Catalytic Effect of Hydrogen Peroxide in the Electrochemical Treatment of Phenolic Pollutants using a BDD Anode

Abstract

Phenolic pollutants are recalcitrant substances that cannot be removed from wastewater using the current treatments. In this study, degradation of phenolic pollutants was studied on the basis of the application of hydrogen peroxide during the electrooxidation process using BDD as anode (EO−H2O2 coupled process). The process was optimized using 4‐chlorophenol (4‐CP) as model compound and later an emerging pollutant, Nonylphenol Ethoxylate‐10 (NP10EO), was degraded using the optimized experimental conditions found. To ascertain treatment effectiveness, experiments with hydrogen peroxide (H2O2), electrooxidation (EO) and EO−H2O2 (coupled process) were carried out. The variables considered in this investigation were pH, current density, quantity of H2O2, and reaction time. It was observed that the coupled process (EO−H2O2) increases degradation efficiency, reaching 81.9 % for 4‐CP and 94.3 % for NP10EO. UV/VIS spectrophotometry, COD and HPLC analysis verified these results. The results of the analysis by cyclic voltammetry after the EO−H2O2 coupled process indicate that pollutants in the solution were efficiently oxidized. It was concluded that small amounts of hydrogen peroxide (250 μL 30 % w/v solution per 1.1 L) are sufficient to attain good results; larger amounts of H2O2 produce inhibitory effects during degradation. The slow cathode (SS) oxidation during the experiments was confirmed by XPS and AFM analysis.

Electrocatalytic generation of reactive species and implications in microbial inactivation

“…For instance, Brillas and co-workers [53] successfully demonstrated this application in their study of the degradation of monoazo, diazo, and triazo dyes using an electrochemical setup consisting of a carbon-ploytetrafluoroethylene (PTFE) air-diffusion cathode and a boron doped diamond anode (BDD). Carbon-PTFE has been used widely as a cathode for the two-electron reduction of oxygen forming H2O2 [54][55][56], while BDD has been extensively studied as an inactive anode for the direct production of heterogeneous HO • [57][58][59][60][61]. It was found that dye degradation occurred to both heterogeneous HO • created at the BDD anode and homogeneous HO • produced by the electro-Fenton process, where H2O2, produced at the carbon-PTFE cathode, reacted with added Fe 2+ .…”

Innovative technologies to remove alkylphenols from wastewater: a review

“…Electrooxidation can be improved by coupling with other oxidation processes. In the case of electrooxidation of nonylphenol ethoxylate-10 with boron-doped diamond anode with addition of hydrogen peroxide, greater efficiency is achieved as showed by Barrera et al (2019). Even a small amount of hydrogen peroxide (0.25 mL 30% v/w per 1.1 L of solution) acts as a promoter for the formation of hydroxyl radicals in the solution by removing 94.3% of pollutant in 375 min of treatment.…”

Use of Electrooxidation as a Polishing Step for the Residual Water Obtained in a Solar Wastewater Treatment

“…The effect of the pH of the aqueous solution was evaluated and two values were selected, 6.2 and 2.7 respectively. Another parameter that has influence in the electrooxidation process is the current density and two values were evaluated 22.2 and 16.6 mA cm -2 [24,25].…”