One-step pyrolysis of ZIF-8 after recovering rare earth elements from mining wastewater as a functional fenton-like catalyst

Abstract

The management of rare earth elements (REEs) from mining wastewater has consistently a key issue. Our previous research has demonstrated the selective adsorption of REEs in mining wastewater by ZIF-8. Herein, one-step pyrolysis of ZIF-8 after recovering REEs from mining wastewater as a high-value product was further proposed. The resulting REEs-based magnetic nanoporous carbon materials (REEs-MPC) was utilized for the activation of peroxymonosulfate (PMS) in the removal of bisphenol A (BPA). Experimental results indicate substantial BPA removal efficiencies of 74.62 %, 83.57 %, and 70.06 % with REEs-MPC synthesized at different pyrolysis temperatures (700 °C, 800 °C, and 900 °C). The detailed characterizations reveal the REEs-MPC at 800 °C was obtained (REEs-MPC/800) exhibit prominent graphitic and defective characteristics. In addition, electrochemical analysis revealed that the REEs-MPC/800 demonstrate elevated conductivity and superior capacitive current, with Tafel slopes as high as 294 mV/dec. Functional theory (DFT) calculations demonstrate that the presence of graphitic-N and REEs-N species significantly enhance PMS activation. Finally, a neural network model constructed through machine learning techniques provided a comprehensive overview of the structure–property relationship. Overall, the proposal to synthesize a high-value product using mining wastewater has been put forward. This initiative is expected to contribute to the advancement of the green economy within the rare earth mining industry.