Boosting efficient removal of organic pollutants by sulfur modified hollow MnFe2O4 nanocage: Synergist of three-dimensional structure and reactive species

Abstract

Bimetal-based peroxymonosulfate advanced oxidation processes (PMS-AOPs) present an enticing avenue for water treatment. The challenge of interference effects persists in addressing complex wastewater, including the occlusion of active sites by natural organic matters (NOMs) and the quenching of free radicals by competitive constituents. A sulfur-modified hollow MnFe2O4 nanocage (S-MnFe2O4) was introduced through a facile Prussian blue analog pyrolysis. The nanocage exhibited high interference resistance in terms of both active sites and reactive species. The hollow architecture, featuring a smaller pore diameter (2–50 nm) than NOMs (255.7 nm), effectively sequestered extraneous macromolecular interferences. Sulfur doping orchestrated a transformation in the PMS activation pathway via expediting the preferential adsorption of terminal oxygen in PMS and reducing the energy barrier to a non-radical pathway dominance (1O2), contributing to a highly discerning removal of target phenol. The performance for target degradation was sustained in the presence of multiple negative factors, including humic acid, competitive organic, and inorganic, due to the synergy between size exclusion and 1O2. Even in natural waters (e.g. tap, lake, river, etc.) or continuous flow systems, the S-MnFe2O4/PMS combination showcased a remarkable removal effect. Co-regulation strategy unfolds a complete perspective to eliminate targets in the interference of other compounds.