title: Competitive removal of Cu-EDTA and Ni-EDTA via microwave-enhanced Fenton oxidation with hydroxide precipitation.
abstract: Ethylenediaminetetraacetic acid (EDTA) can form very stable complexes with heavy metal ions, greatly inhibiting conventional metal-removal technologies used in water treatment. Both the oxidation of EDTA and the reduction of metal ions in metal-EDTA systems via the microwave-enhanced Fenton reaction followed by hydroxide precipitation were investigated. The Cu(II)-Ni(II)-EDTA, Cu(II)-EDTA and Ni(II)-EDTA exhibited widely different decomplexation efficiencies under equivalent conditions. When the reaction reached equilibrium, the chemical oxygen demand was reduced by a microwave-enhanced Fenton reaction in different systems and the reduction order from high to low was Cu(II)-Ni(II)-EDTA ≈ Cu(II)-EDTA > Ni(II)-EDTA. The removal efficiencies of both Cu(2+) and Ni(2+) in Cu-Ni-EDTA wastewaters were much higher than those in a single heavy metal system. The degradation efficiency of EDTA in Cu-Ni-EDTA was lower than that in a single metal system. In the Cu-Ni-EDTA system, the microwave thermal degradation and the Fenton-like reaction created by Cu catalyzed H2O2 altered the EDTA degradation pathway and increased the pH of the wastewater system, conversely inhibiting residual EDTA degradation.
authors.affiliation: School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China E-mail: qintlin@163.com.
authors.forename: Qintie
authors.initials: Q
authors.lastname: Lin
authors.affiliation: School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China E-mail: qintlin@163.com.
authors.forename: Hanping
authors.initials: H
authors.lastname: Pan
authors.affiliation: School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China E-mail: qintlin@163.com.
authors.forename: Kun
authors.initials: K
authors.lastname: Yao
authors.affiliation: Guangzhou Institute of Mechanical Design, Guangzhou 510600, China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Environmental Technology Center of Guangdong Province, Guangzhou 510308, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Long
mesh_terms: D057919:Biological Oxygen Demand Analysis; D056831:Coordination Complexes / Q000032:analysis* / Q000737:chemistry; D003300:Copper / Q000032:analysis* / Q000737:chemistry; D004492:Edetic Acid / Q000032:analysis* / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008872:Microwaves; D009532:Nickel / Q000032:analysis* / Q000737:chemistry; D010084:Oxidation-Reduction; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification / Q000379:methods
chemical_list: D056831:Coordination Complexes; D003300:Copper; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D007501:Iron; D009532:Nickel; D062065:Wastewater; D014874:Water Pollutants, Chemical; C045076:Fenton's reagent