Construction of Bi2O3/CuNiFe LDHs composite and its enhanced photocatalytic degradation of lomefloxacin with persulfate under simulated sunlight.

Advanced oxidation methods based on photocatalysis and sulfate radicals have attached most interest towards contaminant degradation. However, there are a lack of coupling two methods in the field of pollutant degradation. In the present study, a new Bi2O3/CuNiFe LDHs composite was fabricated and it could efficiently activate persulfate (PS) for lomefloxacin (LOM) decomposition under simulated sunlight, in which 84.6% of LOM (10 mg·L-1) was degraded over 40 min with 0.4 g·L-1 of Bi2O3/CuNiFe LDHs composite and 0.74 mM of PS at natural pH. In addition, the Bi2O3/CuNiFe LDHs composite possessed good reusability and stability at least four runs. Moreover, active radical scavenging experiments indicated that hydroxyl radicals (HO·), sulfate radicals (SO4·-), superoxide radicals (O2·-) and hole (h+) were the main radicals under LOM degradation process. Subsequently, the possible degradation intermediates were determined and the decomposition pathways were put forward. At the same time, activated sludge inhibition experiments were performed to assess the variation of toxicity of LOM and its degradation intermediates during oxidation. Finally, possible reaction mechanism of Bi2O3/CuNiFe LDHs composite for PS activation under simulated sunlight was proposed.

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

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 CO32- 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.