Baeyer–Villiger oxidation can synthesize a series of esters or lactones that have essential application value but are difficult to be synthesized by other methods. Cycloketones can be oxidized to lactones using molecular oxygen, peroxy acids, or hydrogen peroxide as an oxidant. Hydrogen peroxide is one of the environmental oxidants. Because of the weak oxidation ability of hydrogen peroxide, Bronsted acids and Lewis acids are used as catalysts to activate hydrogen peroxide or the carbonyl of ketones to increase the nucleophilic performance of hydrogen peroxide. The catalytic mechanisms of Bronsted acids and Lewis acids differ in the Baeyer–Villiger oxidation of cyclohexanone with an aqueous solution of hydrogen peroxide as an oxidant.

Formaldehyde (HCHO) is identified as the most toxic chemical among 45 organic compounds found in industrial wastewater, posing significant harm to both the environment and human health. In this study, a novel approach utilizing the Lanthanum-manganese complex oxide (LaMnO3)/peroxymonosulfate (PMS) system was proposed for the effective removal of HCHO from wastewater. Perovskite-Type LaMnO3 was prepared by sol-gel method. The chemical compositions and morphology of LaMnO3 samples were analyzed through thermogravimetric analysis (TG), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The effects of LaMnO3 dosage, PMS concentration, HCHO concentration, and initial pH on the HCHO removal rate were investigated. When the concentration of HCHO is less than 1.086 mg/mL (5 mL), the dosage of LaMnO3 is 0.06 g, and n(PMS)/n(HCHO) = 2.5, the removal rate of HCHO is more than 96% in the range of pH = 5–13 at 25 °C for 10 min. Compared with single-component MnO2, the perovskite structure of LaMnO3 is beneficial to the catalytic degradation of HCHO by PMS. It is an efficient Fenton-like oxidation process for treating wastewater containing HCHO. The LaMnO3 promoted the formation of SO4•− and HO•, which sequentially oxidized HCHO to HCOOH and CO2.

Removing toxic formaldehyde (HCHO) from environmental water is crucial for human health and the ecosystem. Perovskite-type Lanthanum cobalt oxide (LaCoO₃) has achieved great success in a wide range of catalytic processes; however, this concept has been rarely applied to the degradation of HCHO. Here, we prepared perovskite-type catalysts with different La/Co molar ratios, and the time for HCHO oxidation degradation at room temperature was shortened by 12 times (10 min vs. 119 min) compared to other heterogeneous catalysts. LaCoO₃ exhibits superior catalytic activity for HCHO degradation at room temperature when the La/Co molar ratio is 1:1 compared to lanthanum cobalt oxides with other molar ratios. The X-ray photoelectron spectroscopy (XPS) test results show that increasing the La/Co molar ratio reduces the Co²⁺ content in the catalyst, while Co²⁺ plays the most important role in the catalyst. Quencher experiments indicated that sulfate radicals (SO₄·⁻) and hydroxyl radicals (·OH) were the primary reactive species for the removal of HCHO. This finding suggests that the catalytic oxidation reaction involving HCHO operates as a heterogeneous Fenton-like oxidation reaction.

Formaldehyde reacts with proteins, causing their denaturation and exhibiting high toxicity, carcinogenicity, and teratogenicity. In this study, lanthanum (La) oxide (La2O3)/zeolite Socony Mobil-5 (ZSM-5) catalyst was synthesized using the equal-volume impregnation method, and formaldehyde in wastewater was efficiently degraded using this catalyst and hydrogen peroxide (H2O2) as the oxidant. Based on thermogravimetric analysis of La2O3/ZSM-5, ZSM-5, and La (III) nitrate hexahydrate, the optimal calcination temperature of the La2O3/ZSM-5 precursor was determined to be 600°C. X-ray powder diffraction and transmission electron microscopy analyses revealed that La2O3 was well dispersed on ZSM-5. The effects of La2O3 loading, catalyst dosage, H2O2 concentration, initial formaldehyde concentration, and solution pH on the degradation rate were systematically investigated. The catalyst exhibited dual functionality, enabling both adsorption and activation of formaldehyde and H2O2 molecules. Under optimized conditions—10 wt% La2O3, 50 mg/mL catalyst dosage, a molar ratio of H2O2 to formaldehyde of 3, pH 5–11, and a reaction time of 20 min—the degradation rate of formaldehyde exceeded 95%. This technique can effectively treat formaldehyde concentrations up to 1.497 mg/mL. This finding offers guidance for designing efficient catalysts applicable to non-Fenton oxidation processes for formaldehyde degradation.