Removal of alachlor from water by catalyzed ozonation in the presence of Fe2+, Mn2+, and humic substances.
The effects of Fe(II), Mn(III) and humic substances on the catalyzed ozonation of alachlor, an endocrine disruptor were investigated. Results revealed that small amounts of Fe(II), Mn(II), and humic substances could enhance the ozonation of alachlor, but larger amounts of them would retard the oxidation. These results were successfully identified by an electron paramagnetic resonance (EPR) spectroscopy spin-trapping method that could quantify hydroxyl radicals. The production of hydroxyl radicals was obviously increased with the increasing of Fe(II) concentration, which contributed to enhance ozonation at low concentrations. But the excess Fe(II) consumed some of the radicals when it was added at a higher concentration (1.5 mg/L). However, no obvious radicals were observed when a different amount of Mn(II) was used, and the catalytic ozonation of alachlor by Mn(II) mainly followed the mechanism of "active sites created on the surface of MnO2." The radical pathway was followed when alachlor was ozonated with different concentrations of humic substances because of its radical initiating, promoting, and inhibiting effects.
Li
Hai-Yan
HY
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, PR China.
Qu
Jiu-Hui
JH
Zhao
Xiang
X
Liu
Hui-Juan
HJ
D000081:Acetamides / Q000737:chemistry / Q000302:isolation & purification*; D002384:Catalysis; D006540:Herbicides / Q000737:chemistry / Q000302:isolation & purification*; D017665:Hydroxyl Radical / Q000032:analysis; D007501:Iron / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D016877:Oxidants / Q000032:analysis; D010083:Oxidants, Photochemical / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*
D000081:Acetamides; D006540:Herbicides; D016877:Oxidants; D010083:Oxidants, Photochemical; D014874:Water Pollutants, Chemical; C000188:alachlor; D017665:Hydroxyl Radical; D008345:Manganese; D010126:Ozone; D007501:Iron