A novel catalytic filtration process using MnO₂@sand and peroxymonosulfate for unselective removal of organic contaminants from water

Multiple catalytic oxidation processes involving new synthesized materials have recently been examined to replace conventional oxidative treatment methods for water purification, but upscaling and demonstration stages are mostly lacking, which hinders their practical implementation. In this study, we introduce a novel catalytic process where peroxymonosulfate (PMS) is activated by MnO₂ surfaces that are attached on natural sand as part of a catalytic filtration column (CFC). PMS decomposition in the CFC was stable during steady-state filter operation with different natural waters (tap water and secondary effluent) and sulfate radicals were identified as main radical species. Complete oxidation (>99 %) of 10 mg/L rhodamine B in tap water could be achieved with PMS concentrations as low as 0.2 mM and a residence time of less than 3 min. Furthermore, unselective oxidation of various recalcitrant and environmentally-relevant trace organic chemicals (e.g., carbamazepine, sulfamethoxazole, and benzotriazole) was achieved with 0.6 mM PMS in tap water and secondary effluent, proving the robustness of the process in presence of multiple organic and inorganic constituents. Future investigations are needed to optimize the CFC process for specific applications and confirm its operation in real-world water matrices and to study sustainability aspects. Overall, this study demonstrates the potential of the CFC process to be implemented as a practical nano-enabled water treatment and offers a framework for next steps to be taken before upscaling. It provides important performance data that can be used as reference for future proposals of scalable catalytic oxidation water treatment technology.