Adsorption of low concentration perchlorate from aqueous solution onto modified cow dung biochar: Effective utilization of cow dung, an agricultural waste

In this study, cow dung biochar (CDB) and ferric chloride-modified CDB (Fe@CDB) were synthesized to remove low concentration perchlorate from water. The pseudo-second-order kinetics model was used and satisfactorily described perchlorate removal onto CDB and Fe@CDB. The Langmuir model fit the experimental isotherm data better than the Freundlich model. The maximum adsorption capacity obtained using the Langmuir model was 1787 mu g/g for Fe@CDB and 304 mu g/g for CDB. The detrimental effects of coexisting anions decreased as: NO3- > Cl- . SO. FeCI3 modification enhanced ion exchange, and this was the main mechanism rather than electrostatic interactions. Also, after modification, the surface area, pore volume, and pore size increased and promoted adsorption. The surface hydrophilicity increased and so did the amounts of the surface oxygenated functional groups OH and COOH, which were responsible for perchlorate adsorption. The materials were further characterized using Brunner Emmet Teller (BET) measurements, Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), Scanning Electron Microscopy (SEM), Elemental analysis, X-ray photoelectron spectroscopy (XPS), Boehm tilration, Zeta potential and Fourier transform infrared spectroscopy (FFIR). (C) 2018 Elsevier B.V. All rights reserved.