Several perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been identified as chemicals of concern in the environment due to their persistence, global ubiquity, and classification as reproductive and developmental toxicants, endocrine disrupters, and possible carcinogens. Multiple PFASs are often found together in the environment due to product manufacturing methods and abiotic and biotic transformations. Treatment methods are needed to effectively sequester or destroy a variety of PFASs from groundwater, drinking water, and wastewater. This review presents a comprehensive summary of several categories of treatment approaches: (1) sorption using activated carbon, ion exchange, or other sorbents, (2) advanced oxidation processes, including electrochemical oxidation, photolysis, and photocatalysis, (3) advanced reduction processes using aqueous iodide or dithionite and sulfite, (4) thermal and nonthermal destruction, including incineration, sonochemical degradation, sub- or supercritical tr...

Degradation and Removal Methods for Perfluoroalkyl and Polyfluoroalkyl Substances in Water

ConspectusGrowing worldwide population, climate change, and decaying water infrastructure have all contributed to a need for a better water treatment and conveyance model. Distributed water treatment is one possible solution, which relies on the local treatment of water from various sources to a degree dependent on its intended use and, finally, distribution to local consumers. This distributed, fit-for-purpose water treatment strategy requires the development of new modular point-of-use and point-of-entry technologies to bring this idea to fruition. Electrochemical technologies have the potential to contribute to this vision, as they have several advantages over established water treatment technologies. Electrochemical technologies have the ability to simultaneously treat multiple classes of contaminants through the in situ production of chemicals at the electrode surfaces with low power and energy demands, thereby allowing the construction of compact, modular water treatment technologies that require li...

The Prospect of Electrochemical Technologies Advancing Worldwide Water Treatment.

Recent developments and advances in boron-doped diamond electrodes for electrochemical oxidation of organic pollutants

Electrochemical oxidation of perfluorinated compounds in water

Electrochemical treatment of perfluorooctanoic acid and perfluorooctane sulfonate: Insights into mechanisms and application to groundwater treatment

In this study, alum (Al2(SO4)3⋅18H2O), ferric chloride (FeCl3⋅6H2O) and polyaluminium chloride (PACl) were used to remove perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from water. The influencing factors, including pH and natural organic matter (NOM), were investigated. A positive correlation was found between the size of the flocs and the removal efficiency of PFOX (X=S and A). The removal ratios of PFOS and PFOA were 32% and ∼12%, respectively, when 50 mg/L of FeCl3⋅6H2O was added as the coagulant at the initial pH. Coagulation achieved high removal ratios for PFOX under acidic conditions (∼47.6% and 94.7% for PFOA and PFOS at pH 4, respectively). In addition, increasing NOM concentrations decreased the removal rates of PFOX because of the existence of competitive adsorption between NOM molecules and PFOX on the surface of the coagulants and flocs. The combination of adsorption by powdered activated carbon (PAC) and coagulation increased the removal ratios up to >90% for PFOX at the initial concentration of 1mg/L, implying that the adsorption enhanced coagulation. Meantime, the experiments with natural water showed that coagulation is a feasible method to remove PFOS and PFOA from surface water.

Removal of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from water by coagulation: Mechanisms and influencing factors

An environmentally tolerant, highly stable, cellulose nanofiber-reinforced, conductive hydrogel multifunctional sensor.

Electrochemical degradation of an emerging contaminant, triclosan (5-chloro-2-(2,4-dichlorophenoxy) phenol) by a Ti/SnO2-Sb/Ce-PbO2 anode was investigated. The degradation efficiency attained >99.9% during 5 min of electrolysis at all influential factors, i.e., applied current density (2–10 mA/cm2), pH 3–11, inter-electrode distance (1–4 cm), initial concentration (0.5–5 mg/L triclosan) and supporting electrolyte (10 mmol/L NaCl). Total organic carbon removal ratio achieved 79.7% at the optimal conditions after 2 min of electrolysis. The electrochemical degradation of triclosan followed pseudo-first-order kinetics. The intermediate products namely 2,4-dichlorophenol, 5-chloro-3-(chlorohydroquinone) phenol and 2-chloro-5-(2,4-dichlorophenoxy) benzene-1,4-diol were prominently detected using liquid chromatography–tandem mass spectrometry. A degradation mechanism of triclosan at the Ti/SnO2-Sb/Ce-PbO2 anode was proposed based on the intermediates. The energy consumption of triclosan (4 mg/L) degradation at different electrode distances (1–4 cm) was 0.466–2.225 kWh m−3. The Ti/SnO2-Sb/Ce-PbO2 anodes can be employed preliminary for rapid degradation of triclosan in wastewater.

Zesheng Xu

Papers

Electrochemical oxidation of perfluorinated compounds in water

Removal of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from water by coagulation: Mechanisms and influencing factors

An environmentally tolerant, highly stable, cellulose nanofiber-reinforced, conductive hydrogel multifunctional sensor.

Electrochemical Degradation of Triclosan at a Ti/SnO2‐Sb/Ce‐PbO2 Anode

Electrochemical oxidation of 2,4,5-trichlorophenoxyacetic acid by metal-oxide-coated Ti electrodes.