Decolourization of malachite green using tamarind seed: Optimization, isotherm and kinetic studies

In this work, removal of malachite green (MG) from aqueous solution using a low cost adsorbent, tamarind seed, was investigated. The adsorbent was characterized using SEM, BET surface area analyzer, and FT-IR. Decolorization of malachite green was studied as a function of different adsorption parameters such as temperature, adsorbent dose, contact time, adsorbent size and agitation speed. These parameters were optimized using response surface methodology (RSM). The significance of different adsorption parameters along with their combined effect on the adsorption process has been established through a full 50 factorial design. Langmuir, Freundlich, Redlich Petersen, Dubnin Redushkevich and Tempkin adsorption isotherm equations were used in the equilibrium modeling. Experimental data follows Langmuir adsorption isotherm. The adsorption process follows pseudo first order and intra-particle diffusion is found to be the rate-controlling step.