Degradation of sulfadimethoxine in phosphate buffer solution by UV alone, UV/PMS and UV/H2O2: Kinetics, degradation products, and reaction pathways

Shad, Asam; Chen, Jing; Qu, Ruijuan; Dar, Afzal Ahmed; Bin-Jumah, May; Allam, Ahmed A.; Wang, Zunyao

doi:10.1016/j.cej.2020.125357

Cited by 106 publications

(22 citation statements)

References 81 publications

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“…[15][16][17][18][19] Except hydroxyl radical, sulfate radical (SO 4 c À ) has received increasing attention due to its higher redox potential (E 0 ¼ 2.5-3.1 V) compared with hydroxyl radical (E 0 ¼ 1.9-2.7 V). 20,21 Moreover, the selectivity and half-life of sulfate radical (30-40 ms) are higher and longer than those of hydroxyl radical (1 ms). [22][23][24] Thus, sulfate radical-based AOPs (SR-AOPs) have a good application prospect in removing organic pollution.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and reaction mechanism of photochemical degradation of diclofenac by UV-activated peroxymonosulfate

et al. 2021

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Section: Introductionmentioning

confidence: 99%

Kinetics and reaction mechanism of photochemical degradation of diclofenac by UV-activated peroxymonosulfate

et al. 2021

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“…44 Therefore, the 3 2-Cl-triazines* are simulated using time-dependent density functional theory (TDDFT) at the PBE1PBE/6-311G(d,p) level, which have proven to be a reliable method for studying the excited states with good precision. 45 We subsequently examined electric charges on the nucleophilic sites of 3 2-Cltriazines*, and the electric charges were increased to 6.0596, 6.0471, 6.0318, and 5.9573 for 3 ATZ*, 3 DIA*, 3 DEA*, and 3 DDA*, respectively (Figure 5e). Meanwhile, the C−Cl bond orders of 3 ATZ*, 3 DIA*, 3 DEA*, and 3 DDA* decreased to 1.0173, 1.0228, 1.0237, and 1.0384, respectively.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

New Insights into the Degradation of Atrazine by Ultraviolet-Based Techniques

Chen

et al. 2021

ACS EST Water

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The combination of ultraviolet (UV) light and H2O2 is generally considered a promising technology for removing atrazine from the aqueous environment due to its high degradation efficiency, but the generation of toxic chloro-dealkylated intermediates is usually neglected. In addition, the dechlorination mechanism of the UV/H2O2 system has seldom been investigated. In this study, atrazine degradation is comparatively investigated in the UV and UV/H2O2 systems to clarify the dechlorination mechanism. The results show that direct UV photolysis can induce dechlorination of atrazine to form nontoxic hydroxyatrazine via a nucleophilic substitution reaction of 3atrazine* with nucleophile H2O. For comparison, the degradation rate of atrazine can be enhanced in the UV/H2O2 system but the dechlorination efficiency is dramatically inhibited because in situ-generated •OH preferentially attacks the side chains of atrazine to form chloro-dealkylated intermediates. Meanwhile, further dechlorination of chloro-dealkylated intermediates by H2O via nucleophilic substitution under UV irradiation is substantially slower than that of atrazine. In addition, laser flash photolysis combined with theoretical calculation also confirms that 3chloro-dealkylation intermediates* are more resistant to dechlorination than 3atrazine*. Overall, this study suggests that it is not beneficial to upgrade direct UV photolysis to the UV/H2O2 system for degrading atrazine in light of the dechlorination efficiency.

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“…The aquatic toxicity of AAP and its degradation products was evaluated by using the Structure Activity Relationship (SAR) method with the ECOSAR program [42], which has been successfully used to evaluate the acute and chronic toxicity [43][44][45][46]. Three aquatic organisms of green algae, daphnia and fish were considered to assess the acute and chronic toxicities.…”

Section: Ecotoxicity Calculationmentioning

confidence: 99%

Theoretical Calculation on the Reaction Mechanisms, Kinetics and Toxicity of Acetaminophen Degradation Initiated by Hydroxyl and Sulfate Radicals in the Aqueous Phase

Yao

Sun

et al. 2021

Toxics

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The •OH and SO4•− play a vital role on degrading pharmaceutical contaminants in water. In this paper, theoretical calculations have been used to discuss the degradation mechanisms, kinetics and ecotoxicity of acetaminophen (AAP) initiated by •OH and SO4•−. Two significant reaction mechanisms of radical adduct formation (RAF) and formal hydrogen atom transfer (FHAT) were investigated deeply. The results showed that the RAF takes precedence over FHAT in both •OH and SO4•− with AAP reactions. The whole and branched rate constants were calculated in a suitable temperature range of 198–338 K and 1 atm by using the KiSThelP program. At 298 K and 1 atm, the total rate constants of •OH and SO4•− with AAP were 3.23 × 109 M−1 s−1 and 4.60 × 1010 M−1 s−1, respectively, considering the diffusion-limited effect. The chronic toxicity showed that the main degradation intermediates were harmless to three aquatic organism, namely, fish, daphnia, and green algae. From point of view of the acute toxicity, some degradation intermediates were still at harmful or toxic level. These results provide theoretical guidance on the practical degradation of AAP in the water.

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Degradation of sulfadimethoxine in phosphate buffer solution by UV alone, UV/PMS and UV/H2O2: Kinetics, degradation products, and reaction pathways

Cited by 106 publications

References 81 publications

Kinetics and reaction mechanism of photochemical degradation of diclofenac by UV-activated peroxymonosulfate

Kinetics and reaction mechanism of photochemical degradation of diclofenac by UV-activated peroxymonosulfate

New Insights into the Degradation of Atrazine by Ultraviolet-Based Techniques

Theoretical Calculation on the Reaction Mechanisms, Kinetics and Toxicity of Acetaminophen Degradation Initiated by Hydroxyl and Sulfate Radicals in the Aqueous Phase

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