resumo
The ecotoxicity of methiocarb aqueous solutions treated by electrochemical oxidation was evaluated utilizing the model organism Daphnia magna. The electrodegradation experiments were performed using a boron-doped diamond anode and the influence of the applied current density and the supporting electrolyte (NaCl or Na2SO4) on methiocarb degradation and toxicity reduction were assessed. Electrooxidation treatment presented a remarkable efficiency in methiocarb complete degradation and a high potential for reducing the undesirable ecological effects of this priority substance. The reaction rate followed first-order kinetics in both electrolytes, being more favorable in a chloride medium. In fact, the presence of chloride increased the methiocarb removal rate and toxicity reduction and favored nitrogen removal. A 200x reduction in the acute toxicity towards D. magna, from 370.9 to 1.6 toxic units, was observed for the solutions prepared with NaCl after 5 h treatment at 100 A m(-2). An increase in the applied current density led to an increase in toxicity towards D. magna of the treated solutions. At optimized experimental conditions, electrooxidation offers a suitable solution for the treatment and elimination of undesirable ecological effects of methiocarb contaminated industrial or agricultural wastewaters, ensuring that this highly hazardous pesticide is not transferred to the aquatic environment.
palavras-chave
WATER-TREATMENT KINETICS; WASTE-WATER; ANODIC-OXIDATION; PESTICIDES; REMOVAL; DEGRADATION; DIAMOND; CONTAMINANTS; PRODUCTS
categoria
Chemistry; Engineering; Materials Science; Physics
autores
Fernandes, A; Pereira, C; Coelho, S; Ferraz, C; Sousa, AC; Pastorinho, MR; Pacheco, MJ; Ciriaco, L; Lopes, A
nossos autores
Ana Catarina Almeida Sousa
Colaboradoragradecimentos
This research was funded by Fundacao para a Ciencia e a Tecnologia, FCT, through UID Fiber Materials and Environmental Technologies (FibEnTech), project UIDB/00195/2020. Further financial support was provided by funds from the Health Sciences Research Center (CICS-UBI) through National Funds by FCT (UID/Multi/00709/2019).