Synthesis of magnetic biochar from iron sludge for the enhancement of Cr (VI) removal from solution

Iron sludge was directly reutilized as ferric resource to synthesize magnetic Fe-coated cotton stalk biochar (Fe-CS) for Cr (VI) removal from aqueous solution. Physical analyses revealed that Fe-CS exhibited higher surface area of 129.2 m(2)/g and pore volume of 0.1711 cm(3)/g than those of the original cotton stalk biochar (OCS). Fe-CS showed an excellent enhanced adsorption for Cr (VI) (67.44 mg/g) removal compared with OCS (40.91 mg/g). The adsorption process followed the Langmuir isotherm model and the adsorption kinetic followed pseudo-second order model. Fe-CS can be easily separated from the solution using magnet and regenerated for reuse. The overall findings indicate that iron sludge derived from water treatment plant can be reutilized directly for iron resource, which can bring new direction in the treatment of iron sludge waste. (C) 2017 Published by Elsevier B.V. on behalf of Taiwan Institute of Chemical Engineers.