Efficient degradation of tetracycline via peracetic acid activation using Fe₂SiO₄: performance and mechanisms study

In recent years, advanced oxidation processes (AOPs) based on peracetic acid (PAA) have garnered significant attention for the removal of emerging organic pollutants due to their high efficiency. However, traditional iron-based catalysts used for PAA activation face challenges related to structural instability and high iron leakage. To tackle these issues, this study employed a silicon (Si) doping strategy and synthesized Fe₂SiO₄-NC using Fe-ZIF-8 as a precursor to activate PAA for the removal of tetracycline (TC). The morphology and physicochemical properties of the catalyst were characterized. Density Functional Theory (DFT) calculations revealed that the introduction of Si reduced the formation energy and orbital transition energy, thereby enhancing structural stability and catalytic activity. The degradation tests indicated that 40 μM of TC was completely removed within 10 min using 0.06 g/L of Fe₂SiO₄-NC and 0.15 mM of PAA, achieving a k_obs value of 0.40 min^-1. Additionally, the Fe₂SiO₄-NC exhibited exceptional recyclability and stability, achieving over 90 % TC removal across six consecutive cycles, with Fe ion leakage below 0.3 mg/L. Quenching tests and mechanism analysis indicated that organic radicals of CH₃C(O)OO• played the predominant role in the degradation. Fe redox cycles and surface Si-OH groups were found to promote the activation of PAA. Notably, this work lies in the rational integration of Si doping and Fe-ZIF-8-derived structure to engineer catalyst Fe₂SiO₄-NC with extremely low metal leaching and high PAA activation efficiency, which provides critical insights into the design of Fe-based catalysts with high structural stability and activity.