Can the commonly used quenching method really evaluate the role of reactive oxygen species in pollutant abatement during catalytic ozonation?

Efficient degradation of clofibric acid by heterogeneous catalytic ozonation using CoFe2O4 catalyst in water.

MgMxOy (M = Fe, Mn) powders prepared by the sol-gel method were used as the catalysts for ozonation of p-hydroxybenzoic acid (p-HBA) and acetic acid (AcOH) (20 mg/L) at a neutral pH for 9 min. The study aims to bring an insight into the synergetic mechanism for basic and acid sites of MgMxOy in heterogeneous catalytic ozonation. 84.8 %, 88.2 %, 86.7 % p-HBA were removed by ozonation catalyzed by MgFexOy, MgMnxOy and MgO, respectively. 49.3 %, 65.8 %, 64.3 % AcOH were removed by ozonation catalyzed by the three catalysts, respectively. MgMnxOy exhibited the highest catalytic activity in ozonation of p-HBA and AcOH owing to the action of acid sites of MgMnxOy for additional ozone decomposition. The increase of solution pH, the protonation of surface hydroxyl groups and the electron transfer on acid sites induce ozone decomposition into reactive oxygen species in MgMxOy catalytic ozonation.

Synergetic mechanism for basic and acid sites of MgMxOy (M = Fe, Mn) double oxides in catalytic ozonation of p-hydroxybenzoic acid and acetic acid

Enhanced reactivity of zero-valent aluminum with ball milling for phenol oxidative degradation

Promoting surface oxygen vacancies on ceria via light pretreatment to enhance catalytic ozonation

In this paper, we demonstrate the facile and general synthesis of alkaline-earth metal manganites, denoted as A(Mg, Ca, Ba)MnxOy, for efficient degradation of high-concentration phenolic compounds via catalytic ozonation. The representative CaMnxOy oxides show a hierarchical spherical structure constructed by crystalline nanorods and numerous macropores. They possess mixed Mn4+/Mn3+ chemical valences and abundant surface hydroxyl (OH) groups. The ozone (O3) decomposition rate on the CaMnxOy catalysts is greatly accelerated and follows the first-order law. These catalysts are promising for the degradation of phenolic compounds via catalytic ozonation, exhibiting rapid pseudofirst-order degradation kinetics, a high total organic carbon (TOC) removal efficiency and an excellent stability. Under optimized conditions (a low O3 dosage of 1.5 mg/min and a catalyst dosage of 7.5 g/L), for the treatment of concentrated phenol (50–240 mg/L), the CaMnxOy catalysts show 100% degradation and 50–70% mineralization within 1.0 h. The Ca2+ ions are essential to create redox Mn4+/Mn3+ couples and to significantly reduce manganese leaching. High surface ratios of Mn4+/Mn3+ and OH/lattice oxygen (Olat) are beneficial for enhancing the catalytic performance. Superoxide anion free radicals ( O2–) and singlet oxygen (1O2) are the predominant reactive species for the oxidation degradation. The O2– reaction pathway is proposed. Specifically, the surface OH sites activate O3, displaying highly enhanced decomposition rates. The generated O2– and 1O2 play a role in oxidation. The redox Mn4+/Mn3+ and the Olat/oxygen vacancy (Olat/Ovac) couples play important roles in electron transfer. The proposed mechanism is supported by active site probing, radical scavenging, spectroscopic studies, and the results in the degradation of substituted phenols.

Facile synthesis of alkaline-earth metal manganites for the efficient degradation of phenolic compounds via catalytic ozonation and evaluation of the reaction mechanism.

Sintering- and oxidation-resistant ultrasmall Cu(I)/(II) oxides supported on defect-rich mesoporous alumina microspheres boosting catalytic ozonation.

The invention relates to a preparation method of a calcium manganese oxide compound. The preparation method comprises the following steps: dissolving soluble calcium salt and soluble manganese salt inwater to obtain a mixed solution, wherein the molar ratio of the soluble calcium salt to the soluble manganese salt is 1:(3-4); adding oxidant manganese oxide salt in the mixed solution, then addingan ammonium carbonate aqueous solution in the mixed solution, regulating the pH to 8-9, filtering and drying to obtain solid powder, wherein the molar ratio of an oxidant to the soluble calcium salt is 1:1; calcining the solid powder for 3 hours at a temperature of 800 DEG C to obtain the calcium manganese oxide compound containing trivalent manganese and tetravalent manganese. The invention further discloses application of the calcium manganese oxide compound as a catalyst in the ozone oxidation reaction. The preparation method provided by the invention is mild in reaction condition, simple in production process and low in equipment requirement, and the product has good catalytic performance in the ozone oxidation reaction.

Cunxia Fang

Papers

Facile synthesis of alkaline-earth metal manganites for the efficient degradation of phenolic compounds via catalytic ozonation and evaluation of the reaction mechanism.

Sintering- and oxidation-resistant ultrasmall Cu(I)/(II) oxides supported on defect-rich mesoporous alumina microspheres boosting catalytic ozonation.

Preparation method of calcium manganese oxide compound and application thereof as ozone oxidation catalyst