Activation of persulfate (PS) and peroxymonosulfate (PMS) and application for the degradation of emerging contaminants

Reports that promote persulfate-based advanced oxidation process (AOP) as a viable alternative to hydrogen peroxide-based processes have been rapidly accumulating in recent water treatment literature. Various strategies to activate peroxide bonds in persulfate precursors have been proposed and the capacity to degrade a wide range of organic pollutants has been demonstrated. Compared to traditional AOPs in which hydroxyl radical serves as the main oxidant, persulfate-based AOPs have been claimed to involve different in situ generated oxidants such as sulfate radical and singlet oxygen as well as nonradical oxidation pathways. However, there exist controversial observations and interpretations around some of these claims, challenging robust scientific progress of this technology toward practical use. This Critical Review comparatively examines the activation mechanisms of peroxymonosulfate and peroxydisulfate and the formation pathways of oxidizing species. Properties of the main oxidizing species are scrutinized and the role of singlet oxygen is debated. In addition, the impacts of water parameters and constituents such as pH, background organic matter, halide, phosphate, and carbonate on persulfate-driven chemistry are discussed. The opportunity for niche applications is also presented, emphasizing the need for parallel efforts to remove currently prevalent knowledge roadblocks.

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Persulfate-Based Advanced Oxidation: Critical Assessment of Opportunities and Roadblocks.

Activated persulfate for organic chemical degradation: A review.

Magnetic CuO-Fe3O4 composite was fabricated by a simple hydrothermal method and characterized as a heterogeneous catalyst for phenol degradation. The effects of pH and bicarbonate ions on catalytic activity were extensively evaluated in view of the practical applications. The results indicated that an increase of solution pH and the presence of bicarbonate ions were beneficial for the removal of phenol in the CuO-Fe3O4 coupled with persulfate (PS) process. Almost 100% mineralization of 0.1 mM phenol can be achieved in 120 min by using 0.3 g/L CuO-Fe3O4 and 5.0 mM PS at pH 11.0 or in the presence of 3.0 mM bicarbonate. The positive effect of bicarbonate ion is probably due to the suppression of copper leaching as well as the formation of Cu(III). The reuse of catalyst at pH0 11.0 and 5.6 showed that the catalyst remains a high level of stability at alkaline condition (e.g., pH0 11.0). On the basis of the characterization of catalyst, the results of metal leaching and EPR studies, it is suggested that pheno...

Heterogeneous degradation of organic pollutants by persulfate activated by CuO-Fe3O4: Mechanism, stability, and effects of pH and bicarbonate ions

Critical review of the science and sustainability of persulphate advanced oxidation processes

Oxidative degradation of p-chloroaniline by copper oxidate activated persulfate

In the interest of accelerating aniline degradation, Fe2+ and chelated Fe2+ activated persulfate oxidations were investigated in neutral pH condition. Three kinds of chelating agents were selected including citric acid, oxalic acid and ethylenediamine tetraaceatate (EDTA) to maintain available Fe2+. The results indicate that the concentration of chelating agent and ferrous ion didn’t follow a linear relationship with the degradation rate of aniline. A 1/1 ratio of chelating agent/Fe2+ results in a higher degradation rate compared to the results by other ratios. The oxidation enhancement factor using oxalic acid was found to be relatively low. In contrast, citric acid is more suitable chelating agent in the ferrous iron activated persulfate system and aniline exhibits a highest degradation with a persulfate/Fe2+/citric acid/aniline molar ratio of 50/25/25/1 compared to other molar ratios.

Effect of chelating agent on oxidation rate of aniline in ferrous ion activated persulfate system at neutral pH

The invention discloses a method for treating organic pollutants in water by catalyzing persulfate through heterogeneous copper oxide. At room temperature, the persulfate and the heterogeneous copper oxide are added in water containing the organic pollutants, so that the persulfate generates sulfuric acid free radicals with strong oxidizing property under effect of the heterogeneous copper oxide, the sulfuric acid free radicals further oxidize trace-amount refractory organic matters in water so as to lead the organic matters to be degraded, and accordingly the aim of purifying organic sewage is achieved. The heterogeneous copper oxide added in the method can constantly and effectively catalyze and activate the persulfate to generate the sulfuric acid free radicals so as to oxidize and degrade the organic pollutants at room temperature, and the method is wide in potential of hydrogen (pH) applicable range and can have good effect in neutral and alkaline water. The method for treating organic pollutants in water by catalyzing persulfate through heterogeneous copper oxide is low in cost, high in treating efficiency at room temperature and easy to operate and has great potential in the technical field of refractory organic sewage treatment.

Hai-yun Liang

Papers

Oxidative degradation of p-chloroaniline by copper oxidate activated persulfate

Effect of chelating agent on oxidation rate of aniline in ferrous ion activated persulfate system at neutral pH

Method for treating organic pollutants in water by catalyzing persulfate through heterogeneous copper oxide