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The study focuses on degradation efficiency of non-radical activation and radical activation systems of persulfate (PS) to degrade imidacloprid (IMI) by using sodium persulfate (SPS) as PS source. Copper oxide (CuO)-SPS and CuO/biochar (BC)-SPS were selected as PS non-radical activation systems, and pyrite (PyR)-SPS was selected as PS radical activation system. The degradation by CuO-SPS, CuO/BC-SPS and PyR-SPS systems was investigated from acidic to basic conditions (pH 3.0-11.0). Highest degradation by CuO-SPS and CuO/BC-SPS systems was achieved over pH 11.0. In contrast, highest degradation by PyR-SPS system was achieved over pH 3.0, however, PyR-SPS system was also found effective up to pH 9.0. It was found that degradation was more efficient in PS radical activation system, indicating that IMI could be oxidized by radicals rather than by activated PS. Electron paramagnetic resonance (EPR) analysis was carried out to investigate the generation of sulfate (SO 4 - ) and hydroxyl (OH) radicals, which indicated the presence of SO 4 - and OH in CuO-SPS, CuO/BC and PyR-SPS systems. However, free radical quenching analysis indicated that radicals were main reactive oxygen species for degradation. The lower degradation in PS non-radical activation systems was probably resulted from radicals existed as minor reactive oxygen species. The findings indicated that non-radical oxidation systems showed low reality for degradation and good degradation could be achieved by radical oxidation system. The degradation was also carried out in real waters to investigate the potential applicability of applied systems, which supported PyR-SPS system for effective degradation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

A sensitive and quantitative assay for the detection of cellobiose:quinone oxidoreductase (CBQase) is described. The assay is based on the ability of CBQase to reduce the cation radicals formed by the laccase-mediated oxidation of chlorpromazine (CPZ). Formation of the CPZ radical cation is readily followed at 530 nm, and the net rate of its formation is decreased in proportion to the amount of CBQase activity present. Advantages of this assay are its increased sensitivity due to the high extinction coefficient of the CPZ radical, the high solubility of the substrate in water, and the assay's ability to detect reductive activity in the presence of laccase and other oxidative enzymes. The assay also detects other enzymes, such as glucose oxidase, which have CPZ radical-reducing activity.