Removal of Malachite Green Dye from Aqueous Solution by Adsorption Using Modified and Unmodified Local Agriculture Waste

Abstract

Local agriculture waste (Shell’s seeds of Ziziphus spina christi) (SZC), in both its unmodified SZC and acid-modified (SZC-AC) forms, was investigated for its potential use as a low-cost adsorbent for the removal of malachite green (MG). Characterization of the adsorbents was carried out using scanning electron microscope (SEM), Fourier transforms infra-red spectroscopy (FTIR), pH surface, Boehm titration, including, other physical and chemical properties of adsorbent. The effects of initial dye concentration, contact time, solution of pH, temperature and adsorbent dosage were investigated in detail by batch adsorption experiments. For the adsorption of MG were fitted using Langmuir and Freundlich isotherm models, equilibrium isotherms were applicable with maximum monolayer adsorption capacity wear 48.780 mg/g and 370.370 mg/g for the raw shells seeds of Ziziphus spina christi (SZC) and the activated carbon prepared from shells seeds by sulphuric acid SZC-AC, respectively. Kinetics studies showed that both followed the pseudo-second order. Thermodynamics studies indicated that the adsorption of MG was spontaneous on SZC and SZC-AC, and the reactions were endothermic and exothermic, respectively. The proposed adsorbents were successfully applied to the removal of malachite green dye from different water samples with a recovery % >95% and a relative standard deviation (RSD%) <3%.