Removal of Cr(VI) by biochar derived via co-pyrolysis of oily sludge with corn stalks

Abstract Co-pyrolysis of oily sludge with biomass to prepare carbon materials, is not only an effective way to solve the pollution problem of oily sludge, but also a method to get carbon materials. In this study, a waste recycling adsorbed carbon material (OS-CS AC), was obtained by co-pyrolysis of oily sludge (OS) and corn stalks (CS) directly, and then was applied to Cr(VI) removal. According to the hydroxy and carboxy masking experiments and the characterization of OS-CS AC by FT-IR, SEM, XPS, XRD, N2 physical adsorption-desorption, it shows that Cr(VI) can be adsorbed efficiently through pore filling effect, the surface oxygen-containing functional groups can promote the reduction of Cr(VI) to Cr(III) through electron donors, and the greater electrostatic attraction between the electron-donating functional group of OS-CS AC and Cr(VI), the stronger ability of remove Cr(VI). In addition, the removal process was discussed, the results indicates that the McKay kinetic, Langmuir isotherm and Van 't Hoff thermodynamic models were the most suitable models for the removal process. Furthermore, with the discussion of the main factors affecting the removal of Cr(VI), the removal of Cr(Ⅵ) could reached to 99.14%, which gives a comprehensive utilization way of oily sludge and corn stalks.