Over the last decades, research efforts have been made at developing more effective technologies for the remediation of waters containing persistent organic pollutants. Among the various technologies, the so-called electrochemical advanced oxidation processes (EAOPs) have caused increasing interest. These technologies are based on the electrochemical generation of strong oxidants such as hydroxyl radicals ( OH). Here, we present an exhaustive review on the treatment of various synthetic and real wastewaters by five key EAOPs, i.e., anodic oxidation (AO), anodic oxidation with electrogenerated H 2 O 2 (AO-H 2 O 2 ), electro-Fenton (EF), photoelectro-Fenton (PEF) and solar photoelectro-Fenton (SPEF), alone and in combination with other methods like biological treatment, electrocoagulation, coagulation and membrane filtration processes. Fundamentals of each EAOP are also given.

Electrochemical advanced oxidation processes: A review on their application to synthetic and real wastewaters

Electrochemical processes have been extensively investigated for the removal of a range of organic and inorganic contaminants. The great majority of these studies were conducted using nitrate-, perchlorate-, sulfate-, and chloride-based electrolyte solutions. In actual treatment applications, organic and inorganic constituents may have substantial effects on the performance of electrochemical treatment. In particular, the outcome of electrochemical oxidation will depend on the concentration of chloride and bromide. Formation of chlorate, perchlorate, chlorinated, and brominated organics may compromise the quality of the treated effluent. A critical review of recent research identifies future opportunities and research needed to overcome major challenges that currently limit the application of electrochemical water treatment systems for industrial and municipal water and wastewater treatment. Given the increasing interest in decentralized wastewater treatment, applications of electrolytic systems for treat...

Challenges and Opportunities for Electrochemical Processes as Next-Generation Technologies for the Treatment of Contaminated Water

Electrochemical advanced oxidation processes (EAOPs) have emerged as novel water treatment technologies for the elimination of a broad-range of organic contaminants. Considerable validation of this technology has been performed at both the bench-scale and pilot-scale, which has been facilitated by the development of stable electrode materials that efficiently generate high yields of hydroxyl radicals (OH˙) (e.g., boron-doped diamond (BDD), doped-SnO2, PbO2, and substoichiometic- and doped-TiO2). Although a promising new technology, the mechanisms involved in the oxidation of organic compounds during EAOPs and the corresponding environmental impacts of their use have not been fully addressed. In order to unify the state of knowledge, identify research gaps, and stimulate new research in these areas, this review critically analyses published research pertaining to EAOPs. Specific topics covered in this review include (1) EAOP electrode types, (2) oxidation pathways of select classes of contaminants, (3) rate limitations in applied settings, and (4) long-term sustainability. Key challenges facing EAOP technologies are related to toxic byproduct formation (e.g., ClO4− and halogenated organic compounds) and low electro-active surface areas. These challenges must be addressed in future research in order for EAOPs to realize their full potential for water treatment.

Critical review of electrochemical advanced oxidation processes for water treatment applications

Coupling of membrane filtration and advanced oxidation processes for removal of pharmaceutical residues: A critical review

Evaluating tetracycline degradation pathway and intermediate toxicity during the electrochemical oxidation over a Ti/Ti4O7 anode

This research investigates the characterization and testing of an anodic reactive electrochemical membrane (REM) for water treatment. The REM consists of a porous substoichiometric titanium dioxide (Ti4O7) tubular, ceramic electrode operated in cross-flow filtration mode. Advection-enhanced mass transfer rates, on the order of a 10-fold increase, are obtained when the REM is operated in filtration-mode, relative to a traditional flow-through mode. Oxidation experiments with model organic compounds showed that the REM was active for both direct oxidation reactions and formation of hydroxyl radicals (OH•). Electrochemical impedance spectroscopy data interpreted by transmission line modeling determined that the electro-active surface area was 619 times the nominal geometric surface area. Results from filtration-mode experiments with p-methoxyphenol indicate that compound removal occurred by electro-assisted adsorption and subsequent oxidation. Electro-assisted adsorption was the primary removal mechanism at ...

Porous Substoichiometric TiO2 Anodes as Reactive Electrochemical Membranes for Water Treatment

This research investigated the removal mechanisms of p-nitrophenol, p-methoxyphenol, and p-benzoquinone at a porous Ti4O7 reactive electrochemical membrane (REM) under anodic polarization. Cross-flow filtration experiments and density functional theory (DFT) calculations indicated that p-benzoquinone removal was primarily due to reaction with electrochemically formed OH(•), while the dominant removal mechanism of p-nitrophenol and p-methoxyphenol was a function of the anodic potential. At low anodic potentials (1.7-1.8 V/SHE), p-nitrophenol and p-methoxyphenol were removed primarily by an electrochemical adsorption/polymerization mechanism on the REM. Increasing anodic potentials (1.9-3.2 V/SHE) resulted in the electroassisted adsorption mechanism contributing far less to p-methoxyphenol removal compared to p-nitrophenol. DFT calculations indicated that an increase in anodic potential resulted in a shift in p-methoxyphenol removal from a 1e(-) direct electron transfer (DET) reaction that resulted in radical formation and significant adsorption/polymerization, to a 2e(-) DET reaction that formed nonadsorbing products (i.e., p-benzoquinone). However, the anodic potentials were too low for the 2e(-) DET reaction to be thermodynamically favorable for p-nitrophenol. The decreased COD adsorption for p-nitrophenol at higher anodic potentials was attributed to reaction of soluble/adsorbed organics with OH(•). These results provide the first mechanistic explanation for p-substituted phenolic compound removal during advanced electrochemical oxidation processes.

Mechanism of p-substituted phenol oxidation at a Ti4O7 reactive electrochemical membrane

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Efficacy of Trichloroacetic Acid in Patients with Alopecia Areata: A Clinico-Histopathological Study

Background: Vitiligo is a frequent hypopigmentary disorder that can impact both adults and children and has significant psychosocial consequences due to its leopard skin-like look. Vitiligo must be treated and studied more frequently, even if it is not life-threatening or asymptomatic. Aim of the study: A comparative intra-individual study was conducted to evaluate the efficacy of intralesional methotrexate against intralesional triamcinolone acetonide in the therapy of localized non-segmental vitiligo. Patients and Methods: Our study was carried out on 30 patients complaining of vitiligo from August 2021 to January 2022. Thirty subjects with two comparable patches, one of them was randomly selected and treated with Intralesional Methotrexate and the other was treated with Intralestional Triamcinolone Acetonide . Patients were selected from out-patient clinic of Dermatology, Venereology and Andrology Department of Al-Azhar University Hospitals. Results: The present study showed improvement in Patches treated with Intralesional Methotrexate as excellent response in13.3% of patients, good response in 13.3% of patients, fair response in 10% of patients and poor response in 63.3% of patients. Improvement in Patches treated with Intralesional Triamcinolone Acetonide as excellent response in 13.3% of patients, good response in 13.3% of patients, fair response in 16.7% of patients and poor response in 56.7% of patients. Conclusion: using Intralesional Methotrexate and intralesional Triamcinolone Acetonide considered a promising, safe and effective therapeutic options for localized vitiligo with no significant side effects.

Evaluation of the efficacy of intralesional methotrexate versus intralesional triamcinolone acetonide in treatment of localized vitiligo: comparative intra individual study

Amr M. Zaky

Papers

Porous Substoichiometric TiO2 Anodes as Reactive Electrochemical Membranes for Water Treatment

Mechanism of p-substituted phenol oxidation at a Ti4O7 reactive electrochemical membrane

Efficacy of Trichloroacetic Acid in Patients with Alopecia Areata: A Clinico-Histopathological Study

Evaluation of the efficacy of intralesional methotrexate versus intralesional triamcinolone acetonide in treatment of localized vitiligo: comparative intra individual study