New progress has been made in the treatment of organic pollutants in water by advanced oxidation method

Persulfate advanced oxidation technology is one of the methods for deep treatment of trace amounts of persistent organic pollutants in water, which has the characteristics of simple operation and rapid process. This technology uses persulfate as an oxidant to produce SO4·-, · Reactive oxygen species such as OH, O2·-and 1O2 achieve oxidative degradation of pollutants. Among them, 1O2 of non-free radicals has a mild oxidation capacity, a long half-life, a reaction selectivity for electron-rich organic pollutants, and a stronger resistance to inorganic ions and organic background interference. Therefore, the 1O2-led non-free radical degradation pathway provides new possibilities for the selective removal of organic pollutants in water. At the same time, the precise regulation of 1O2-led non-free radical oxidative degradation has gradually become a research hotspot. 

The Catalysis New Process Research Group of the National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, on the basis of the highly efficient activation oxidant OMS-2 of the previous three-dimensional structure of manganese oxide molecular sieve OMS-2 to remove organic pollutants in water (Environmental Science: Nano, 2022, 9, 1541; Separation and Purification Technology, 2021, 263, 118397By using the bimetallic doping strategy on the OMS-2 catalyst, the catalytic activation mechanism of persulfate dominated by 1O2 and electron-mediated transfer was precisely regulated, and the selective oxidation removal of electron-rich organic pollutants in water was realized (Figure 1).

Figure 1. Bimetallic doped OMS-2 catalytically activates persulfates to degrade organic contaminants in water

The researchers synthesized a bimetallic-doped Cu-Nd-OMS-2 catalyst (Figure 2) using the transition metal Cu and lanthanide metal Nd as doping reagents, and the bimetals were uniformly dispersed in the material phase, which not only caused a large number of oxygen and metal defects to form on the surface and edge of the catalyst, but also greatly improved the oxidation performance of the catalyst. In the study of the mechanism of catalytic activation of potassium perivosulfate degradation of paraben, it was found that the non-free radical process of oxidative degradation with 1O2 as the main and electron-mediated transfer as the supplement, the doping of Cu improved the texture characteristics of OMS-2, and the doping of Nd triggered the electron-mediated transfer process, which in turn made the catalytic system have a wide range of pH applicability in water, and also showed excellent tolerance in natural organic pollutants and background ion interference (Figure 3).

Figure 2. Synthesis of bimetallic doped OMS-2 catalytic materials

Figure 3. Electron microscopic characterization, EPR experiments, and degradation performance of catalytic materials

The above work was recently published in the title “Doping strategy-tuned non-radical pathway on manganese oxide for catalytic degradation of parabens.”Chemical Engineering Journalabove. Dr. Xiaopei Wang is the first author of the paper. 

The research work was supported by the National Natural Science Foundation of China, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and the National Engineering Research Center for Fine Petrochemical Intermediates of Lanzhou Institute of Chemicals. (Source: Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences)

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