Removal of malachite green from aqueous solution using waste pea shells as low-cost adsorbent – adsorption isotherms and dynamics

Abstract

The adsorptive removal of malachite green (MG) from aqueous solution using waste pea shells (Pisum sativum L.) is reported. Optimized conditions for maximum uptake were established. The adsorption was best described by the Freundlich model. A pseudo-second-order kinetic model correlated best with the data. Liquid-film and intra-particle diffusion control the overall process. Thermodynamic parameters indicated that adsorption was spontaneous, endothermic, and accompanied with an increase in entropy. Low contact time and high removal efficiency at natural pH of water recommend pea shells as efficient low-cost adsorbent for removal of MG from wastewaters.