified Ball clay (MBC) and chitosan composite (MBC-CH) was prepared and its application for methylene blue (MB) adsorption from aqueous solution in an industrial prototype fixed-bed column adsorption was investigated. Morphological structure and functional groups of the MBC-CH were determined by scanning electron spectroscopy and Fourier transform infrared spectroscopy analysis, respectively. Batch adsorption studies revealed that MB adsorption on MBC-CH increased with increase in initial concentration and solution pH 4-12. Study on effect of some inorganic salts on MB adsorption revealed that sodium sulphate anions (SO42-) had greater inhibition effect than those of sodium chloride and sodium bicarbonate on both MBC and MBC-CH. The effects of initial concentration (30-300 mg/L), adsorbent bed height (2.5-4.5 cm) and influent flow rate (5-10 mL/min) on fixed-bed column adsorption breakthrough curves were evaluated. Column sorption capacities were 70 mg/g for MBC and 142 mg/g for MBC-CH. Dynamic modeling analysis revealed that Bohart-Adams model can best be used to predict the effluent breakthrough curves for successful design of MB adsorption than Yoon-Nelson model. Adsorption system failure studies showed that the adsorbents were resilient with some improvement observed at time of exhaustion and increased volume of effluent treated. The MBC-CH had above 50% adsorption uptake capacity after five regeneration cycles, this was higher than MBC. Adsorption of MB on MBC-CH was spontaneous, endothermic and had great affinity between the adsorbate and adsorbent. The findings of this study revealed that MBC-CH is a potential adsorbent for cationic dye pollution remediation. (C) 2013 Elsevier B.V. All rights reserved.