微乳液的增溶、相态及微乳液/中空纤维膜萃取钕

通过考察非离子型微乳液体系（OP-4+OP-7）/ 苯甲醇/D2EHPA/煤油/盐酸中的混合表面活性剂OP-4［壬基酚聚氧乙烯（4）醚］和OP-7［壬基酚聚氧乙烯（7）醚］配比、盐酸浓度、温度和NaCl对盐酸增溶量的影响以及D2EHPA［二（2-乙基己基）磷酸］和盐酸浓度对体系相态的影响,制备了适合作为液膜分离介质的微乳液体系,同时提出了新的膜萃取过程：微乳液/中空纤维膜萃取,并用于稀土钕的萃取.结果表明,微乳液中盐酸的增溶量随混合表面活性剂HLB值以及盐酸浓度的增大而增大,随温度的升高、NaCl浓度的增大而减小;D2EHPA的加入有利于WinsorⅡ体系的形成;盐酸浓度小于6 mol•dm^-3时也可形成WinsorⅡ体系,而盐酸浓度为7 mol•dm^-3和8 mol•dm^-3时则分别形成WinsorⅢ体系或WinsorⅠ体系;将W/O非离子型微乳液通过中空纤维膜从浓度为300 mg•dm^-3的料液中萃取钕时,采用3个中空纤维膜器串连一次萃取即可使萃取率达95.3%,内相富集倍数18.1.该新膜萃取体系同时具有液膜与固膜萃取的优点,不需进行反萃操作.     

微乳液体系(OP-7+OP-4)/苯甲醇/ D2EHPA/煤油/盐酸的增溶性能及其对钕的膜萃取

研究了以OP-7[壬基酚聚氧乙烯(7)醚]和OP-4[壬基酚聚氧乙烯(4)醚] 为非离子表面活性剂、苯甲醇为助表面活性剂所形成的W/O型微乳液体系(OP-7 OP-4) / 苯甲醇 / D2EHPA / 煤油 / 盐酸在不同混合表面活性剂配比、盐酸浓度、温度、NaCl浓度等条件下对盐酸的增溶性能;将微乳液作为液膜用于对稀土钕的萃取时,采用了新的膜萃取过程即微乳液/中空纤维膜接触器萃取.结果表明,微乳液对盐酸的增溶量随混合表面活性剂的亲水亲油平衡值(HLB值)以及盐酸浓度的增大而增大,随温度的升高、NaCl浓度的增大而减小.当以逆流方式萃取时,微乳液内相盐酸浓度越大,萃取率越高,但内相富集倍数减小;当微乳液流量为6 mL·min-1、料液初始浓度为200 mg·L-1、有效萃取时间为 6 min时,Nd3 的萃取率达96.3%,微乳液内相浓度富集倍数为21.2,有效萃取时间超过6 min后,萃取率基本不变,表明该非离子型微乳液对钕Nd3 具有很好的萃取和富集功能,所采用的新膜萃取过程同时具有膜萃取过程的热力学稳定性和液膜分离过程非平衡性的优点.     

微乳液膜萃取L-谷氨酸的研究

用NaOH皂化HA/煤油溶液能形成稳定的微乳液。通过该微乳液对L-谷氨酸水溶液进行萃取实验。结果表明,该微乳液萃取L-谷氨酸的最佳工艺条件为:萃取时间20 m in,油相中HA的浓度为1.0 mol/L,乳水比(体积比)为1∶4,外水相pH值为3,L-谷丙氨酸的一次性萃取率可达89.33%。微乳液膜具有稳定性好、无明显溶胀和泄漏、萃取效率高、可自动破乳且油相可重复使用等优点。     

皂化P204微乳液膜处理含锌废水的研究

研究以皂化P204为载体的微乳液膜配方及其稳定性.采用P204/Span80/煤油/NaOH微乳体系萃取废水中Zn^2＋,考察了P204与煤油和Span80的质量比、NaOH的浓度、乳水比、外水相pH值、油相重复使用次数等因素对Zn^2＋萃取率的影响.结果表明,当P204与煤油的质量比为1：2.5,P204与Span80的质量比为1：1,NaOH浓度为1.5mol/L,乳水比为1：4（体积比）,废水pH值为5.5时,萃取10min,P204/煤油/NaOH微乳液膜对Zn^2＋萃取率可达99.72%,P204/Span80/煤油/NaOH微乳液膜对Zn^2＋萃取率可达99.98%,微乳液膜不仅稳定性好、萃取效率高,而且工艺简单、膜相可自动破乳、油相可重复使用.     

微乳液膜法萃取钕

进行了微乳液膜法萃取Nd3+的研究,考察了不同盐酸浓度时微乳液的溶水量及其对Nd3+的萃取率、内相富集浓度的影响,同时还考察了温度、料液浓度、缓冲剂对萃取Nd3+的影响.结果表明,随着盐酸浓度增大,微乳液溶水量增加;内相Nd3+富集倍数最高为24.3倍,料液Nd3+浓度相同时,内相Nd3+富集浓度和富集倍数随溶水量增加而减小,萃取率则变化不大,一般在70%～80%范围,于料液中加入缓冲剂对Nd3+的萃取率有很大影响.根据微乳液膜渗透速率方程计算了传质系数.通过在微乳液和料液之间加载一层亲水性微孔滤膜,避免了微乳液与料液直接接触所产生的乳化,内相泄漏也得到了抑制.     

Cu2+在支撑液膜中的传质过程

研究了以疏水性多孔聚丙烯膜(Celgard 2500)为支撑体和LIX984的煤油溶液为膜液的支撑液膜体系萃取Cu2+的传质过程. 采用双膜理论描述Cu2+通过平板支撑液膜的传质过程,建立了其在稳态下的传质动力学方程,且当反萃取侧酸浓度大于2 mol/L时,反萃取侧的传质阻力可以忽略;利用膜内分传质系数km表征支撑液膜膜液的流失行为,在传质过程中,km先增大而后逐渐减小,且载体的流失速率大于稀释剂煤油的流失速率. 考察了操作条件对传质和膜液流失速率的影响,结果表明,Cu2+初始传质通量随载体初始浓度、料液初始pH值和料液初始Cu2+浓度的增大而增大;载体初始浓度越大,膜液流失越快;料液初始Cu2+浓度增大,膜液流失越慢;料液相pH值的改变对膜液流失速率没有影响.     

中空纤维更新液膜传质性能的研究

研究了中空纤维更新液膜(HFRLM)技术的传质性能.以CuCl2水溶液-10%P204 煤油-盐酸为实验体系,研究结果表明,中空纤维更新液膜技术可以实现同级萃取-反萃,且总传质系数随料液相流速的增大而增大,在实验条件下,总传质系数受反萃相流速的影响较小.实验研究探讨了混合方式(料液与萃取剂混合和反萃剂与萃取剂混合)和体系分配系数对传质性能的影响.实验结果表明,由于相间分配系数的不同,总传质系数受混合方式的影响较大,以分配系数较大的一相与萃取相混合流经管程的方式对传质过程有利.     

D2EHPA萃取回收Cr(Ⅲ)的研究

以回收废水中Cr(Ⅲ)为目的,选择2-乙基己基磷酸(D2EHPA)为萃取剂,煤油为稀释剂,进行了萃取回收Cr(Ⅲ)的实验研究.考察了皂化剂种类、溶液pH值、助溶剂种类、萃取剂浓度等因素对于萃取平衡影响以及三种无机酸、两种有机酸对于负载Cr(Ⅲ)的D2EHPA反萃效果的影响.结果表明,pH值是影响D2EHPA/煤油萃取Cr(Ⅲ)的重要因素, 在pH＜2时,D2EHPA几乎不萃取Cr(Ⅲ),通过萃取剂的皂化,提高水相pH值,可以实现D2EHPA萃取Cr(Ⅲ).随平衡水相pH值的升高,D2EHPA显示出良好的萃取效果.NaOH溶液作为皂化剂比氨水的分相效果好.加入助溶剂后萃取效率提高,其中10%～20%正辛醇是适宜的助溶剂选择.D2EHPA/正辛醇/煤油萃取Cr(Ⅲ)后立即用无机酸或有机酸反萃,其中硫酸、盐酸或草酸的反萃率能够达到90%以上.     

OP-10/异戊醇/煤油/NaOH微乳液体系萃取钼(Ⅵ)的研究

采用电导率法研究了OP-10/异戊醇/煤油/NaOH水溶液微乳液体系的性质,并以此微乳液体系为油相,以TOA为载体研究了萃取水溶液中钼(Ⅵ)的工艺条件。实验结果表明:异戊醇和OP-10的最佳比例为1∶1时,该微乳液体系具有最大溶水量;拟三元相图表明该微乳液体系的稳定区域与NaOH浓度关系不大;外水相中加入一定量的NaCl可有效避免萃取过程中液膜的溶胀与破裂;当外水相中HCl浓度为0.05mol/L、膜相中TOA浓度为0.04mol/L、内水相中NaOH浓度为0.04mol/L时,微乳液体系对钼的单级萃取率可达98%。     

一种新的非离子型乳化液膜体系的稳定性研究

制备了一种新的非离子型乳化液膜体系OP-4/D2EHPA/液体石蜡/煤油/盐酸,通过测定乳液电导率、破损率、溶胀率、乳滴粒径大小等,研究了乳化剂浓度、油内比、D2EHPA皂化度、内相盐酸浓度以及温度等因素对乳液稳定性的影响,并与以液膜传统专用乳化剂Span80、ENJ-3029、兰-113A所制得的W/O型乳液进行了加热破乳对比实验。结果表明该乳液体系表现出两个异常的稳定特性:(1)随着OP-4浓度的增加,乳液稳定性呈现先增加后下降的现象,OP-4在油相中的浓度为3%～5%(wt)时,乳液的稳定性较好。(2)当温度低于45℃时乳液表现出相当好的稳定性,温度超过50℃后乳液稳定性急剧下降。加热破乳对比实验表明,该乳液在60℃加热破乳10min,破乳率达100%,而分别以专用乳化剂Span80、ENJ-3029、兰-113A制备的乳液在60℃下加热60min仍不能破乳。通过控制适当条件,可以制备常温稳定性好而加热条件下容易破乳的乳化液膜体系。     

The Transport of Copper(II) through Hollow Fiber Renewal Liquid Membrane and Hollow Fiber Supported Liquid Membrane

Abstract

In this paper, hollow fiber renewal liquid membrane (HFRLM) and hollow fiber supported liquid membrane (HFSLM) were used to simultaneously remove and recover copper(II) from aqueous solutions, and the transport performance of these two techniques were compared under the similar conditions for the system of CuSO₄ +D2EHPA in kerosene +HCl. The results showed that the HFRLM process was more stable than the HFSLM process. The HFRLM process had a higher overall mass transfer coefficient than that of HFSLM process in single-pass experiments. These were because the renewal effect of the liquid membrane layer could reduce the mass transfer resistance of the lumen side and replenish the loss of the membrane liquid in the HFRLM process. The transport results were better in the HFRLM process than that in the HFSLM process with recycling experiments. Therefore, HFRLM technique is a promising method for simultaneous removal and recovery of heavy metal from aqueous solutions.     

采用不同载体的中空纤维更新液膜Cu(Ⅱ)传质的研究(英文)

The extraction ability of organophosphorus extractant D2EHPA (di-2-ethylhexyl phosphoric acid) and hydroximic extractant Lix984N are investigated by the extraction equilibrium experiments. Effects of carrier concentration and organic/aqueous volume ratio on the mass transfer of hollow fiber renewal liquid membrane (HFRLM) are studied. Results show that, in the extracting process, kerosene and n-heptane are more suitable than methyl-isobutyl ketone, butylacetate and benzene as the diluents of D2EHPA or Lix984N. The favorable feed pH is 4.4 for D2EHPA and 2.6 for Lix984N. The mass transfer flux of HFRLM increases with carrier concentration and finally reaches a plateau. The mass transfer flux and the overall transfer coefficient increase with the or-ganic/aqueous volume ratio, reach the maximum and then decrease.     

中空纤维支撑液膜萃取Cu(II)的传递性能

The transport of Cu(II) from aqueous solutions containing buffer media through hollow fiber supported liquid membrane (HFSLM) using di(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in kerosene as membrane phase and hydrochloric acid as striping phase was investigated. A set of factors were studied, including tube side velocity, shell side velocity, pH of the feed phase, Cu(II) concentration in the feed phase, buffer media concentration and D2EHPA concentration in the membrane phase. Experimental results indicate that the mass transfer coefficient increases with increasing both carrier concentration in the organic phase and flow rates on the tube side and shell side, and decreases with increasing initial Cu(II) concentration in the feed phase. With increasing pH value and acetate concentration in the feed phase, the mass transfer coefficient reaches a maximum value then decreases. The optimal operating conditions are obtained at pH value of 4.44 and 0.1 mol&;#8226;L－1 acetic ion concentration in feed phase, and carrier volume fraction of around 10% in kerosene as organic phase. A mathematical model of the transport mechanism through HFSLM is devel-oped. The modeled results agree well with the experimental ones.     

Solvent extraction of copper in a reciprocating plate column

Equilibrium data for the distribution of copper between an aqueous solution and a 20% solution of di-(2 ethyl hexyl) phosphoric acid in kerosene has been obtained by shake-flask experiments. The capacity of the organic phase for copper is greatly improved when the ammonium salt of D2EHPA is used. The performance of a 5 cm diameter Karr reciprocating plate extraction column for continuous counter-current extraction of copper by ammoniated D2EHPA has been measured. The results, expressed as heights of a transfer unit, have been compared with data for a non-metallic system (kerosene/acetic acid/water) in the same column. The lowest H.T.U. values measured were 43 cm for copper transfer and 23 cm for acetic acid transfer, with the difference being attributed mainly to the lower molecular diffusivity in the copper/D2EHPA system.     

Synergistic extraction and separation of Fe(III) and Zn(II) using TBP and D2EHPA

Waste chloride pickle liquors from hot-dip galvanizing plants, steel plants and flue dust contain reasonable amounts of heavy metals such as Zn, Cr, Ni, etc. Iron is invariably associated with most of these materials and comes into solution during leaching. Thus, the synergistic extraction of zinc(II) and iron(III) from leach solutions in tri-n-butyl phosphate (TBP)–di(2-ethylhexyl) phosphoric acid (D2EHPA) system diluted in kerosene was investigated. The Zn and Fe concentrations in the leach liquor used in the present study were 2 g/L. Experiments were carried out in the pH range of 0.5–4.0, temperature of 25°C, using sole D2EHPA, sole TBP and D2EHPA–TBP mixtures at different ratios. Results showed that the co-extraction of zinc(II) and iron(III) increased with increasing equilibrium pH using D2EHPA. It is demonstrated that the mixtures of TBP and D2EHPA are more efficient and selective than D2EHPA alone. At low pH values, the separation factor is low when pure D2EHPA is used as an extractant; however, using TBP as a synergist, the separation factor increases and results in a better separation of zinc from iron. Increasing TBP to D2EHPA ratios in the organic phase caused a slight shift to the right in the extraction isotherm of iron and a marked shift to the right in the extraction isotherm of zinc, and the maximum separation factor of 13.3 × 10³ was achieved at a TBP to D2EHPA volume ratio of 4:1 (0.58 M TBP: 0.12 M D2EHPA). Furthermore, the effect of equilibrium pH, organic to aqueous phase ratio and Cl^? concentration on the selective extraction was investigated. Using two extraction stages at the O/A ratio of 2:1 and pH_e (equilibrium pH) of 3 and 1 for zinc and iron, respectively, 99% of zinc(II) and 96.25% of iron(III) were extracted.     

Separation of Zinc by a Non‐dispersion Solvent Extraction Process in a Hollow Fiber Contactor

Abstract

A process for recovery of zinc from acid solution with di(2‐ethyl hexyl phosphoric acid) (D2EHPA) dissolved in iso‐dodecane was carried out at 20°C in a countercurrent tubular membrane extractor using a hollow fiber as solid support. Experiments were performed at different aqueous metal concentrations (0.1–1.0 g/L), pH 0.1–2.1, and D2EHPA concentrations (2–8 v%). It was found that both the flux of metal and the extraction extent was highly influenced by the extractant concentration and the pH of the feed solution. Overall mass transfer coefficients were determined and related to the tube side, the membrane, and the shell side mass transfer by varying the aqueous flow rate (0.38–0.80 L/min) and organic flow rate (0.22–0.57 L/min) in countercurrent flow. The overall mass transfer coefficient for zinc extraction ranged from 6.2×10^?6 m/s to 25.3×10^?6 m/s. It was concluded that extraction kinetics were a major contributor to the overall resistance to mass transfer.     

中空纤维支撑液膜萃取法提铟工艺比较研究

采用中空纤维支撑液膜(SLM)技术,模拟酸性铟渣浸出液,以磷酸二异辛酯(P204)、磺化煤油体积比3:7为液膜萃取相,盐酸溶液为反萃相,研究了单组件膜萃取系统、双膜组件萃取-反萃系统、双膜组件萃取-超滤系统对酸性浸出液中In的提取与分离效率。结果表明,双膜组件萃取-超滤技术可同时实现浸出液中In的提取与反萃液中In的高纯度富集,浸出液中In的提取率可达90%以上,反萃液中In含量可达浸出液中In含量的70%,In的质量分数高于90%。     

Hollow‐fiber dispersion‐free extraction and stripping of Pb(II) in the presence of Cd(II) using D2EHPA under recirculating operation mode

Lead(II) and cadmium(II) solvent extraction (SX) with D2EHPA dissolved in heptane and kerosene from aqueous chloride media was studied. Extraction reaction stoichiometries and extraction equilibrium constants were evaluated. Application of a dispersion‐free membrane‐based extraction and stripping technique with two hollow‐fiber contactors under recirculating operation mode allowed a quantitative (>97%) removal of lead from the aqueous solution in the extraction module with a separation factor of 19 and a 62% recovery in the back‐extraction module with a separation factor of 6.3 after 7 h under optimum conditions. Mass‐transfer coefficients for the system were evaluated. Optimal conditions for transport and separation are reported and compared using SX and the membrane‐based technique. Copyright © 2004 Society of Chemical Industry