Enhanced Fenton-like Catalytic Activation of Peroxymonosulfate over Macroporous LaFeO3 for Water Remediation

Four different-sized carbon microspheres, CS, obtained by a facile hydrothermal method, are applied as a hard template for the preparation of a series of macroporous LaFeO3. The average particle size of the CS obtained is between 0.350 and 0.700 µm. The macroporous LaFeO3 are tested in a Fenton-like activation of peroxymonosulfate, PMS, for oxidation of tetracycline hydrochloride, TCH, in model water solution under visible-light irradiation. The effect of parameters such as type of irradiation, temperature of the reaction, and type of the water matrixes was tested. The oxidation of the pollutant TCH is evaluated by total organic carbon and organic nitrogen measurements. The results showed the superior catalytic activity of macroporous LaFeO3 in comparison to pure LaFeO3. Rate constants between 0.036 and 0.184 min−1 at 25 °C were obtained. The activation energy for the process with the most active macroporous LaFeO3 was 33.88 kJ/mol, a value lower than for the catalytic process with PMS only, proving the positive role of the macroporous LaFeO3 for TCH degradation. Radical scavenger measurements showed that singlet oxygen, produced during the catalytic degradation process, was responsible for the performance of macroporous LaFeO3/PMS/visible light for TCH degradation. The catalysts proved to be efficient and recyclable.