The conventional rare earth solvent extraction equipments have many problems such as long mixing time, low processing capacity, large factory area occupation, high energy consumption and so on. In order to solve the p...The conventional rare earth solvent extraction equipments have many problems such as long mixing time, low processing capacity, large factory area occupation, high energy consumption and so on. In order to solve the problems, many types of equipments were brought out. In this work, studies were carried out on the La(III) extraction process with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA) by membrane dispersion micro-extractor. Equilibrium studies showed that the initial aqueous pH value 4.15 with the saponification rate 40%was the optimal operation condition. The effects of membrane dispersion micro-extractor operational conditions such as dispersion mode, bulk flow rate and organic phase flow rate on the extraction efficiency were studied. The results showed that when the organic solution was the dispersed phase, the extraction efficiency was higher than that of others. Increasing bulk flow ratio could enhance the extraction efficiency greatly. When the ratio of organic phase flow rate to that of aque-ous phase was 80:80, the extraction efficiency was over 95%. The effect of stripping phase acidity on the La(III) recovery was studied. The results showed that when the stripping phase pH was 2.0, organic phase flow rate to stripping phase flow rate was 20:80;the re-covery efficiency of La(III) can reach 82%.展开更多
The extraction of low concentration rare earth elements at high phase ratio was investigated. The traditional extraction set-up, such as mixer-settler, have drawbacks of easy emulsification, difficult separation and l...The extraction of low concentration rare earth elements at high phase ratio was investigated. The traditional extraction set-up, such as mixer-settler, have drawbacks of easy emulsification, difficult separation and low efficiency if operated at the above condition. Membrane dispersion micro-extractor,owing to its well-dispersed, high surface-to-volume ratio and fast mass transfer rate, was employed in our work. Nd(Ⅲ),Eu(Ⅲ),Er(Ⅲ) were chosen to represent light, medium,heavy rare earth elements(REEs). The extraction process of REEs with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(P507) was investigated by membrane dispersion micro-extractors. Firstly, the extraction equilibrium of these three elements was explored in the stirred conical flasks, and it is indicated that the extraction efficiencies can be 0.95, 0.97 and 0.98, respectively within 40 min at phase ratio of 100:1. Then the effects of operational conditions such as the residence time, organic and aqueous flow rates on extraction efficiency were also explored in micro-extractors. The results indicate that the efficiency decreases and then increases if increasing aqueous phase flow rate, residence time and droplets' diameter are the key factors of this process. Increasing the phase ratio reduces the extraction efficiency significantly. When the REEs solution has an initial pH of 4.00, the flow rates of continuous and dispersed phase are 40 and 1.6 mL/min,respectively, and 90 mg/L Nd(Ⅲ), Eu(Ⅲ) and Er(Ⅲ) is extracted by 1 mol/L P507 at the out-let length of8 m. The extraction efficiencies are 0.978,0.983 and 0.991, respectively. Finally the stripping process was also studied with the micro-extractor. The stripping efficiencies of Nd(Ⅲ), Eu(Ⅲ) and Er(Ⅲ) can reach0.99, 0.96 and 0.91, respectively when the out-let length is 8 m and the concentration of hydrochloric acid is 1 mol/L. The developed approach offers a novel and simple strategy on the fast extraction and enrichment of low concentration rare earth elements from waste water.展开更多
By using membrane dispersion micro-extractor, Ce(IIl) solvent extraction experiments were conducted. Cerium chloride solution with certain acidity was used as aqueous phase and 2-ethylhexyl phosphoric acid-2-ethylhe...By using membrane dispersion micro-extractor, Ce(IIl) solvent extraction experiments were conducted. Cerium chloride solution with certain acidity was used as aqueous phase and 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA) kerosene solution as organic phase. The effects of system physicochemical properties and operational conditions, such as initial EHEHPA concentration, initial aqueous acidity, total flow rate and continuous phase flow rate, etc., on the extraction efficiency and the overall volume mass transfer coefficient were evaluated. As the total flow rate increased fi'om 20 to 160 mL/min, the overall volume mass transfer coefficient was enhanced from 0.1 to 0.54 S1. Under the optimal conditions, the Ce(III) extraction efficiency could reach 99.92% in 2.98 s. A mathematical model was set up to predict the overall volume mass transfer coefficient, and the calculation results agreed well with the experimental results, most relative error was within +10%.展开更多
The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(...The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb(III) and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on the transport of Tb(III) have also been investigated, respectively. As a result, the optimum transport conditions of Tb(III) were obtained, i.e., the concentration of HCl solution was 4.0 mol/L, the concentration of D2EHPA was 0.16 mol/L, the volume ratio of membrane solution to stripping solution was 30:30 in the dispersion phase and pH value was 4.5 in the feed phase. Ionic strength had no obvious effect on the transport of Tb(III). Under the optimum conditions, the transport percentage of Tb(III) was up to 96.1% in a transport time of 35 min when the initial concentration of Tb(IIl) was 1.0× 10 -4 mol/L. The diffusion coefficient of Tb(III) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.82×10 -8 m2/s and 5.61 um, respectively. The calculated results were in good agreement with the literature data.展开更多
The transport of Dy(III) through a dispersion supported liquid membrane (DSLM) consisting of polyvinylidene fluoride membrane (PVDF) as the liquid membrane support and dispersion solution including HCI solution ...The transport of Dy(III) through a dispersion supported liquid membrane (DSLM) consisting of polyvinylidene fluoride membrane (PVDF) as the liquid membrane support and dispersion solution including HCI solution as the stripping solution and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (PC-88A) dissolved in kerosene as the membrane solution, was studied. The effects of pH value, initial concentration of Dy(III) and different ionic strength in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on transport of Dy(III) were also investigated, respectively. As a result, when the concentration of HCI solution was 4.0 mol/L, concentration of PC-88A was 0.10 mol/L, and volume ratio of membrane solution and stripping solution was 40:20 in the dispersion phase, and pH value was 5.0 in the feed phase, the transport effect of Dy(III) was the best. Ionic strength had no obvious effect on transport of Dy(III). Under the optimum condition studied, when initial concentration of Dy(III) was 0.8×10^-4 mol/L, the transport rate of Dy(III) was up to 96.2% during the transport time of 95 rain. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The diffusion coefficient of Dy(III) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.99×10^-7 m^2/s and 15.97 μm, respectively. The results were in good agreement with experimental results.展开更多
Three dimensional (3D) flower-like basic zinc carbonate constructed by multilayered nanoplates were rapidly prepared at room temperature through the direct precipitation method coupled with membrane dispersion technol...Three dimensional (3D) flower-like basic zinc carbonate constructed by multilayered nanoplates were rapidly prepared at room temperature through the direct precipitation method coupled with membrane dispersion technology, and porous ZnO with similar structures could be obtained after calcining the precursor. The structural properties of the products before and after the calcining process were characterized by SEM, TEM and XRD.The supersaturation of the reaction system due to the membrane dispersion played an important role in the formation of uniform Zn_5(CO_3)_2(OH)_6 precursors. A plausible mechanism was proposed for the formation of the flower-like ZnO assembled by nanoplates composed of nanoparticles. The obtained ZnO microspheres showed excellent photocatalytic properties, which could be attributed to the open structure and remarkable amount of porous nanoplates.展开更多
The transport of La(III) through a dispersion supported liquid membrane with polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and...The transport of La(III) through a dispersion supported liquid membrane with polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in kerosene as the membrane solution, was studied. As a result, the optimum transport conditions of La(Ⅲ) were obtained as that concentration of HCl solution was 4.0 mol/L, concentration of PC-88A 0.16 mol/L, and volume ratio of membrane to stripping solution 30:30 in the dispersion phase, and pH value 4.0 in the feed phase. Ionic strength had no obvious effect on the transport of La(Ⅲ). Under the optimum conditions, when initial concentration of La(Ⅲ) was 0.8×10-4 mol/L, the transport rate was up to 96.3% during the transport time of 125 min. The kinetic equation was developed based on the law of mass diffusion and theory of interface chemistry. The diffusion coefficient of La(Ⅲ) in the membrane and the thickness of diffusion layer between feed and membrane phases were obtained as 3.20×10-7 m2/s and 3.22×10-5 m, respectively. The calculated results were in good agreement with experimental results.展开更多
Mild stir-assisted membrane dispersion extraction(MDE) method was employed to enhance propionic acid(HA)extraction and compared to the mechanical stirred extraction(MSE) method. Triocylamine(TOA) and tributyl phosphat...Mild stir-assisted membrane dispersion extraction(MDE) method was employed to enhance propionic acid(HA)extraction and compared to the mechanical stirred extraction(MSE) method. Triocylamine(TOA) and tributyl phosphate(TBP) were chosen as model extractant to extract HA. Firstly, droplet size and the size distribution of organic phase were analyzed, and then the effects of phase ratio, extractant and HA concentration on extraction performance were investigated. Comparing the two extraction methods, the results show mild stir-assisted MDE method reduced the mass transfer equilibrium time compared to MSE method. The mass transfer mechanism was explored by analyzing mass transfer resistance. Mild stir-assisted MDE had less total mass transfer resistance than MSE. When the extractant concentration was 40%, the extraction process was controlled by organic phase mass transfer process with HA volume fraction was 1% and controlled by both of reaction process and organic phase mass transfer process when HA concentration increased to 5%. This work may provide a new type of extraction method for the recovery of organic carboxylic acid.展开更多
Treatment to crystallization mother liquor containing high concentration of organic and inorganic substances is a challenge in zero liquid discharge of industrial wastewater.Acid precipitation coupled membrane-dispers...Treatment to crystallization mother liquor containing high concentration of organic and inorganic substances is a challenge in zero liquid discharge of industrial wastewater.Acid precipitation coupled membrane-dispersion advanced oxidation process(MAOP)was proposed for organics degradation before salt crystallization by evaporation.With acid-MAOP treatment CODCrin mother liquor of pulping wastewater was eliminated by 55.2%from ultrahigh initial concentration up to 12,500 mg·L^-1.The decolorization rate was 96.5%.Recovered salt was mainly NaCl(83.3 wt%)having whiteness 50 brighter than industrial baysalt of whiteness 45.The oxidation conditions were optimized as CO3=0.11 g·L^-1 and CH2O2=2.0 g·L^-1 with dispersing rate 0.53 ml·min^-1 for 100 min reaction toward acidified liquor of p H=2.Acidification has notably improved evaporation efficiency during crystallization.Addition of H2O2 made through membrane dispersion has eliminated hydroxyl radical"quench effect"and enhanced the degradation capacity,in particular,the breakage of carbon-chloride bonds(of both aliphatic and aromatic).As a result,the proposed coupling method has improved organic pollutant reduction so as the purity of salt from the wastewater mixture which can facilitate water and salt recycling in industry.展开更多
A non-dispersive extraction technique, using an emulsion liquid membrane within a hollow-fiber-contactor for the extraction and enrichment of Nd^3+ from the dilute feed aqueous, was applied. The emulsion system is co...A non-dispersive extraction technique, using an emulsion liquid membrane within a hollow-fiber-contactor for the extraction and enrichment of Nd^3+ from the dilute feed aqueous, was applied. The emulsion system is consisted of span80 [ sorbitian monooleate], paraffin oil, D2EHPA [ 2-( 2-ethylhexyl- phosphonic acid)], kerosene as well as HCl solution. The extraction under various conditions such as the span80 concentrations, the flow rate of aqueous, the extraction time and HCl concentrations in receiving phase were studied. Results show that the lower the flow rates of aqueous are, the higher the extraction percentage and enrichment-fold are, and the extraction percentage increases with the increasing of HCl concentrations. When the initial Nd^3+ concentration in feed is maintained at 1000 mg· L^-1 and the emulsion is recycled with 70 times by a counter-flow,展开更多
A functional hybrid nano-hydroxyapatite(carboxymethyl cellulose-phytic acid-n-HA,CMC-PA-n-HA)was prepared by adding CMC and PA.The results of Fourier transformation infrared spectra,X-ray diffraction,thermal gravimetr...A functional hybrid nano-hydroxyapatite(carboxymethyl cellulose-phytic acid-n-HA,CMC-PA-n-HA)was prepared by adding CMC and PA.The results of Fourier transformation infrared spectra,X-ray diffraction,thermal gravimetric analysis and dispersion experiments indicated that the addition of CMC and PA affected the morphology,crystallinity and crystal size of hybrid n-HA,and CMC endowed hybrid n-HA with excellent dispersion.Scanning electron microscope results showed that CMC-PA-n-HA nanoparticle could be uniformly dispersed in chitosan(CS)matrix to obtain composite membrane by casting technology,so that the highest tensile strength of CMC-PA-n-HA/CS composite membrane was 69.64%and 144.45%higher than that of CS membrane and n-HA/CS composite membrane,respectively.Contact angle test showed that CMC-PA-n-HA effectively improved hydrophilicity of the CS membrane.The simulated body fluid immersion results indicated that the CMC-PA-n-HA/CS composite membrane not only exhibited good degradability but also promoted bone-like apatite deposition.The cell proliferation experiments proved that the introduction of PA made the composite membrane have better cell adhesion and proliferation ability.Antibacterial tests demonstrated that PA could effectively improve the antibacterial properties of the composite membrane,which is expected to be applied as guide bone tissue regeneration membrane.展开更多
Effective protection against X-ray is the premise of utilizing the X-ray,thus it is critical to develop novel X-ray shielding materials with both low density and high X-ray attenuation efficiency.As the even distribut...Effective protection against X-ray is the premise of utilizing the X-ray,thus it is critical to develop novel X-ray shielding materials with both low density and high X-ray attenuation efficiency.As the even distribution of high-Z element components is of great significance for increasing the attenuation efficiency of X-ray shielding materials,in this study,the microfiber membrane(MFM),a type of synthetic leather featuring hierarchical structure was chosen to provide large surface area for the dispersion of rare earth(RE)element.Meanwhile,plant polyphenol was utilized to achieve the stable loading and uniform dispersion of the Ce or Er into MFM.Benefiting from the assistance of polyphenol and hierarchical structure of MFM,the even dispersion of RE element was successfully realized.The resultant shielding materials displayed approximately 10%superior X-ray attenuation efficiency compared to that without polyphenol,and an averagely 9%increment in X-ray attenuation efficiency than that without hierarchical structure.Moreover,the obtained composite with a thickness of 2.8 mm displayed superior X-ray shielding performance compared to 0.25 mm lead sheet in 16-83 keV and retained an ultralow density of 1.4 g cm^(-3).Our research results would shed new light on the manufacture of high-performance X-ray shielding materials with excellent X-ray shielding performance.展开更多
The Eu(III) separation in supported dispersion liquid membrane (SDLM), with polyvinylidene fluoride membrane (PVDF) as the support and dispersion solution containing HNO3 solution as the stripping solution and D...The Eu(III) separation in supported dispersion liquid membrane (SDLM), with polyvinylidene fluoride membrane (PVDF) as the support and dispersion solution containing HNO3 solution as the stripping solution and Di(2-ethylhexyl) phosphoric acid (D2EHPA) dis- solved in kerosene as the membrane solution, was studied. The effects ofpH value, initial concentration of Eu(III) and different ionic strengths in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HNO3 solution, concentration of carrier, different stripping agents in the dispersion phase on the separation of Eu(III) were also investigated, respectively. As a result, the optimum separation conditions of Eu(III) were obtained as the concentration of HNO3 solution was 4.00 mol/L, concentration of D2EHPA was 0.160 mol/L, and volume ratio of membrane solution to stripping solution was 30:30 in the dispersion phase, and pH value was 5.00 in the feed phase. Ionic strength had no obvious effect on the separation of Eu(III). Under the optimum conditions studied, when initial concentration of Eu(III) was 1.00× 10^-4 mol/L, the separation rate of Eu(III) was up to 94.2% during the separation period of 35 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The results were in good agreement with the literature data.展开更多
A mathematical model for the transport of Ce (IV) from hydrochloric acid solutions through dispersion flat combined liquid membrane (DFCLM) with contain 2- ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (P...A mathematical model for the transport of Ce (IV) from hydrochloric acid solutions through dispersion flat combined liquid membrane (DFCLM) with contain 2- ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (P507) as the carrier, dissolved in kerosene as the membrane solution have been studied. This process of facilitated transport, based on membrane technology, is a variation on the conventional technique of solvent extraction and may be described mathematically using Fick's second law. The equations for transport velocity are derived considering the diffusion of P507 and its metallic complexes through the liquid membrane. In this work, the system is considered to be in a transient state, and chemical reaction between Ce(IV) and the carrier to take place only at the solvent-aqueous interfaces. Model concentration profiles are obtained for the Ce(IV), from which extraction velocities are predicted. The experimental and simulated Ce(IV) extractions showed similar tendencies for a high Ce (IV) concentration and acidity case.The model results indicate that high initial Ce(IV) concentrations and acidity both have detrimental effects on Ce(IV) extraction and stripping. The diffusion coefficient of Ce(IV) in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and the values are 6.31 × 10-8m2·s-1 and 31.2 μm, respectively. The results are in good agreement with experimental results.展开更多
The separation of Sm(III) through stripping dispersion hollow fiber liquid membrane system (SDHFLM) containing feed phase adding acetate buffer solution and dispersion solution with HC1 solution as the stripping s...The separation of Sm(III) through stripping dispersion hollow fiber liquid membrane system (SDHFLM) containing feed phase adding acetate buffer solution and dispersion solution with HC1 solution as the stripping solution and membrane solution of di(2-ethylhexyl) phosphoric acid (p204) dissolved in kerosene, has been studied. A set of factors were studied, including pH value, initial concentration of Sm(III) and different ionic strength of feed phase, volume ratio of membrane solution and stripping solution (O/W), HC1 concentration, carrier concentration, different stripping agents of dispersion phase on Sm(III) separation. Experimental results indicate that the optimum separa- tion conditions of Sm(III) were obtained as that HC1 concentration was 4.00 tool/L, p204 concentration was 0.150 mol/L, and volume ratio of membrane solution and stripping solution (O/W) was 1.00 in the dispersion phase, and pH value was 4.60 in the feed phase. Ionic strength had no obvious effect on separation of Sm(III). When initial Sm(III) concentration was 1.00 × 10^-4 mol/L, the separation rate of Sm(III) was up to 93.5% in 85 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The modeled results were in good agreement with the experiment data.展开更多
In this paper,we present a new method for preparing γ-alumina nanoparticles with a bimodal pore size distribution by using an efficiently mixing membrane dispersion microreactor.NH4HCO3and AI2(SO4)3.18H2Owere reacted...In this paper,we present a new method for preparing γ-alumina nanoparticles with a bimodal pore size distribution by using an efficiently mixing membrane dispersion microreactor.NH4HCO3and AI2(SO4)3.18H2Owere reacted under vigorous mixing to give an ammonium aluminum carbonate hydroxide (AACH)precursor.γ-Alumina was obtained by calcination of AACH at 550℃ for 6h.The effects of NH4HCO3concentration,pH during aging,and reaction temperature were investigated.The mechanism of bimodal pore formation was clarified.The results showed that large pores (10-100nm) were mainly formed in the reactor and during aging,and small pores (0-10nm)were mainly formed during calcination.When the concentration of NH4HCO3was 1.5mol/L,the aging pH was 9.2,and the reaction temperature was 80℃,γ-alumina with a specific surface area of 504.7m^2/g and pore volume of 1.76mL/g was obtained.The average size of the large pores was about 30nm,and the average size of the small pores was about 4nm.展开更多
Stripping dispersion hollow fiber liquid membrane system(SDHFLM) containing feed phase adding acetate buffer solution and dispersion solution with HNO_3 solution as the stripping solution and membrane solution of 2-...Stripping dispersion hollow fiber liquid membrane system(SDHFLM) containing feed phase adding acetate buffer solution and dispersion solution with HNO_3 solution as the stripping solution and membrane solution of 2-ethyl hexyl phosphoric acid-mono-2-ethylhexyl ester(PC-88A) dissolved in kerosene,has been studied for the extraction of Sm^(3+).Many factors including pH value, volume ratio of membrane solution to stripping solution(OAV) and carrier concentration on Sm^(3+) extraction were investigated. Experimental results indicate that the optimum extraction conditions of Sm^(3+) were obtained as that PC-88A concentration was 0.120 mol/L,and OAV was 1.00 in the dispersion phase,and pH value was 4.80 in the feed phase.When initial Sm^(3+) concentration was 1.20×10^(-4) mol/L,the extraction percentage of Sm^(3+) was up to 92.8%in 160 min.展开更多
基金supported by National Basic Research Program of China(2012CBA01203)the National Natural Science Foundation of China(90210034,20221603)
文摘The conventional rare earth solvent extraction equipments have many problems such as long mixing time, low processing capacity, large factory area occupation, high energy consumption and so on. In order to solve the problems, many types of equipments were brought out. In this work, studies were carried out on the La(III) extraction process with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA) by membrane dispersion micro-extractor. Equilibrium studies showed that the initial aqueous pH value 4.15 with the saponification rate 40%was the optimal operation condition. The effects of membrane dispersion micro-extractor operational conditions such as dispersion mode, bulk flow rate and organic phase flow rate on the extraction efficiency were studied. The results showed that when the organic solution was the dispersed phase, the extraction efficiency was higher than that of others. Increasing bulk flow ratio could enhance the extraction efficiency greatly. When the ratio of organic phase flow rate to that of aque-ous phase was 80:80, the extraction efficiency was over 95%. The effect of stripping phase acidity on the La(III) recovery was studied. The results showed that when the stripping phase pH was 2.0, organic phase flow rate to stripping phase flow rate was 20:80;the re-covery efficiency of La(III) can reach 82%.
基金Project supported by the National Safety Academy Foundation(U1530107)National Natural Science Foundation of China(21476121,21636004)+1 种基金National Key Basic Research Program of China(2012CBA01203)Beijing Natural Science Foundation(2162020)
文摘The extraction of low concentration rare earth elements at high phase ratio was investigated. The traditional extraction set-up, such as mixer-settler, have drawbacks of easy emulsification, difficult separation and low efficiency if operated at the above condition. Membrane dispersion micro-extractor,owing to its well-dispersed, high surface-to-volume ratio and fast mass transfer rate, was employed in our work. Nd(Ⅲ),Eu(Ⅲ),Er(Ⅲ) were chosen to represent light, medium,heavy rare earth elements(REEs). The extraction process of REEs with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(P507) was investigated by membrane dispersion micro-extractors. Firstly, the extraction equilibrium of these three elements was explored in the stirred conical flasks, and it is indicated that the extraction efficiencies can be 0.95, 0.97 and 0.98, respectively within 40 min at phase ratio of 100:1. Then the effects of operational conditions such as the residence time, organic and aqueous flow rates on extraction efficiency were also explored in micro-extractors. The results indicate that the efficiency decreases and then increases if increasing aqueous phase flow rate, residence time and droplets' diameter are the key factors of this process. Increasing the phase ratio reduces the extraction efficiency significantly. When the REEs solution has an initial pH of 4.00, the flow rates of continuous and dispersed phase are 40 and 1.6 mL/min,respectively, and 90 mg/L Nd(Ⅲ), Eu(Ⅲ) and Er(Ⅲ) is extracted by 1 mol/L P507 at the out-let length of8 m. The extraction efficiencies are 0.978,0.983 and 0.991, respectively. Finally the stripping process was also studied with the micro-extractor. The stripping efficiencies of Nd(Ⅲ), Eu(Ⅲ) and Er(Ⅲ) can reach0.99, 0.96 and 0.91, respectively when the out-let length is 8 m and the concentration of hydrochloric acid is 1 mol/L. The developed approach offers a novel and simple strategy on the fast extraction and enrichment of low concentration rare earth elements from waste water.
基金Project supported by the National Basic Research Program of China(2012CBA01203)the National Natural Science Foundation of China(90210034,20221603)
文摘By using membrane dispersion micro-extractor, Ce(IIl) solvent extraction experiments were conducted. Cerium chloride solution with certain acidity was used as aqueous phase and 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA) kerosene solution as organic phase. The effects of system physicochemical properties and operational conditions, such as initial EHEHPA concentration, initial aqueous acidity, total flow rate and continuous phase flow rate, etc., on the extraction efficiency and the overall volume mass transfer coefficient were evaluated. As the total flow rate increased fi'om 20 to 160 mL/min, the overall volume mass transfer coefficient was enhanced from 0.1 to 0.54 S1. Under the optimal conditions, the Ce(III) extraction efficiency could reach 99.92% in 2.98 s. A mathematical model was set up to predict the overall volume mass transfer coefficient, and the calculation results agreed well with the experimental results, most relative error was within +10%.
基金Supported by the National Natural Science Foundation of China(No90401009)the Natural Science Foundation of Shaanxi Province, China(NoSJ08B16)+1 种基金the Science Research Program of Education Department of Shaanxi Province, China (No06JK215)the Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology, China (No602-210805)
文摘The transport of Tb(III) in dispersion supported liquid membrane(DSLM) with polyvinylidene fluoride membrane(PVDF) as the support and dispersion solution including HCl solution as the stripping solution and di(2-ethylhexyl) phosphoric acid(D2EHPA) dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb(III) and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on the transport of Tb(III) have also been investigated, respectively. As a result, the optimum transport conditions of Tb(III) were obtained, i.e., the concentration of HCl solution was 4.0 mol/L, the concentration of D2EHPA was 0.16 mol/L, the volume ratio of membrane solution to stripping solution was 30:30 in the dispersion phase and pH value was 4.5 in the feed phase. Ionic strength had no obvious effect on the transport of Tb(III). Under the optimum conditions, the transport percentage of Tb(III) was up to 96.1% in a transport time of 35 min when the initial concentration of Tb(IIl) was 1.0× 10 -4 mol/L. The diffusion coefficient of Tb(III) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.82×10 -8 m2/s and 5.61 um, respectively. The calculated results were in good agreement with the literature data.
基金supported by the National Natural Science Foundation of China (90401009)Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology (602-210805)
文摘The transport of Dy(III) through a dispersion supported liquid membrane (DSLM) consisting of polyvinylidene fluoride membrane (PVDF) as the liquid membrane support and dispersion solution including HCI solution as the stripping solution and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (PC-88A) dissolved in kerosene as the membrane solution, was studied. The effects of pH value, initial concentration of Dy(III) and different ionic strength in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on transport of Dy(III) were also investigated, respectively. As a result, when the concentration of HCI solution was 4.0 mol/L, concentration of PC-88A was 0.10 mol/L, and volume ratio of membrane solution and stripping solution was 40:20 in the dispersion phase, and pH value was 5.0 in the feed phase, the transport effect of Dy(III) was the best. Ionic strength had no obvious effect on transport of Dy(III). Under the optimum condition studied, when initial concentration of Dy(III) was 0.8×10^-4 mol/L, the transport rate of Dy(III) was up to 96.2% during the transport time of 95 rain. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The diffusion coefficient of Dy(III) in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.99×10^-7 m^2/s and 15.97 μm, respectively. The results were in good agreement with experimental results.
基金Supported by the National Natural Science Foundation of China(21125629,21306079,21276124)Innovative Research Team Program by the Ministry of Education of China(IRT13070)+3 种基金China Postdoctoral Science Foundation(2014M561640)Jiangsu Planned Projects for Postdoctoral Research Funds(1401082B)Jiangsu province scientific supporting project(No.BE2014717)the Natural Science Foundation of Jiangsu Province(BK20150277)
文摘Three dimensional (3D) flower-like basic zinc carbonate constructed by multilayered nanoplates were rapidly prepared at room temperature through the direct precipitation method coupled with membrane dispersion technology, and porous ZnO with similar structures could be obtained after calcining the precursor. The structural properties of the products before and after the calcining process were characterized by SEM, TEM and XRD.The supersaturation of the reaction system due to the membrane dispersion played an important role in the formation of uniform Zn_5(CO_3)_2(OH)_6 precursors. A plausible mechanism was proposed for the formation of the flower-like ZnO assembled by nanoplates composed of nanoparticles. The obtained ZnO microspheres showed excellent photocatalytic properties, which could be attributed to the open structure and remarkable amount of porous nanoplates.
基金Supported by the National Natural Science Foundation of China (No.90401009)Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology (No.602-210805)
文摘The transport of La(III) through a dispersion supported liquid membrane with polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in kerosene as the membrane solution, was studied. As a result, the optimum transport conditions of La(Ⅲ) were obtained as that concentration of HCl solution was 4.0 mol/L, concentration of PC-88A 0.16 mol/L, and volume ratio of membrane to stripping solution 30:30 in the dispersion phase, and pH value 4.0 in the feed phase. Ionic strength had no obvious effect on the transport of La(Ⅲ). Under the optimum conditions, when initial concentration of La(Ⅲ) was 0.8×10-4 mol/L, the transport rate was up to 96.3% during the transport time of 125 min. The kinetic equation was developed based on the law of mass diffusion and theory of interface chemistry. The diffusion coefficient of La(Ⅲ) in the membrane and the thickness of diffusion layer between feed and membrane phases were obtained as 3.20×10-7 m2/s and 3.22×10-5 m, respectively. The calculated results were in good agreement with experimental results.
基金Supported by the National Natural Science Foundation of China(90401009) the Foundation for Planning Project of West Action of Chinese Academy of Sciences(KZCX2-XB2-13) the Research Fund for Excellent Doctoral Thesis of Xi’an University of Technology(602-210805)
基金Supported by the Chinese High Technology Research and Development Program(2015CB251402,17-163-12-ZD-001-013-01)the National Natural Science Foundation of China(21676215,21676273,U1507203)+3 种基金China Petroleum Enterprise Cooperation Project(PRIKY17094)China Postdoctoral Science Foundation(2018M633556)the Youth Innovation Promotion Association,CAS(2016043)the Shaanxi Provincial Science Foundation(2017SF-201,2018JQ2052).
文摘Mild stir-assisted membrane dispersion extraction(MDE) method was employed to enhance propionic acid(HA)extraction and compared to the mechanical stirred extraction(MSE) method. Triocylamine(TOA) and tributyl phosphate(TBP) were chosen as model extractant to extract HA. Firstly, droplet size and the size distribution of organic phase were analyzed, and then the effects of phase ratio, extractant and HA concentration on extraction performance were investigated. Comparing the two extraction methods, the results show mild stir-assisted MDE method reduced the mass transfer equilibrium time compared to MSE method. The mass transfer mechanism was explored by analyzing mass transfer resistance. Mild stir-assisted MDE had less total mass transfer resistance than MSE. When the extractant concentration was 40%, the extraction process was controlled by organic phase mass transfer process with HA volume fraction was 1% and controlled by both of reaction process and organic phase mass transfer process when HA concentration increased to 5%. This work may provide a new type of extraction method for the recovery of organic carboxylic acid.
基金Financial supports from the Prospective Joint Research Project of Jiangsu Province(BY2014005-06)National Natural Science Foundation of China(U1510202)the Jiangsu National Synergistic Innovation Center for Advanced Materials(SICAM)。
文摘Treatment to crystallization mother liquor containing high concentration of organic and inorganic substances is a challenge in zero liquid discharge of industrial wastewater.Acid precipitation coupled membrane-dispersion advanced oxidation process(MAOP)was proposed for organics degradation before salt crystallization by evaporation.With acid-MAOP treatment CODCrin mother liquor of pulping wastewater was eliminated by 55.2%from ultrahigh initial concentration up to 12,500 mg·L^-1.The decolorization rate was 96.5%.Recovered salt was mainly NaCl(83.3 wt%)having whiteness 50 brighter than industrial baysalt of whiteness 45.The oxidation conditions were optimized as CO3=0.11 g·L^-1 and CH2O2=2.0 g·L^-1 with dispersing rate 0.53 ml·min^-1 for 100 min reaction toward acidified liquor of p H=2.Acidification has notably improved evaporation efficiency during crystallization.Addition of H2O2 made through membrane dispersion has eliminated hydroxyl radical"quench effect"and enhanced the degradation capacity,in particular,the breakage of carbon-chloride bonds(of both aliphatic and aromatic).As a result,the proposed coupling method has improved organic pollutant reduction so as the purity of salt from the wastewater mixture which can facilitate water and salt recycling in industry.
文摘A non-dispersive extraction technique, using an emulsion liquid membrane within a hollow-fiber-contactor for the extraction and enrichment of Nd^3+ from the dilute feed aqueous, was applied. The emulsion system is consisted of span80 [ sorbitian monooleate], paraffin oil, D2EHPA [ 2-( 2-ethylhexyl- phosphonic acid)], kerosene as well as HCl solution. The extraction under various conditions such as the span80 concentrations, the flow rate of aqueous, the extraction time and HCl concentrations in receiving phase were studied. Results show that the lower the flow rates of aqueous are, the higher the extraction percentage and enrichment-fold are, and the extraction percentage increases with the increasing of HCl concentrations. When the initial Nd^3+ concentration in feed is maintained at 1000 mg· L^-1 and the emulsion is recycled with 70 times by a counter-flow,
基金supported by Postgraduate Scientific Research Innovation Project of Hunan Province (China) (Grant No.CX20230518).
文摘A functional hybrid nano-hydroxyapatite(carboxymethyl cellulose-phytic acid-n-HA,CMC-PA-n-HA)was prepared by adding CMC and PA.The results of Fourier transformation infrared spectra,X-ray diffraction,thermal gravimetric analysis and dispersion experiments indicated that the addition of CMC and PA affected the morphology,crystallinity and crystal size of hybrid n-HA,and CMC endowed hybrid n-HA with excellent dispersion.Scanning electron microscope results showed that CMC-PA-n-HA nanoparticle could be uniformly dispersed in chitosan(CS)matrix to obtain composite membrane by casting technology,so that the highest tensile strength of CMC-PA-n-HA/CS composite membrane was 69.64%and 144.45%higher than that of CS membrane and n-HA/CS composite membrane,respectively.Contact angle test showed that CMC-PA-n-HA effectively improved hydrophilicity of the CS membrane.The simulated body fluid immersion results indicated that the CMC-PA-n-HA/CS composite membrane not only exhibited good degradability but also promoted bone-like apatite deposition.The cell proliferation experiments proved that the introduction of PA made the composite membrane have better cell adhesion and proliferation ability.Antibacterial tests demonstrated that PA could effectively improve the antibacterial properties of the composite membrane,which is expected to be applied as guide bone tissue regeneration membrane.
基金The National Natural Science Foundation of China(No.21878191).
文摘Effective protection against X-ray is the premise of utilizing the X-ray,thus it is critical to develop novel X-ray shielding materials with both low density and high X-ray attenuation efficiency.As the even distribution of high-Z element components is of great significance for increasing the attenuation efficiency of X-ray shielding materials,in this study,the microfiber membrane(MFM),a type of synthetic leather featuring hierarchical structure was chosen to provide large surface area for the dispersion of rare earth(RE)element.Meanwhile,plant polyphenol was utilized to achieve the stable loading and uniform dispersion of the Ce or Er into MFM.Benefiting from the assistance of polyphenol and hierarchical structure of MFM,the even dispersion of RE element was successfully realized.The resultant shielding materials displayed approximately 10%superior X-ray attenuation efficiency compared to that without polyphenol,and an averagely 9%increment in X-ray attenuation efficiency than that without hierarchical structure.Moreover,the obtained composite with a thickness of 2.8 mm displayed superior X-ray shielding performance compared to 0.25 mm lead sheet in 16-83 keV and retained an ultralow density of 1.4 g cm^(-3).Our research results would shed new light on the manufacture of high-performance X-ray shielding materials with excellent X-ray shielding performance.
基金Project supported by the National Natural Science Foundation of China (90401009)the Action Plan for the Development of Western China of the Chinese Academy of Sciences (KZCX2-XB2-13)Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology (602-210805)
文摘The Eu(III) separation in supported dispersion liquid membrane (SDLM), with polyvinylidene fluoride membrane (PVDF) as the support and dispersion solution containing HNO3 solution as the stripping solution and Di(2-ethylhexyl) phosphoric acid (D2EHPA) dis- solved in kerosene as the membrane solution, was studied. The effects ofpH value, initial concentration of Eu(III) and different ionic strengths in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HNO3 solution, concentration of carrier, different stripping agents in the dispersion phase on the separation of Eu(III) were also investigated, respectively. As a result, the optimum separation conditions of Eu(III) were obtained as the concentration of HNO3 solution was 4.00 mol/L, concentration of D2EHPA was 0.160 mol/L, and volume ratio of membrane solution to stripping solution was 30:30 in the dispersion phase, and pH value was 5.00 in the feed phase. Ionic strength had no obvious effect on the separation of Eu(III). Under the optimum conditions studied, when initial concentration of Eu(III) was 1.00× 10^-4 mol/L, the separation rate of Eu(III) was up to 94.2% during the separation period of 35 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The results were in good agreement with the literature data.
基金This research was supported by the National Natural Science Foundation of China for Young Scientists (Grant No. 51109197), the Fnndation for Planning project of West Action of Chinese Academy of Sciences CKZCX2-XB2-13) and Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology (602-210805).
文摘A mathematical model for the transport of Ce (IV) from hydrochloric acid solutions through dispersion flat combined liquid membrane (DFCLM) with contain 2- ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (P507) as the carrier, dissolved in kerosene as the membrane solution have been studied. This process of facilitated transport, based on membrane technology, is a variation on the conventional technique of solvent extraction and may be described mathematically using Fick's second law. The equations for transport velocity are derived considering the diffusion of P507 and its metallic complexes through the liquid membrane. In this work, the system is considered to be in a transient state, and chemical reaction between Ce(IV) and the carrier to take place only at the solvent-aqueous interfaces. Model concentration profiles are obtained for the Ce(IV), from which extraction velocities are predicted. The experimental and simulated Ce(IV) extractions showed similar tendencies for a high Ce (IV) concentration and acidity case.The model results indicate that high initial Ce(IV) concentrations and acidity both have detrimental effects on Ce(IV) extraction and stripping. The diffusion coefficient of Ce(IV) in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and the values are 6.31 × 10-8m2·s-1 and 31.2 μm, respectively. The results are in good agreement with experimental results.
基金Project supported by the National Natural Science Foundation of China (or Young Scientists (Nos. 41001131 and 51009126), the Action Plan for the Development of Western China of the Chinese Academy of Sciences (No. KZCX2-XB2-13), the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KSCX2-YW-N-003) and Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology (Nos. 602-210805 and 602-210804).
文摘The separation of Sm(III) through stripping dispersion hollow fiber liquid membrane system (SDHFLM) containing feed phase adding acetate buffer solution and dispersion solution with HC1 solution as the stripping solution and membrane solution of di(2-ethylhexyl) phosphoric acid (p204) dissolved in kerosene, has been studied. A set of factors were studied, including pH value, initial concentration of Sm(III) and different ionic strength of feed phase, volume ratio of membrane solution and stripping solution (O/W), HC1 concentration, carrier concentration, different stripping agents of dispersion phase on Sm(III) separation. Experimental results indicate that the optimum separa- tion conditions of Sm(III) were obtained as that HC1 concentration was 4.00 tool/L, p204 concentration was 0.150 mol/L, and volume ratio of membrane solution and stripping solution (O/W) was 1.00 in the dispersion phase, and pH value was 4.60 in the feed phase. Ionic strength had no obvious effect on separation of Sm(III). When initial Sm(III) concentration was 1.00 × 10^-4 mol/L, the separation rate of Sm(III) was up to 93.5% in 85 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The modeled results were in good agreement with the experiment data.
基金This work was financially supported by the National Basic Research Foundation of China (grant number 2013CB733600)and the National Natural Science Foundation (grant numbers 21276140,20976096,and 21036002).
文摘In this paper,we present a new method for preparing γ-alumina nanoparticles with a bimodal pore size distribution by using an efficiently mixing membrane dispersion microreactor.NH4HCO3and AI2(SO4)3.18H2Owere reacted under vigorous mixing to give an ammonium aluminum carbonate hydroxide (AACH)precursor.γ-Alumina was obtained by calcination of AACH at 550℃ for 6h.The effects of NH4HCO3concentration,pH during aging,and reaction temperature were investigated.The mechanism of bimodal pore formation was clarified.The results showed that large pores (10-100nm) were mainly formed in the reactor and during aging,and small pores (0-10nm)were mainly formed during calcination.When the concentration of NH4HCO3was 1.5mol/L,the aging pH was 9.2,and the reaction temperature was 80℃,γ-alumina with a specific surface area of 504.7m^2/g and pore volume of 1.76mL/g was obtained.The average size of the large pores was about 30nm,and the average size of the small pores was about 4nm.
基金financially supported by the National Natural Science Foundation of China for Young Scientists(Nos. 51109197 and 51009126)the Action Plan for the Development of Western China of the Chinese Academy of Sciences (No.KZCX2-XB2-13)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KSCX2-YW-N -003)Research Fund for Excellent Doctoral Thesis of Xi'an University of Technology(Nos.602-210805 and 602-210804)
文摘Stripping dispersion hollow fiber liquid membrane system(SDHFLM) containing feed phase adding acetate buffer solution and dispersion solution with HNO_3 solution as the stripping solution and membrane solution of 2-ethyl hexyl phosphoric acid-mono-2-ethylhexyl ester(PC-88A) dissolved in kerosene,has been studied for the extraction of Sm^(3+).Many factors including pH value, volume ratio of membrane solution to stripping solution(OAV) and carrier concentration on Sm^(3+) extraction were investigated. Experimental results indicate that the optimum extraction conditions of Sm^(3+) were obtained as that PC-88A concentration was 0.120 mol/L,and OAV was 1.00 in the dispersion phase,and pH value was 4.80 in the feed phase.When initial Sm^(3+) concentration was 1.20×10^(-4) mol/L,the extraction percentage of Sm^(3+) was up to 92.8%in 160 min.