Cerium oxide nanoparticles(CeO_(2) NPs)are likely to have dramatic impacts on plant performances,yet the effects of CeO_(2) NPs on seed germination and seedling growth have not been fully explored.In this study,the se...Cerium oxide nanoparticles(CeO_(2) NPs)are likely to have dramatic impacts on plant performances,yet the effects of CeO_(2) NPs on seed germination and seedling growth have not been fully explored.In this study,the seed germination and seedling growth of subshrub species Vitex negundo under different concentrations of CeO_(2) NPs(low-1 mg/L,medium-100 mg/L,high-500 mg/L)have been discussed.Results showed that:(1)The seed germination rate reduces by 11.25%and 2.5%under the low and medium concentrations of CeO_(2) NPs,respectively,but increased by 7.08%under the high concentration;(2)CeO_(2) NPs had significant effects on the growth traits(root length,shoot height and biomass)of seedlings,being the highest under the medium concentration and the lowest under the highest concentration;(3)The superoxide dismutase activity was the maximum(355.91 U/g),but the protein concentration was the minimum(3.85 ug/mL)under the high concentration of CeO_(2) NPs.Our results indicated that the effects of CeO_(2) NPs on seed germination and seedling growth are concentration-dependency,i.e.,low and medium concentrations inhibited while high concentration promoted seed germination,however,seedling growth showed opposite responses.Therefore,appropriate CeO_(2) NPs concentrations are beneficial to the seed germination and seedling growth of Vitex negundo and improve the physiological performance of seedlings and enhance their adaptability to environmental adversity.展开更多
CeO2nanoparticles(NPs) were synthesized in alkaline medium via the homogeneous precipitation method and were subsequently calcined at 80 ℃/24 h(assigned as CeO2-80) and 500 ℃/2 h(assigned as CeO2-500). The as-prepar...CeO2nanoparticles(NPs) were synthesized in alkaline medium via the homogeneous precipitation method and were subsequently calcined at 80 ℃/24 h(assigned as CeO2-80) and 500 ℃/2 h(assigned as CeO2-500). The as-prepared materials and the commercial ceria(assigned as CeO2-com) were characterized using TGA-MS, XRD, SEM-EDX, UV-vis DRS and IEP techniques. The photocatalytic performances of all obtained photocatalysts were assessed by the degradation of Congo red azo-dye(CR) under UVAlight irradiation at various environmental key factors(e.g., reaction time and calcination temperature).Results reveal that CeO2compounds crystalize with cubic phase, CeO2-500 exhibits smaller crystallite size(9 nm vs 117 nm) than that of bare CeO2-com. SEM analysis shows that the materials are sphericallike in shape NPs with strong assembly of CeO2NPs observed in the CeO2-500 NPs. EDX analysis confirms the stoichiometry of CeO2NPs. UV-vis DRS measurement reveals that, CeO2-500 NPs exhibits a red-shift of absorption band and a more narrow bandgap(2.6 eV vs 3.20 eV) than that of bare CeO2-com. On the contrary, Urbach energy of Eu is found to be increased from 0.12 eV(CeO2-com) to 0.17 eV(CeO2-500),highlighting an increase of crystalline size and internal microstrain in the CeO2-500 NPs sample. Zeta potential(IEP) of CeO2-500 NPs is found to be 7.2. UVA-light-responsive photocatalytic activity is observed with CeO2-500 NPs at a rate constant of 10×10-3min-1, which is four times higher than that of CeO2-com(Kapp=2.4×10-3min-1) for the degradation of CR. Pseudo-first-order kinetic model gives the best fit. On the basis of the energy band diagram positions, the enhanced photocatalytic performance of CeO2-500 nano-catalyst can be ascribed to O2-, ’OH and R’+as the primary oxidative species involved in the degradation of RC under UVA-light irradiation.展开更多
基金This study was supported by the Science and Technology Innovation Foundation of Henan Agricultural University(30601458)the Scientific Research Foundation for the Doctor of Henan Agriculture University(30500848).
文摘Cerium oxide nanoparticles(CeO_(2) NPs)are likely to have dramatic impacts on plant performances,yet the effects of CeO_(2) NPs on seed germination and seedling growth have not been fully explored.In this study,the seed germination and seedling growth of subshrub species Vitex negundo under different concentrations of CeO_(2) NPs(low-1 mg/L,medium-100 mg/L,high-500 mg/L)have been discussed.Results showed that:(1)The seed germination rate reduces by 11.25%and 2.5%under the low and medium concentrations of CeO_(2) NPs,respectively,but increased by 7.08%under the high concentration;(2)CeO_(2) NPs had significant effects on the growth traits(root length,shoot height and biomass)of seedlings,being the highest under the medium concentration and the lowest under the highest concentration;(3)The superoxide dismutase activity was the maximum(355.91 U/g),but the protein concentration was the minimum(3.85 ug/mL)under the high concentration of CeO_(2) NPs.Our results indicated that the effects of CeO_(2) NPs on seed germination and seedling growth are concentration-dependency,i.e.,low and medium concentrations inhibited while high concentration promoted seed germination,however,seedling growth showed opposite responses.Therefore,appropriate CeO_(2) NPs concentrations are beneficial to the seed germination and seedling growth of Vitex negundo and improve the physiological performance of seedlings and enhance their adaptability to environmental adversity.
文摘CeO2nanoparticles(NPs) were synthesized in alkaline medium via the homogeneous precipitation method and were subsequently calcined at 80 ℃/24 h(assigned as CeO2-80) and 500 ℃/2 h(assigned as CeO2-500). The as-prepared materials and the commercial ceria(assigned as CeO2-com) were characterized using TGA-MS, XRD, SEM-EDX, UV-vis DRS and IEP techniques. The photocatalytic performances of all obtained photocatalysts were assessed by the degradation of Congo red azo-dye(CR) under UVAlight irradiation at various environmental key factors(e.g., reaction time and calcination temperature).Results reveal that CeO2compounds crystalize with cubic phase, CeO2-500 exhibits smaller crystallite size(9 nm vs 117 nm) than that of bare CeO2-com. SEM analysis shows that the materials are sphericallike in shape NPs with strong assembly of CeO2NPs observed in the CeO2-500 NPs. EDX analysis confirms the stoichiometry of CeO2NPs. UV-vis DRS measurement reveals that, CeO2-500 NPs exhibits a red-shift of absorption band and a more narrow bandgap(2.6 eV vs 3.20 eV) than that of bare CeO2-com. On the contrary, Urbach energy of Eu is found to be increased from 0.12 eV(CeO2-com) to 0.17 eV(CeO2-500),highlighting an increase of crystalline size and internal microstrain in the CeO2-500 NPs sample. Zeta potential(IEP) of CeO2-500 NPs is found to be 7.2. UVA-light-responsive photocatalytic activity is observed with CeO2-500 NPs at a rate constant of 10×10-3min-1, which is four times higher than that of CeO2-com(Kapp=2.4×10-3min-1) for the degradation of CR. Pseudo-first-order kinetic model gives the best fit. On the basis of the energy band diagram positions, the enhanced photocatalytic performance of CeO2-500 nano-catalyst can be ascribed to O2-, ’OH and R’+as the primary oxidative species involved in the degradation of RC under UVA-light irradiation.
