CoFe-LDO nanoparticles as a novel catalyst of peroxymonosulfate (PMS) for histidine removal

Dissolved organic nitrogen (DON) has been a research subject due to its potential to form nitrogenous disinfection byproducts (N-DBPs) in drinking water treatment. In our study, CoFe layered double oxide (CoFe-LDO) was selected as an effective catalyst for the removal of histidine by activation of peroxymonosulfate (PMS). The results investigated that the removal of DON and histidine within 1 h in the CoFe-LDO/PMS system were up to 61% and 72%, respectively. The influences of CoFe-LDO dosage, PMS dosage, and pH value for DON removal were also elucidated. The optimum pH was 8, and the optimal dosage of CoFe-LDO and PMS were 0.04 g/L and 0.5 mmol/L. It was found that SO₄^•- and •OH induced by the transformation of Co²⁺-Co³⁺ and Fe²⁺-Fe³⁺ on the catalyst surface were responsible for the degradation by ESR detection, in which SO₄^•- played a more important role. The degradation pathway of histidine indicated that it was partly oxidized to NH₄⁺-N in the 60 min and no evident generation of N₂ during the whole process. Furthermore, degradation products of histidine have also been revealed by the analysis of HPLC-MS. In addition, the generation potentials of two typical N-DBPs were also clarified. The formation potential of dichloroacetonitrile (DCAN) decreased, while that of dichloroacetamide (DCAcAm) increased firstly before declining.