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Nitrogen doped graphene oxide loaded CuFe2O4 nanoparticles (CuFe2O4-NG) catalyst was successfully synthesized by thermal annealing and hydrothermal reaction approaches for degrading organic pollutants by peroxymonosulfate (PMS) activation. CuFe2O4-NG exhibited superior degradation efficiency toward orange II among GO, NG, CuFe2O4 and CuFe2O4-NG. The obtained catalysts were systemically characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectrum analysis and X-ray photoelectron spectroscopy to understand the relationship between inner structure and catalytic activity. It can recognize the key reactive oxygen species including SO4•–, •OH, O2•– and 1O2 in CuFe2O4-NG/PMS degradation system by electron paramagnetic resonance and free radical quenching studies, indicating the existence of both radical pathway and non-radical pathway. Based on the valence state changes of Cu and Fe in XPS spectra, the redox cycles between Fe(III) and Fe(II), Cu(II) and Cu(I) mediated by HSO5– contributed to the production of SO4•–, •OH and O2•–. Carbonyl groups and ketonic groups on the catalyst could promote the self-decomposition of PMS, leading to the generation of 1O2. The synergistic effect between NG and CuFe2O4 can accelerate the activation of PMS and pose the new insight for organic pollutants removal. more...

Three magnetic biochar nanocomposites named as C800-1, C800-2 and C800-3 with increased iron deposition amount, decreased graphitized degree and gradually destroyed graphitized carbon layers, respectively, were prepared using potassium ferrate as activator and corn straw as biomass. C800-1, C800-2 and C800-3 exhibited much different bisphenol A degradation effect in presence of peroxymonosulfate among which C800-3 owned the best catalytic performance. For the degradation mechanism, the dominant role of electron transfer pathway was gradually replaced by the SO4•- pathway with the increase of iron amount and the destruction of graphitized carbon layers. This work would provide a simple and feasible method, namely changing the ratio of potassium ferrate and biochar, to manipulate the radical and nonradical degradation pathway in PMS-based organic wastewater purification. more...

Three types of hierarchically porous magnetic biochars (HMBs) were prepared by pyrolyzing low-cost wheat straw and potassium ferrate (K2FeO4) under a nitrogen atmosphere at 600, 700 and 800 °C, respectively, which could be used as amendments for cadmium (Cd) in water and soil. HMB fabricated at 700 °C (HMB700) had the best remediation performance for Cd in water and soil, which was mainly due to its largest specific surface area and micropore volume. Batch sorption experiments showed that Cd(II) sorption onto HMBs were well-described by a pseudo-second-order model and Sips (Freundlich-Langmuir) model, indicating that HMBs removed Cd(II) mainly through chemical adsorption. MINTEQ modeling evidenced that HMBs adsorbed Cd(II) mainly through precipitation rather than surface complexation. The adsorption behavior of HMB700 to Cd(II) could be explained by surface complexation (–OCd, –COOCd), precipitation (Cd(OH)2 and CdCO3), physical adsorption (rich pore structure) and ion exchange (K+, Ca2+, Mg2+). Furthermore, adding HMBs (1 wt%) (incubation 60 days) could also significantly increase soil pH and electrical conductivity (EC), and significantly reduce the available Cd content in soil (47.97%–61.38%). Adding HMBs could promote the conversion of bioavailable to less bioavailable Cd forms. These results provided a new idea for fabricating agricultural waste-based HMBs to remediate Cd in water and soil. more...

The biochar loaded with CoFe2O4 nanoparticles (CoFe2O4/HPC) fabricated by pyrolysis exhibited strong magnetic property, hierarchical porous and graphitized structure. CoFe2O4/HPC showed much better bisphenol A degradation than CoFe2O4 in presence of peroxymonosulfate. The graphitized structure and the synergistic effect between graphitized structure and CoFe2O4 were found to be responsible for the superiority of CoFe2O4/HPC among all the other catalysts. The prominent role including radical way mainly contributed by SO4 − and non-radical way achieved by 1O2, and the secondary role of electron transfer way proceeded by graphitized structure were uncovered. The processes such as redox between Co(III)/Co(II) and Fe(III)/Fe(II), the reduction of Fe(III) by O2 −, and the participation of C O in 1O2 production were significant to the excellent catalytic performance of CoFe2O4/HPC. Considering its excellent separation, stability, adaptability and reusability, CoFe2O4/HPC opened up a novel way to develop green catalyst to activate PMS for organic pollutants degradation. more...

In this work, porous defective g-C3N4 ultrathin nanosheets were prepared through thermal condensation of freeze-dried precursor. First-principles density functional theory (DFT) calculations well predicted the role of VN in modulating energy levels and photocatalytic properties. The optimally defective g-C3N4 manifested the better photocatalytic disinfection performance towards E. coli and S. aureus than pristine g-C3N4, respectively. The gradual damaged cell membrane for E. coli and the intimate mechanical constraint for S. aureus was imaged to further decipher the antibacterial behavior. The synergistic effect of enhanced visible light absorption ability, more exposed active sites and improved photogenerated charge separation was responsible for excellent photocatalytic disinfection activity. The photocatalytic disinfection mechanism towards E. coli was explored by electron spinning resonance (EPR), radical scavenger and spectral quantification technology, confirming the major role of h+ and O2 −. This study provides alternative strategy for rational design of effective g-C3N4-based photocatalysts by defective engineering for environmental remediation. more...

In this work, a novel AgInS2 nanosheets/TiO2 nanobelts photocatalyst was prepared by a facile hydrothermal method. The AgInS2/TiO2 with the optimal ration showed excellent photocatalytic performance in simultaneous Escherichia coli (E. coli) disinfection and Cr(VI) reduction or E. coli disinfection and bisphenol A (BPA) degradation. The superior photocatalytic effect were possibly attributed to formation of heterojunction between AgInS2 nanosheets and TiO2 nanobelts, which could increase the absorption of visible light, facilitate the separation of photo-induced carrier and held the redox of photo-generated e– and h+. The production of reactive species during the disinfection process was also investigated by employing chemical scavengers, electron spin resonance, and spectroscopy technique, revealing the paramount role of h+ and O2•–. This study paves a new way to rationally design the novel TiO2 nanobelts or AgInS2 nanosheets based photocatalysts for combined pollution remediation in water environment. more...

The novel quinazolinone alkaloids (I) and (II) are isolated along with seven known analogues from the BuOH extract of the marine-derived bacterium Bacillus cereus.