Thermoresponsive Ionic Liquid/Water Mixtures: From Nanostructuring to Phase Separation

The thermodynamics, structures, and applications of thermoresponsive systems, consisting primarily of water solutions of organic salts, are reviewed. The focus is on organic salts of low melting temperatures, belonging to the ionic liquid (IL) family. The thermo-responsiveness is represented by a temperature driven transition between a homogeneous liquid state and a biphasic state, comprising an IL-rich phase and a solvent-rich phase, divided by a relatively sharp interface. Demixing occurs either with decreasing temperatures, developing from an upper critical solution temperature (UCST), or, less often, with increasing temperatures, arising from a lower critical solution temperature (LCST). In the former case, the enthalpy and entropy of mixing are both positive, and enthalpy prevails at low T. In the latter case, the enthalpy and entropy of mixing are both negative, and entropy drives the demixing with increasing T. Experiments and computer simulations highlight the contiguity of these phase separations with the nanoscale inhomogeneity (nanostructuring), displayed by several ILs and IL solutions. Current applications in extraction, separation, and catalysis are briefly reviewed. Moreover, future applications in forward osmosis desalination, low-enthalpy thermal storage, and water harvesting from the atmosphere are discussed in more detail.     

反胶团相转移法提取青霉素G的研究

报道了非蛋白质类活性物质青霉素Ｇ在反胶团相转移提取中的特性和机理。结果表明，青霉素Ｇ在ＣＴＡＢ／正辛醇：氯仿（４：１，Ｖ／Ｖ）反胶团体系中的相转移提取为离子对静电作用与胶团溶解机理；在室温及ｐＨ值５～８的条件下，提取率在９０％以上，且保持了青霉素的稳定性。     

Associative thickeners. Part I: Synthesis,rheology and aggregation behavior

Nonionic associative thickeners with systematic changes in chemical composition have been synthesized. Rheological measurements of thickened latexes are presented as well as measurements of relaxation times, intrinsic viscosity and osmotic pressure of polymers in pure water solution. We find that the general hydrophobicity of the polymers' end groups control both rheology and efficiency. Hydrophobic parts in the interior of the polymer do not seem to effect rheology in latex systems. Viscosity increases with molecular weight in the low molecular region (Mw<10000), and passes through a maximum in the high molecular region. The thickeners seem to form micelle-like aggregates even at very low concentrations, while at higher concentrations the viscoelastic properties may be modeled by means of one Maxwell element. Only the network relaxation times but not the network structure seems to be dependent on the polymers' end group.     

Predicting ion selectivity in water purification by capacitive deionization: Electric double layer models

Ion-selective water treatment is needed to address emerging problems in an energy- and cost-efficient manner. Capacitive deionization (CDI) is a membraneless water treatment technology, which relies on storing ions in charged electric double layers (EDLs) of micropores. CDI has shown remarkable selectivity, with local density approximations (LDAs) showing some success in guiding selective separations. However, many underlying processes are represented by lumped fitting parameters in LDA models, hindering further progress. Atomistic models help unravel selectivity mechanisms, but are difficult to integrate with cell-level CDI theory. Here, we review and extend LDA models for CDI, highlight a knowledge gap in connecting between LDA and atomistic models for CDI, and emphasize and build upon analogies between micropore EDLs and nanofiltration membranes.     

聚电解质型正渗透汲取液

聚电解质作为正渗透汲取液具有渗透压高、溶质反向渗透、易于回收等特点,符合理想正渗透汲取液的要求。此外,多种分离方法诸如纳滤、超滤和热处理可用于其回收,使得聚电解质型汲取液成为诸如氯化钠等的传统无机汲取液的理想代替物。近年来关于聚电解质型汲取液的研究日益增加,而聚电解质型汲取液较无机型汲取液有许多独特的性质,应对相关研究进展予以总结。本文以聚电解质的化学结构分类对其研究进展进行了概述。重点总结了不同种类聚电解质的分子量、渗透压、黏度等性质,以及正渗透过程的水通量及溶质反向渗透情况,同时还介绍了相应的正渗透机理。最后,探讨和总结了各类汲取液的特点,并展望了未来的研究方向。     

一种新型聚酰亚胺-氨酯反渗透复合膜材料的合成及表征

采用关键功能单体N,N'-二甲基间苯二胺(DMMPD)和多元酰氯5-氯甲酰氧基-异肽酰氯(CFIC)聚合制备了一种耐氧化的聚酰亚胺-氨酯(DMMPD-CFIC)反渗透复合膜材料. 研究了水相溶剂、 多元胺浓度和组成及两相接触时间等因素对DMMPD聚合成膜的影响. 结果表明, 虽然DMMPD-CFIC膜的脱盐率不够理想, 但将4-甲基间苯二胺(MMPD)与DMMPD以2∶1(质量比)组合后制得的MMPD/DMMPD-CFIC膜的脱盐率得到显著提高, 并且对膜的耐氯性能影响不大. 采用傅里叶衰减全反射红外光谱(FTIR)和X射线光电子能谱(XPS)分析了2种膜的活性层的结构, 并利用扫描电镜(SEM)和原子力显微镜(AFM)对膜的表面形态进行了表征.     

反相流动注射-化学发光法测定苯胺

在酸性介质中,苯胺与过量亚硝酸盐重氮化,剩余亚硝酸盐快速氧化亚铁氰化钾,生成的铁氰化钾与鲁米诺发生化学发光反应。据此,建立了反相流动注射 化学发光法测定苯胺的新方法。方法的线性范围为0 070～10.0mg L,检出限为0 03mg L,相对标准偏差(n=11,ρ=1.0mg L)为2 0%。方法已用于环境水样中苯胺的测定。     

十四烷基芳基磺酸盐形成的分子有序组合体

以表面张力法、碘光谱法、水增溶法和相态图法研究了自制的三种十四烷基芳基磺酸盐在不同条件下形成的分子有序组合体(胶束、反胶束和微乳液),并考察了分子结构、溶剂、无机盐和短链醇等对其的影响.结果表明:增加十四烷基芳基磺酸盐分子亲油基支化度,不利于其在水溶液或混合极性溶剂(乙二醇-水)中形成胶束而有利于其在非极性溶剂正庚烷中形成反胶束;溶剂极性的降低,促使表面活性剂溶液由胶束溶液→单体溶液→反胶束溶液转变;无机盐或短链醇的加入促进了水溶液中胶束的形成,且反离子价态数或醇烷基碳原子数越大,越有利于胶束形成;无机盐浓度的增加导致表面活性剂/正丁醇/正辛烷/NaCl/水形成的微乳液体系在一定温度下发生由WinsorI→WinsorIII→WinsorII型的转变.     

反相微乳液介质中纳米Sm2O3的制备

用十六烷基三甲基溴化铵(CTAB)/正丁醇/正辛烷/钐盐水溶液(氨水)所形成的反相微乳液体系, 控制合成Sm2O3球形纳米粒子. 绘制出25 ℃下CTAB/正丁醇/正辛烷/钐盐水溶液(氨水)体系的拟三元相图, 得到了反相微乳液区.在此反相微乳区内合成了Sm2O3的前驱体, 对前驱体进行热分析(TG-DSC), 确定了得到纳米Sm2O3产物的适宜焙烧温度为900 ℃, 并考察了微乳液中反应物浓度、反应时间等因素对合成产物的影响. 采用X射线衍射(XRD)、透射电镜(TEM)、激光粒度仪(NSA)、荧光光谱(FS)仪等分析方法对Sm2O3产物的形貌、晶形、粒径及荧光性质进行了表征. 结果表明, 25 益下利用反相微乳液法, 成功地制备了粒径分布较窄、分散性良好的球形纳米Sm2O3粒子, 粒径约20 nm左右, 且表现出较强的荧光性质.