Biosorption of malachite green from an aqueous solution using pomegranate peel: Equilibrium modelling, kinetic and thermodynamic studies

Abstract

The use of economical, high efficient and environment-friendly adsorbents has been considered as a new source for active carbon, for the removal of dyes from industrial wastes. This study offers the removal of harmful malachite green (MG) with carbonized pomegranate peel (CPP). Characterization of biosorbent was made by FTIR, SEM, BET and pHzpc (zero point of charge). The effects of adsorbent dose, solution pH, initial dye concentration, contact time and temperature on the removal were analyzed by adsorption experiments and the optimum conditions were determined as pH: 6, initial dye concentration: 30mgL−1, adsorbent dose: 0.1g, temperature: 50°C, and contact time: 90min. Among Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Redlich-Peterson isotherms, Langmuir with R2=0.992 was the best fitting isotherm for the experimental data. The maximum adsorption capacity was determined as 31.45mgg−1. Analyses of the kinetic data were conducted by pseudo first order, pseudo second order, Elovich and intraparticle diffusion model. The results indicated that the pseudo-first-order kinetic model was the best one with R2≥0.955 for the analysis of kinetic data. Characteristics of adsorption were determined as spontaneous for ΔG°≤−1.92kJmol−1 and endothermic for ΔH° value of 139.30kJmol−1. Environmental wastewater evaluation and dye removal from wastewater were carried out on CPP, which is a low-cost adsorbent. Results indicated that the CPP can be used as a biomass adsorbent for the removal of dyes from aqueous solutions with good performance.