Preparation of spherical flower-like Mg(OH)2 from waste magnesite and its immobilization performance for Cu2+, Zn2+ and Pb2.

Spherical flower-like Mg(OH)2 was successfully synthesized under conditions of Mg2+ concentration of 2 mol·L-1, molar ratio of Mg2+/NH4OH of 1:0.5, temperature of 120 °C and time of 1 h using MgSO4 solution as raw material obtained from waste magnesite through several procedures. Spherical Mg(OH)2 exhibits flower-like structure composed of lamellar crystals. The immobilization ability of spherical flower-like Mg(OH)2 for Cu2+, Zn2+ and Pb2+ obtained at variable dosage and ion concentrations shows it displays an excellent immobilization performance for Cu2+, Zn2+ and Pb2+. 50 mL solution with ion concentrations of 200 mg·L-1 could be almost completely immobilized by 200, 250 and 60 mg Mg(OH)2 within 6 min, and the immobilization efficiencies were 97.55%, 99.99% and 91.56%, respectively. Langmuir model well describes the immobilization process, involving chemisorption emphasized as monolayer.