Modification of catalysts by multi-heteroatom doping (S, P, B) is an effective way to improve the peroxomonosulfate activation performance of catalysts. In recent years, highly toxic and persistent trace organic contaminants have been frequently detected in water. Consequently, we proposed the advanced oxidation processes of peroxomonosulfate activated by multi-heteroatom doped Fe@CN (X-Fe@CN) to eliminate trace organic contaminants. The physical phases of X-Fe@CN and its precursors were characterized by X-ray diffraction and scanning electron microscopy. In evaluating the catalytic properties and iron ion leaching of X-Fe@CN-activated PMS for the removal of dicamba and atenolol, B-Fe@CN and PB-Fe@CN were selected and optimized. The active sites of the catalysts were characterized by X-ray photoelectron spectroscopy and Raman. The pathways of PMS activation by B-Fe@CN and PB-Fe@CN were identified in combination with electron paramagnetic resonance and electrochemical experiments. Defects, O-B-O and pyrrolic nitrogen on the surface of B-Fe@CN could adsorb and activate PMS to produce SO₄^•−, ·OH and ¹O₂. Further doping with P enhanced the electron transfer on the catalyst surface, thus accelerating the activation of peroxomonosulfate. This study compared the effects of multi-heteroatom modifications and further demonstrated the synergistic effect between P and B, which can provide a theoretical basis for the selection of multi-heteroatom doped catalysts in water treatment.

Copper (Cu) pollution poses environmental and health risks. Owing to its adaptability and potential for water purification, Nymphoides peltata (N. peltata) is being considered for use in the remediation of Cu pollution. However, the feasibility of using N. peltata for the remediation of Cu-polluted water bodies has not yet been assessed. Here, the physiological response of N. peltata to Cu stress was determined. N. peltata samples were exposed to varying Cu concentrations (0.2, 0.4, 0.6 and 0.8 mg∙L⁻¹), and the activities of glutamine synthetase (GS), nitrate reductase (NR), nitrite reductase (NiR), ribulose-1,5-diphosphate carboxylase (Rubisco), and glycolate oxidase (GO) were measured together with the concentrations of photosynthetic pigments. The results revealed that under Cu stress, NR and GS activities significantly decreased, while NiR activity significantly increased. Exposure to 0.2 mg∙L⁻¹ Cu promoted chlorophyll synthesis and enhanced Rubisco and GO activities; in contrast, exposure to Cu concentrations above 0.4 mg∙L⁻¹ significantly inhibited the aforementioned parameters. These findings indicate that Cu stress, regardless of concentration, significantly affects nitrogen metabolism in N. peltata by decelerating nitrate reduction and impairing the ammonification process. Meanwhile, only high Cu concentrations significantly affected photosynthesis. N. peltata can survive low Cu stress by regulating its photosynthetic enzymes. Therefore, N. peltata has potential for the ecological restoration of water bodies polluted with low Cu concentrations.