Tea waste-enhanced degradation of phenolic and pharmaceutical pollutants in the ferric ion/peroxymonosulfate system

This study explores the practical potential of tea waste for degrading phenolic and pharmaceutical pollutants in water. The addition of tea waste to the Fenton-like system (i.e., the ferric ion/peroxymonosulfate (Fe^III/PMS) system) notably enhanced its efficiency in degrading 4-chlorophenol (4-CP), increasing from 7.1 % without tea waste to 100 % with tea waste after 2 h of reaction. Electron paramagnetic resonance spectroscopy, UV−visible spectroscopy, and liquid chromatography demonstrate that catechins extracted from tea waste play a crucial role in increasing degradation efficiency by reducing Fe^III to Fe^II through the formation of catechin-Fe^III complexes. This process facilitates the activation of PMS to radical species, such as sulfate (SO₄^●−) and hydroxyl radicals (^●OH). Among these two radical species, SO₄^●− acts as the main oxidant for the degradation of 4-CP, as verified by radical quenching experiments. The optimal condition of the Fe^III/PMS/tea waste system was investigated by conducting experiments that varied the pH, PMS concentration, Fe^III concentration, tea waste dosage, and the presence of water impurities. The Fe^III/PMS/tea waste system efficiently degraded all 11 tested phenolic and pharmaceutical pollutants. The strategy of utilizing tea waste as an accelerator in Fenton-like systems reduces not only the material cost for water treatment but also the disposal cost of tea waste.