Natural Psilomelane for the Activation of Persulfate to Degrade Tetracycline: Effect of the Temperature

Tetracycline (TC) is a prominent antibiotic that remains largely unmetabolized in humans and animals, resulting in significant excretion into the environment. This poses a substantial threat to human health, highlighting the urgent necessity for effective removal of TC from water sources.

A series of catalytic materials were prepared by subjecting natural psilomelane (NP) to roasting at varying temperatures and subsequently employed to activate persulfate for the degradation of tetracycline.

The natural psilomelane roasted at 500 °C (NP-500) exhibited the excellent catalytic activity compared to the unroasted natural psilomelane. The removal rate of tetracycline at a concentration of 30 mg/L was 84.6% when a dosage of 0.5 g/L of catalyst and 0.5g/L of PMS was employed. Furthermore, an appropriate calcination temperature could facilitate the generation of oxygen vacancies and active metal ions (Fe, Mn), which were crucial for the formation of active oxygen. Besides, superoxide radicals (O₂•⁻) and singlet oxygen (¹O₂) were the primary reactive species. And the initial pH and co-existing anion experiments showed that the NP-500/PMS system presented a wide range of potential applications. Finally, based on the LC-MS and experimental results, a possible degradation pathway and mechanistic map of TC were proposed.