The cationic dye removal by novel Si-Zn composites prepared from zinc ash

Zinc ash, a waste in hot dip galvanizing, was firstly used for the successful synthesis of Si-Zn composites (SZC) and for the removal of methylene blue (MB) from effluent. Materials were characterized by XRD, FE-SEM, FT-IR and XPS. The adsorption properties and optimum parameters were determined by operating different conditions (contact time, concentration of the dye, pH and temperature). Interestingly, the morphology was found to have significant impact on adsorption results. The adsorption quantities of SZC-1, SZC-2 and SZC-3 were 60.06 mg g(-1), 20.13 mg g(-1) and 11.76 mg g(-1), respectively. The equilibrium data were analyzed by different isothermal models (Langmuir and Freundlich) and the mechanistic studies demonstrated that the pseudo-second-order kinetic model was fitted well to the adsorption. The increased values of enthalpy indicated an endothermic process. The result of XPS was discussed and the binding energy of Zn and S showed negative shifts, which suggested a chemisorption process due to the generation of the coordinate bond. The regeneration assessment was carried out by conducting a calcination method at 773 K and the material indicated a steady mass ratio (89%) and adsorption capacity (55.76 mg g(-1)) after four-time reuse. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.