Jia Manke

Synthesis of a magnetic micro/nano Fe x O y -CeO 2 composite and its application for degradation of hexachlorobenzene

A micrometer-sized nanostructured, magnetic, ball-like FexOy-CeO2 composite was synthesized through an ethylene-glycol mediated process. The synthesized samples were characterized by scanning electron microscopy combined with energydisperse X-ray analysis, transmission electron microscopy and X-ray powder diffraction. In the synthesis system, polyethylene glycol (PEG) and urea were found to play significant roles in the formation of the micrometer-sized spherical architecture of the precursor. The details of morphology and particle size could be changed with the initial concentration of Fe(NO3)3·9H2O and Ce(NO3)3·6H2O as the reactants. The magnetic FexOy-CeO2 composite with a similar morphology was readily obtained by calcination from the precursor. The characterization of transmission electron microscopy showed the calcined ball-like architecture was a highly porous structure consisting of many nanoparticles. Because of the micrometer-sized nanostructure and the multi-components as well as the magnetism, the as-obtained FexOy-CeO2 composite showed better activity and potentially easy recovery for the harmless degradation of hexachlorobenzene (HCB).

The contrastive research in the photocatalytic activity of BiOBr synthesized by different reactants

BiOBr nanoplates, marked as α-BiOBr and β-BiOBr, were synthesized via hydrothermal method using cetylpyridinium bromide (CPB) and NaBr as reactants, respectively. X-Ray Diffraction (XRD), transmission electron microscope (TEM), N2 adsorption/desorption, UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), and cyclic voltammetry (CV) were employed to characterize the obtained BiOBr. The results showed that α-BiOBr and β-BiOBr can absorb visible light and both the band gaps of them were about 2.76 eV. Under visible light irradiation, the photodegradation of organic dye sulforhodamine (SRB) and salicylic acid (SA) using α-BiOBr and β-BiOBr as the catalysts was carried out. The reaction kinetic constants of the degradation of SRB by α-BiOBr and β-BiOBr were 0.00602 min-1 and 0.0047 min-1, respectively, which indicated that the photocatalytic activity of α-BiOBr was higher than that of β-BiOBr. The UV-Vis DRS and total organic carbon (TOC) were also monitored, and the TOC removal rate of α-BiOBr and β-BiOBr was 86% and 48%, respectively. At the same time, hydrogen peroxide (H2O2) and active radicals were measured and analyzed, which showed that the main active species was OH during the photocatalytic reaction.

Heterogeneous degradation of toxic organic pollutants by hydrophobic copper Schiff-base complex under visible irradiation

A hydrophobic complex of Cu2+[bis-salicylic aldehyde-o-phenylenediamine], Cu-SPA, was prepared and used as a heterogeneous photocatalyst to degrade organic pollutants in water under visible irradiation (λ ⩾ 420 nm) at neutral pH. The structure of complex was characterized by using nuclear magnetic resonance (NMR), elemental analysis, IR and UV-vis spectrometries. Degradation of Rhodamine B (RhB), Sulforhodamine B (SRB) and Benzoic acid (BA) in water were used as model reactions to evaluate the photocatalytic activities of Cu-SPA. The results indicated that RhB and SRB were easily adsorbed on the hydrophobic surface of Cu-SPA from aqueous solution (the maximum adsorption amount: Qmax = 11.09 and 8.05 μmol/g, respectively). Under visible irradiation, RhB and SRB were decolorized completely after 210 and 240 min, respectively, and BA was removed completely after 5 h. The efficiency of H2O2 was > 95%, in contrast to that of the reaction without catalyst or light (< 20%). In water soluble medium, the hydrophobic Cu-SPA can be used more than 6 cycles. ESR results and the behavior of cyclic voltammetry showed that, in the reaction process, Cu2+-SPA was reduced to intermediate state Cu+-SPA firstly, which was extremely unstable and reacted rapidly with H2O2, leading to high reactive oxygen species (·OH radical ) to degrade the substrate.