Abstract:Modified sludge biochar (NSBC) was prepared using NaOH activation of original sludge biochar and used for removing Cd(Ⅱ) from acid mine wastewater. The effects of initial pH, co-existing ions, adsorption time and initial concentration on the Cd(Ⅱ) removal were investigated by batch adsorption experiment, and the mechanism of removing Cd(Ⅱ) from aqueous solutions was also explored. Compared with SBC, the surface of NSBC was porous and the number of oxygen-containing groups was increased. Compared with SBC, NSBC maintained a Cd(Ⅱ) removal efficiency of more than 95% in the solution pH range of 4.0~7.0 and possessed stronger resistance to ionic interference. The Cd(Ⅱ) removal behaviors of SBC and NSBC were in accordance with pseudo-second-order and Langmuir model. The saturated adsorption capacities of Cd(Ⅱ) by SBC and NSBC were 67.44 and 196.62 mg/g, respectively, under the conditions of dosage 0.5 g/L, solution pH 4.0, and reaction temperature 25℃. The removal mechanisms of Cd(Ⅱ) by NSBC included the complexation of O-containing groups, dissolution-precipitation of minerals, and electrostatic interaction. It was shown that NSBC provided a potential remediation material for the remediation of acidic mine wastewater containing Cd(Ⅱ).