Adsorption Characteristics of Heavy Metals Pb(2+) and Zn(2+) by Magnetic Biochar Obtained from Modified AMD Sludge

Acid mine drainage (AMD) sludge can be used to prepare adsorbent materials for the removal of heavy metals in water, which is an effective means for its resource utilization. Magnetic modified biochar (MMB), which can be recovered by magnetic separation, was prepared from sludge generated from the carbonate rock neutralization treatment of AMD and rice straw agricultural waste. Unmodified biochar (UMB) was obtained from rice straw and chemically modified and treated by ultraviolet radiation to produce MMB. The Pb(2+) and Zn(2+) adsorption capacities of UMB and MMB were investigated. Simultaneously, the materials were characterized by SEM, FTIR, BET, and ZETA. The results showed that the specific surface area (130.89 m(2)·g(−1)) and pore volume (0.22 m(2)·g(−1)) of MMB were significantly increased compared to those of UMB (9.10 m(2)·g(−1) and 0.05 m(2)·g(−1), respectively). FTIR images showed that MMB was successfully loaded with Fe(3)O(4). The adsorption process of Pb(2+) and Zn(2+) onto MMB was consistent with the Langmuir adsorption isotherm and second-order kinetic models, with maximum adsorption capacities of 329.65 mg·g(−1) and 103.67 mg·g(−1), respectively. In a binary system of Pb(2+) and Zn(2+), MMB preferentially binds Pb(2+). The adsorption efficiencies of MMB reached >80% for Pb(2+) and Zn(2+).