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Insights into the activation of ozonation by hydroxylamine: Influential factors, degradation mechanism and reaction kinetics
- Qin, Wenlei, Yuan, Xiangjuan, Sun, Lei, Qiang, Zhimin, Xia, Dongsheng
- Journal of hazardous materials 2019 v.373 pp. 600-607
- decontamination, hydroxyl radicals, hydroxylamine, kinetics, ozonation, ozone, pH, pollutants, prometon, reaction kinetics, singlet oxygen, water treatment
- The decontamination of prometon (PMT) by ozone/hydroxylamine hydrochloride (O3/HAC) was systematically investigated in this study with focus on the degradation mechanism and kinetics. Experimental results revealed that there was an enhancement of PMT degradation efficiency by 42.1% and the pseudo-first-order rate constant by more than 5.7 times in O3/HAC process under low HAC dosage (5 mg L−1) after 3 min in comparison with O3 alone. The second-order rate constant of PMT with hydroxyl radical (•OH) was determined to be (1.84 ± 0.1) × 109 M−1 s−1 and 7.80 × 109 M−1 s−1 via competition kinetics and •OH steady-state hypothesis, respectively. The PMT removal in O3/HAC process was highly pH-dependent and the optimum degradation performance was achieved under pH 5.0. In addition, •OH and singlet oxygen were identified as the primary reactive oxygen radicals in O3/HAC process. Meanwhile, eleven transformation products of PMT were identified and possible degradation mechanisms were proposed. Moreover, a kinetic model based on chemical kinetics and steady-state hypothesis was developed and modified to predict the PMT abatement in O3/HAC process. The results demonstrated that the O3/HAC process provided a promising alternative for refractory organic pollutants decontamination in water treatment.