Efficient removal of lead from aqueous solution by urea-functionalized magnetic biochar: Preparation, characterization and mechanism study

A novel urea-functionalized magnetic biochar (MBCU) was prepared, characterized and evaluated for removal of lead (II) from aqueous solution. The results of SEM, BET, XPS, FFIR, VSM and Zeta-potential exhibited a successful fabrication of MBCU. The magnetism magnitude of magnetic biochar could simultaneously affect the adsorption and recovery efficiency of lead (II) on magnetic biochar. Hence, the optimum mass ratio range of MBCU was determined to be 1.7:1-2.3:1, which could guarantee high removal (> 73.14%) and recovery (> 78.35%) efficiency. The experimental results indicated that the adsorption isotherm and kinetics were well described by the Sips model and pseudo-second-order model, respectively. The maximum adsorption capacity of lead (II) on MBCU was 188.18 mg/g at 323 K. Five-cycle reusability tests demonstrated MBCU could be effectively recovered and repeatedly used with a small adsorption loss (<20%). Mechanism study demonstrated that the adsorption process involved in electrostatic interaction, ion exchange and complexation. The unique features of its outstanding adsorption performance, reusability and separation efficiency suggested that the magnetic biochar can be potentially applied in elimination of lead (II) from wastewater. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.