Based on the determined affinity series of rare earth element complexes with IMDA for the anion-exchangers, purification of macroquantities of Nd 3+ from Y 3+, Sm 3+ from Ho 3+, La 3+ from Nd 3+ and ...Based on the determined affinity series of rare earth element complexes with IMDA for the anion-exchangers, purification of macroquantities of Nd 3+ from Y 3+, Sm 3+ from Ho 3+, La 3+ from Nd 3+ and La 3+ from Pr 3+ on the weakly basic gel anion-exchanger Amberlite IRA-68 was studied. Using the presented method on 1 L of Amberlite IRA-68 in the acetate form, it is possible to obtain about 240 g Nd 2O 3 purified from Y 2O 3. Great difference in affinity of La 3+ and Nd 3+ as well as Pr 3+ complexes for this anion-exchanger in the acetate form indicates the possibility of applying this process for purification of lanthanum on the increased scale. On 1 L of Amberilte IRA-68 in the acetate form it is possible to obtain about 1125 g La 2O 3 purified from Nd 2O 3. On the basis of these results it can be assumed that unique properties of polyacrylate anion-exchangers enable their application for separation of rare earth elements.展开更多
Development of high-performance hydroxide-conductive membranes is a focus research subject owing to promising applications in electrochemical reduction of CO_(2)(eCO_(2)RR).However,few satisfactory membranes have been...Development of high-performance hydroxide-conductive membranes is a focus research subject owing to promising applications in electrochemical reduction of CO_(2)(eCO_(2)RR).However,few satisfactory membranes have been developed to maximize the performance of CO_(2) electrolyzers,despite its role as the core in regulating ion transport and preventing product crossover or fuel loss.Herein,we report the synthesis of alkaline anion-exchange membranes fabricated by poly(vinyl-alcohol)(PVA)and poly[(3-methyl-1-vinylimidazoliummethylsulfate)-co-(1-vinylpyrrolidone)](PQ44)for use in CO_(2) electrolysis.Owing to the unique imidazolium ring structure coupled with a three-dimensional semiinterpenetrating porous internal architecture,the PVA/PQ44-OH-membranes provide a high hydroxide conductivity(21.47 mS cm^(-1)),preferable mechanical property and thermal stability.In particular,the eCO_(2)RR used PVA/PQ44-OH^(-) as electrolyte membrane realized a charming Faradaic efficiency(88%)and partial current density(29 mA cm^(-2))at0.96 VRHE and,delivered the excellent durability over 20 h electrolysis in 0.5 mol L^(-1) KHCO_(3) electrolyte.Notably,it can even enable an ultrahigh current density beyond 100 mA cm^(-2) at^(-1).11 VRHE when the electrolyte was KOH instead,and produced the FEHCOOof 85%at a low potential of0.81 VRHE,superior to both commercial alkaline A201 and acidic Nafion117 membrane.展开更多
Chloromethylated poly(phthalazinone ether sulfone ketone) (CMPPESK) was prepared from poly(phthalazinone ether sulfone ketone) (PPESK) using chloromethyl octyl ethers (CMOE) with lower toxicity as chlorometh...Chloromethylated poly(phthalazinone ether sulfone ketone) (CMPPESK) was prepared from poly(phthalazinone ether sulfone ketone) (PPESK) using chloromethyl octyl ethers (CMOE) with lower toxicity as chloromethylated regent. CMPPESK was soluble in N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc) and chloroform. Quaternized poly(phthalazinone ether sulfone ketone) (QAPPESK) was prepared from CMPPESK by quaternization. QAPPESK had excellent solvent resistance, which was only partly soluble in sulfuric acid (98%) and swollen in N,N-dimethylformamide (DMF). The vanadium redox flow battery (V-RFB) using QAPPESK anion-exchange membrane had better performance with 88.3% of overall energy efficiency.展开更多
A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates (PMS) and petroleum disulfonates (PDS) in crude oil that was simply diluted wi...A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates (PMS) and petroleum disulfonates (PDS) in crude oil that was simply diluted with the dichloromethane/methanol (60/40). The high performance liquid chromatography (HPLC) system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.展开更多
The removal of phosphate from aqueous solution by Donnan dialysis with anion-exchange membrane was investigated.The results show that phosphate could be removed from aqueous solution without supplying external high pr...The removal of phosphate from aqueous solution by Donnan dialysis with anion-exchange membrane was investigated.The results show that phosphate could be removed from aqueous solution without supplying external high pressure or electrical potential.Under the conditions of influent phosphate of 2.0 mg/L,counterion(Cl-)concentration of 0.1 mol/L,stirring speed of 500 r/min and phase temperature of 298 K,the removal of phosphate achieves 70.0%.Decreasing counterion concentration has little influence on the removal of phosphate,but phosphate amount in anion-exchange membrane increases significantly.With the increase of stirring speed and phase temperature,the removal efficiency of phosphate greatly is improved.Existing forms of phosphate in aqueous solution affected transport of phosphate and only strong acidic pH of feed solution(pH=3.0)decreases the removal of phosphate.Transport of phosphate is also accompanied by change of pH value of feed solution.In consequence,it might be a promise potential process for phosphate advanced wastewater treatment,especially in the area where high salted nature water can be utilized.展开更多
A La^3+-Cu/Pt modified electrode was fabricated by electrodepositing process in CuS04 solution by adding a small amount of lanthium compound, and it was employed for direct current (DC) amperometric detection of sp...A La^3+-Cu/Pt modified electrode was fabricated by electrodepositing process in CuS04 solution by adding a small amount of lanthium compound, and it was employed for direct current (DC) amperometric detection of spectinomycin by anion-exchange chromatography. Without derivatization, this method can simultaneously determine the main component and impurities in spectinomycin pharmaceutical raw material. Ease of preparation, being applied in DC detection mode and good catalytic stability confirmed the interests of this modified electrode as amperometric sensor for the determination of spectinomycin.展开更多
Metallothionein (MT) has a great capacity of binding heavy metals showing an interesting connection with metal toxicology, as a biochemical marker for environmental metal pollution. Anino-exchange high per formance li...Metallothionein (MT) has a great capacity of binding heavy metals showing an interesting connection with metal toxicology, as a biochemical marker for environmental metal pollution. Anino-exchange high per formance liquid chromatography (HPLC) was used to isolate and quantitate MT in livers of minks which were contaminated with heavy metals. MT isoforms (MT-I and MT-II) were eluted at approximately 11.3 and 14.3 min respectively from a DEAE-5 PW anion-exchange column with a Tris-HCl buffer (0.01 -0.25 mol/L, pH 8.6) and detected by UV absorbance at 254 nm. The cadmium concentrations in mink liver MT elutkms were determined by graphite furnace atomic absorption spectrometry (GFAAS) . Obvious increase in liver MT-I concentration rather than liver MT-II was found when the minks were contaminated by feeding contaminated fish captured from the heavy metal-polluted river. The cadmium concentration in mink liver MT-I also increased to some extent as the contaminated level increased.展开更多
Silk is made of sericin and fibroin proteins. The sericin constitutes 20%- 30% of silk proteins and it covers the fibmin. Sericin is usually treated as impurity and removed during the process of degumming in dyeing an...Silk is made of sericin and fibroin proteins. The sericin constitutes 20%- 30% of silk proteins and it covers the fibmin. Sericin is usually treated as impurity and removed during the process of degumming in dyeing and printing factories. However, sericin is a useful natural protein. In this paper, viscose auion-exchange fibers have been used to absorb seriein from waste water. The amount of adsorbed sericin into the viscose anion-exchange fibers at different temperatures and times has been studied. The study show that the anion-exchange fibers can adsorb sericin from the waste water. Furthermore, the equilibrium adsorption data show that the adsorption of sericin onto anion-exchange fiber fit the Freundlich isotherm at 25 1C and 50 ℃, and fit the Langmuir isotherm at 75 ℃.展开更多
The use of solid phase spectrophotometry for the determination of trace phosphorus in the system of phosphomolybdate-fructose is described. The adsorption of the system on anion-exchange resin is reported.
A Lactobacillus brevis CGMCC 1306 isolated from fresh milk without pasteurization was found to have higher glutamate decarboxylase (GAD) activity. An effective isolation and purification procedure of GAD from a cell...A Lactobacillus brevis CGMCC 1306 isolated from fresh milk without pasteurization was found to have higher glutamate decarboxylase (GAD) activity. An effective isolation and purification procedure of GAD from a cell-free extract of Lactobacillus brevis was developed, and the procedure included four steps: 30%-90% saturation (NH4)2SO4 fractional precipitation, Q sepharose FF anion-exchange chromatography, sephacryl S-200 gel filtration, and resource Q anion-exchange chromatography. Using this protocol, the purified GAD was demonstrated to possess electrophoretic homogeneity via SDS-PAGE. The purification fold and activity recovery of GAD were 43.78 and 16.95%, respectively. The molecular weight of the purified GAD was estimated to be approximately 62 kDa via SDS-PAGE. The optimum pH and temperature of the purified GAD were 4.4 and 37℃, respectively. The purified GAD had a half-life of 50rain at 45℃ and the Km value of the enzyme from Lineweaver-Burk plot was found to be 8.22.5'-pyridoxal phosphate (PLP) had little effect on the regulation of its activity.展开更多
The process parameters were optimized for the eleetrodeposition of nickel in an electrolytic membrane reactor. Nickel(Ⅱ) and boric acid concentrations, pH and temperature were varied to evaluate the changes in curr...The process parameters were optimized for the eleetrodeposition of nickel in an electrolytic membrane reactor. Nickel(Ⅱ) and boric acid concentrations, pH and temperature were varied to evaluate the changes in current efficiency and specific energy consumption of nickel electrodeposition. The catholyte was aqueous nickel(Ⅱ) sulfate and boric acid, and the anolyte was sulfuric acid solution. An anionic membrane separated the anolyte from the catholyte while maintained a conductive path between the two compartments. The results indicated that the cathode current efficiency increased with the increase of nickel concentration, pH and boric acid concentration, and decreased with the increase of current density and stirring rate. A maximum current efficiency of 97.15% was obtained under the optimized conditions of electrolyte composition of 40 g/L Ni and 40 g/L boric acid at temperature of 42 ℃ and pH of 6 with a cathode current density of 300 A/m2.展开更多
Bismuth-based materials(e.g., metallic, oxides and subcarbonate) are emerged as promising electrocatalysts for converting CO_(2) to formate. However, Bio-based electrocatalysts possess high overpotentials, while bismu...Bismuth-based materials(e.g., metallic, oxides and subcarbonate) are emerged as promising electrocatalysts for converting CO_(2) to formate. However, Bio-based electrocatalysts possess high overpotentials, while bismuth oxides and subcarbonate encounter stability issues. This work is designated to exemplify that the operando synthesis can be an effective means to enhance the stability of electrocatalysts under operando CO_(2)RR conditions. A synthetic approach is developed to electrochemically convert Bi^(O)Cl into Cl-containing subcarbonate(Bi_(2)O_(2)(CO_(3))_(x)Cl_(y)) under operando CO_(2)RR conditions. The systematic operando spectroscopic studies depict that BiOCl is converted to Bi_(2)O_(2)(CO_(3))_(x)Cl_(y) via a cathodic potential-promoted anion-exchange process. The operando synthesizedBi_(2)O_(2)(CO_(3))_(x)Cl_(y) can tolerate-1.0 V versus RHE, while for the wet-chemistry synthesized pure Bi_(2)O_(2)CO_(3),the formation of metallic Bio occurs at-0.6 V versus RHE. At-0.8 V versus RHE, Bi_(2)O_(2)(CO_(3))_(x)Cl_(y) can readily attain a FEHCOO-of 97.9%,much higher than that of the pure Bi_(2)O_(2)CO_(3)(81.3%). DFT calculations indicate that differing from the pure Bi_(2)O_(2)CO_(3)-catalyzed CO_(2)RR, where formate is formed via a *OCHO intermediate step that requires a high energy input energy of 2.69 eV to proceed, the formation of H COO-over Bi_(2)O_(2)(CO_(3))_(x)Cl_(y) has proceeded via a *COOH intermediate step that only requires low energy input of 2.56 eV.展开更多
Removal of zinc from cyanide barren solution is obligatory for its reuse in leach process. Batch experiments were carried out to evaluate the adsorption capacity of resins under different experimental conditions, incl...Removal of zinc from cyanide barren solution is obligatory for its reuse in leach process. Batch experiments were carried out to evaluate the adsorption capacity of resins under different experimental conditions, including con- centration, resin amount, initial pH, contact time and temperature. More than 99% of adsorption was achieved under the optimal condition. High adsorption rates on the resin were observed at the beginning and plateau values were obtained in 60 rain. The thermodynamic parameters (free energy change AG, enthalpy change AS and entropy change AH) for the adsorption were evaluated, The adsorption kinetic mechanism was studied with four models. The experimental results show that the adsorption follows the Langmuir isotherm and the kinetics follows the pseudo-second-order model.展开更多
Recent advancement of proton exchange membrane fuel cells has led to commercial sales of fuel-cell cars but market barrier exists because this technology heavily relies on platinum catalyst.Given the permission of ado...Recent advancement of proton exchange membrane fuel cells has led to commercial sales of fuel-cell cars but market barrier exists because this technology heavily relies on platinum catalyst.Given the permission of adopting platinum-group-metal-free catalysts,anion-exchange membrane fuel cell has received notable attention.However,the sluggish kinetics of anodic hydrogen oxidation reaction(HOR)largely limit the cell efficiency.Although many high-performance HOR catalysts have been reported,there are analytical uncertainties in the literature concerning the assessment of the catalyst activity.Here we determine the origin of false HOR currents in the recorded polarization curves and propose a rigorous approach to eliminate them.We unveil experimentally the uncertainties of obtaining exchange current densities(j0)using Tafel plot from Bulter–Volmer equation and recommend employing the micro-polarization region method.For bulky catalysts that cannot establish a well-defined diffusion layer,we suggest applying external stirring bar to offer certain level of enforced convection and using j0 to compare the activity.展开更多
During our studies on separation of rare earth complexes with aminopolycarboxylic acids on anion-exchangers, it is found that the affinity series of these elements with IMDA (Ln 3+ ∶IMDA=1∶2) for the anion-excha...During our studies on separation of rare earth complexes with aminopolycarboxylic acids on anion-exchangers, it is found that the affinity series of these elements with IMDA (Ln 3+ ∶IMDA=1∶2) for the anion-exchanger Dowex 1 in the acetate and IMDA forms is non-typical: Dy 3+ > Ho 3+ > Gd 3+ >Eu 3+ >Er 3+ >Y 3+ >Sm 3+ >Tm 3+ >Nd 3+ >Pr 3+ >>La 3+ . In the affinity series La 3+ is characterised as the lowest affinity in comparison with other rare earth elements, which indicates possibility of purification of La 3+ from all remaining lanthanides as well as Pr 3+ in the macro-micro systems by the frontal analysis technique. In the investigations strongly basic gel anion-exchangers Dowex 1×8 (type 1) and Dowex 2×8 (type 2) and strongly basic and weakly basic macroporous anion-exchangers Dowex MSA-1 and Dowex MWA 1 were used. Macroporous ion-exchangers have a sponge-like matrix which contains pores larger than molecules in size and the exchange of large ions is faster. The studies indicate that both the gel and macroporous anion-exchangers are useful for purification of La 3+ from Pr 3+ complexes with iminodiacetic acid.展开更多
Decomposition of acetone cyanohydrin is the first-step reaction for preparing (S)-α-cyano-3-phenoxybenzyl alcohol (CPBA) by the one-pot method in organic media. Considering the compatibility of biocatalysts with...Decomposition of acetone cyanohydrin is the first-step reaction for preparing (S)-α-cyano-3-phenoxybenzyl alcohol (CPBA) by the one-pot method in organic media. Considering the compatibility of biocatalysts with chemical catalysts and the successive operation in the bioreactor, anion exchange resin (D301) was used as catalyst for this reaction. External diffusion limitation was excluded by raising rotational speed to higher than 190r·min^-1 in both solvents. Internal diffusion limitation was verified to be insignificant in this reaction system. The effect of acetone cyanohydrin concentration on the reaction was also investigated. An intrinsic kinetic model was proposed when the mass transfer limitation was excluded, and the average deviation of the model is 10.5%.展开更多
Ion-exclusion/anion-exchange chromatography(IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH——form with basic eluent has been developed.The separation mechanism is based on the ion-exclus...Ion-exclusion/anion-exchange chromatography(IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH——form with basic eluent has been developed.The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase.This system is useful for simultaneous separation and determination of ammonium ion(NH+4),nitrite ion(NO-2),and nitrate ion(NO-3) in water samples.The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column.In this study,several separation columns,which consisted of different particle sizes,different functional groups and different anion-exchange capacities,were compared.As the results,the separation column with the smaller anion-exchange capacity(TSKgel Super IC-Anion) showed well-resolved separation of cations and anions.In the optimization of the basic eluent,lithium hydroxide(LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L,considering the resolution of analyte ions and the whole retention times.In the optimal conditions,the relative standard deviations of the peak areas and the retention times of NH+4,NO-2,and NO-3 ranged 1.28%-3.57% and 0.54%-1.55%,respectively.The limits of detection at signal-to-noise of 3 were 4.10 μmol/L for NH+4,1.87 μmol/L for NO-2 and 2.83 μmol/L for NO-3.展开更多
Using nanocrystalline [Mg-Al-CO3] and [Zn-Al-CO3] as precursors, [Mg-Al-PO4], [Zn-Al-PO4], [Mg-Al-P2O7] and [Zn-Al-P2O7] have been successfully synthesized by a direct reaction with the free PO43- or P2O74- using the ...Using nanocrystalline [Mg-Al-CO3] and [Zn-Al-CO3] as precursors, [Mg-Al-PO4], [Zn-Al-PO4], [Mg-Al-P2O7] and [Zn-Al-P2O7] have been successfully synthesized by a direct reaction with the free PO43- or P2O74- using the microwave techniques and the anion-exchange method. And the samples thus obtained were characterized by TEM, FT-IR and XRD. The results show that the initial interlayer carbonate ions can be completely replaced by the free PO43- or P2O74-under controlled microwave conditions employed for a short time.展开更多
The reactor unit for one-stage technology for production of concentrated ethylene glycol-water solutions is described.Such solutions could be useful for production of automotive antifreezes. The technology is based on...The reactor unit for one-stage technology for production of concentrated ethylene glycol-water solutions is described.Such solutions could be useful for production of automotive antifreezes. The technology is based on the highly selective hydration ofethylene oxide in the presence of heterogeneous catalyst-anion-exchange resin in HCO3-/CO/3/2-_form. The mathematical model of reactor allowed evaluating of economical benefit in comparison with conventional method.展开更多
文摘Based on the determined affinity series of rare earth element complexes with IMDA for the anion-exchangers, purification of macroquantities of Nd 3+ from Y 3+, Sm 3+ from Ho 3+, La 3+ from Nd 3+ and La 3+ from Pr 3+ on the weakly basic gel anion-exchanger Amberlite IRA-68 was studied. Using the presented method on 1 L of Amberlite IRA-68 in the acetate form, it is possible to obtain about 240 g Nd 2O 3 purified from Y 2O 3. Great difference in affinity of La 3+ and Nd 3+ as well as Pr 3+ complexes for this anion-exchanger in the acetate form indicates the possibility of applying this process for purification of lanthanum on the increased scale. On 1 L of Amberilte IRA-68 in the acetate form it is possible to obtain about 1125 g La 2O 3 purified from Nd 2O 3. On the basis of these results it can be assumed that unique properties of polyacrylate anion-exchangers enable their application for separation of rare earth elements.
基金support from the“Scientific and Technical Innovation Action Plan”Basic Research Field of Shanghai Science and Technology Committee (19JC1410500)the National Natural Science Foundation of China (21972017).
文摘Development of high-performance hydroxide-conductive membranes is a focus research subject owing to promising applications in electrochemical reduction of CO_(2)(eCO_(2)RR).However,few satisfactory membranes have been developed to maximize the performance of CO_(2) electrolyzers,despite its role as the core in regulating ion transport and preventing product crossover or fuel loss.Herein,we report the synthesis of alkaline anion-exchange membranes fabricated by poly(vinyl-alcohol)(PVA)and poly[(3-methyl-1-vinylimidazoliummethylsulfate)-co-(1-vinylpyrrolidone)](PQ44)for use in CO_(2) electrolysis.Owing to the unique imidazolium ring structure coupled with a three-dimensional semiinterpenetrating porous internal architecture,the PVA/PQ44-OH-membranes provide a high hydroxide conductivity(21.47 mS cm^(-1)),preferable mechanical property and thermal stability.In particular,the eCO_(2)RR used PVA/PQ44-OH^(-) as electrolyte membrane realized a charming Faradaic efficiency(88%)and partial current density(29 mA cm^(-2))at0.96 VRHE and,delivered the excellent durability over 20 h electrolysis in 0.5 mol L^(-1) KHCO_(3) electrolyte.Notably,it can even enable an ultrahigh current density beyond 100 mA cm^(-2) at^(-1).11 VRHE when the electrolyte was KOH instead,and produced the FEHCOOof 85%at a low potential of0.81 VRHE,superior to both commercial alkaline A201 and acidic Nafion117 membrane.
基金partly financed by the Major State Basic Research Development Program of China(No.2003 CB615700)the National Natural Science Foundation of China(No.20604005).
文摘Chloromethylated poly(phthalazinone ether sulfone ketone) (CMPPESK) was prepared from poly(phthalazinone ether sulfone ketone) (PPESK) using chloromethyl octyl ethers (CMOE) with lower toxicity as chloromethylated regent. CMPPESK was soluble in N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc) and chloroform. Quaternized poly(phthalazinone ether sulfone ketone) (QAPPESK) was prepared from CMPPESK by quaternization. QAPPESK had excellent solvent resistance, which was only partly soluble in sulfuric acid (98%) and swollen in N,N-dimethylformamide (DMF). The vanadium redox flow battery (V-RFB) using QAPPESK anion-exchange membrane had better performance with 88.3% of overall energy efficiency.
基金the National Nature Science Foundation of China(No.20675085)the support from the Program of the Light in China's Western Region(2003)the Province Nature Science Foundation of Gansu(No.3ZS041-A25-23).
文摘A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates (PMS) and petroleum disulfonates (PDS) in crude oil that was simply diluted with the dichloromethane/methanol (60/40). The high performance liquid chromatography (HPLC) system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.
基金Project(50778065)supported by the National Natural Science Foundation of China
文摘The removal of phosphate from aqueous solution by Donnan dialysis with anion-exchange membrane was investigated.The results show that phosphate could be removed from aqueous solution without supplying external high pressure or electrical potential.Under the conditions of influent phosphate of 2.0 mg/L,counterion(Cl-)concentration of 0.1 mol/L,stirring speed of 500 r/min and phase temperature of 298 K,the removal of phosphate achieves 70.0%.Decreasing counterion concentration has little influence on the removal of phosphate,but phosphate amount in anion-exchange membrane increases significantly.With the increase of stirring speed and phase temperature,the removal efficiency of phosphate greatly is improved.Existing forms of phosphate in aqueous solution affected transport of phosphate and only strong acidic pH of feed solution(pH=3.0)decreases the removal of phosphate.Transport of phosphate is also accompanied by change of pH value of feed solution.In consequence,it might be a promise potential process for phosphate advanced wastewater treatment,especially in the area where high salted nature water can be utilized.
基金supported by National Natural Science Foundation of China(No.20775070)Zhejiang Provincial Natural Science Foundation of China(No.Y407153)sponsored by Zhejiang Provincial Assay Foundation of China(No.2007F70017)
文摘A La^3+-Cu/Pt modified electrode was fabricated by electrodepositing process in CuS04 solution by adding a small amount of lanthium compound, and it was employed for direct current (DC) amperometric detection of spectinomycin by anion-exchange chromatography. Without derivatization, this method can simultaneously determine the main component and impurities in spectinomycin pharmaceutical raw material. Ease of preparation, being applied in DC detection mode and good catalytic stability confirmed the interests of this modified electrode as amperometric sensor for the determination of spectinomycin.
文摘Metallothionein (MT) has a great capacity of binding heavy metals showing an interesting connection with metal toxicology, as a biochemical marker for environmental metal pollution. Anino-exchange high per formance liquid chromatography (HPLC) was used to isolate and quantitate MT in livers of minks which were contaminated with heavy metals. MT isoforms (MT-I and MT-II) were eluted at approximately 11.3 and 14.3 min respectively from a DEAE-5 PW anion-exchange column with a Tris-HCl buffer (0.01 -0.25 mol/L, pH 8.6) and detected by UV absorbance at 254 nm. The cadmium concentrations in mink liver MT elutkms were determined by graphite furnace atomic absorption spectrometry (GFAAS) . Obvious increase in liver MT-I concentration rather than liver MT-II was found when the minks were contaminated by feeding contaminated fish captured from the heavy metal-polluted river. The cadmium concentration in mink liver MT-I also increased to some extent as the contaminated level increased.
文摘Silk is made of sericin and fibroin proteins. The sericin constitutes 20%- 30% of silk proteins and it covers the fibmin. Sericin is usually treated as impurity and removed during the process of degumming in dyeing and printing factories. However, sericin is a useful natural protein. In this paper, viscose auion-exchange fibers have been used to absorb seriein from waste water. The amount of adsorbed sericin into the viscose anion-exchange fibers at different temperatures and times has been studied. The study show that the anion-exchange fibers can adsorb sericin from the waste water. Furthermore, the equilibrium adsorption data show that the adsorption of sericin onto anion-exchange fiber fit the Freundlich isotherm at 25 1C and 50 ℃, and fit the Langmuir isotherm at 75 ℃.
文摘The use of solid phase spectrophotometry for the determination of trace phosphorus in the system of phosphomolybdate-fructose is described. The adsorption of the system on anion-exchange resin is reported.
基金Supported by the National Natural Science Foundation of China (No.30570411)the Research Plan of Zhejiang Province, China.
文摘A Lactobacillus brevis CGMCC 1306 isolated from fresh milk without pasteurization was found to have higher glutamate decarboxylase (GAD) activity. An effective isolation and purification procedure of GAD from a cell-free extract of Lactobacillus brevis was developed, and the procedure included four steps: 30%-90% saturation (NH4)2SO4 fractional precipitation, Q sepharose FF anion-exchange chromatography, sephacryl S-200 gel filtration, and resource Q anion-exchange chromatography. Using this protocol, the purified GAD was demonstrated to possess electrophoretic homogeneity via SDS-PAGE. The purification fold and activity recovery of GAD were 43.78 and 16.95%, respectively. The molecular weight of the purified GAD was estimated to be approximately 62 kDa via SDS-PAGE. The optimum pH and temperature of the purified GAD were 4.4 and 37℃, respectively. The purified GAD had a half-life of 50rain at 45℃ and the Km value of the enzyme from Lineweaver-Burk plot was found to be 8.22.5'-pyridoxal phosphate (PLP) had little effect on the regulation of its activity.
文摘The process parameters were optimized for the eleetrodeposition of nickel in an electrolytic membrane reactor. Nickel(Ⅱ) and boric acid concentrations, pH and temperature were varied to evaluate the changes in current efficiency and specific energy consumption of nickel electrodeposition. The catholyte was aqueous nickel(Ⅱ) sulfate and boric acid, and the anolyte was sulfuric acid solution. An anionic membrane separated the anolyte from the catholyte while maintained a conductive path between the two compartments. The results indicated that the cathode current efficiency increased with the increase of nickel concentration, pH and boric acid concentration, and decreased with the increase of current density and stirring rate. A maximum current efficiency of 97.15% was obtained under the optimized conditions of electrolyte composition of 40 g/L Ni and 40 g/L boric acid at temperature of 42 ℃ and pH of 6 with a cathode current density of 300 A/m2.
基金financially supported by Australian Research Council Discovery Project(DP200100965)。
文摘Bismuth-based materials(e.g., metallic, oxides and subcarbonate) are emerged as promising electrocatalysts for converting CO_(2) to formate. However, Bio-based electrocatalysts possess high overpotentials, while bismuth oxides and subcarbonate encounter stability issues. This work is designated to exemplify that the operando synthesis can be an effective means to enhance the stability of electrocatalysts under operando CO_(2)RR conditions. A synthetic approach is developed to electrochemically convert Bi^(O)Cl into Cl-containing subcarbonate(Bi_(2)O_(2)(CO_(3))_(x)Cl_(y)) under operando CO_(2)RR conditions. The systematic operando spectroscopic studies depict that BiOCl is converted to Bi_(2)O_(2)(CO_(3))_(x)Cl_(y) via a cathodic potential-promoted anion-exchange process. The operando synthesizedBi_(2)O_(2)(CO_(3))_(x)Cl_(y) can tolerate-1.0 V versus RHE, while for the wet-chemistry synthesized pure Bi_(2)O_(2)CO_(3),the formation of metallic Bio occurs at-0.6 V versus RHE. At-0.8 V versus RHE, Bi_(2)O_(2)(CO_(3))_(x)Cl_(y) can readily attain a FEHCOO-of 97.9%,much higher than that of the pure Bi_(2)O_(2)CO_(3)(81.3%). DFT calculations indicate that differing from the pure Bi_(2)O_(2)CO_(3)-catalyzed CO_(2)RR, where formate is formed via a *OCHO intermediate step that requires a high energy input energy of 2.69 eV to proceed, the formation of H COO-over Bi_(2)O_(2)(CO_(3))_(x)Cl_(y) has proceeded via a *COOH intermediate step that only requires low energy input of 2.56 eV.
基金Supported by Shandong provincial Natural Science Foundation,China(ZR2013EEM005)the High Education Science Technology Program of Shandong Province,China(J12LA04)
文摘Removal of zinc from cyanide barren solution is obligatory for its reuse in leach process. Batch experiments were carried out to evaluate the adsorption capacity of resins under different experimental conditions, including con- centration, resin amount, initial pH, contact time and temperature. More than 99% of adsorption was achieved under the optimal condition. High adsorption rates on the resin were observed at the beginning and plateau values were obtained in 60 rain. The thermodynamic parameters (free energy change AG, enthalpy change AS and entropy change AH) for the adsorption were evaluated, The adsorption kinetic mechanism was studied with four models. The experimental results show that the adsorption follows the Langmuir isotherm and the kinetics follows the pseudo-second-order model.
基金supported by the National Basic Research Program of China(No.2018YFA0702001)the National Natural Science Foundation of China(Nos.22225901,21975237,and 22175162)+3 种基金the Anhui Provincial Research and Development Program(No.202004a05020073)the Fundamental Research Funds for the Central Universities(No.WK2340000101)the USTC Research Funds of the Double First-Class Initiative(No.YD2340002007)the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(No.RERU2022007).
文摘Recent advancement of proton exchange membrane fuel cells has led to commercial sales of fuel-cell cars but market barrier exists because this technology heavily relies on platinum catalyst.Given the permission of adopting platinum-group-metal-free catalysts,anion-exchange membrane fuel cell has received notable attention.However,the sluggish kinetics of anodic hydrogen oxidation reaction(HOR)largely limit the cell efficiency.Although many high-performance HOR catalysts have been reported,there are analytical uncertainties in the literature concerning the assessment of the catalyst activity.Here we determine the origin of false HOR currents in the recorded polarization curves and propose a rigorous approach to eliminate them.We unveil experimentally the uncertainties of obtaining exchange current densities(j0)using Tafel plot from Bulter–Volmer equation and recommend employing the micro-polarization region method.For bulky catalysts that cannot establish a well-defined diffusion layer,we suggest applying external stirring bar to offer certain level of enforced convection and using j0 to compare the activity.
文摘During our studies on separation of rare earth complexes with aminopolycarboxylic acids on anion-exchangers, it is found that the affinity series of these elements with IMDA (Ln 3+ ∶IMDA=1∶2) for the anion-exchanger Dowex 1 in the acetate and IMDA forms is non-typical: Dy 3+ > Ho 3+ > Gd 3+ >Eu 3+ >Er 3+ >Y 3+ >Sm 3+ >Tm 3+ >Nd 3+ >Pr 3+ >>La 3+ . In the affinity series La 3+ is characterised as the lowest affinity in comparison with other rare earth elements, which indicates possibility of purification of La 3+ from all remaining lanthanides as well as Pr 3+ in the macro-micro systems by the frontal analysis technique. In the investigations strongly basic gel anion-exchangers Dowex 1×8 (type 1) and Dowex 2×8 (type 2) and strongly basic and weakly basic macroporous anion-exchangers Dowex MSA-1 and Dowex MWA 1 were used. Macroporous ion-exchangers have a sponge-like matrix which contains pores larger than molecules in size and the exchange of large ions is faster. The studies indicate that both the gel and macroporous anion-exchangers are useful for purification of La 3+ from Pr 3+ complexes with iminodiacetic acid.
基金Supported by the National Natural Science Foundation of China(No.29876037)and the Natural Science Foundation ofZhejiang Province(No.296068)
文摘Decomposition of acetone cyanohydrin is the first-step reaction for preparing (S)-α-cyano-3-phenoxybenzyl alcohol (CPBA) by the one-pot method in organic media. Considering the compatibility of biocatalysts with chemical catalysts and the successive operation in the bioreactor, anion exchange resin (D301) was used as catalyst for this reaction. External diffusion limitation was excluded by raising rotational speed to higher than 190r·min^-1 in both solvents. Internal diffusion limitation was verified to be insignificant in this reaction system. The effect of acetone cyanohydrin concentration on the reaction was also investigated. An intrinsic kinetic model was proposed when the mass transfer limitation was excluded, and the average deviation of the model is 10.5%.
基金supported by Grant-in-Aid for Scientific Research(23615003)in Japan Society for the Promotion of Science(JSPS)
文摘Ion-exclusion/anion-exchange chromatography(IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH——form with basic eluent has been developed.The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase.This system is useful for simultaneous separation and determination of ammonium ion(NH+4),nitrite ion(NO-2),and nitrate ion(NO-3) in water samples.The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column.In this study,several separation columns,which consisted of different particle sizes,different functional groups and different anion-exchange capacities,were compared.As the results,the separation column with the smaller anion-exchange capacity(TSKgel Super IC-Anion) showed well-resolved separation of cations and anions.In the optimization of the basic eluent,lithium hydroxide(LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L,considering the resolution of analyte ions and the whole retention times.In the optimal conditions,the relative standard deviations of the peak areas and the retention times of NH+4,NO-2,and NO-3 ranged 1.28%-3.57% and 0.54%-1.55%,respectively.The limits of detection at signal-to-noise of 3 were 4.10 μmol/L for NH+4,1.87 μmol/L for NO-2 and 2.83 μmol/L for NO-3.
文摘Using nanocrystalline [Mg-Al-CO3] and [Zn-Al-CO3] as precursors, [Mg-Al-PO4], [Zn-Al-PO4], [Mg-Al-P2O7] and [Zn-Al-P2O7] have been successfully synthesized by a direct reaction with the free PO43- or P2O74- using the microwave techniques and the anion-exchange method. And the samples thus obtained were characterized by TEM, FT-IR and XRD. The results show that the initial interlayer carbonate ions can be completely replaced by the free PO43- or P2O74-under controlled microwave conditions employed for a short time.
文摘The reactor unit for one-stage technology for production of concentrated ethylene glycol-water solutions is described.Such solutions could be useful for production of automotive antifreezes. The technology is based on the highly selective hydration ofethylene oxide in the presence of heterogeneous catalyst-anion-exchange resin in HCO3-/CO/3/2-_form. The mathematical model of reactor allowed evaluating of economical benefit in comparison with conventional method.