Preparation of Fe3O4 magnetic porous microspheres (MPMs) and their application in treating mercury-containing wastewater from the polyvinyl chloride industry by calcium carbide method

Fe3O4 magnetic porous microspheres (MPMs) were successfully synthesized by an easy one-step solvothermal method. The structure, specific surface area, and magnetic property of the MPMs were analyzed and confirmed by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Brunauer-Emmett-Teller (BET) method, and vibrating sample magnetometry. The application of the MPMs in the treatment of Hg-containing wastewater released from a polyvinyl chloride plant by calcium carbide method was researched. Results indicated that the pore size of Fe3O4 MPMs ranged from similar to 31.0 to 56.0 nm, their BET surface area was 86.39 m(2)/g, and their pore volume was 0.3528 cm(3)/g. Their saturation magnetization was 87.15 emu/g. Their adsorption efficiency for mercury reached 99.1%, and the Hg concentration in wastewater can be decreased from 24.18 to 0.242 mu g/L, in accordance with the national discharge standard of China. The saturated adsorbent of Fe3O4 MPMs was regained easily with a magnetic field and reused for 10 times after desorption by 0.1% HNO3. The adsorption of Hg2+ by the MPMs well fitted the Langmuir isotherm model and followed pseudo-second-order kinetics. These results can enable the rational design of MPMs for the treatment of Hg-containing wastewater. (C) 2014 Elsevier B.V. All rights reserved.