Model sorption of industrial wastewater containing Cu2+, Cd2+, and Pb2+ using individual and mixed rice husk biochar

Abstract Few studies have used biochar mixtures to remove potentially toxic elements from industrial wastewater. The present batch studies compare the adsorption of Cu 2 + , Cd 2 + , and Pb 2 + by single and mixed sorbents using rice husk feedstock (RH), rice husk biochar (RHB), ethylene-diamine-tetra-acetic acid-modified biochar (EDTA-RHB), and a mixture (MB) of these biosorbents. Metal sorption studies were carried out by varying the adsorbents, metal ion concentrations, contact time, and solution pH in a synthetic industrial wastewater. In all experiments, RHB, EDTA-RHB, and MB removed up to 98% of the metal ions within 60 min at pH 4. Kinetic studies showed that first- and second-order models gave the best fit for MB; whereas, the Freundlich model gave the best fit for the isotherm data. Results indicate that MB and EDTA-RHB treatments were more effective for adsorbing the studied heavy metals than RH or RHB. Such biosorbents could be useful in the treatment of co-existing potentially toxic elements from wastewater.