Removal of Cr（VI） from aqueous solution by strong alkaline anion exchange fiber （SAAEF） was achieved using batch adsorption experiments. The effect of contact time, initial Cr（VI） concentration and pH was invest...Removal of Cr（VI） from aqueous solution by strong alkaline anion exchange fiber （SAAEF） was achieved using batch adsorption experiments. The effect of contact time, initial Cr（VI） concentration and pH was investigated. The results showed that the maximum adsorption capacity of SAAEF was 187.7 mg/g at pH=1.0. The adsorption capacity increased with Cr（VI） concentration but decreased with pH value when pH〉1.0. Adsorption isotherms at various temperatures were obtained. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models were adopted and the equilibrium data fitted best with the Langmuir isotherm. The constants of these models indicated that the adsorption process involved both chemisorption and physisorption. The values of thermodynamic parameters, including DH, DG and DS, suggested that the adsorption of Cr（VI） on SAAEF was a spontaneous, entropy-driven and endothermic process. Q（iso） was not a constant value, which indicated an inhomogenous energy distribution on SAAEF.展开更多
Electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)plays an important role in deciphering interfacial reaction mechanisms at molecular level.However,the corrosive ...Electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)plays an important role in deciphering interfacial reaction mechanisms at molecular level.However,the corrosive etching of Si internal reflection element by OH−largely impedes reliable SEIRAS measurements in strong alkaline electrolytes.Herein,a dense and chemically inert nanocrystalline diamond(NCD)film is successfully fabricated at a thickness of~120 nm through hot filament chemical vapor deposition on a micromachined Si wafer to insulate the OH^(−)etching.A reversible interfacial water feature without spectral interference of Si-O band is obtained in 1.0 mol·L^(–1)KOH on Au/NCD/Si film electrode.Afterwards,electrochemical CO reduction reaction on Cu film electrode is explored in different KOH concentrations ranging from 0.1 to 3.0 mol·L^(-1)as a model reaction.A redshift of CO_(L)band,as well as its lower intensity but faster depletion kinetics,is noted with increasing electrolyte pH,whereas CO_(B)is identified as an inert spectator accumulating on Cu surface.Our present work demonstrates the alkaline resistant feature of diamond/Si composite internal reflection element,which could be a powerful platform to study electrocatalytic reactions in strong alkaline media.展开更多
基金Project (20080242009) supported by Basic Research Foundation of Beijing Institute of Technology, China
文摘Removal of Cr（VI） from aqueous solution by strong alkaline anion exchange fiber （SAAEF） was achieved using batch adsorption experiments. The effect of contact time, initial Cr（VI） concentration and pH was investigated. The results showed that the maximum adsorption capacity of SAAEF was 187.7 mg/g at pH=1.0. The adsorption capacity increased with Cr（VI） concentration but decreased with pH value when pH〉1.0. Adsorption isotherms at various temperatures were obtained. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models were adopted and the equilibrium data fitted best with the Langmuir isotherm. The constants of these models indicated that the adsorption process involved both chemisorption and physisorption. The values of thermodynamic parameters, including DH, DG and DS, suggested that the adsorption of Cr（VI） on SAAEF was a spontaneous, entropy-driven and endothermic process. Q（iso） was not a constant value, which indicated an inhomogenous energy distribution on SAAEF.
基金supported by the National Key R&D Program of China(2022YFB4102000,2022YFA1503803 and 2022YFA1505100)National Natural Science Foundation of China(22002088,22272033,22241201 and 52175423)Shanghai Science and Technology Innovation Action Plan(22dz1205500).
文摘Electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy(ATR-SEIRAS)plays an important role in deciphering interfacial reaction mechanisms at molecular level.However,the corrosive etching of Si internal reflection element by OH−largely impedes reliable SEIRAS measurements in strong alkaline electrolytes.Herein,a dense and chemically inert nanocrystalline diamond(NCD)film is successfully fabricated at a thickness of~120 nm through hot filament chemical vapor deposition on a micromachined Si wafer to insulate the OH^(−)etching.A reversible interfacial water feature without spectral interference of Si-O band is obtained in 1.0 mol·L^(–1)KOH on Au/NCD/Si film electrode.Afterwards,electrochemical CO reduction reaction on Cu film electrode is explored in different KOH concentrations ranging from 0.1 to 3.0 mol·L^(-1)as a model reaction.A redshift of CO_(L)band,as well as its lower intensity but faster depletion kinetics,is noted with increasing electrolyte pH,whereas CO_(B)is identified as an inert spectator accumulating on Cu surface.Our present work demonstrates the alkaline resistant feature of diamond/Si composite internal reflection element,which could be a powerful platform to study electrocatalytic reactions in strong alkaline media.
