离子液体支撑液膜用于有机物分离的研究进展

离子液体支撑液膜传质速率高,选择性好,稳定性高,在有机物分离中具有独特的优势.总结了离子液体作为膜液相的优点,介绍了离子液体支撑液膜材料的选择,制备以及在有机物分离中的应用,分析了影响离子液体支撑液膜稳定性的因素,展望了其工业化前景.     

海藻酸钠与PVA共混膜用于渗透汽化分离乙醇—水混合物

制备了天然高分子海藻酸钠与ＰＶＡ的不同比例共混膜，并用于渗透气化法分离乙醇－水混合物。结果表明，与均质ＰＶＡ膜相比，透过系数及分离系数均大幅度提高，尤其是当乙醇浓度低于８０％时，共混膜依然保持较高分离系数，在共混膜中，ＰＶＡ可起到增强力学强度，易于交联的作用。     

渗透汽化复合膜的支撑层对分离性能的影响

研究了多种聚合物膜作为复合膜的多孔支撑层时的性能及其复合膜分离乙醇水给 物时的渗透汽化性能。结果表明,ＣＡ、ＰＡＮ－ＳＳ和ＰＳＡ分别为多孔支撑层的膜材料时,ＰＶＡ复俣的渗透汽化性能优良,尤其是ＰＶＡ／ＣＡ复合膜表现出特别优异的渗秀汽化分离性能。用国产涤纶布增强、聚合物浓度较高的铸膜液制备成厚度适宜的膜为支撑层,可获得理想分离性能的渗透汽化复合物。     

渗透汽化分离有机物

用不同的方法制备了几种分离有机物的膜，如CA/PAN、PVA/PAN的复合膜，以及含金属离子载体的PVA膜，这些膜是复合膜或非对称膜．测量了膜材料(CA和PVA—Me^n )的吸附特性并评价了其性能．结果表明，CA和CTA膜以及几种复合膜适于分离MTBE/MeOH，修正的溶解-扩散模型可成功地估算MTBE／MeOH透过CA膜的渗透汽化分离性能．从初步吸附试验看，含金属离子载体的PVA膜对分离苯／环乙烷体系可能是一好的候选膜．     

海藻酸钠与PVA共混膜用于渗透汽化分离乙醇┐水混合物

制备了天然高分子海藻酸钠与ＰＶＡ的不同比例共混膜，并用于渗透汽化法分离乙醇－水混合物。结果表明，与均质ＰＶＡ膜相比，透过系数及分离系数均大幅度提高，尤其是当乙醇浓度低于８０％时，共混膜依然保持较高分离系数，在共混膜中，ＰＶＡ可起到增强力学强度，易于交联的作用。     

PDMS中空纤维复合膜渗透汽化分离丙酮-水溶液

采用干湿相转化法纺制了聚砜(PSF)中空纤维超滤底膜,并采用溶液浸渍法制备PDMS/PSF中空纤维复合膜.研究了PDMS膜的溶胀性能和PDMS/PSF膜渗透汽化性能,考察了PDMS/PSF膜的稳定性以及料液温度、料液丙酮浓度和渗透物侧压力等因素对膜渗透汽化性能的影响.结果表明,PDMS膜对丙酮有很强的吸附能力而对水的吸附能力则相对较弱,渗透液中丙酮浓度大于膜溶胀液中丙酮浓度,远远大于浸泡液中丙酮浓度,连续操作72 h膜的渗透汽化性能保持稳定,渗透通量随料液温度以及料液浓度的升高而增加,分离系数随料液浓度的增加而降低,基本不受温度的影响.当丙酮质量分数5%、料液温度为60℃时,渗透通量为632 g/(m2.h),分离系数为35.8,丙酮和水的表观活化能分别为45.7和49 kJ/mol.     

离子液体充填型支撑液膜分离乙醇／水混合物

使用离子液体"充填型"支撑液膜,进行乙醇/水混合物的蒸汽渗透膜分离实验,比较了原料浓度、操作温度对分离性能的影响.结果表明,离子液体支撑液膜的蒸汽渗透过程能够实现乙醇脱水,用于制备无水乙醇.经过140 h的实验测定,支撑液膜分离性能稳定.在50℃温度下,原料中含水摩尔分数0.024～0.24时,蒸汽渗透分离因子5.5～3.2,渗透通量55 g/(m2·h).离子液体支撑液膜的蒸汽渗透膜分离过程,有望用于醇类水溶液组成的恒沸体系脱水.     

硅橡胶膜用于乙酸/水渗透汽化分离的研究

以聚二甲基硅氧烷(PDMS)为活性层制备了PDMS均质膜和分别以聚四氟乙烯(PTFE)、聚丙烯(PP)微滤膜为支撑层的PDMS/PTFE膜、PDMS/PP膜。通过扫描电镜(SEM)、视频接触角仪、热重分析(TGA)及溶胀测试等手段研究了膜的物化性能。通过渗透汽化实验考察了膜对乙酸/水体系的分离性能。结果表明,料液中乙酸质量分数提高,渗透通量和分离因子均随之提高;操作温度提高,渗透通量增加而分离因子减小;进料流速在14～38L/h范围变化,对分离因子影响较大,对渗透通量影响较小;支撑层对膜的分离性能有重要影响:30℃下,对于进料流速26L/h的10%(质量分数)乙酸水溶液,PDMS均质膜、PDMS/PTFE膜和PDMS/PP膜的分离因子、通量分别为2.51、2.74、2.15和35.29、42.09、40.84g/(m2·h)。以上结论,对于选择合适的渗透汽化膜支撑层材料和操作条件具有一定的指导意义。     

VTES交联PDMS渗透汽化膜分离水中乙醇性能的研究

以乙烯基三乙氧基硅烷(VTES)为交联剂对端羟基聚二甲基硅氧烷(H-PDMS)进行交联制备了疏水性更强的渗透汽化膜.通过考察交联温度、交联剂用量及料液温度等对该PDMS膜渗透汽化性能的影响发现:对乙醇浓度为6%的体系,交联温度为80℃,质量比m(H-PDMS)∶m(VTES)∶m(DBTDL)(二丁基二月桂酸锡)=1∶0.2∶0.02,原料液温度为40℃时,分离因子和渗透通量分别达到15.5和421.67 g/(m2.h),表明该VTES交联的PDMS膜具有良好的优先透醇性.     

Recovery of phenol from aqueous solution by supported liquid membrane using vegetable oils as liquid membrane

The transport of phenol through a flat sheet supported liquid membrane (SLM) containing vegetable oil as liquid membrane (LM) has been investigated. The permeation of phenol was investigated by varying the experimental conditions like, selection of LM, support material, feed phase pH, stripping solution concentration, stirring speed and different initial concentration of phenol. It has been found that, each LM investigated in the present study shows the effective removal of phenol using polytetrafluoroethylene (PTFE) membrane and PP supported membrane as a solid support. Among the various oils tested, palm oil has chosen to be the best LM with permeability of 8.5x10(-6) m/s in acidic feed of pH 2.0 with 0.2 M sodium hydroxide as effective stripping agent. After 6 h all the phenol from the feed side gets transported to strip solution with an initial concentration of 100 mg/L. A concentration factor of five has been achieved in the present investigation easily with 0.2 M sodium hydroxide as stripping reagent. After 10 transport studies with one impregnation of LM, the LM showed no significant loss in the transport rate with average permeability of 7.9x10(-6) m/s with initial concentration 100 mg/L. Further study has also been attempted with cresols to explore the possibility of applying this to industrial wastewater under the optimized conditions for phenol. After 14 h of the transport studies in the phenol-formaldehyde industry wastewater, phenolic concentration in the feed solution was found to be below detectable level (1x10(-2) mg/L). For wood processing industry wastewater the transport takes place at the initial permeability of 7.1x10(-5) m/s. Thus it has been demonstrated the use of renewable, cheap, non toxic, naturally occurring vegetable oils as a novel, green liquid membrane for the recovery of phenol from aqueous solution in SLM, which has never been employed before in liquid membrane techniques.     

碳分子筛填充聚醚共聚乙酰胺膜渗透汽化分离水溶液中的醋酸正丁酯

将碳分子筛(CMS)引入到聚醚共聚乙酰胺(PEBA)中制备填充膜,采用FTIR、SEM对膜的物理化学结构进行了表征,结果显示CMS与PEBA间未发生化学交联,CMS在膜中分散均匀且与PEBA结合紧密.通过拉伸实验,测定了膜的机械性能.借助溶胀实验,考察了膜在醋酸正丁酯水溶液中的溶胀性能.通过渗透汽化实验,验证了膜的渗透汽化性能,结果表明通量随着温度的升高而增大,分离因子则随温度升高而下降;当料液浓度增大时,醋酸正丁酯的通量和分离因子都显著增大;当CMS填充量为20%时,膜的分离效果最佳,总通量和分离因子分别可达到421.6 g/(m2.h)和590.4.利用Arrhennius方程,关联了通量与温度的关系.另外,还对膜结构与溶液组分的相互作用以及膜中CMS存在通道作用的机理进行了探讨.     

动态LBL组装聚离子膜对乙醇/水体系的渗透汽化性能

采用动态层-层吸附成膜法(动态LBL),以聚醚砜超滤膜为基膜,以聚丙烯酸(PAA)、聚乙烯亚胺(PEI)为聚离子制备了聚离子复合膜.考察了动态成膜与静态吸附成膜的膜性能比较,研究了动态过滤时间、聚离子浓度、进料浓度、温度等因素对该复合膜渗透汽化性能的影响;并对复合膜表面和截面做了扫描电镜分析.在40℃时,该复合膜对乙醇/水体系的分离因子可达1300,渗透通量约150 g/(m2.h),体现了较好的渗透汽化分离性能.     

Extraction of Co(II) from aqueous solution using emulsion liquid membrane

The extraction equilibrium of Co(II) from thiocyanate medium by CYANEX 923 (mixture of straight chain alkylated phosphine oxides) in cyclohexane was studied. The stoichiometry of the extraction reaction was postulated based on slope analysis method and the extraction constant Kex was calculated. The stripping percentage of Co(II) with sulphuric acid from the loaded CYANEX 923 was found to increase with the increase in acid concentration. The extraction of Co(II) from aqueous thiocyanate medium into emulsion liquid membrane using CYANEX 923 extractant was also studied. The influence of different parameters such as stirring speed, surfactant concentration, pH of the extractant phase, carrier concentration, internal phase stripping acid concentration, initial Co(II) concentration as well as temperature on the emulsion stability were investigated. The applicability of the emulsion liquid membrane (ELM) process using CYANEX 923 as extractant and SPAN 80 as surfactant for the removal and the concentration of Co(II) from thiocyanate solution was investigated. The results show that it is possible to recover 95% of cobalt in the inner phase after 10 min of contacting time with a concentration factor of 5.     

Removal of dyes and their mixtures from aqueous solution using liquid emulsion membrane

Extraction of dyes from aqueous solution was studied using liquid emulsion membrane. Study was carried out using two dyes, namely, crystal violet (CV) and methylene blue (MB). Extraction of single component system of each dye and their binary mixture were investigated. Liquid emulsion membrane was formed using n-heptane as membrane phase, sodium hydroxide solution as the internal phase and dye solution as the external phase. Surfactant span 80 was used as the emulsion stabilizer. Effects of concentration of span 80, concentration of NaOH, stirring speed, composition of feed solution and the volume ratio of the oil phase to the aqueous phase (O/A) were studied in detail both for single and binary system. Maximum extraction of MB was found to be 99% and that for CV was about 95% in single component system. In binary mixture, these values were 97% and 90%, respectively.     

PDMS-b-PPO非对称渗透汽化膜对乙醇/水的分离性能

以聚二甲基硅氧烷聚苯醚(PDMS-PPO)嵌段共聚物为膜材料,正丁醇为添加剂,氯仿为溶剂,采用凝胶溶胶法制备非对称渗透汽化膜,利用扫描电镜和能谱仪对膜进行形貌表征及元素分析.研究了铸膜液浓度、膜后侧压力、进料液流速对乙醇/水混合物渗透汽化分离性能的影响.结果表明,随着铸膜液中嵌段共聚物质量分数的增大,非对称膜的分离因子和渗透通量呈先上升后下降的趋势;随着膜后侧压力的增加,分离因子呈上升趋势,而渗透通量下降较快;随着料液流速的提高,分离因子先上升后下降,而渗透通量呈减小的趋势.以嵌段共聚物质量分数为11%制备的非对称膜,在进料液乙醇含量(质量分数)5%、温度60℃、膜后侧压力10kPa、料液流速0.267L/min时,膜的渗透通量为850.7g/(m2.h),分离因子为8.78.实验表明,PDMS-b-PPO非对称膜对乙醇具有优先选择性,并有较高的渗透通量.