Kinetic studies on the electron transfer(ET) reaction of [Co(NH3)5(ImH)]3+/[Fe(CN)6]4- and trans-[Co(NH3)(en)2(ImH)]3+/[Fe(CN)6]4- have been carried out at various temperatures. The results indicated that these two ET...Kinetic studies on the electron transfer(ET) reaction of [Co(NH3)5(ImH)]3+/[Fe(CN)6]4- and trans-[Co(NH3)(en)2(ImH)]3+/[Fe(CN)6]4- have been carried out at various temperatures. The results indicated that these two ET reactions followed the outersphere mechanism. At 25℃,I=0.50mol’L-1, the ion pair formation constants Qip ofthe prectirsor complexes in the ET reactions are 2.6×102 and 4.9 × 1O2mol’L-1 ,and theelectron transfer rate constants kct are 2.1 ×10-4 and 5.2 ×10-5s-1 respectively. The activation enthalpy and the activation entropy of these two processes are 1.2×1O2,0.8 ×102kJ ’mol -1 and 5. 1×102, 3.6 ×102J·mol-1 ·K-1 respectively.展开更多
Arsenic pollution poses a serious threat to human health,and is one of the most concerning environmental problems worldwide.The adsorption,fixation,and dissolution behaviors of arsenic on the surface of iron-(hydr-)ox...Arsenic pollution poses a serious threat to human health,and is one of the most concerning environmental problems worldwide.The adsorption,fixation,and dissolution behaviors of arsenic on the surface of iron-(hydr-)oxides influence the environmental routes of arsenic cycle geochemistry.Both inner-sphere and outer-sphere adsorption configurations of arsenic on iron oxides have been proposed based on X-ray adsorption spectra.However,there is no systematic study on the in situ speciation analysis and adsorption kinetics of these species at such interfaces,because of the lack of an efficient monitoring strategy.The correlation of surface speciation and environmental stability is still unknown.Here,a shell-isolated SiO_(2)@Ag@Au-based surface-enhanced Raman spectroscopy(SERS)platform was developed for speciation analysis of the adsorbed arsenic species by eliminating the chemical interaction between arsenic and silver.Using ferrihydrite as a typical iron oxide,the intrinsic Raman spectra of the inner-sphere(~830 cm^(−1))and outer-sphere(~660 cm^(−1))complexes at the adsorption interface were identified.For the first time,the in situ kinetic monitoring of the formation and transformation of these species was realized.By correlating the speciation to the sequential extraction results,the environmental stability of arsenic on ferrihydrite was shown to be closely related to the adsorption configuration.It was shown that stability can be significantly promoted by transforming loosely bonded species(outer-sphere complexes)into inner-sphere structures.Our work demonstrated the applicability of SERS with shell-isolated plasmonic particles for arsenic geochemical cycle monitoring and mechanism studies.It also provided a convenient tool for developing effective strategies for arsenic pollutant control and abatement.展开更多
The influence of Na2 SO4 on the formation of ZnO whiskers was investigated in this paper. ZnO whiskers with aspect ratios of up to 50 were synthesized by dissolving ε-Zn（OH）2 precursor in NaOH/Na2SO4 solution at ro...The influence of Na2 SO4 on the formation of ZnO whiskers was investigated in this paper. ZnO whiskers with aspect ratios of up to 50 were synthesized by dissolving ε-Zn（OH）2 precursor in NaOH/Na2SO4 solution at room temperature, followed by aging of the resulting solution at 140 ℃ for 6 h. Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy analyses revealed that SO4^2- ions were primarily adsorbed on the （1 00） plane of the ZnO whiskers via an outer-sphere com- plex configuration （O-H……O）, thereby promoting the one-dimensional growth of ZnO whiskers along the c-axis.展开更多
文摘Kinetic studies on the electron transfer(ET) reaction of [Co(NH3)5(ImH)]3+/[Fe(CN)6]4- and trans-[Co(NH3)(en)2(ImH)]3+/[Fe(CN)6]4- have been carried out at various temperatures. The results indicated that these two ET reactions followed the outersphere mechanism. At 25℃,I=0.50mol’L-1, the ion pair formation constants Qip ofthe prectirsor complexes in the ET reactions are 2.6×102 and 4.9 × 1O2mol’L-1 ,and theelectron transfer rate constants kct are 2.1 ×10-4 and 5.2 ×10-5s-1 respectively. The activation enthalpy and the activation entropy of these two processes are 1.2×1O2,0.8 ×102kJ ’mol -1 and 5. 1×102, 3.6 ×102J·mol-1 ·K-1 respectively.
基金the National Natural Science Foundation of China(Nos.22106147 and 22076052)Natural Science Foundation of Hubei Province(No.2021CFB131)+1 种基金China Postdoctoral Science Foundation(No.2021M703005)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.G1323521102).
文摘Arsenic pollution poses a serious threat to human health,and is one of the most concerning environmental problems worldwide.The adsorption,fixation,and dissolution behaviors of arsenic on the surface of iron-(hydr-)oxides influence the environmental routes of arsenic cycle geochemistry.Both inner-sphere and outer-sphere adsorption configurations of arsenic on iron oxides have been proposed based on X-ray adsorption spectra.However,there is no systematic study on the in situ speciation analysis and adsorption kinetics of these species at such interfaces,because of the lack of an efficient monitoring strategy.The correlation of surface speciation and environmental stability is still unknown.Here,a shell-isolated SiO_(2)@Ag@Au-based surface-enhanced Raman spectroscopy(SERS)platform was developed for speciation analysis of the adsorbed arsenic species by eliminating the chemical interaction between arsenic and silver.Using ferrihydrite as a typical iron oxide,the intrinsic Raman spectra of the inner-sphere(~830 cm^(−1))and outer-sphere(~660 cm^(−1))complexes at the adsorption interface were identified.For the first time,the in situ kinetic monitoring of the formation and transformation of these species was realized.By correlating the speciation to the sequential extraction results,the environmental stability of arsenic on ferrihydrite was shown to be closely related to the adsorption configuration.It was shown that stability can be significantly promoted by transforming loosely bonded species(outer-sphere complexes)into inner-sphere structures.Our work demonstrated the applicability of SERS with shell-isolated plasmonic particles for arsenic geochemical cycle monitoring and mechanism studies.It also provided a convenient tool for developing effective strategies for arsenic pollutant control and abatement.
基金supported by the National Natural Science Foundation of China(Nos.51174125,51234003,and 51374138)
文摘The influence of Na2 SO4 on the formation of ZnO whiskers was investigated in this paper. ZnO whiskers with aspect ratios of up to 50 were synthesized by dissolving ε-Zn（OH）2 precursor in NaOH/Na2SO4 solution at room temperature, followed by aging of the resulting solution at 140 ℃ for 6 h. Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy analyses revealed that SO4^2- ions were primarily adsorbed on the （1 00） plane of the ZnO whiskers via an outer-sphere com- plex configuration （O-H……O）, thereby promoting the one-dimensional growth of ZnO whiskers along the c-axis.
