Toward Selective Oxidation of Contaminants in Aqueous Systems

Abstract

The presence of diverse pollutants in water has been threating human health and aquatic ecosystems on a global scale. For more than a century, chemical oxidation using strongly oxidizing species was one of the most effective technologies to destruct pollutants and to ensure a safe and clean water supply. However, the removal of increasing amount of pollutants with higher structural complexity, especially the emerging micropollutants with trace concentrations in the complicated water matrix, requires excessive dosage of oxidant and/ or energy input, resulting in a low cost-effectiveness and possible secondary pollution. Consequently, it is of practical significance but scientifically challenging to achieve selective oxidation of pollutants of interest for water decontamination. Currently, there are a variety of examples concerning selective oxidation of pollutants in aqueous systems. However, a systematic understanding of the relationship between the origin of selectivity and its applicable water treatment scenarios, as well as the rational design of catalyst for selective catalytic oxidation, is still lacking. In this critical review, we summarize the state-of-the-art selective oxidation strategies in water decontamination and probe the origins of selectivity, that is, the selectivity resulting from the reactivity of either oxidants or target pollutants, the selectivity arising from the accessibility of pollutants to oxidants via adsorption and size exclusion, as well as the selectivity due to the interfacial electron transfer process and enzymatic oxidation. Finally, the challenges and perspectives are briefly outlined to stimulate future discussion and interest on selective oxidation for water decontamination, particularly toward application in real scenarios.

Hybrid Enzymatic/Photocatalytic Degradation of Antibiotics via Morphologically Programmable Light‐Driven ZnO Microrobots

“…In general, the presence of four copper sites in the structure of the laccase enzyme can be the underlying reason for its ability to degrade OTC. [38] With this structure, laccase can catalyze the oxidation of aromatic compounds having electrondonating groups by using molecular oxygen in multicopperelectron redox reactions. [2,4] For the condition involving only H 2 O 2 fuel, it is possible to remove OTC via oxidation reactions that can be enhanced under UV irradiation.…”

Insights into the relationship of reactive oxygen species and anions in persulfate-based advanced oxidation processes for saline organic wastewater treatment

“…The second is that ROS (except direct oxidation and electron transfer) produced by catalysis need to diffuse into water to react with pollutants. 26 The two processes are equally important. If any of the two processes is influenced, the degradation of pollutants would be seriously affected.…”

Insights into singlet oxygen generation and electron-transfer process induced by a single-atom Cu catalyst with saturated Cu-N4 sites

“…Owing to the generation of powerful oxidizing radicals (e.g., hydroxyl radical ⋅ OH and sulfate radical SO 4 ⋅− ), persulfate-mediated advanced oxidation processes (AOPs) are regarded as efficient technologies for water purification ( Wang et al., 2021a ; Zhang et al., 2021 ). However, in actual water with complex chemical compositions, radicals are inevitably consumed by natural organic matter (NOM) and inorganic substrates (e.g., HCO 3 − and Cl − ), hindering the degradation of target pollutant and increasing the toxicity caused by halogenated byproducts ( Yang et al., 2021 ). Therefore, selective degradation of emerging micropollutants in complex water matrices remains a significant challenge for water treatment.…”

“…À and Cl À ), hindering the degradation of target pollutant and increasing the toxicity caused by halogenated byproducts (Yang et al, 2021). Therefore, selective degradation of emerging micropollutants in complex water matrices remains a significant challenge for water treatment.…”