title: Dechlorination of PCBs in the simulative transformer oil by microwave-hydrothermal reaction with zero-valent iron involved.
abstract: The conventional hydrothermal reaction with iron powder, NaOH and H(2)O as reactants was reported to occur at temperature above 423K, and iron oxides (Fe(3)O(4) and NaFeO(2)) and hydrogen were produced. In this study, microwave heating was adopted to take the place of conventional heating to induce the hydrothermal reaction. Under microwave irradiation, NaOH and H(2)O absorbed microwave energy by space charge polarization and dipolar polarization and instantly converted it into thermal energy, which initiated the hydrothermal reaction that involved with zero-valent iron. X-ray diffraction (XRD) analysis found Fe(3)O(4)/NaFeO(2) and confirmed the occurrence of microwave-induced hydrothermal reaction. The developed microwave-hydrothermal reaction was employed for the dechlorination of PCBs. Hexadecane containing 100mgL(-1) of Aroclor1254 was used as simulative transformer oil, and the dechlorination of PCBs was evaluated by GC/ECD, GC/MS and ion chromatography. For PCBs in 10mL simulative transformer oil, almost complete dechlorination was achieved by 750W microwave irradiation for 10min, with 0.3g iron powder, 0.3g NaOH and 0.6mL H(2)O added. The effects of important factors including microwave power and the amounts of reactants added, on the dechlorination degree were investigated, moreover, the dechlorination mechanism was suggested. Microwave irradiation combined with the common and cheap materials, iron powder, NaOH and H(2)O, might provide a fast and cost-effective method for the treatment of PCBs-containing wastes.
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China. liuxt@bnu.edu.cn
authors.forename: Xitao
authors.initials: X
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Ke
authors.initials: K
authors.lastname: Sun
authors.forename: Guixiang
authors.initials: G
authors.lastname: Zhang
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D055615:Electrical Equipment and Supplies; D059029:Electronic Waste; D054879:Halogenation; D006361:Heating; D007501:Iron / Q000737:chemistry*; D008872:Microwaves; D009821:Oils / Q000737:chemistry*; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D012037:Refuse Disposal / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D009821:Oils; D011078:Polychlorinated Biphenyls; D007501:Iron