Ce (Ⅳ) nitrato complexes were adsorbed on two anion exchangers based on polyvinyl pyridine (PVP) and quatemized PVP incorporated into porous silica matrix. The effect of nitric acid concentration (0.5~6 mol...Ce (Ⅳ) nitrato complexes were adsorbed on two anion exchangers based on polyvinyl pyridine (PVP) and quatemized PVP incorporated into porous silica matrix. The effect of nitric acid concentration (0.5~6 mol·L^-1) and temperature (278 ~318 K) on Ce( Ⅳ ) sorption efficiency was investigated. Sorption increased with increasing nitric acid concentration, indicating that [Ce(NO3)6]^2- complex is the main adsorbed Ce(Ⅳ) species. Oxidation of sorbents by adsorbed Ce ( Ⅳ ) species resulting in Ce ( Ⅲ ) release to the solution was observed. Pyridine based anion exchangers exhibited higher oxidation stability compared to the commercial strong base anion exchanger. Ce( Ⅳ ) reduction was temperature dependent and obeyed pseudo-first-order reaction kinetics. Column separation of Ce ( Ⅳ ) from La ( Ⅲ ) and Y ( Ⅲ ) was carried out from 6 mol·L^-1 nitric acid with PVP based anion exchanger. Reasonable Ce (Ⅳ) breakthrough capacity (0.7 mol·kg^-1 PVP) was achieved. No remarkable decrease of capacity was observed within 3 consequent runs. In contrast, Ce (Ⅲ) leakage due to reduction decreased and breakthrough capacity slightly increased. This effect was more pronounced with increasing temperature. Regeneration with 0.1 mol·L^- 1 nitric acid was successful (recovery 100% ± 4% ) and Ce solution of high purity ( 〉 99.97% ) with respect to La and Y content was gained.展开更多
The use of polar organic solvents for the separations of rare earth elements (Ⅲ) is effective especially for their extensive separations despite the solubility limitations. The study shows that polyacrylate anion exc...The use of polar organic solvents for the separations of rare earth elements (Ⅲ) is effective especially for their extensive separations despite the solubility limitations. The study shows that polyacrylate anion exchangers, particularly the weakly basic, gel anion exchanger Amberlite IRA 68, can be applied to the separation of rare earth complexes with EDTA in H_2O-methanol and H_2O-ethanol systems. In most cases the determined distribution coefficients of Ln^(3+) complexes with EDTA in mixed media like water-methanol on polyacrylate anion exchangers are larger than those in pure water (media.)展开更多
In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterpart...In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.展开更多
In this work,the structure,viscosity and ion-exchange process of Na_(2)O-MgO-Al_(2)O_(3)-SiO_(2) glasses with different Al_(2)O_(3)/SiO_(2) molar ratios were investigated.The results showed that,with increasing Al_(2)...In this work,the structure,viscosity and ion-exchange process of Na_(2)O-MgO-Al_(2)O_(3)-SiO_(2) glasses with different Al_(2)O_(3)/SiO_(2) molar ratios were investigated.The results showed that,with increasing Al_(2)O_(3)/SiO_(2) ratio,the simple structural units Q_(1) and Q_(2) transformed into highly aggregated structural units Q_(3) and Q_(4),indicating the increase of polymerization degree of glass network.Meanwhile,the coefficient of thermal expansion decreased from 9.23×10^(-6)℃^(-1) to 8.88×10^(-6)℃^(-1).The characteristic temperatures such as melting,forming,softening and glass transition temperatures increased with the increase of Al_(2)O_(3)/SiO_(2) ratio,while the glasses working temperature range became narrow.The increasing Al_(2)O_(3)/SiO_(2) ratio and prolonging ion-exchange time enhanced the surface compressive stress(CS)and depth of stress layer(DOL).However,the increase of ion exchange temperature increased the DOL and decreased the CS affected by stress relaxation.There was a good linear relationship between stress relaxation and surface compressive stress.Chemical strengthening significantly improved the hardness of glasses,which reached the maximum value of(622.1±10)MPa for sample with Al_(2)O_(3)/SiO_(2) ratio of 0.27 after heat treated at 410℃for 2 h.展开更多
Heterogeneous membranes were obtained by using styrene-acrylonitrile copolymer(SAN)blends with low content of ion-exchanger particles(5 wt.%). The membranes obtained by phase inversion were used for the removal of...Heterogeneous membranes were obtained by using styrene-acrylonitrile copolymer(SAN)blends with low content of ion-exchanger particles(5 wt.%). The membranes obtained by phase inversion were used for the removal of copper ions from synthetic wastewater solutions by electrodialytic separation. The electrodialysis was conducted in a three cell unit, without electrolyte recirculation. The process, under potentiostatic or galvanostatic control, was followed by p H and conductivity measurements in the solution. The electrodialytic performance,evaluated in terms of extraction removal degree(rd) of copper ions, was better under potentiostatic control then by the galvanostatic one and the highest(over 70%) was attained at8 V. The membrane efficiency at small ion-exchanger load was explained by the migration of resin particles toward the pores surface during the phase inversion. The prepared membranes were characterized by various techniques i.e. optical microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis and differential thermal analysis and contact angle measurements.展开更多
A novel series of halogen free, hydroxyl group containing poly(ionic liquid)s(PILs) was first synthesized from glycerol dimethyl acrylate(GDA) and 1-vinyl imidazole(1-VIM) through free radical polymerization, follow b...A novel series of halogen free, hydroxyl group containing poly(ionic liquid)s(PILs) was first synthesized from glycerol dimethyl acrylate(GDA) and 1-vinyl imidazole(1-VIM) through free radical polymerization, follow by an alkylation step and an ion-exchange procedure to form the final imidazolium hydrogen carbonate heterogenous catalyst poly(HCO_(3)-OH-n). The chemical and physical properties were investigated by varying the monomer ratio between GDA and 1-VIM. Among them, poly(HCO_(3)-OH-2) exhibited the highest catalytic activity for CO_(2)cycloaddition, with the yield of chloropropene carbonate 90% under mild conditions(80℃, 0.1 MPa, 12 h, 0.15 g catalyst for 32 mmol epichlorohydrin) in the absence of any cocatalyst, metal or solvent. A range of substrates with good to excellent yields under atmosphere was obtained. The poly(HCO_(3)-OH-n) catalyst is collectable and still remains acceptable catalytic activity after six runs. Finally, a preliminary kinetic is calculated on the basis of poly(HCO_(3)-OH-2) with the activation energy value of 79.5 kJ·mol^(-1). This study highlights that the poly(HCO_(3)-OH-n) enable to reach efficient CO_(2) conversion under mild conditions.展开更多
Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electrochemical activity and Coulombic efficiency.The annealing temperature of the Na precursors was important to control th...Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electrochemical activity and Coulombic efficiency.The annealing temperature of the Na precursors was important to control the P3-P2 phase transition,which directly affected the structure and electrochemical characteristics of the final products obtained by ion exchange.The O3-Li_(0.78)[Li_(0.25)Fe_(0.075)Mn_(0.675)]O_(δ) cathode made from a P3-type precursor calcined at 700℃ was analyzed using X-ray photoelectron spectrometry and electron paramagnetic resonance.The results showed that the presence of abundant trivalent manganese and defects resulted in a discharge capacity of 230 mAh/g with an initial Coulombic efficiency of about 109%.Afterward,galvanostatic intermittent titration was performed to examine the Li^(+) ion diffusion coefficients,which affected the reversible capacity.First principles calculations suggested that the charge redistribution induced by oxygen vacancies(OV_(s))greatly affected the local Mn coordination environment and enhanced the structural activity.Moreover,the Li-deficient cathode was a perfect match for the pre-lithiation anode,providing a novel approach to improve the initial Coulombic efficiency and activity of Mn-based materials in the commercial application.展开更多
A nickel hexacyanoferrate(NiHCF)film electrode was prepared with NiHCF,conductive carbon black,and polyvinylidene difluoride,which was coated on graphite plate substrate for selective extraction of Cs^(+)ions by using...A nickel hexacyanoferrate(NiHCF)film electrode was prepared with NiHCF,conductive carbon black,and polyvinylidene difluoride,which was coated on graphite plate substrate for selective extraction of Cs^(+)ions by using electrochemically switched ion exchange(ESIX)technology.A potential-responsive ionpump system for efficient extraction of Cs+ions was designed,and the effect of wet film thicknesses,charging modes,flow rates,and chamber widths on Cs+ions extraction performance was investigated.In the system,the adsorption capacity and removal percentage of Cs^(+)ions on the NiHCF film electrode reached as high as 147.69 mg·g^(-1)and 92.47%,respectively.Furthermore,the NiHCF film electrode showed high selectivity for Cs^(+)ions and stability.After seven cycles of adsorption/desorption,the desorption percentage could reach about 100%.The excellent Cs^(+)extraction performance should be attributed to the strong driving force produced by the potential-responsive ion-pumping effect in the ESIX process,as well as the low ion transfer resistance of the film electrode which is caused by the special crystal structure of NiHCF.In addition,the NiHCF film electrode was implemented to work together with the bismuth oxybromide(BiOBr)film electrode to accomplish the simultaneous extraction of Cs^(+)and Br^(-).And the adsorption capacity and removal percentage of Br^(-)ions on the BiOBr film electrode reached 69.53 mg·g^(-1)and 77.32%,correspondingly.It is expected that such a potential-responsive ion-pump system based on NiHCF and BiOBr film electrodes could be used for the selective extraction and concentration of Cs^(+)and Br^(-)ions from salt lake brine.展开更多
CO_(2) electroreduction(CO_(2) ER)to high value-added chemicals is considered as a promising technology to achieve sustainable carbon neutralization.By virtue of the progressive research in recent years aiming at desi...CO_(2) electroreduction(CO_(2) ER)to high value-added chemicals is considered as a promising technology to achieve sustainable carbon neutralization.By virtue of the progressive research in recent years aiming at design and understanding of catalytic materials and electrolyte systems,the CO_(2) ER performance(such as current density,selectivity,stability,CO_(2) conversion,etc.)has been continually increased.Unfortunately,there has been relatively little attention paid to the large-scale CO 2 electrolyzers,which stand just as one obstacle,alongside series-parallel integration,challenging the practical application of this infant technology.In this review,the latest progress on the structures of low-temperature CO_(2) electrolyzers and scale-up studies was systematically overviewed.The influence of the CO_(2) electrolyzer configurations,such as the flow channel design,gas diffusion electrode(GDE)and ion exchange membrane(IEM),on the CO_(2) ER performance was further discussed.The review could provide inspiration for the design of large-scale CO_(2) electrolyzers so as to accelerate the industrial application of CO_(2) ER technology.展开更多
The effciency of sodium hydroxide treated rubber (Hevea brasiliensis) leaves powder (NHBL) for removing copper ions from aqueous solutions has been investigated. The e?ects of physicochemical parameters on biosorption...The effciency of sodium hydroxide treated rubber (Hevea brasiliensis) leaves powder (NHBL) for removing copper ions from aqueous solutions has been investigated. The e?ects of physicochemical parameters on biosorption capacities such as stirring speed, pH, biosorbent dose, initial concentrations of copper, and ionic strength were studied. The biosorption capacities of NHBL increased with increase in pH, stirring speed and copper concentration but decreased with increase in biosorbent dose and ionic strength. The isotherm study indicated that NHBL fitted well with Langmuir model compared to Freundlich and Dubinin-Radushkevich models. The maximum biosorption capacity determined from Langmuir isotherm was 14.97 mg/g at 27°C. The kinetic study revealed that pseudo- second order model fitted well the kinetic data, while Boyd kinetic model indicated that film diffusion was the main rate determining step in biosorption process. Based on surface area analysis, NHBL has low surface area and categorized as macroporous. Fourier transform infrared (FT-IR) analyses revealed that hydroxyl, carboxyl, and amino are the main functional groups involved in the binding of copper ions. Complexation was one of the main mechanisms for the removal of copper ions as indicated by FT-IR spectra. Ion exchange was another possible mechanism since the ratio of adsorbed cations (Cu2+ and H+) to the released cations (Na+, Ca2+, and Mg2+) from NHBL was almost unity. Copper ions bound on NHBL were able to be desorbed at > 99% using 0.05 mol/L HCl, 0.01 mol/L HNO3, and 0.01 mol/L EDTA solutions.展开更多
The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initia...The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, adsorbent dosage and different initial concentration of Pb(II) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non–linear Langmuir isotherm for chitosan, chitosan-GLA and chitosan-alginate beads in single metal system were 34.98, 14.24 and 60.27 mg/g, respectively. However, the adsorption capacity of Pb(II) ions were reduced in the binary metal system due to the competitive adsorption between Pb(II) and Cu(II) ions. Based on the ion exchange study, the release of Ca2+, Mg2+, K+ and Na+ ions played an important role in the adsorption of Pb(II) ions by all three adsorbents but only at lower concentrations of Pb(II) ions. Infrared spectra showed that the binding between Pb(II) ions and the adsorbents involved mostly the nitrogen and oxygen atoms. All three adsorbents showed satisfactory adsorption capacities and can be considered as an efficient adsorbent for the removal of Pb(II) ions from aqueous solutions.展开更多
An alkaline precipitation method was introduced to produce hydrous cerium oxides.The prepared powder was characterized by Brunauer-Emmett-Teller(BET) nitrogen adsorption-desorption,X-ray diffraction(XRD),Fourier t...An alkaline precipitation method was introduced to produce hydrous cerium oxides.The prepared powder was characterized by Brunauer-Emmett-Teller(BET) nitrogen adsorption-desorption,X-ray diffraction(XRD),Fourier transform infrared(FTIR) spectrometry,and thermal gravimetry(TG) approaches.The adsorbent has a chemical formula of CeO2·nH2O(n 2) and a cubic fluorite-type structure after high temperature treatment.Adsorption capacity of different temperature treated hydrous cerium oxides does not directly correlate with BET specific surface area.Phosphate adsorption isotherms follow the Langmuir equation below the treatment temperature of 800°C.Phosphate adsorption causes no change on the structure of a hydrous cerium oxides,and no signs of CePO4 precipitates are found.The ion-exchanging structure of hydrous cerium oxide plays a fundamental role in phosphate adsorption.The structure is highly temperature resistant and forms adsorption sites which adsorb both water and some anions.Complete loss of adsorption ability cannot be achieved unless the treatment temperature is higher than 1200°C.Mechanism study shows that the adsorption of phosphates is mainly an anion-exchange process.展开更多
In this paper, humic acid (HA) was ultra-filtered into different molecular weight sections and was characterized by multielement analysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric. Since hum...In this paper, humic acid (HA) was ultra-filtered into different molecular weight sections and was characterized by multielement analysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric. Since humic acids of different molecular weights have different hydrophilic and molecular size, the maximum adsorption capacity of basic ion exchange resins appears on the humic acid whose molecular weight ranges from 6000 to 10,000 Da.展开更多
A novel open-framework ecomaterial silicotitanate (Na_4Ti_4Si_3O_(10)) wassynthesized by a combination of solgel and hydrothermal methods. The investigation on ion exchangeproperties shows that Na_4Ti_4Si_3O_(10) exhi...A novel open-framework ecomaterial silicotitanate (Na_4Ti_4Si_3O_(10)) wassynthesized by a combination of solgel and hydrothermal methods. The investigation on ion exchangeproperties shows that Na_4Ti_4Si_3O_(10) exhibits high ad-sorption for cesium, i.e., K_d is as highas 60 000 mL/g in neutral solution. The crystal structure of Na_4Ti_4Si_3O_(10) was characterized byX-ray difiraction (XRD), scanning electronic microscope (SEM), transmission electron microscope(TEM), Raman spectrum, differential thermal and thermogravimetric analysis (DTA/TGA), inductivelycoupled plasma (ICP), and X fluorescence analysis. The compound is tetragonal, P4_2, a=b = 0.781 10nm, c = 1.196 45 nm, alpha =beta = gamma = 90 deg, Z = 4, and R^a = 0.041; Na_4Ti_4Si_3O_(10) has athree dimensional framework consisting of Ti-O octahedral clusters and Si-O tetrahedra. The resultsshow that Na_4Ti_4Si_3O_(10) has good chemical stability, thermal stability, and high cesium ionexchange capacity in the whole pH range.展开更多
A promising catalyst, KNaY was prepared by an ion exchange method with aqueous potassium chloride solution, Compared with NaY, KNaY was an effective catalyst for the dehydration of methyl lactate to methyl acrylate. U...A promising catalyst, KNaY was prepared by an ion exchange method with aqueous potassium chloride solution, Compared with NaY, KNaY was an effective catalyst for the dehydration of methyl lactate to methyl acrylate. Under the optimized conditions, an improved yield of 37.9 mol% was achieved.展开更多
There are numerous impurities in wet-process phosphoric acid,among which manganese is one of detrimental metallic impurities,and it causes striking negative effects on the industrial phosphoric acid production and dow...There are numerous impurities in wet-process phosphoric acid,among which manganese is one of detrimental metallic impurities,and it causes striking negative effects on the industrial phosphoric acid production and downstream commodity.This article investigated the adsorption behavior of manganese from phosphoric acid employing Sinco-430 cationic ion-exchange resin.Resorting FT-IR and XPS characterizations,the adsorption mechanism was proved to be that manganese was combined with sulfonic acid group.Several crucial parameters such as temperature,phosphoric acid content and resin dose were studied to optimize adsorption efficiency.Through optimization,removal percentage and sorption capacity of manganese reached 53.12 wt%,28.34 mg·g^-1,respectively.Pseudo-2nd-order kinetic model simulated kinetics data best and the activation energy was evaluated as 6.34 kJ·mol^-1 for the sorption reaction of manganese.In addition,the global adsorption rate was first controlled by film diffusion process and second determined by pore diffusion process.It was found that the resin could adsorb up to 50.24 mg·g^-1 for manganese.Equilibrium studies showed that Toth adsorption isotherm model fitted best,followed by Temkin and Langmuir adsorption isotherm models.Thermodynamic analysis showed that manganese adsorption was an endothermic process with enhanced randomness and spontaneity.展开更多
Artificial molecular chaperone (AMC) and ion exchange chromatography (IEC) were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography (AMC-IEC) was developed. Compar...Artificial molecular chaperone (AMC) and ion exchange chromatography (IEC) were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography (AMC-IEC) was developed. Compared with AMC and IEC, the activity recovery of lysozyme obtained by AMC-IEC was much higher in the investigated range of initial protein concentrations, and the results show that AMC-IEC is very efficient for protein refolding at high concentrations. When the initial concentration of lysozyme is 180 mg/mL, its activity recovery obtained by AMC-IEC is still as high as 76.6%, while the activity recoveries obtained by AMC and IEC are 45.6% and 42.4%, respectively.展开更多
EAB zeolite was successfully prepared and applied to selective adsorption of Li^(+),Na^(+)and K^(+)ions.The physical and chemical properties of the adsorbent were characterized by X-ray diffraction(XRD),X-ray fluoresc...EAB zeolite was successfully prepared and applied to selective adsorption of Li^(+),Na^(+)and K^(+)ions.The physical and chemical properties of the adsorbent were characterized by X-ray diffraction(XRD),X-ray fluorescence(XRF),scanning electron microscope(SEM)and thermogravimetry(TG)methods.The ion exchange behaviours for Li^(+),Na^(+)and K^(+)ions in monomcomponent and multicomponent solutions were studied.In independent ion exchange,the ion exchange capacities ratiosα(/Na/Li)andα(K/Li)were 3.8 and 6.2,respectively.In competitive ion exchange,the selectivitiesβ(Na/Li)andβ(K/Li)increased with the initial concentrations and reached 409 and 992 when the initial concentrations was 100 mmol/L.The thermodynamic study results showed that Gibbs free energy change(ΔGΘ)of ion exchange reaction between Li-EAB and K^(+)was-34.96 kJ/mol,indicating that ion exchange of K^(+)ions was more energetically favourable than Li^(+)ions.The calculation results showed that the energy barriers of ion exchange increased in the order K^(+)Na^(+)<Li^(+).The study shows that EAB zeolite is potential to be used in the separation of alkali ions.展开更多
The aim of the study was to taste mask ciprofloxacin(CP)by using ion-exchange resins(IERs)followed by sustain release of CP by forming interpenetrating polymer network(IPN).IERs based on the copolymerization of acryli...The aim of the study was to taste mask ciprofloxacin(CP)by using ion-exchange resins(IERs)followed by sustain release of CP by forming interpenetrating polymer network(IPN).IERs based on the copolymerization of acrylic acid with different cross linking agents were synthesised.Drug-resin complexes(DRCs)with three different ratios of drug to IERs(1:1,1:2,1:4)were prepared&evaluated for taste masking by following in vivo and in vitro methods.Human volunteers graded ADC 1:4,acrylic acid-divinyl benzene(ADC-3)resin as tasteless.Characterization studies such as FTIR,SEM,DSC,P-XRD differentiated ADC 1:4,from physical mixture(PM 1:4)and confirmed the formation of complex.In vitro drug release of ADC 1:4 showed complete release of CP within 60 min at simulated gastric fluid(SGF)i.e.pH 1.2.IPN beads were prepared with ADC 1:4 by using sodium alginate(AL)and sodium alginate-chitosan(AL-CS)for sustain release of CP at SGF pH and followed by simulated intestinal fluid(SIF i.e.pH 7.4).FTIR spectra confirmed the formation of IPN beads.The release of CP was sustain at SGF pH(<20%)whereas in SIF media it was more(>75%).The kinetic model of IPN beads showed the release of CP was non-Fickian diffusion type.展开更多
Mineral sulphide (MS)-lime (CaO) ion exchange reactions (MS + CaO = MO + CaS) and the effect of CaO/C mole ratio during carbothermic reduction (MS + CaO + C = M + CaS + CO(g)) were investigated for com...Mineral sulphide (MS)-lime (CaO) ion exchange reactions (MS + CaO = MO + CaS) and the effect of CaO/C mole ratio during carbothermic reduction (MS + CaO + C = M + CaS + CO(g)) were investigated for complex froth flotation mineral sulphide concentrates. Phases in the partially and fully reacted samples were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The primary phases during mineral sulphide-lime ion exchange reactions are Fe304, CaSO4 Cu2S, and CaS. A complex liquid phase of Ca2CuFeO3S forms during mineral sulphide-lime exchange reactions above 1173 K. The formation mechanisms of Ca2CuFeO3S liquid phase are determined by characterising the partially reacted samples. The reduction rate and extent of mineral sulphides in the presence of CaO and C increase with the increase in CaO/C ratio. The metallic phases are surrounded by the CaS rich phase at CaO/C 〉 1, but the metallic phases and CaS are found as separate phases at CaO/C 〈 1. Experimental results show that the stoichiometric ratio of carbon should be slightly higher than that of CaO. The reactions between CaO and gangue minerals (SiO2 and A1203) are only observed at CaO/C 〉 1 and the reacted samples are excessively sintered.展开更多
基金Project supported bythe Japan Societyfor the Promotion of Science (JSPS)
文摘Ce (Ⅳ) nitrato complexes were adsorbed on two anion exchangers based on polyvinyl pyridine (PVP) and quatemized PVP incorporated into porous silica matrix. The effect of nitric acid concentration (0.5~6 mol·L^-1) and temperature (278 ~318 K) on Ce( Ⅳ ) sorption efficiency was investigated. Sorption increased with increasing nitric acid concentration, indicating that [Ce(NO3)6]^2- complex is the main adsorbed Ce(Ⅳ) species. Oxidation of sorbents by adsorbed Ce ( Ⅳ ) species resulting in Ce ( Ⅲ ) release to the solution was observed. Pyridine based anion exchangers exhibited higher oxidation stability compared to the commercial strong base anion exchanger. Ce( Ⅳ ) reduction was temperature dependent and obeyed pseudo-first-order reaction kinetics. Column separation of Ce ( Ⅳ ) from La ( Ⅲ ) and Y ( Ⅲ ) was carried out from 6 mol·L^-1 nitric acid with PVP based anion exchanger. Reasonable Ce (Ⅳ) breakthrough capacity (0.7 mol·kg^-1 PVP) was achieved. No remarkable decrease of capacity was observed within 3 consequent runs. In contrast, Ce (Ⅲ) leakage due to reduction decreased and breakthrough capacity slightly increased. This effect was more pronounced with increasing temperature. Regeneration with 0.1 mol·L^- 1 nitric acid was successful (recovery 100% ± 4% ) and Ce solution of high purity ( 〉 99.97% ) with respect to La and Y content was gained.
文摘The use of polar organic solvents for the separations of rare earth elements (Ⅲ) is effective especially for their extensive separations despite the solubility limitations. The study shows that polyacrylate anion exchangers, particularly the weakly basic, gel anion exchanger Amberlite IRA 68, can be applied to the separation of rare earth complexes with EDTA in H_2O-methanol and H_2O-ethanol systems. In most cases the determined distribution coefficients of Ln^(3+) complexes with EDTA in mixed media like water-methanol on polyacrylate anion exchangers are larger than those in pure water (media.)
基金supported by the Teli Fellowship from Beijing Institute of Technology,the National Natural Science Foundation of China(Nos.52303366,22173109).
文摘In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.
基金Funded by National Natural Science Foundation of China(Nos.52172019 and 52072148)Shandong Provincial Youth Innovation Team Development Plan of Colleges and Universities(No.2022K1100)。
文摘In this work,the structure,viscosity and ion-exchange process of Na_(2)O-MgO-Al_(2)O_(3)-SiO_(2) glasses with different Al_(2)O_(3)/SiO_(2) molar ratios were investigated.The results showed that,with increasing Al_(2)O_(3)/SiO_(2) ratio,the simple structural units Q_(1) and Q_(2) transformed into highly aggregated structural units Q_(3) and Q_(4),indicating the increase of polymerization degree of glass network.Meanwhile,the coefficient of thermal expansion decreased from 9.23×10^(-6)℃^(-1) to 8.88×10^(-6)℃^(-1).The characteristic temperatures such as melting,forming,softening and glass transition temperatures increased with the increase of Al_(2)O_(3)/SiO_(2) ratio,while the glasses working temperature range became narrow.The increasing Al_(2)O_(3)/SiO_(2) ratio and prolonging ion-exchange time enhanced the surface compressive stress(CS)and depth of stress layer(DOL).However,the increase of ion exchange temperature increased the DOL and decreased the CS affected by stress relaxation.There was a good linear relationship between stress relaxation and surface compressive stress.Chemical strengthening significantly improved the hardness of glasses,which reached the maximum value of(622.1±10)MPa for sample with Al_(2)O_(3)/SiO_(2) ratio of 0.27 after heat treated at 410℃for 2 h.
文摘Heterogeneous membranes were obtained by using styrene-acrylonitrile copolymer(SAN)blends with low content of ion-exchanger particles(5 wt.%). The membranes obtained by phase inversion were used for the removal of copper ions from synthetic wastewater solutions by electrodialytic separation. The electrodialysis was conducted in a three cell unit, without electrolyte recirculation. The process, under potentiostatic or galvanostatic control, was followed by p H and conductivity measurements in the solution. The electrodialytic performance,evaluated in terms of extraction removal degree(rd) of copper ions, was better under potentiostatic control then by the galvanostatic one and the highest(over 70%) was attained at8 V. The membrane efficiency at small ion-exchanger load was explained by the migration of resin particles toward the pores surface during the phase inversion. The prepared membranes were characterized by various techniques i.e. optical microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis and differential thermal analysis and contact angle measurements.
基金supported by the National Natural Science Foundation of China (21776122, 21676134, 21878141 and 21576129)Natural Science Foundation of Jiangsu Province (BM2018007, BK20210185)。
文摘A novel series of halogen free, hydroxyl group containing poly(ionic liquid)s(PILs) was first synthesized from glycerol dimethyl acrylate(GDA) and 1-vinyl imidazole(1-VIM) through free radical polymerization, follow by an alkylation step and an ion-exchange procedure to form the final imidazolium hydrogen carbonate heterogenous catalyst poly(HCO_(3)-OH-n). The chemical and physical properties were investigated by varying the monomer ratio between GDA and 1-VIM. Among them, poly(HCO_(3)-OH-2) exhibited the highest catalytic activity for CO_(2)cycloaddition, with the yield of chloropropene carbonate 90% under mild conditions(80℃, 0.1 MPa, 12 h, 0.15 g catalyst for 32 mmol epichlorohydrin) in the absence of any cocatalyst, metal or solvent. A range of substrates with good to excellent yields under atmosphere was obtained. The poly(HCO_(3)-OH-n) catalyst is collectable and still remains acceptable catalytic activity after six runs. Finally, a preliminary kinetic is calculated on the basis of poly(HCO_(3)-OH-2) with the activation energy value of 79.5 kJ·mol^(-1). This study highlights that the poly(HCO_(3)-OH-n) enable to reach efficient CO_(2) conversion under mild conditions.
基金The Beijing Municipal Education Commission(KZ201910005003)supported this work。
文摘Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electrochemical activity and Coulombic efficiency.The annealing temperature of the Na precursors was important to control the P3-P2 phase transition,which directly affected the structure and electrochemical characteristics of the final products obtained by ion exchange.The O3-Li_(0.78)[Li_(0.25)Fe_(0.075)Mn_(0.675)]O_(δ) cathode made from a P3-type precursor calcined at 700℃ was analyzed using X-ray photoelectron spectrometry and electron paramagnetic resonance.The results showed that the presence of abundant trivalent manganese and defects resulted in a discharge capacity of 230 mAh/g with an initial Coulombic efficiency of about 109%.Afterward,galvanostatic intermittent titration was performed to examine the Li^(+) ion diffusion coefficients,which affected the reversible capacity.First principles calculations suggested that the charge redistribution induced by oxygen vacancies(OV_(s))greatly affected the local Mn coordination environment and enhanced the structural activity.Moreover,the Li-deficient cathode was a perfect match for the pre-lithiation anode,providing a novel approach to improve the initial Coulombic efficiency and activity of Mn-based materials in the commercial application.
基金supported by the National Natural Science Foundation of China(22108188,U21A20303,U20A20141)CAS Project for Young Scientists in Basic Research(YSBR-039)。
文摘A nickel hexacyanoferrate(NiHCF)film electrode was prepared with NiHCF,conductive carbon black,and polyvinylidene difluoride,which was coated on graphite plate substrate for selective extraction of Cs^(+)ions by using electrochemically switched ion exchange(ESIX)technology.A potential-responsive ionpump system for efficient extraction of Cs+ions was designed,and the effect of wet film thicknesses,charging modes,flow rates,and chamber widths on Cs+ions extraction performance was investigated.In the system,the adsorption capacity and removal percentage of Cs^(+)ions on the NiHCF film electrode reached as high as 147.69 mg·g^(-1)and 92.47%,respectively.Furthermore,the NiHCF film electrode showed high selectivity for Cs^(+)ions and stability.After seven cycles of adsorption/desorption,the desorption percentage could reach about 100%.The excellent Cs^(+)extraction performance should be attributed to the strong driving force produced by the potential-responsive ion-pumping effect in the ESIX process,as well as the low ion transfer resistance of the film electrode which is caused by the special crystal structure of NiHCF.In addition,the NiHCF film electrode was implemented to work together with the bismuth oxybromide(BiOBr)film electrode to accomplish the simultaneous extraction of Cs^(+)and Br^(-).And the adsorption capacity and removal percentage of Br^(-)ions on the BiOBr film electrode reached 69.53 mg·g^(-1)and 77.32%,correspondingly.It is expected that such a potential-responsive ion-pump system based on NiHCF and BiOBr film electrodes could be used for the selective extraction and concentration of Cs^(+)and Br^(-)ions from salt lake brine.
基金supported by National Key R&D Program of China(2020YFA0710200)the National Natural Science Foundation of China(21838010,22122814)+2 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2018064)State Key Laboratory of Multiphase complex systems,Institute of Process Engineering,Chinese Academy of Sciences(No.MPCS-2022-A-03)Innovation Academy for Green Manufacture Institute,Chinese Academy of Science(IAGM2020C14).
文摘CO_(2) electroreduction(CO_(2) ER)to high value-added chemicals is considered as a promising technology to achieve sustainable carbon neutralization.By virtue of the progressive research in recent years aiming at design and understanding of catalytic materials and electrolyte systems,the CO_(2) ER performance(such as current density,selectivity,stability,CO_(2) conversion,etc.)has been continually increased.Unfortunately,there has been relatively little attention paid to the large-scale CO 2 electrolyzers,which stand just as one obstacle,alongside series-parallel integration,challenging the practical application of this infant technology.In this review,the latest progress on the structures of low-temperature CO_(2) electrolyzers and scale-up studies was systematically overviewed.The influence of the CO_(2) electrolyzer configurations,such as the flow channel design,gas diffusion electrode(GDE)and ion exchange membrane(IEM),on the CO_(2) ER performance was further discussed.The review could provide inspiration for the design of large-scale CO_(2) electrolyzers so as to accelerate the industrial application of CO_(2) ER technology.
基金Universiti Sains Malaysia for the financial support under Short Term Research Grant(Grant No.304/PKIMIA/638056)
文摘The effciency of sodium hydroxide treated rubber (Hevea brasiliensis) leaves powder (NHBL) for removing copper ions from aqueous solutions has been investigated. The e?ects of physicochemical parameters on biosorption capacities such as stirring speed, pH, biosorbent dose, initial concentrations of copper, and ionic strength were studied. The biosorption capacities of NHBL increased with increase in pH, stirring speed and copper concentration but decreased with increase in biosorbent dose and ionic strength. The isotherm study indicated that NHBL fitted well with Langmuir model compared to Freundlich and Dubinin-Radushkevich models. The maximum biosorption capacity determined from Langmuir isotherm was 14.97 mg/g at 27°C. The kinetic study revealed that pseudo- second order model fitted well the kinetic data, while Boyd kinetic model indicated that film diffusion was the main rate determining step in biosorption process. Based on surface area analysis, NHBL has low surface area and categorized as macroporous. Fourier transform infrared (FT-IR) analyses revealed that hydroxyl, carboxyl, and amino are the main functional groups involved in the binding of copper ions. Complexation was one of the main mechanisms for the removal of copper ions as indicated by FT-IR spectra. Ion exchange was another possible mechanism since the ratio of adsorbed cations (Cu2+ and H+) to the released cations (Na+, Ca2+, and Mg2+) from NHBL was almost unity. Copper ions bound on NHBL were able to be desorbed at > 99% using 0.05 mol/L HCl, 0.01 mol/L HNO3, and 0.01 mol/L EDTA solutions.
基金the financial support under the Short Term Grant (No.304/PKIMIA/636065)
文摘The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, adsorbent dosage and different initial concentration of Pb(II) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non–linear Langmuir isotherm for chitosan, chitosan-GLA and chitosan-alginate beads in single metal system were 34.98, 14.24 and 60.27 mg/g, respectively. However, the adsorption capacity of Pb(II) ions were reduced in the binary metal system due to the competitive adsorption between Pb(II) and Cu(II) ions. Based on the ion exchange study, the release of Ca2+, Mg2+, K+ and Na+ ions played an important role in the adsorption of Pb(II) ions by all three adsorbents but only at lower concentrations of Pb(II) ions. Infrared spectra showed that the binding between Pb(II) ions and the adsorbents involved mostly the nitrogen and oxygen atoms. All three adsorbents showed satisfactory adsorption capacities and can be considered as an efficient adsorbent for the removal of Pb(II) ions from aqueous solutions.
基金support from the National Natural Science Foundation of China (No.20876157)
文摘An alkaline precipitation method was introduced to produce hydrous cerium oxides.The prepared powder was characterized by Brunauer-Emmett-Teller(BET) nitrogen adsorption-desorption,X-ray diffraction(XRD),Fourier transform infrared(FTIR) spectrometry,and thermal gravimetry(TG) approaches.The adsorbent has a chemical formula of CeO2·nH2O(n 2) and a cubic fluorite-type structure after high temperature treatment.Adsorption capacity of different temperature treated hydrous cerium oxides does not directly correlate with BET specific surface area.Phosphate adsorption isotherms follow the Langmuir equation below the treatment temperature of 800°C.Phosphate adsorption causes no change on the structure of a hydrous cerium oxides,and no signs of CePO4 precipitates are found.The ion-exchanging structure of hydrous cerium oxide plays a fundamental role in phosphate adsorption.The structure is highly temperature resistant and forms adsorption sites which adsorb both water and some anions.Complete loss of adsorption ability cannot be achieved unless the treatment temperature is higher than 1200°C.Mechanism study shows that the adsorption of phosphates is mainly an anion-exchange process.
基金support provided by the National Nature Science Fund(No.50778088)China National Funds for Distinguished Young Scientists(No.50825802)Resources Special Subject of National High Technology Research & Development Project(863 project,No.2006AA06Z383),China.
文摘In this paper, humic acid (HA) was ultra-filtered into different molecular weight sections and was characterized by multielement analysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric. Since humic acids of different molecular weights have different hydrophilic and molecular size, the maximum adsorption capacity of basic ion exchange resins appears on the humic acid whose molecular weight ranges from 6000 to 10,000 Da.
基金This work was financially supported by the Foundation for the Author of National Excellent Doctor Dissertation of China.
文摘A novel open-framework ecomaterial silicotitanate (Na_4Ti_4Si_3O_(10)) wassynthesized by a combination of solgel and hydrothermal methods. The investigation on ion exchangeproperties shows that Na_4Ti_4Si_3O_(10) exhibits high ad-sorption for cesium, i.e., K_d is as highas 60 000 mL/g in neutral solution. The crystal structure of Na_4Ti_4Si_3O_(10) was characterized byX-ray difiraction (XRD), scanning electronic microscope (SEM), transmission electron microscope(TEM), Raman spectrum, differential thermal and thermogravimetric analysis (DTA/TGA), inductivelycoupled plasma (ICP), and X fluorescence analysis. The compound is tetragonal, P4_2, a=b = 0.781 10nm, c = 1.196 45 nm, alpha =beta = gamma = 90 deg, Z = 4, and R^a = 0.041; Na_4Ti_4Si_3O_(10) has athree dimensional framework consisting of Ti-O octahedral clusters and Si-O tetrahedra. The resultsshow that Na_4Ti_4Si_3O_(10) has good chemical stability, thermal stability, and high cesium ionexchange capacity in the whole pH range.
文摘A promising catalyst, KNaY was prepared by an ion exchange method with aqueous potassium chloride solution, Compared with NaY, KNaY was an effective catalyst for the dehydration of methyl lactate to methyl acrylate. Under the optimized conditions, an improved yield of 37.9 mol% was achieved.
文摘There are numerous impurities in wet-process phosphoric acid,among which manganese is one of detrimental metallic impurities,and it causes striking negative effects on the industrial phosphoric acid production and downstream commodity.This article investigated the adsorption behavior of manganese from phosphoric acid employing Sinco-430 cationic ion-exchange resin.Resorting FT-IR and XPS characterizations,the adsorption mechanism was proved to be that manganese was combined with sulfonic acid group.Several crucial parameters such as temperature,phosphoric acid content and resin dose were studied to optimize adsorption efficiency.Through optimization,removal percentage and sorption capacity of manganese reached 53.12 wt%,28.34 mg·g^-1,respectively.Pseudo-2nd-order kinetic model simulated kinetics data best and the activation energy was evaluated as 6.34 kJ·mol^-1 for the sorption reaction of manganese.In addition,the global adsorption rate was first controlled by film diffusion process and second determined by pore diffusion process.It was found that the resin could adsorb up to 50.24 mg·g^-1 for manganese.Equilibrium studies showed that Toth adsorption isotherm model fitted best,followed by Temkin and Langmuir adsorption isotherm models.Thermodynamic analysis showed that manganese adsorption was an endothermic process with enhanced randomness and spontaneity.
基金the National Natural Science Foundation in China(No.20705028)the Foundation of Key Laboratory of Modem Separation Science in Shaanxi Province(No.05JS61).
文摘Artificial molecular chaperone (AMC) and ion exchange chromatography (IEC) were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography (AMC-IEC) was developed. Compared with AMC and IEC, the activity recovery of lysozyme obtained by AMC-IEC was much higher in the investigated range of initial protein concentrations, and the results show that AMC-IEC is very efficient for protein refolding at high concentrations. When the initial concentration of lysozyme is 180 mg/mL, its activity recovery obtained by AMC-IEC is still as high as 76.6%, while the activity recoveries obtained by AMC and IEC are 45.6% and 42.4%, respectively.
文摘EAB zeolite was successfully prepared and applied to selective adsorption of Li^(+),Na^(+)and K^(+)ions.The physical and chemical properties of the adsorbent were characterized by X-ray diffraction(XRD),X-ray fluorescence(XRF),scanning electron microscope(SEM)and thermogravimetry(TG)methods.The ion exchange behaviours for Li^(+),Na^(+)and K^(+)ions in monomcomponent and multicomponent solutions were studied.In independent ion exchange,the ion exchange capacities ratiosα(/Na/Li)andα(K/Li)were 3.8 and 6.2,respectively.In competitive ion exchange,the selectivitiesβ(Na/Li)andβ(K/Li)increased with the initial concentrations and reached 409 and 992 when the initial concentrations was 100 mmol/L.The thermodynamic study results showed that Gibbs free energy change(ΔGΘ)of ion exchange reaction between Li-EAB and K^(+)was-34.96 kJ/mol,indicating that ion exchange of K^(+)ions was more energetically favourable than Li^(+)ions.The calculation results showed that the energy barriers of ion exchange increased in the order K^(+)Na^(+)<Li^(+).The study shows that EAB zeolite is potential to be used in the separation of alkali ions.
文摘The aim of the study was to taste mask ciprofloxacin(CP)by using ion-exchange resins(IERs)followed by sustain release of CP by forming interpenetrating polymer network(IPN).IERs based on the copolymerization of acrylic acid with different cross linking agents were synthesised.Drug-resin complexes(DRCs)with three different ratios of drug to IERs(1:1,1:2,1:4)were prepared&evaluated for taste masking by following in vivo and in vitro methods.Human volunteers graded ADC 1:4,acrylic acid-divinyl benzene(ADC-3)resin as tasteless.Characterization studies such as FTIR,SEM,DSC,P-XRD differentiated ADC 1:4,from physical mixture(PM 1:4)and confirmed the formation of complex.In vitro drug release of ADC 1:4 showed complete release of CP within 60 min at simulated gastric fluid(SGF)i.e.pH 1.2.IPN beads were prepared with ADC 1:4 by using sodium alginate(AL)and sodium alginate-chitosan(AL-CS)for sustain release of CP at SGF pH and followed by simulated intestinal fluid(SIF i.e.pH 7.4).FTIR spectra confirmed the formation of IPN beads.The release of CP was sustain at SGF pH(<20%)whereas in SIF media it was more(>75%).The kinetic model of IPN beads showed the release of CP was non-Fickian diffusion type.
基金the financial support by the Copperbelt University in Zambia and the Institute of Materials,Minerals and Mining(IOM~3)
文摘Mineral sulphide (MS)-lime (CaO) ion exchange reactions (MS + CaO = MO + CaS) and the effect of CaO/C mole ratio during carbothermic reduction (MS + CaO + C = M + CaS + CO(g)) were investigated for complex froth flotation mineral sulphide concentrates. Phases in the partially and fully reacted samples were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The primary phases during mineral sulphide-lime ion exchange reactions are Fe304, CaSO4 Cu2S, and CaS. A complex liquid phase of Ca2CuFeO3S forms during mineral sulphide-lime exchange reactions above 1173 K. The formation mechanisms of Ca2CuFeO3S liquid phase are determined by characterising the partially reacted samples. The reduction rate and extent of mineral sulphides in the presence of CaO and C increase with the increase in CaO/C ratio. The metallic phases are surrounded by the CaS rich phase at CaO/C 〉 1, but the metallic phases and CaS are found as separate phases at CaO/C 〈 1. Experimental results show that the stoichiometric ratio of carbon should be slightly higher than that of CaO. The reactions between CaO and gangue minerals (SiO2 and A1203) are only observed at CaO/C 〉 1 and the reacted samples are excessively sintered.