Methiocarb Degradation by Electro-Fenton: Ecotoxicological Evaluation

Abstract

This paper studies the degradation of methiocarb, a highly hazardous pesticide found in waters and wastewaters, through an electro-Fenton process, using a boron-doped diamond anode and a carbon felt cathode; and evaluates its potential to reduce toxicity towards the model organism Daphnia magna. The influence of applied current density and type and concentration of added iron source, Fe2(SO4)3·5H2O or FeCl3·6H2O, is assessed in the degradation experiments of methiocarb aqueous solutions. The experimental results show that electro-Fenton can be successfully used to degrade methiocarb and to reduce its high toxicity towards D. magna. Total methiocarb removal is achieved at the applied electric charge of 90 C, and a 450× reduction in the acute toxicity towards D. magna, on average, from approximately 900 toxic units to 2 toxic units, is observed at the end of the experiments. No significant differences are found between the two iron sources studied. At the lowest applied anodic current density, 12.5 A m−2, an increase in iron concentration led to lower methiocarb removal rates, but the opposite is found at the highest applied current densities. The highest organic carbon removal is obtained at the lowest applied current density and added iron concentration.

Degradation of C. I. Direct Red 80 by the Electro-Fenton Process

“…The initial pH of the solutions prepared with iron sulfate and ferric chloride was around 3-4, which is the optimum pH for the EF process, due to its influence on iron speciation and on H 2 O 2 decomposition [5,6]. However, the solutions prepared with iron oxide and chalcopyrite presented a higher initial pH, especially the solution prepared with iron oxide.…”

“…Freshwater contamination by synthetic dyes is a global environmental concern. According to the literature, there are more than 100,000 commercially available dyes, with an estimated annual production of more than 7×10 5 tonnes, which are used by different types of industry, such as textile, papermill, cosmetic, pharmaceutical, food industry, among others [1]. As a result, large volumes of wastewater, containing high concentrations of dyes, are daily produced, being aesthetic and with potential toxicity and carcinogenicity [2].…”

“…( 1)). In this electrochemical process, Fe 3+ is reduced at the cathode, generating Fe 2+ , which results in a higher degradation rate of organic pollutants than the traditional Fenton process [5]. Iron sulfate or chloride are the most common iron sources for EF process, but, in the recent years, the use of heterogeneous iron sources, such as pyrite (FeS 2 ) and chalcopyrite (CuFeS 2 ), have gained significant attention [6].…”

“…According to the literature, the efficiency of the EF process can be further enhanced by utilizing a high O 2 -overpotential anode, such as boron-doped diamond (BDD) anode, being the organic compounds additionally oxidised through adsorbed hydroxyl radicals (BDD(HO ⋅ )), formed as an intermediate of the anodic water discharge (Eq. ( 3)) [5,6].…”

Degradation study of some pharmaceuticals in commercial formulation by electro‐Fenton process using a dimensionally stable anode cathode: Analytical technique, optimization conditions, and energy consumption

“…It is one of the most promising and attractive electrochemical techniques due to its simplicity, efficiency, and relatively low operating cost. [22,25] Numerous studies have shown that this process has been effective in the degradation of toxic and refractory compounds such as dyes, [26][27][28][29] pesticides, [30][31][32] and pharmaceutical compounds. [33][34][35][36][37][38] In this process, hydroxyl radicals are generated in-situ via Fenton reagents (H 2 O 2 and Fe 2+ ).…”