As(III) removal from drinking water using FMCTO@Fe3O4 in the adsorption-magnetic separation-sand filtration equipment: Trade-off between As removal efficiency and adsorbent utilization rate

Due to the carcinogenicity and high environmental mobility of arsenic (As), its contamination in the groundwater environment is widespread, continuously threatening human health through the food chain. The adsorption technologies for As removal, which demonstrate simplicity and cost-effectiveness, have received much attention. Despite these merits, the difficult separation between adsorbent and As-contaminated water in traditional adsorption limited the development of large-scale applications. An adsorbent of Fe-Mn-Cu ternary oxide modified with magnetite (FMCTO@Fe₃O₄) was synthesized to develop a highly efficient As removal device based on an Adsorption-magnetic separation integrated safety device. Its safety and applicability were evaluated by optimizing the reactor design parameters using dynamic experiments. X-ray photoelectron spectroscopy, X-ray diffraction, and zeta potential results show that FMCTO@Fe₃O₄ has high adsorption and oxidation performance, in which 77 % of As(III) in the section was oxidized to As(V). As particle (As-p) electrostatically adsorbed to the surface of the material, with a removal efficiency of 84 % in the magnetic separation section and manganese sand filtration section. In this process, FMCTO@Fe₃O₄ isolated from magnetic separation section showed far stronger adsorption capacity. Specifically, FMCTO@Fe₃O_4, after being used 2 or 3 times, achieved an 80 % As(tot) removal efficiency. The section B functional area recycled Fe (99.24 %), Cu (98.2 %), and Mn (98.6 %), which demonstrated the equipment with higher stability and economic recovery. This device is promising in groundwater As removal, providing theoretical support and application innovation for drinking water safety and security.