Electrochemical investigations of 1,2,4-triazole and benzotriazole in aqueous acidic media has been carried out by cyclic voltammetric measurements. Cyclic voltammetric experiments were carried on glassy carbon (GC) working electrode. Effect of potential scan rate, pH of the solution and use of different surfactant on the electrochemical behavior has been investigated. Single reduction wave was observed for 1,2,4-triazole due to the reduction of N=N moiety and no oxidation peak was observed in the reverse scan. In case of benzotriazole one clear reduction peak was observed in the cathodic scan and no anodic peak was seen. Effect of pH, sweep rate, analyte concentrations and the presence of different surfactants on the reduction peak current was evaluated. Electro-reduction processes of both the compounds were found to be diffusion controlled in nature. The plausible mechanism for the electroreduction process was proposed. Electrochemical property of two compounds was also studied under hydrodynamic conditions using glassy carbon rotating disc electrode.

Dehalogenation is one of the most important reactions for eliminating trace organic pollutants in natural and engineering systems. This study investigated the dehalogenation of a model organohalogen compound, triclosan (TCS), by aqueous biochars (a-BCs) (<450 nm). We found that TCS can be anaerobically degraded by reduced a-BCs with a pseudo first-order degradation rate constant of 0.0011−0.011 h −1 . The 288 h degradation fraction of TCS correlated significantly with the amount of a-BCbound electrons (0.055 ± 0.00024 to 0.11 ± 0.0016 mol e − /mol C) available for donation after 24 h of pre-reduction by Shewanella putrefaciens CN32. Within the reduction period, the recovery of chlorine based on residual TCS and generated Cl − ranged from 73.6 to 85.2%, implying that a major fraction of TCS was fully dechlorinated, together with mass spectroscopic analysis of possible degradation byproducts. Least-squares numerical fitting, accounting for the reactions of hydroquinones/semiquinones in a-BCs with TCS and byproducts, can simulate the reaction kinetics well (R 2 > 0.76) and suggest the first-step dechlorination as the rate-limiting step among the possible pathways. These results showcased that the reduced a-BCs can reductively degrade organohalogens with potential applications for wastewater treatment and groundwater remediation. While TCS was used as a model compound in this study, a-BC-based degradation can be likely applied to a range of redox-sensitive trace organic compounds.

No abstract

No abstract