Tea polyphenols promote Fenton-like reaction: pH self-driving chelation and reduction mechanism

Tea polyphenols (TP) are natural green organic compounds with chelating and reducing properties, which can promote the catalytic reaction, but the mechanism of promotion is still uncertain. In this paper, the chelation and reduction of TP were used to promote the degradation of lincomycin (LCM) by zero-valent iron Fenton-like reaction, and the mechanism of the two properties of TP was analyzed. The results showed that in the Fe-0/H2O2 system, the degradation rate of the reaction system was increased from 27% to 100% in two hours after the addition of TP, and the reaction rate was increased about 26 times. Moreover, the parameters of pH, Fe2+, (OH)-O-center dot, oxidation reduction potential (ORP) and so forth indicating that the chelating structure of TP and iron ions was formed under pH= 4-9, which obviously promoted the mutual conversion of Fe3+/Fe2+. It is propitious to the proper amount of iron dissolution in order to facilitate the continuous and efficient Fenton reaction. Under acidic conditions, the TP are more reductive due to the destruction of the chelate structure, which promotes the conversion of Fe3+ to Fe2+ or even zero-valent iron, significantly improves the Fe3+/Fe2+ cycle capacity and increases the amount of % OH produced.