共查询到20条相似文献,搜索用时 15 毫秒
1.
《Physics and Chemistry of Liquids》2012,50(2):181-191
Abstract Salt in polyethylene glycol (PEG)/salt aqueous two-phase systems was excluded by PEG and concentrated in the solvent volume available for dissolution of salt (PEG-free solvent). The concentration of salt in the PEG-free solvent of the PEG-rich phase was the same as that at the critical point regardless of the compositions of the PEG/salt two-phase systems. This explained that the phase separation of PEG/salt two-phase systems occurs when the concentration of salt in the PEG-free solvent reaches its solubility limit. The concentration of salt required in the PEG-free solvent for the phase separation was lower with higher molecular weight of PEG. The solubility of salt in the PEG-free solvent decreased with increases in the molal surface tension increment of salt. The solubility limit of salt in the PEG-free solvent was 0.93 M for ammonium sulfate, 0.77 M for potassium phosphate, 0.75 M for sodium tartrate, 0.67 M for sodium phosphate, and 0.53 M for potassium citrate. 相似文献
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Iyyaswami Regupathi Shanon L. Monteiro 《Journal of Dispersion Science and Technology》2014,35(3):418-427
The partitioning behavior of the model protein (bovine serum albumin) was investigated in ionic liquid (1-hexyl-3-methylimidazolium chloride) -salt (potassium carbonate) based aqueous two phase system (ATPS). The phase diagram with binodal curve and tie lines for the selected ATPS was developed at different temperatures and analyzed through effective excluded volume (EEV) and Othmer-Tobias and Bancroft equations, respectively. The influence of various process parameters like the ionic liquid and salt concentration, system temperature, tie line length, phase volume ratio, and neutral salt addition on partition coefficient/extraction efficiency of BSA protein was evaluated. 相似文献
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脂肪酸盐-烷基吡啶盐混合体系的双水相 总被引:4,自引:0,他引:4
研究了脂肪酸盐和烷基吡啶盐混合水溶液中双水相的形成规律和性质.考察了形成双水相的组成范围和烷基碳链长的影响。测定了两相的密度及化学组成.应用电子显微镜观察了两相的微观结构.结果表明,两相均存在囊泡结构.两相含水均在95%以上.上相为表面活性剂富集的囊泡絮凝相,浓度远远大干下相,相差均在二十倍以上.下相为含有分散的囊泡的表面活性剂稀溶液. 相似文献
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对辛基三甲基溴化铵(OTAB)与辛基硫酸钠(SOS)正、负离子混合表面活性剂水溶液的相行为进行了研究.在高浓度的溶液中,混合表面活性剂形成液晶相,随着混合摩尔比OTAB/SOS接近于1,液晶结构由六角相转层状相,同时夹杂少量沉淀物;在中等浓度时,任意混合摩尔比例下皆为均相透明溶液;在低浓度下,在很宽的OTAB/SOS混合摩尔比的范围,出现双水相,其中的表面活性剂稀薄相,为不同大小的胶团与囊泡组成的稀溶液,另一表面活性剂富集相中则为数密度很大的囊泡聚集体,富集相对油溶性染料的增溶作用比非富集相高得多. 相似文献
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在298.15 K下使用目测法和浊度法绘制了1-丁基-3-甲基咪唑四氟硼酸盐([Bmim]BF4)+十二烷基苯磺酸钠(SDBS)+水体系的三元相图,得到了狭窄的靠近离子液体和水一侧的双水相(ATPS)区域。从三元相图的双水相区域周围选择不同组成的样品,用等温滴定微量热(ITC)测定了样品中逐滴加入三次水后体系热量的变化,发现随样品中水含量的增加,量热曲线会出现一个不太明显的吸热和放热过程,且与三元相图中双水相的形成和消失的位置完全吻合,这说明ITC对于双水相体系的热力学研究是一种可行且有效的方法。对本文体系双水相的研究结果表明,双水相的形成是吸热过程(ΔH > 0),而消失是放热过程(ΔH < 0),由于双水相的形成是等温等压下的热力学自发过程(ΔG < 0),因此可以判断该体系双水相的形成是一个熵驱动过程,而消失是一个熵焓共驱过程。 相似文献
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Phase behavior and extraction ability of aqueous two-phase systems(ATPs) consisting of ionic liquids(ILs), Cs2CO3 and water were investigated in this paper. Four kinds of ionic liquids, namely, 1-amyl-3-methylimidazolium bromide([C5mim]Br), 1-hexyl-3-methylimidazolium bromide([C6mim]Br), 1-heptyl-3-methylimidazolium bromide ([C7mim]Br) and 1-octyl-3-methylimidazolium bromide([C8mim]Br), were examined to discuss the influence of alkyl groups. Binodal curves and tie-lines at 288.15, 298.15 and 308.15 K were obtained. The partitioning behavior for L-tryptophan in such ATPs was further investigated. The effect of temperature, pH, Cs2CO3 concentration and the structure of ionic liquids on the partitioning were discussed in detail. 相似文献
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环境因素对正负表面活性剂体系相行为的影响 总被引:3,自引:0,他引:3
在1:1正负离子表面活性剂混合体系(十二烷基硫酸钠/辛基三甲基溴化铵 SDS-C8NM3Br; 十二烷基硫酸钠/十二烷基三甲基溴化铵,SDS-C12NM3Br)中加入短链脂肪醇 (乙醇,正丙醇,正丁醇),正负离子表面活性剂沉淀溶解,出现表面活性剂双水相.上相有液晶存在,下相有囊泡自发形成.折光率数据和电镜结果表明:上相为表面活性剂富集相,下相表面活性剂浓度较低.混合体系中,出现表面活性剂双水相所需短链脂肪醇的体积百分数,随短链脂肪醇的链长增加而降低.温度升高,出现表面活性剂双水相所需短链脂肪醇的体积百分数降低.对SDS/C8NM3Br/H2O体系的研究结果表明:超声处理,可使混合体系中沉淀向囊泡转化,与短链脂肪醇的加入后的作用类似. 相似文献
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正负离子表面活性剂与高聚物混合双水相体系的相行为及蛋白质的分配 总被引:10,自引:0,他引:10
报道了由正负离子表面活性剂与高聚物混合溶液形成的一种可用于蛋白质的分离及分析的新型双水相萃取体系.研究了正负离子表面活性剂(溴化十二烷基三乙铵/十二烷基硫酸钠)分别与葡聚糖和聚乙二醇混合双水相体系的形成规律、相行为及牛血清蛋白和溶菌酶在双水相体系中的分配.通过在高聚物分子中接上亲和配基,研究蛋白质在双水相体系中的亲和分配.结果表明,在该体系中,表面活性剂与高聚物分别富集于不同相中.升高温度及加入无机盐均可促进双水相体系的形成,不同蛋白质可分配于不同的相中.亲和配基的引入极大地增强了蛋白质分配的选择性. 相似文献
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利用双水相体系的温度诱导效应萃取甘草酸 总被引:11,自引:0,他引:11
利用双水相分配技术结合温度诱导效应提取甘草酸,研究甘草酸单铵盐在环氧乙烷-环氧丙烷共聚物(EOPO)/混合磷酸钾(KHP)体系中的分配行为,通过实验确定了最佳体系:EOPO L64浓度为28(wt)%,K2HPO4浓度为32(wt)%。甘草酸单铵盐最大总收率达68.4%,为工业上采用双水相技术提取干草酸提供了一种新途径。 相似文献
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K. Khederlou G. R. Pazuki V. Taghikhani M. Vossoughi C. Ghotbi 《Journal of solution chemistry》2009,38(2):171-186
In this paper, a new Gibbs energy model is proposed to study the thermophysical properties of aqueous electrolyte solutions
at various temperatures. The proposed model assumes that the electrolytes completely dissociate in solution. The model also
has two temperature-independent adjustable parameters that were regressed using experimental values of the mean ionic activity
coefficients (MIAC) for 87 electrolyte solutions at 298.15 K. Results from the proposed model for the MIAC were compared with
those obtained from the E-Wilson, E-NRTL, Pitzer and the E-UNIQUAC models, and the adjustable model parameters were used directly
to predict the osmotic coefficients at this temperature. The results showed that the proposed model can accurately correlate
the MIAC and predict the osmotic coefficients of the aqueous electrolyte solutions better on the average than the other models
studied in this work at 298.15 K. Also, the proposed model was examined to study the osmotic coefficient and vapor pressure
for a number of aqueous electrolyte solutions at high temperatures. It should be stated that in order to calculate the osmotic
coefficients for the electrolyte solutions, the regressed values of parameters obtained for the vapor pressure at high temperatures
were used directly. The results obtained for the osmotic coefficients and vapor pressures of electrolyte solutions indicate
that good agreement is attained between the experimental data and the results of the proposed model. In order to unequivocally
compare the results, the same experimental data and same minimization procedure were used for all of the studied models. 相似文献
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氨基酸在乙醇/磷酸氢二钾双水相体系中分配行为 总被引:1,自引:0,他引:1
研究了5种结构和性质各异的氨基酸(谷氨酸,半胱氨酸,苯丙氨酸,赖氨酸,精氨酸)在亲水性有机溶剂乙醇和磷酸盐溶液形成的乙醇/K2HPO4双水相体系中的分配行为及其影响因素。当双水相体系中乙醇的质量分数从22%增加到30%时,半胱氨酸和苯丙氨酸的分配系数明显增大,其它三种氨基酸的分配系数变化幅度不大;当磷酸盐的质量分数从14%增加到22%时,氨基酸的分配系数的变化均不明显;双水相体系的pH值对氨基酸的分配系数影响较大,当pH增加时,5种氨基酸的分配系数均增加,但是当pH约为9.5时,苯丙氨酸、半胱氨酸的分配系数接近相等但与其它3种氨基酸的分配系数相差较多,当pH为6.0~8.0时,苯丙氨酸的分配系数远远大于另外4种氨基酸。氨基酸的支链结构中含有非极性基团将导致其分配系数的增加。 相似文献
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Aqueous two-phase flotation (ATPF), a novel technique which integrates the principles of aqueous two-phase systems and mass transfer mode of solvent sublation, has been successfully applied for the separation and purification of biological materials in the field of biotechnology. From the studies done so far, ATPF has demonstrated as an effective, economical and environment-friendly technique for separation of labile biomolecules from their crude aqueous extracts of natural plants or fermentation broths, under mild separation condition. In this article, the basic principles, experimental apparatus set up, key design variables of ATPF, ATPF applications and a comparative study between ATPF and other conventional methods are discussed. This review is intended to present a comprehensive summary on the research works carried out so far related to ATPF since its introduction in 2009 until present, which will be helpful for further research in ATPF. 相似文献
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一种用于鸡蛋中氯霉素残留测定的吡啶类离子液体双水相体系 总被引:5,自引:0,他引:5
建立了由亲水性离子液体N-乙基吡啶溴化盐([Epy]Br)和K2HPO4形成的双水相体系对鸡蛋中痕量氯霉素(CAP)检测的高效液相色谱方法.优化了离子液体[Epy]Br和K2HPO4成相的条件,研究了萃取CAP的最佳体系.采用混合溶液(pH=7磷酸盐溶液,NaCl溶液,甲醇)提取样品,离子液体双水相体系富集,V(甲醇):V(水)=30:70为流动相,流速1.0 mL/min,UV检测器,检测波长278 nm,柱温25 ℃,进样量20 μL.对鸡蛋中氯霉素残留进行了测定,在0.05~15 mg/L范围内,CAP的响应峰面积与其相应浓度呈良好相关性(r=0.9994).不同浓度的回收率为90.3%~101.7%,相对标准偏差为1.7%~2.6%.本该法检测鸡蛋中氯霉素残留具有干扰小、速度快、灵敏度高等优点.最低检出限为1 μg/kg. 相似文献
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Hong‐Yun Gao 《合成通讯》2013,43(22):3283-3286
Aristogin C (4), a new diaryl either isolated from the leaves of Aristolochia elegans, was synthesized through a three‐step procedure with readily available materials. All of the three reactions were carried out in aqueous systems. 相似文献
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Yuntao Tang Yige Zhang Xi Chen Xiaowen Xie Ning Zhou Dr. Zhifeng Dai Prof. Dr. Yubing Xiong 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215722
Thermally induced reversible up/down migration of poly(ionic liquid)s (PILs) in aqueous two-phase systems (ATPSs) was achieved for the first time in this study. Novel ATPSs were fabricated using azobenzene (Azo)- and benzyl (Bn)-modified PILs, and their upper and lower phases could be easily tuned using the grafting degree (GD) of the Azo and Bn groups. Bn-PIL with higher GDBn could go up into the upper phase and Azo-PIL come down to the lower phase when the temperature increased (>65 °C); this behavior was reversed at lower temperatures. Moreover, a reversible two-phase/single-phase transition was realized under UV irradiation. Experimental and simulation results revealed that the difference in the hydration capacity between Bn-PIL and Azo-PIL accounted for their unique phase-separation behavior. A versatile platform for fabricating ATPSs with tunable stimuli-responsive behavior can be realized based on our findings, which can broaden their applications in the fields of smart separation systems and functional material development. 相似文献
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In order to obtain a better enantioselectivity of phenylalanine enantiomers and establish the optimal chiral extraction conditions, the distribution behavior was investigated in aqueous two‐phase systems which were composed of polyethylene glycol and ammonium sulfate containing combinatorial chiral selector: β‐cyclodextrin and HP‐β‐cyclodextrin. The influence of the molar concentration ratio of combinatorial chiral selectors, the total molar concentration of combinatorial chiral selectors, pH value, buffer type and its concentration were thoroughly studied, respectively. The results show that the enantioselectivity reaches 1.53 under the optimal chiral extraction conditions. This extraction is a potential economical and effective way for chiral resolution. 相似文献