Performance of new mesoporous carbon sorbent prepared from grape industrial processing wastes for malachite green and congo red removal

Sorptive properties of a novel activated carbon (GWAC) prepared at optimized conditions from grape processing waste (GW) by ZnCl2 activation were tested using the textile dyes as cationic dye, malachite green (MG) and anionic dye, congo red (CR), from aqueous solutions. Batch experiments were conducted to study the effects of sorbent dose, initial dye concentration, agitation time and temperature at natural pH of dyes in aqueous solution on GWAC-dyes sorption systems. Equilibrium sorption isotherms and kinetics were investigated. The equilibrium experimental data were analyzed by the Langmuir and Freundlich models. Kinetic experiments revealed that the sorptions of MG and CR onto GWAC can be described with pseudo-second order model and the equilibrium isotherm data were well described by the Langmuir model. The sorption diffusion mechanisms were determined from the intra-particle diffusion model. Thermodynamic parameters showed that the process was spontaneous and endothermic. The sorption capacities of GWAC for the MG and CR removal were found to be 667 and 455 mg/g, respectively. These results clearly indicate the efficiency of GWAC as a promising sorbent for treatment of wastewater containing MG and CR. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.