| Title: | Radical attack and mineralization mechanisms on electrochemical oxidation of p-substituted phenols at boron-doped diamond anodes |
| Author(s): | Jiang H; Dang C; Liu W; Wang T; |
| Address: | "College of Environmental Sciences and Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871, China. College of Environmental Sciences and Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871, China; The Beijing Innovation Center for Engineering Science and Advanced Technology (BIC-ESAT), Peking University, Beijing, 100871, China; Beijing Engineering Research Center for Advanced Wastewater Treatment, Department of Environmental Engineering, Peking University, Beijing, 100871, China. College of Environmental Sciences and Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, 100871, China; Beijing Engineering Research Center for Advanced Wastewater Treatment, Department of Environmental Engineering, Peking University, Beijing, 100871, China. Electronic address: wang_ting@pku.edu.cn" |
| DOI: | 10.1016/j.chemosphere.2020.126033 |
| ISSN/ISBN: | 1879-1298 (Electronic) 0045-6535 (Linking) |
| Abstract: | "Degradation of phenols with different substituent groups (including -OCH(3), -CHO, -NHCOCH(3), -NO(2), and -Cl) at boron-doped diamond (BDD) anodes has been studied previously based on the removal efficiency and *OH detection. Innovatively, formations of CO(2) gas and various inorganic ions were examined to probe the mineralization process combined with quantitative structure-activity relationship (QSAR) analysis. As results, all phenols were efficiently degraded within 8 h with high COD removal efficiency. Three primary intermediates (hydroquinone, 1,4-benzoquinone and catechol) were identified during electrochemical oxidation and degradation pathway was proposed. More importantly, CO(2) transformation efficiency ranked as: no N or Cl contained phenols (p-CHO, p-OCH(3) and Ph) > N-contained phenols (p-NHCOCH(3) and p-NO(2)) > Cl-contained phenols (p-Cl and o,p-Cl). Carbon mass balance study suggested formation of inorganic carbon (H(2)CO(3), CO(3)(2-) and HCO(3)(-)) and CO(2) after organic carbon elimination. Inorganic nitrogen species (NH(4)(+), NO(3)(-) and NO(2)(-)) and chlorine species (Cl(-), ClO(3)(-) and ClO(4)(-)) were also formed after N- and Cl-contained phenols mineralization, while no volatile nitrogen species were detected. The phenols with electron-withdrawing substituents were easier to be oxidized than those with electron-donating substituents. QSAR analysis indicated that the reaction rate constant (k(1)) for phenols degradation was highly related to Hammett constant ( summation operatorsigma(o,m,p)) and energy gap (E(LUMO) - E(HOMO)) of the compound (R(2) = 0.908), which were key parameters on evaluating the effect of structural moieties on electronic character and the chemical stability upon radical attack for a specific compound. This study presents clear evidence on mineralization mechanisms of phenols degradation at BDD anodes" |
| Keywords: | Biological Oxygen Demand Analysis Boron/chemistry Carbon/chemistry Carbon Dioxide/chemistry Chlorine/chemistry Diamond/chemistry Electrochemical Techniques/*instrumentation *Electrodes Nitrogen/chemistry Oxidation-Reduction Phenols/*chemistry *Quantitativ; |
| Notes: | "MedlineJiang, Huan Dang, Chenyuan Liu, Wen Wang, Ting eng England 2020/02/01 Chemosphere. 2020 Jun; 248:126033. doi: 10.1016/j.chemosphere.2020.126033. Epub 2020 Jan 25" |
