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Abstract An effective advanced oxidation process for the degradation of quinclorac (QC) in water is reported. This method is based on the oxidation of quinclorac by sulfate radicals generated from the decomposition of peroxymonosulfate (PMS) mediated by Co (Ⅱ) ion in the aqueous phase. The effects of the concentration of PMS and Cl-, molar ratio of Co (Ⅱ)/PMS as well as the initial concentration of QC on the degradation efficiency of QC were examined. The results showed that the degradation of QC in the homogeneous Co (Ⅱ)/PMS system fitted well to the pseudo-first-order kinetic model. The degradation rate of QC increased with the decreasing of molar ratio of QC/PMS, but declined as the ratio of QC/PMS lower than 1/100 when the initial concentration of QC was in the range of 0.02~0.2mmol/L. The reaction rates linearly increased with the increase of PMS concentration with a QC decomposition as high as 94% within 4 hours at an initial concentration of 32mmol/L PMS. The ratio of Co (Ⅱ)/PMS had positive effect on the degradation of QC, while Cl- had negative impact. The results of LC/MS analysis indicated that 3,7-dichloro-8-hydroxy quinoline and 7-chloro-8-quinoline carboxaldehyde were the two major intermediates of QC degradation.
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Received: 15 April 2015
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