二-(2-乙基己基)磷酸萃取剂皂化过程中微乳状液的形成条件与相区变化

本文系统地研究用不同浓度的NaOH,KOH和NH₄OH对D₂EHPA(1M)-仲辛醇(15%)-煤油萃取体系进行皂化过程中微乳状液的生成和相区变化:1.测定了有机相中微乳状液生成的条件;2.测定了皂化过程中有机相的电导、粘度和含水量,发现在等当点时有机相都生成微乳状液,而且电导、粘度和含水量也有最大值;3.研究了长链醇的存在与含量对生成微乳状液的影响.通过这些研究,有助于选择和确定这一体系的皂化与萃取条件.     

萃取有机相的微结构和性质的研究

本文用FTIR, 荧光, ICP/AES等方法研究了含稀土的HDEHP[二(2-乙基己基)磷酸, HA]-正庚烷的萃取有机相的结构和聚集态。结果表明: (1)不同稀土离子与萃取剂的配位能力不一样, La相似文献   

稀土与酸性萃取剂形成的溶液聚集态结构

用Fourier变换红外光谱(FT—IR)和光子相关光谱(PCS)研究了皂化的有机磷酸酯类萃取剂和环烷酸萃取剂在正庚烷或正庚烷与2-辛醇的混合溶剂中所形成的聚集物,以及萃取稀土元素后有机相聚集物的变化.结果表明,有机磷酸酯在正庚烷中皂化后形成反向胶团((?)_h<5.0nm),其平均流体力学半径与萃取剂分子的长度相当;2-辛醇的加入可增大反向胶团的粒径.环烷酸皂化后能在混合溶剂中形成W/O型微乳状液(5.0 nm<(?)_h<100 nm).皂化萃取剂萃取稀土元素后,有机相中形成不稳定的聚集物,继而产生聚凝.讨论了聚凝过程的可能机理.     

环烷酸铕-环烷酸钠微乳体系的荧光光谱

许多萃取剂也是表面活性剂 ,在萃取过程中 ,涉及到反向胶团和微乳状液的形成、变和破坏等现象．研究含稀土反胶团和微乳状液中稀土离子的存在状态 ,了解稀土对微乳状液结构的影响 ,对了解稀土萃取过程的机制具有重要的意义［１］．我们曾应用多种手段 ,如红外光谱、核磁共振、小角Ｘ 射线衍射、激光光散射、透射电镜等 ,对皂化环烷酸／水／仲辛醇／正庚烷微乳体系的结构和性质进行了研究［２ -７］．在透射电镜下观察到皂化环烷酸体系形成的微乳状液结构呈球形 ,萃取稀土离子后 ,有机相中形成的聚集体颗粒在电镜下观察 ,离子的平均直径介于…     

十四烷基二甲基苄基氯化铵萃取Au(CN)2-的微观机理

通过萃取平衡、傅里叶变换红外光谱及分峰技术研究了季铵盐十四烷基二甲基苄基氯化铵(TDM-BAC)-磷酸三丁酯(TBP)-正庚烷体系萃取Au(CN)₂^-的机理及过程.提出了萃合物的结构模型是基于氢键的超分子体系,组成为[R₄N⁺]·[Au(CN)₂^-]·4H₂O·4TBP.当有机相金浓度大于3g·L^-1时,有机相中存在聚集现象.通过激光光散射技术测定了有机相中反向胶团的大小,表明萃取过程是分散在水相中的胶团在协萃剂(或助表面活性剂)作用下溶入有机相,转型为反向胶团或微乳液(W/O型)聚集状态.     

萃取过程的量热研究(Ⅳ)——皂化P507萃取有机相中反向胶束和微乳状液的形成

利用量热滴定法研究皂化P507萃取有机相中反向胶束的形成和滴水过程中微乳状液的形成.求得临界胶束浓度、胶束形成常数K、聚集数n以及热力学函数,并用激光动态光散射仪测定胶团和微乳颗粒的流体力学半径。     

离子水化过程的核磁共振研究——二-(2-乙基己基)膦酸-长链醇-煤油-水体系

本文利用无水皂化萃取剂加水生成微乳状液研究离子水化的新方法,研究了酸性膦酸酯D₂EHPA(碱金属盐)-ROH-煤油-水体系中,通过对水质子化学位移变化的规律来研究碱金属的水合作用,所得结果与环烷酸体系相似。当[M⁺]/[H₂O]从100/1向1/100变化时,可以看到配位水的化学位移比缔合水(即正常液体水)向低场移动近2ppm,这比通常在浓盐水溶液中观察到的差值提高了一个数量级。当[M⁺]/[H₂O]大于100/1时,配位水的化学位移随阳离子不同而趋于不同的极限值,其顺序为NH₄⁺(6.76)>Li⁺(6.60)>Na⁺(5.96)>K⁺(5.40)。 从不同体系NMR图峰形和半高宽度Δv_1/2的变化,可以观察到阴离子的结构和组成对离子的水化作用有较大的影响。有关阴离子水合情况的研究工作正在进行中。     

有机磷(膦)酸萃取剂的结构与萃取分离钴(Ⅱ)、镍(Ⅱ)性能的研究

本文对磷酸二烷基酯(P₂₀₄)、单烷基膦酸单烷酯(P₅₀₇)、二烷基膦酸的结构与萃取Co(Ⅱ)、Ni(Ⅱ)的性能进行了较细致、深入的研究。测定了萃取平衡及温度、pH值、浓度等对平衡的影响。随着萃取剂酸性降低,它们对Co(Ⅱ)/Ni(Ⅱ)的分离效果提高。这与萃取体系有机相中Co(Ⅱ)四面体构型萃合物的稳定性增强相一致。     

国家自然科学基金资助项目(1992年度化学部分)

序号负责人____一一一一~~~~~~~~~~‘.‘.......门..,1一.一~~一~~一一~~一~一-----~一~一一-有机超薄膜体系功能与结构关系的研究膜模拟体系的谱学研究酶促成合成有机光电活性材料的研究c’。的物理和化学研究分子工程的光谱学基础研究衫原子址的校准质谱法测定过渡金属与液态Sn间金属间化合物的生长规律和控制皂化萃取剂微乳状液的研究萃取化学中微乳状液等界面现象的研究得的包合型鳌合物鼠杂大环稀土配合物的合成结构和性能新型稀土大环荧光配合物的合成及其特性研究苯既胺类多巴胺脑受体显像剂的研究非平衡萃取分离的研究湿法磷酸脱氟…     

P204萃取剂皂化过程中的物理化学性质及相区变化

Ｐ２０４萃取剂皂化过程中的物理化学性质及相区变化曾平,王贵清（湘潭大学化学系,湘潭,４１１１０５）关键词皂化Ｐ２０４萃取剂,物理化学性质,相区,微乳状液二－（２－乙基己基）磷酸（简称Ｐ２０４或ＨＡ）是一种良好的工业螫合萃取剂,在湿法冶金中得到广泛应用...     

Microemulsions in separation sciences

Fundamental properties of microemulsions in relation to their utilization in liquid state separation methods of ionic and non-ionic compounds are briefly reviewed. Discussions are focused on some characteristics functions of o/w (L₁) and w/o (L₂) single-phase microemulsions and the two-phase microemulsion systems of Winsor I and Winsor II from the viewpoint of their use as separation media in solvent extraction, liquid chromatography and capillary electrophoresis. Through reviewing, practical advantages of the microemulsion media in the separation of metal ions and biological compounds are assessed.     

过渡金属离子的掺杂对TiO2光催化活性的影响

考察了过渡金属离子对TiO₂ 光催化性能的影响,结果发现:第二过渡系列金属离子对TiO₂ 膜的修饰作用比第一过渡系列金属离子的修饰作用更加明显;第二、六副族的金属离子对TiO₂ 膜的修饰效果较好.通过X射线衍射(XRD)、电镜分析 (SEM)、光电能谱分析 (XPS)及差热分析 (DTA)对催化剂表面进行了表征,结果表明:TiO₂ 的晶型为锐钛矿型,粒子半径为 32.58nm.     

A new strategy for supercritical fluid extraction of copper ions

Complexation combined with supercritical fluid extraction was used to extract Cu²⁺. The effects of pressure, temperature, and total volume of CO₂ on the efficiency of extraction were systematically investigated. The extraction recovery was low (57.32%) only by pure supercritical CO₂. Addition of a suitable amount of methanol (v/v=5%) to supercritical CO₂ could enhance the extraction of Cu²⁺ (72.69%, relative standard deviation (R.S.D.)=2.12%, n=3), and the recovery increased largely (90.52%, R.S.D.=2.20%, n=3) in the presence of nonionic surfactant Triton X-100. Reverse micelle formation is presented as a new strategy of improving the extraction of metal ions with supercritical CO₂ in this paper.     

Uranium micelle-mediated extraction in acetate medium: factorial design optimization

A micelle-mediated extraction (CPE) procedure has been developed to remove trace amounts of uranium from wastewater using a non-ionic surfactant (Triton (X-100)) and lipophilic chelating extracting agent (D2EHPA) in acetate medium. The methodology used is based on the formation of metal complexes soluble in a micellar phase of a non-ionic surfactant. The uranyl ions complexes are then extracted into the surfactant-rich phase at a ambient temperature. The effects of different operating parameters such as the concentrations of Triton (X-100), D2EHPA and metal ions, temperature, sodium acetate rate and pH on the cloud point extraction of uranyl ions were studied in details and a set of optimum conditions were obtained. The results showed, without contribution of energy (ambient temperature), that up to 1000?ppm of uranyl ions can quantitatively be removed (>97?%) in a single CPE extraction using optimum conditions.     

Zn(II), Cd(II) and Cu(II) separation through organic–inorganic Hybrid Membranes containing di-(2-ethylhexyl) phosphoric acid or di-(2-ethylhexyl) dithiophosphoric acid as a carrier

A membrane process for metal recovery from aqueous solutions was studied. Metal ions diffused from the feed solution to the stripping phase through an Hybrid Membrane containing di-(2-ethylhexyl) phosphoric acid (D2EHPA) and/or di-(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA) as a carrier. Such membranes were prepared by a sol–gel route including cellulose triacetate and polysiloxanes. Transport behaviour was evaluated for both carriers under similar experimental conditions. The transport experiments reported here concerned transport at different cycles and selectivity towards different metal ions. Using D2EHPA the membrane provided a selective transport of zinc to the stripping compartment of the membrane cell, while copper and cadmium remained in the feed compartment. Whereas, using D2EHDTPA as carrier the transport rate increased and the selectivity profiles were inverted in relation with those of D2EHPA. With a mixture of both extracting agents it was observed an intermediate behaviour in selective transport, being possible to modulate it.     

Solvent extraction of zinc from sulphate leaching solution of a sulphide-oxide sample using D2EHPA and Cyanex 272

Solvent extraction of zinc from sulphate leach solution obtained from the treatment of a sulphide-oxide sample, was investigated using D2EHPA and Cyanex 272 diluted in kerosene in a batch reactor. According to the results, D2EHPA exhibited the higher extraction efficiencies than Cyanex 272 at the organic/aqueous ratio of 1:1. The optimum concentration and pH for D2EHPA and Cyanex 272 were distinguished to be 0.5?mol/L and 2.5, and 0.035?mol/L and 3.5, respectively. Under these conditions, extraction efficiency was found to be ～75% for D2EHPA against 41% for Cyanex 272. The plot of log D versus log [D2EHPA] confirmed the presence of 1 mole D2EHPA in dimeric form for 1 mole Zn in the extraction system. Thermodynamic data showed that the zinc extraction process is endothermic. For D2EHPA, two-stage simulated counter-current extraction experiments were performed on the basis of the McCabe-Thiele diagram and the extraction percentage of zinc was found to be about 88%. The synergistic effect of Cyanex 272 and TBP with D2EHPA was particularly investigated. It was found that the mixture of 80% D2EHPA and 20% Cyanex 272 exhibited the best synergistic effect for Zn-extraction with a synergistic coefficient of 1.04.     

Liquid-Membrane Transport of Rare Earth Metal Ions Facilitated by Di(2-Ethylhexyl) Phosphoric Acid: Comparison with the Results of Corresponding Centrifugal Partition Chromatography

Abstract

Selective liquid-membrane transport of rare earth metal ions were found to be effectively attained by the use of di(2-ethylhexyl)phosphoric acid (D2EHPA) carrier. This finding was obtained on the basis of the idea that liquid-membrane transport phenomena would be basically correlated with those of “separator-aided centrifugal partition chromatography”, a separation technique based on the counter-current continuous extraction method. For the rare earth metal ion samples direct comparison of liquid-membrane transport with the corresponding centrifugal partition chromatography by employing the same two-phase liquid systems both containing D2EHPA showed that a close parallelism in the results obtained with the two separation systems.     

镧系金属离子的水化能

一、水化能公式 离子水化能是重要的热化学数据,前人曾作过很多研究^[1-4]。     

UiO-66-NH2/wood的设计构筑及高效去除水中微量重金属离子性能

矿山开采、 金属冶炼、 新型金属材料的发展以及城市供水系统老化所造成的重金属(铅、 镉、 汞、 砷、 铬、 铜及锌等)污染问题已日趋严重. 传统的水处理方法很难有效地去除低浓度的重金属污染物. 本文以天然木材为载体, 采用溶剂热合成法, 在木材三维孔道中原位合成UiO-66-NH₂金属有机框架材料(MOFs)纳米颗粒, 制备了UiO-66-NH₂/wood复合膜材料. 该复合膜材料对去除水中微量重金属离子(Hg²⁺, Cu²⁺)表现出优异的性能. 当处理速率为1.1×10² L?m^-2?h^-1时, 该复合膜材料去除水中微量重金属离子的效率仍可达到90%以上, 且处理后水中重金属离子含量低于国家饮用水标准. 这可归因于木材本身独特的三维孔道结构, 在提高水通量的同时, 还可以增加水溶液中重金属离子与MOFs颗粒的接触机会, 以及孔道内均匀分布的UiO-66-NH₂ MOFs颗粒中的—NH₂可以与重金属离子通过配位作用相结合. 该UiO-66-NH₂/wood复合膜材料还具有良好的重复利用性, 在连续6次循环使用后其去除效率无明显变化, 有望进行实际应用.     

FREE RADICALS FROM THE PHOTODECOMPOSITION OF BLEOMYCIN

Abstract— Irradiation of bleomycin with light (λ > 320 nm) leads to a decrease in absorbance at 290 nm, which is suppressed by metal ions and by oxygen. Light-induced oxygen consumption is diminished by the enzymes superoxide dismutase and catalase, implying that toxic reduced species of oxygen (O₂ and H₂O₂) are formed during irradiation. Spin-trapping measurements with 5,5-dimethyl-1-pyrroline-1-oxide and 2-methyl-2-nitrosopropane demonstrated that hydroxyl radical and methyl radical adducts also are generated in the system. In addition, direct ESR measurements have shown that methyl radicals are produced during irradiation of bleomycin solutions at low temperatures, together with radicals probably derived from the bithiazole moiety of the bleomycin. The latter are also produced from irradiation of the model compound bithia. Radical production is diminished by complexation of bleomycin with metal ions.