Acid groups decorated bimetal-organic catalyst for advanced oxidation technology at full pH range

As a wastewater treatment technology, the activity of advanced oxidation process (AOPs) is strongly dependent on pH value. Herein, considering the low activity of AOPs under alkaline conditions, the acid organic ligand (nitrilotriacetic acid, NTA) was chosen to design Co-NTA metal-organic catalyst for efficient photo-Fenton reaction at full pH range. The experimental results indicate the acid ligands in Co-NTA offers more·OH that can achieve high activity under alkaline conditions. To further enhance the electron injection ability and redox cycles of Co(II)/Co(III), Ferrocene (Fc) nanoparticles was introduced to form bimetallic organic catalyst Fc-Co-NTA. The mechanism study indicates that the synergistic effect between Co-NTA and Fc promotes the activation of potassium persulfate and improves the stability of the catalyst under extreme pH conditions, while the π-π interaction between TC and Fc-Co-NTA can improve the electron injection capability and accelerate the production of·OH/SO4•-, so as to accelerate the redox cycles of Fe(II)/Fe(III) and Co(II)/Co(III), bringing about prolonged carrier lifetime and better photocatalytic activity. The possible degradation pathway of TC was investigated by Fukui function and LC-MS. A machine learning model is used to optimize the synthesis and photocatalytic parameters of Fc-Co-NTA. This study provides a new design idea to prepare highly efficient and stable photo-Fenton advanced oxidation technology at full pH range.