Mangifera indica leaves powder for the removal of rhodamine B.: isotherm and kinetic studies

Abstract

Adsorption of Rhodamine B (RB) dye onto a non-conventional plant biosorbent, Mangifera indica (mango tree) leaves powder (MLP), was investigated in batch adsorption experiments. Process parameters which include initial dye concentration, contact time and adsorbent dosage were varied in order to evaluate their influence on the adsorption process. Maximum adsorption efficiency (87.00%) was obtained at 75 min. The experimental data fitted well to pseudo-second-order kinetic model and the intra-particle diffusion model, however, diffusion was not only the rate-controlling step. The isotherm modeling suggested that Freundlich isotherm best described the process, with R² value of 0.972, which is an indication of presence of multi-layer adsorption. The nf value (1.073) shows the adsorption process is favourable, indicating a physisorption. FT-IR results showed the shifting of peak down field and up field which depicts an interaction between the adsorbent and the dye molecules. The results showed that Mangifera indica leaves powder can be used as a low-cost adsorbent for the removal of RB from aqueous media.

Keywords: Adsorption, Isotherms, Kinetics, Mangifera indica, Rhodamine B.