Solvent extraction of La(III) with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA) by membrane dispersion micro-extractor

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%.

Efficient extraction and stripping of Nd(Ⅲ),Eu(Ⅲ) and Er(Ⅲ) by membrane dispersion micro-extractors

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.

Solvent extraction performance of Ce(Ⅲ) from chloride acidic solution with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(EHEHPA) by using membrane dispersion micro-extractor

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%.

Tb(III) Transport in Dispersion Supported Liquid Membrane System with D2EHPA as Carrier in Kerosene

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.

Study on transport of Dy(Ⅲ) by dispersion supported liquid membrane

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.

Controllable preparation of ZnO porous flower through a membrane dispersion reactor and their photocatalytic properties

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.

La(Ⅲ) Transport in Dispersion Supported Liquid Membrane Including PC-88A as the Carrier and HCl Solution as the Stripping Solution

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.

Separation of Eu^3＋ Using a Novel Dispersion Combined Liquid Membrane with P507 in Kerosene as the Carrier

Eu3+的分离与分散被学习联合液体膜( DCLM )，在哪个 polyvinylidene 氟化物膜( PVDF )被用作液体膜支持，是的分散答案包含 HCl 答案脱衣的答案，并且2乙醇己基的酉旨( P507 )作为膜答案在煤油溶解了的己基的磷的 acid-mono-2-ethyl 。pH 价值， Eu3+ 的起始的集中和在 feed 的不同离子的力量的效果分阶段执行，剥去解决方案的膜答案的卷比率， HCl 答案的集中，搬运人的集中，在分离上的分散阶段的不同脱衣代理人被调查。为 Eu3+ 的分离的最佳条件是 HCl 答案的集中是 4.0 摩尔吗？？

Mild stir-assisted membrane dispersion for enhancing propionic acid extraction

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.

Acid precipitation coupled membrane-dispersion advanced oxidation process(MAOP)to treat crystallization mother liquor of pulp wastewater

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.

Extraction of Neodymium by Emulsion-Liquid-Membrane within Hollow-Fiber-contactor and Its Mass Transfer Properties

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,

一体式再生燃料电池双功能氧电极高分散工艺研究

一体式再生燃料电池(PEM-URFC)将燃料电池和电解池融为一体,正向耗氢发电,反向电解产氢,是理想的储能装置。双功能氧电极(BOE)是承担氧还原反应与析氧反应的核心场所,通常由Pt和IrO_(2)两种材料混合制备而成。制备BOE的浆料难分散,导致催化剂利用率低、耐久性差。为了克服上述难题,本研究通过结合巯基-聚乙二醇-羧基稳定剂与间隔超声分散工艺的方法,提升了Pt-IrO_(2)浆料的分散效果和稳定性,并在此基础上制备了高分散的BOE。实验结果表明,本研究所制备的BOE富含纳米级孔,相较于通过持续超声分散工艺制备的BOE,催化剂利用率更高。极化性能测试结果表明,由本研究制备BOE所组装的PEM-URFC在0.5 A/cm^(2)工作条件下双向效率最高可达51.12%,比由持续超声分散工艺制备BOE所组装PEM-URFC的双向效率高9%;此外,在3000次加速实验后,由本研究制备BOE所组装的PEM-URFC双向效率仅衰减0.249%,低于由持续超声分散工艺制备BOE所组装PEM-URFC的1.675%。本工作所提出的结合稳定剂与间隔超声分散工艺提升分散效果的方法,对优化双功能电极的制备工艺具有一定的参考价值。

Improving chitosan-based composite membrane by introducing a novel hybrid functional nano-hydroxyapatite with carboxymethyl cellulose and phytic acid

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.

Wearable synthetic leather-based high-performance X-ray shielding materials enabled by the plant polyphenol-and hierarchical structure-facilitated dispersion

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.

基于膜系理论的疾病治疗原则

膜系是全身膜状结构及其附属组织共同构成的多层次复杂系统,根据其是否与外界相通,可分为外通性膜系与内通性膜系。外通性膜系具有屏障保护功能,是与外界环境物质、信息和能量交换的重要结构;内通性膜系具有联络协调的功能,是机体各脏腑器官之间物质、信息和能量交换的重要结构。基于膜系理论,可指导临床膜系疾病的治疗。外通性膜系是重要的祛邪途径,临床可采用汗、吐、下等方法,通过调畅外通性膜系的气津输布,以祛邪而出。内通性膜系是疾病传变的重要途径,其常见病理为气机郁滞、水液代谢异常等,可通过调理膜系气津输布治疗疾病。调畅膜系气津输布时,应重点关注少阳与中焦气机,以恢复全身气机升降出入。全身膜系起源于肾,在膜系疾病早期注重顾护肾膜,可先安未受邪之地;在疾病中晚期调补肾阴肾阳,可治疾病之本,顾护正气。

Separation of Eu(Ⅲ) with supported dispersion liquid membrane system containing D2EHPA as carrier and HNO_3 solution as stripping solution

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.

Modeling of Ce（IV） transport through a dispersion flat combined liquid membrane with carrier P507

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.

Separation of Trivalent Samarium through Facilitated Stripping Dispersion Hollow Fiber Liquid Membrane Using p204 as Mobile Carrier

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.

Controllable preparation of γ-alumina nanoparticles with bimodal pore size distribution in membrane dispersion microreactor

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.

Stripping dispersion hollow fiber liquid membrane containing carrier PC-88A and HNO_3 for the extraction of Sm^(3+)

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.