Decolorization of water through removal of methylene blue and malachite green on biodegradable magnetic Bauhinia variagata fruits

Abstract

Batch sorption experiments were performed to investigate the potential of Bauhinia variagata fruit (BVf) and nano-magnetic Bauhinia variagata fruit (nM-BVf) to remove methylene blue (MB) and malachite green (MG). Equilibrium studies have been carried out using various experimental parameters such as the amount of biosorbent, initial solution concentration, contact time, pH, and temperature. The Langmuir, Freundlich, Scatchard, D-R and Temkin adsorption models were applied for the experimental information of MB and MG. The Freundlich model fits better than the Langmuir model. Freundlich model confirmed the magnificent dye sorption ability; 19.3 mg/g for BVf/MB, 21.2 mg/g for nM-BVf/MB, 19.7 mg/g for BVf/MG, and 30.1 mg/g for nM-BVf/MG. The pseudo-second-order kinetic model displayed a more suitable behavior to the experimental result for the removal of MG and MB. Thermodynamic parameters such as changes in Gibbs free energy (ΔG o), enthalpy (ΔH o), and entropy (ΔS o) were investigated and the fine details in the adsorption system were completed. The conclusion from this study is that the prepared nano biosorbent can be efficient for the removal of cationic dyes from wastewater.