A GREEN APPROACH: MALACHITE GREEN ADSORPTION ONTO WASTE GREEN TEA BIOMASS. ISOTHERM AND KINETIC STUDIES

Dye (malachite green, MG) removal from aqueous solution using a green approach, adsorption onto waste green tea biomass, was considered in this work. Influence of the initial concentration over the MG uptake was considered in order to collect the experimental data necessary for equilibrium and kinetic modelling. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm equations were used to model the obtained experimental data. The best fit was obtained for Dubinin-Radushkevich model (R-2=0.994) indicating a chemisorption process (16.01 kJ/mol). The maximum monolayer coverage from Langmuir isotherm model was determined to be 14.08 mg/g. The considered kinetic models (pseudo-first pseudo-second-order, Elovich, intra-particle film diffusion) showed that experimental data best fitted on the pseudo-second-order model. The obtained results showed that the considered green and low cost biomass is an efficient material for dye removal from wastewaters.