الفهرس 
titelOnly 14 pages are availabe for public view
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Abstract
Various studies have revealed the non-biodegradable and endocrine disrupting properties of sulfonated organic UV absorbers, directing people’s attention toward their risks on ecological and human health and hence their removal -#102;-#114;-#111;-#109; water. In this study, UV254nm/H2O2 advanced oxidation process (AOP) was investigated for degrading a model UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA). The degradation and mineralization results were compared with three PBSA structurally related compounds 1H-benzimidazole-2-sulfonic acid (BSA), 2-phenylimidazole (2-PIZ) and benzimidazole (BZ) to estimate the feasibility of the applied treatment process. At 4.0 mM [H2O2]0, a complete removal of 40.0 µM parent PBSA and 25% decrease in TOC were achieved with 190 min of UV irradiation; SO42− was formed and reached its maximum level while the release of nitrogen as NH4+ was much lower (around 50%) at 190 min. Sulfate removal was strongly enhanced by increasing [H2O2]0 in the range of 0−4.0 mM, with slight inhibition in 4.0−12.0 mM. Faster and earlier ammonia formation was observed at higher [H2O2]0. The presence of Br− slowed down the degradation and mineralization of PBSA and BSA compounds while a negligible effect on the degradation was observed in the presence of Cl−. The transformation byproducts and pathways -#102;-#114;-#111;-#109; the degradation of 2-phenylbenzimidazole-5-sulfonic acid (PBSA) by UV254nm /H2O2 advanced oxidation process (AOP) were also elucidated in the current study by mass spectrometry. Fourteen byproducts were identified, including two environmentally hazardous byproducts benzamide (BD) and benzamidine br XXV ABSTRACT br (BZD). Beside of aromatic ring opening, desulfonation (−80 Da) and hydroxylation (+16 Da) were also two main reaction pathways. There was no apparent direct photolysis noticed in all pollutants, while the degradation of 1 µM pollutants (i.e., PBSA, 2-PIZ, BZ, BD and BZD) in the presence of 1 mM H2O2 followed pseudo-first--#111;-#114;-#100;-#101;-#114; kinetics, with their observed rate constant (kobs) in the -#111;-#114;-#100;-#101;-#114; 2-PIZ-gt;PBSA-gt;BZ-gt;BD-gt;BZD, which was consistent with their respective second--#111;-#114;-#100;-#101;-#114; rate constant (𝑘𝐻𝑂•,pollutant). At high pollutants and oxidant concentrations, i.e. 50 µM and 5 mM, respectively, light attenuation and formation of hydroxylated byproducts (HBPs) contributed to the change in kobs in the following manner, 2-PIZ~BZ-gt;PBSA~BD-gt;BZD. Release of SO42− -#102;-#114;-#111;-#109; 50µM PBSA/5.0mM H2O2 degradation system reached 70% at 190 min. At the same time interval, NH4+ ions were ≤ 50% for all 2-PIZ, BZ, BD and BZD pollutants studied herein. At 50 µM pollutant initial concentration, ultimate mineralization of PBSA, 2-PIZ, BZ, BD and BZD in terms of TOC% at 190 min was found to be 23, 38, 45, 57 and 62%, respectively. Our study provides important technical and fundamental results on the HO• based degradation and mineralization of −SO3H and N-containing UV absorber compounds. Moreover, UV/H2O2 was shown to be an efficient method for the removal of organic sunscreen agents -#102;-#114;-#111;-#109; water, however, special attention towards the formation of environmentally hazardous byproducts (e.g., BD and BZD) should be considered. Keywords : UV254nm /H2O2 advanced oxidation process; UV absorber; 2-Phenylbenzimidazole-5-sulfonic acid (PBSA) ; sunscreen agent ; hydroxyl radical ; transformation byproducts ; mineralization