Electrochemically Assisted Remediation of Pesticides in Soils and Water: A Review

International audienc

Degradation of Alizarin Red by electro-Fenton process using a graphite-felt cathode

The removal of the anthraquinone dye Alizarin Red S (AR) has been investigated by electro-Fenton process using a commercial graphite-felt to electrogenerate in situ hydrogen peroxide and regenerate ferrous ions as catalyst. The effect of operating conditions such as applied current, catalyst concentration, and initial dye content on AR degradation has been studied. AR decay kinetic, the evolution of its oxidation intermediates and the mineralization of the aqueous solutions were monitored during the electrolysis by UV-vis analysis and TOC measurements. The experimental results showed that AR was completely removed by the reaction with \u2022OH radicals generated from electrochemically assisted Fenton\u2019s reaction, and the decay kinetic always follows a pseudo-first-order reaction. The optimum applied current and catalyst concentration values were determined as 300 mA and 0.2 mM Fe2+. In these conditions, after 210 min of electrolysis 95% of the initial TOC was removed, meaning the almost complete mineralization of the organic content of the treated solution

Indirect electrochemical treatment of bisphenol A in water via electrochemically generated Fenton's reagent

PubMedID: 12953886Bisphenol A (BPA) has been treated with electrochemically generated Fenton's reagent in aqueous medium. Hydroxyl radicals that were formed in Fenton's reagent reacted with the organic substrate producing two different isomers of monohydroxylated product and, upon successive hydroxylation, mainly one dihydroxylated product. Further hydroxylation first degraded one of the aromatic rings, and the side chain thus formed was then cleaved off the other aromatic ring. The second aromatic ring was also degraded upon successive hydroxylations. Small saturated and unsaturated aliphatic acids were the last products prior to mineralization. It was found that use of cuprous/ cupric ion pair resulted a faster conversion of BPA and faster mineralization when compared using ferrous/ferric ions, but this happened at the expence of excess electrical charge utilized for an equivalent conversion or mineralization. Degradation by using ferrous/ferric ions was more efficient than cuprous/cupric ions case in terms of total mineralization versus charge utilized, and a mineralization of 82% had been achieved by applying 107.8 mF of charge to a 0.7 mM BPA solution of 0.200 dm3. The rate constant of the monohydroxylation of BPA in the presence of ferrous/ ferric ions had been determined as 1.0 × 1010 M-1 s-1 where BPA and salicylic acid competitively reacted with hydroxyl radicals in aqueous medium with the initial concentrations of Fe2+, BPA, and SA of 1.0, 0.5, and 0.5 mM, respectively. In a similar experiment where the initial concentrations of Cu2+, BPA, and SA were 1.0, 0.5, and 0.5 mM, respectively, the corresponding rate constant was determined to be the same as the rate constant obtained for Fe2+ (i.e., 1.0 × 1010 M-1 s-1). While the use of Cu2+ cannot be advised for processing BPA and similar substrates by using the electro-Fenton technique for both technical and economical reasons, the use of [Fe2+]/[BPA]0 values in the range 3-4 will be sufficient to achieve an efficient mineralization of BPA and similar substrates by the electro-Fenton process in aqueous medium

Elimination of radiocontrast agent Diatrizoic acid by photo-Fenton process and enhanced treatment by coupling with electro-Fenton process.

International audienc

Elimination of radiocontrast agent Diatrizoic acid by photo-Fenton process and enhanced treatment by coupling with electro-Fenton process.

International audienc

Influence of solubilizing agents (cyclodextrin or surfactant) on phenanthrene degradation by electro-Fenton process - Study of soil washing recycling possibilities and environmental impact

One of the aims in soil washing treatment is to reuse the extracting agent and to remove the pollutant in the meantime. Thus, electro-Fenton (EF) degradation of synthetic soil washing solutions heavily loaded with phenanthrene was suggested for the first time. Two solubilising agents hydroxypropyl-beta-cyclodextrin (HPCD) and Tween 80 (R) (TW 80) were chosen as cyclodextrin (CD) and surfactant representatives, respectively. In order to reuse HPCD and to degrade the pollutant simultaneously, the following optimal parameters were determined: [Fe2+] = 0.05 mM (catalyst), I = 2000 mA, and natural solution pH (around 6), without any adjustment. Only 50% of TW 80 (still higher than the critical micelle concentration (civic)) can be reused against 90% in the case of HPCD while phenanthrene is completely degraded in the meantime, after only 180 min of treatment. This can be explained by the ternary complex formation (Fe2+-HPCD-organic pollutant) (equilibrium constant K = 56 mM(-1)) that allows (OH)-O-center dot to directly degrade the contaminant. This confirms that Fe2+ plays an important role as a catalyst since it can promote formation of hydroxyl radicals near the pollutant and minimize HPCD degradation. After 2 h of treatment, HPCD/phenanthrene solution got better biodegradability (BOD5/COD = 0.1) and lower toxicity (80% inhibition of luminescence of Vibrio fischeri bacteria) than TW 80/phenanthrene (BOD5/COD = 0.08; 99% inhibition of V. fischeri bacteria). According to these data, HPCD employed in this integrated (soil washing + EF degradation) approach gave promising results in order to be reused whereas the pollutant is degraded in the meanwhile

Influence of the anode materials on the electrochemical oxidation efficiency. Application to oxidative degradation of the pharmaceutical amoxicillin

International audienc

A comparison between Flow-through cathode and mixed tank cells for the electro-Fenton process with CDEO anode.

International audienc

Présence et traitement des micropolluants organiques dans les lixiviats d'installation de stockage de déchets par des procédés avancés d'oxydation électrochimique

International audienceIn recent years, electrochemical advanced oxidation processes have been shown to be an effective alternative for the removal of refractory organic compounds from water. This study is focused on the effective removal of recalcitrant organic matter (micropollutants, humic substances, etc.) present in municipal solid waste landfill leachates. A mixture of eight landfill leachates has been studied by the electro-Fenton process using a Pt or boron-doped diamond (BDD) anode and a carbon felt cathode or by the anodic oxidation process with a BDD anode. These processes exhibit great oxidation ability due to the in situ production of hydroxyl radicals (OH), a highly powerful oxidizing species. Both electrochemical processes were shown to be efficient in the removal of dissolved total organic carbon (TOC) from landfill leachates. Regarding the electro-Fenton process, the replacement of the classical anode Pt by the anode BDD allows better performance in terms of dissolved TOC removal. The occurrence and removal yield of 19 polycyclic aromatic hydrocarbons, 15 volatile organic compounds, 7 alkylphenols, 7 polychlorobiphenyls, 5 organochlorine pesticides, and 2 polybrominated diphenyl ethers in landfill leachate were also investigated. Both electrochemical processes allow one to reach a quasicomplete removal (about 98%) of these organic micropollutants