Octadecylamine degradation through catalytic activation of peroxymonosulfate by FeMn layered double hydroxide

Highlights: • Fe-Mn-LDH was fabricated as the PMS activator. • Emerging contaminator ODA could be effectively degraded by Fe-Mn-LDH/PMS system. • Controlling factors of ODA degradation were evaluated. • Fe-Mn-LDH exhibited high activity and stability. • The mechanism and pathway of the ODA degradation were elucidated. -- Abstract: A kind of heterogeneous catalyst, FeMn layered double hydroxide (Fe-Mn-LDH), was fabricated by coprecipitation process and used as PMS activator to degrade a novel organic pollutant octadecylamine (ODA). And the X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microcopy (TEM), Mapping and X-ray photoelectron spectra (XPS) measurements were utilized to characterize the fresh and used Fe-Mn-LDH. After a serious of degradation experiments, it was clearly to see that the activator possessed excellent activation property for PMS and was capable of removing 85% ODA (10 mg·L⁻¹) within 25 min obviously higher than pure PMS. Moreover, the effect of some elements (such as PMS consumption, catalyst consistence and initial pH value), different reaction system and catalyst repeatability on ODA degradation were also explored. And by identification of main radical experiment, SO₄^— and HO were both confirmed the primary radicals. What's more, extra anion and nature organic matter (NOM) addition experiment displayed that NOM, NO₃^— and CO₃^2— perform a negative effect on ODA degradation but Cl^— could promote it. In addition, repeated experiments and metal leaching after degradation showed good stability of Fe-Mn-LDH. Finally, based on the XPS and Gas Chromatography-Mass Spectrometer (GS-MS) technology, the possible degradation mechanism and pathway were proposed.