Pine needle biochar as a low cost adsorbent for removal of malachite green dye from wastewater

Abstract

Pine needle biochar (PNB) has been examined as a promising cost-effective adsorbent using batch method for mitigation of Malachite green (MG) dye from synthetic wastewater. The effects of time of equilibration, equilibrium pH, dye concentration and temperature have been studied on adsorption of malachite green. Adsorption kinetics of MG onto PNB conformed to pseudo-first-order reaction. Adsorption of the dye onto PNB fitted well to Freundlich isotherm model indicating that multilayer adsorption and adsorption capacities (KF) are the highest (6837.40 mg/kg) at pH 7.0, intermediate (4073.61 mg/kg) at pH 9.0 and minimum (1196.05 mg/kg) at pH 4.6. Adsorption of malachite green regularly increased with increase in temperature. The evaluation of thermodynamic parameters indicate that adsorption of MG onto PNB was a spontaneous and endothermic reaction with increase in the disorderliness of the system. Fourier transformed infra-red spectroscopy (FTIR) studies indicate involvement of H-bonding and electron exchange between aromatic nuclei and electron donor groups onto PNB.