Influence of Humic Acid on the Photolysis of Triclosan in Different Dissociation Forms

Optimizing Constructed Wetlands for Safe Removal of Triclosan: A Box–Behnken Approach

“…Of the two dioxins searched for, 2,7-DCDD was never detected and 2,8-DCDD was only found in the pH 8 direct phototransformation experiment, at (3–8) × 10 –5 mM, representing less than 0.5% of initial triclosan. This is in line with the previous studies that showed the dominance of 2,8-DCDD over 2,7-DCDD by triclosan photocyclization ,,,,, and the absence of dioxin generation in indirect photolysis experiments with humic substances . Compound #3 with chemical formula C 12 H 5 Cl 3 O 3 , potentially 5-chloro-2-(2,4-dichlorophenoxy)-1,4-dione, ,, was never detected.…”

“…The same pH dependence of triclosan phototransformation in the presence of various forms of DOC was reported previously. 46,47 Conversely, the most significant effects of increased nitrate concentration on triclosan phototransformation were observed at low pH, i.e., pH 6, with a 51% decrease in the k value, from (17 ± 1.9) to (8.3 ± 0.49) × 10 −6 s −1 , whereas, at pH 8 and 10, larger concentrations of nitrate resulted in no or small changes, i.e., either a 20% increase at low DOC or a 13% decrease at high DOC in the pseudo-first-order phototransformation rate constants, respectively. The effect of nitrate concentration on k at low DOC concentration is consistent with the former studies.…”

“…This is in line with the previous studies that showed the dominance of 2,8-DCDD over 2,7-DCDD by triclosan photocyclization 12,29,43,47,52,53 and the absence of dioxin generation in indirect photolysis experiments with humic substances. 46 Compound #3 with chemical formula C 12 H 5 Cl 3 O 3 , potentially 5-chloro-2-(2,4-dichlorophenoxy)-1,4dione, 42,50,55 was never detected. Former studies indicated its formation through the reaction of triclosan with singlet oxygen 42 or sequential reactions with hydroxyl radicals.…”

Hydrothermal Conversion of Triclosan—The Role of Activated Carbon as Sorbent and Reactant

“…The transformation degree was higher in seawater or wastewater than in fresh water. The presence of humic acid inhibited the TCS photolysis in the phenolate form (pH 11), while the reactivity at pH 5 of the phenol form was enhanced …”

“…The presence of humic acid inhibited the TCS photolysis in the phenolate form (pH 11), while the reactivity at pH 5 of the phenol form was enhanced. 14 Because of its low water solubility (2−4.6 mg L −1 ) and high hydrophobicity (log K OW = 4.8), TCS removal from aqueous solution by adsorption is feasible. 15 Activated carbon (AC) has been tested as an adsorbent in wastewater treatment plants (WWTP) in order to eliminate micropollutants in a postbiological treatment step.…”