Improving biodegradability of clopyralid wastes by photoelectrolysis - The role of the anode material

At a Glance

Metadata	Details
Publication Date	2020-03-19
Journal	Journal of Electroanalytical Chemistry
Authors	Géssica de Oliveira Santiago Santos, Isabelle M.D. Gonzaga, Katlin Ivon Barrios Eguiluz, Giancarlo R. Salazar‐Banda, Cristina Sáez
Institutions	Universidade Tiradentes, Instituto de Tecnologia e Pesquisa
Citations	21

Abstract

In this work, the removal of the non-readily biodegradable herbicide clopyralid by electrochemical (EC) and photoelectrochemical (PhEC) oxidation with different anode materials were conducted looking to improve not only its oxidation but also its biodegradability. First, in order to find out optimal conditions, it was carried out EC and PhEC degradations in chloride medium, at current densities ranging from 30 to 100 mA cm−2 during 1 h (0.8-2.7 A h L−1), using as anodes MMO-RuO2TiO2, MMO-RuO2IrO2, MMO-IrO2Ta2O5 and boron-doped diamond (BDD). Results show better efficiencies on clopyralid removal for MMO-RuO2IrO2 and BDD anodes at lower current densities. Then, the influence of all anodes on clopyralid transformation was evaluated, extending the electrolysis and photoelectrolysis for 8 h applying 30 mA cm−2 (6.4 A h cm−3). At these conditions, better outcomes are observed for PhEC degradation, where complete pollutant removal is attained for BDD anode and 88.7% for MMO-RuO2IrO2, while COD removal is 47.7% for MMO and 43.1% for BDD anode. Then, short-term biodegradability tests, conducted for EC and PhEC processes, pointed out that MMO-RuO2TiO2 is the most promising anode material, being capable of improving biodegradability in 48.2% and 53% for EC and PhEC degradation, respectively. The toxicity of treated solutions using MMO-RuO2TiO2 and BDD anodes in both EC and PhEC degradation were compared, employing the inhibitory effect in the bioluminescence of marine bacteria Vibrio Fisheri. Toxicity assessments show that toxicity significantly reduces by using the MMO-RuO2TiO2 in NaCl and Na2SO4 medium for both processes. Finally, this study demonstrates that photoelectrolysis with MMO anodes was the most effective strategy in order to increase biodegradability in chloride media, as well as to reduce the toxicity of the treated waste.

Tech Support

Original Source

DOI: https://doi.org/10.1016/j.jelechem.2020.114084

References

2014 - Electrochemically assisted remediation of pesticides in soils and water: a review [Crossref]
2019 - Radiation-assisted electrochemical processes in semi-pilot scale for the removal of clopyralid from soil washing wastes [Crossref]
2010 - Electro-Fenton treatment of aqueous clopyralid solutions [Crossref]
2016 - Photocatalytic degradation of the herbicide clopyralid: kinetics, degradation pathways and ecotoxicity evaluation [Crossref]
2011 - Combination of advanced oxidation processes and biological treatments for wastewater decontamination—a review [Crossref]
2018 - Improving biodegradability of soil washing effluents using anodic oxidation [Crossref]
2014 - Electrochemical advanced oxidation and biological processes for wastewater treatment: a review of the combined approaches [Crossref]
2015 - Single and coupled electrochemical processes and reactors for the abatement of organic water pollutants: a critical review [Crossref]
2017 - Electrochemical mineralization of cephalexin using a conductive diamond anode: a mechanistic and toxicity investigation [Crossref]
2017 - Is it really important the addition of salts for the electrolysis of soil washing effluents? [Crossref]