The Effect of Organic Diluent on the Extraction of Eu(III) by HEH[EHP]

ABSTRACT

Because there are fewer tools available to probe the interactions therein, the effect of the fundamental chemistry of the organic diluent on solvent extraction equilibria has been under-characterized relative to the aqueous. As a result, diluents for solvent extraction are often selected for an application not for their utility as a medium for reaction, but for other (often equally) important reasons (like low flammability). To begin to improve this imbalance in the science, twenty different diluents have been used in a study of the extraction of radiotracer ^152/154Eu³⁺ from dilute nitric acid solutions using the extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]). To increase the utility of the study and to honor the memory of Professor Jan Rydberg, this investigation was conducted by a cadre of comparatively inexperienced separation scientists (who are as a result no longer inexperienced separation scientists) as a radioanalytical chemistry and solvent extraction educational exercise. Slope analysis was used to determine the apparent stoichiometry of the extracted metal complex. The results discussed in the following indicate that, while the pH dependence exhibits the expected three H⁺ exchanged per metal ion extracted, the extractant dependence suggests that the number of protonated extractant molecules in the extracted complex changes with the organic diluent. The experimentally observed “extractant dependency” ranges from 2.5 to 3.0 dimer equivalent molecules per extracted metal ion. Ironically, in the diluents exhibiting the highest apparent M:(HA)₃ stoichiometry, HEH[EHP] extracts Eu³⁺ less efficiently. Europium luminescence spectroscopy was used to probe for changes in the first coordination sphere of the complex in different diluents. A model and conceptual framework for understanding these observations is described.     

上海地区应用燃气热泵的天然气定价探讨

简要介绍了燃气热泵(GHP)和电动多联机(EHP)的性能;对上海的几种典型用户,按照负荷配置目标建筑的室内、室外机,计算其逐时负荷,确定GHP机组的全年天然气耗量、辅助电耗等,并与实际耗气量进行比较;作为对比,同样计算确定EHP的耗电量;结合现行的电价和天然气价格,分析GHP机组的经济性并提出建议的分季节天然气价格。     

Transport Behaviour of La~（3＋） with Flat－Sheet－Sandwich Supported Liquid Membrane Extraction System

ＴｒａｎｓｐｏｒｔＢｅｈａｖｉｏｕｒｏｆ Ｌａ~（３＋） ｗｉｔｈ Ｆｌａｔ－Ｓｈｅｅｔ－ＳａｎｄｗｉｃｈＳｕｐｐｏｒｔｅｄ ＬｉｑｕｉｄＭｅｍｂｒａｎｅＥｘｔｒａｃｔｉｏｎＳｙｓｔｅｍＹｉＴａｏ（易涛）；ＹａｎＣｈｕｎｈｕａ（严纯华）；ＬｉＢｉａｏｇｕ?..     

轴向柱塞式电液泵能量转化效率研究

电液泵是一种将电动机与液压泵共转子、共壳体进行高度融合的新型液压动力单元,与传统通过联轴器联结的电动机-泵组相比,具有结构紧凑、功率重量比大等优点。作为新型高集成液压源,电液泵的能量转化效率是业内关注的一个重要指标。介绍轴向柱塞式电液泵的结构与工作过程,分析轴向柱塞式电液泵的电磁、机械、容积各部分损耗,建立相应各部分效率与总效率的计算模型,在此基础上给出轴向柱塞式电液泵定子与转子间油隙损耗、各部分效率以及总效率随转速、压力、温度变化的曲线,分析电液泵的油隙损耗对电液泵效率的影响以及电液泵能量转化效率的特点。理论计算与试验结果的对比验证表明,计算模型是准确的。计算结果表明,研究的这种轴向柱塞式电液泵在油温50℃、转速4 500 r/min、压力28MPa时的油隙损耗为1.85%,低于电动机-泵组中电动机的风扇与机械损耗;其总效率为81.2%,高于电动机-泵组的总效率。     

燃气热泵应用分析

燃气热泵(GHP)是一种节能、环保、经济的空调系统形式,并可以平衡大中城市的燃气和电力使用负荷。本文对燃气吸收式热泵(GAHP)的应用进行了简单分析,并重点分析了燃气发动机驱动热泵(GEHP)与电动热泵(EHP)在系统结构、技术性能、投资、运行等方面的应用特点。     

Dimerization of 2-Ethylhexylphosphonic Acid Mono-2-ethylhexyl Ester (HEH[EHP]) as Determined by NMR Spectrometry

ABSTRACT

The aggregation state of extractant molecules is an important consideration in characterizing or modeling solvent extraction systems used in hydrometallurgy. For example, previously reported efforts to measure organic-phase dimerization constants have required the presence of an additional phase, either aqueous phase or gas phase. NMR spectroscopy can be used to probe organic-phase inter-molecular interactions without requiring the presence of an additional phase, making it possible to study the simplest organic system, that contain only extractant and diluent. In this report, the dimerization of 2-ethylhexylphosphonic acid mono-2-ethylhexl ester (HEH[EHP]) in n-dodecane and in toluene was investigated by two different NMR-based methods: chemical shifts and Diffusion Ordered SpectroscopY (DOSY). The chemical-shift analysis requires monitoring the chemical shift of the acidic proton as the concentration of HEH[EHP] changes. DOSY is a 2D NMR technique used to probe the size of molecules. The size of diffusing species was related back to the average aggregate molecular weight via a calibration curve. Because the DOSY method had not been used in this manner before, a validation of the method using the interaction constant between HDEHP and CMPO was performed. After this validation, DOSY was applied to HEH[EHP] dimerization. DOSY results demonstrated that the chemical shift of the acidic proton was the peak most affected by the dimerization state of the HEH[EHP]. All other peaks, including that of ³¹P, were affected more significantly by the changing dielectric constant of the solution. The dimerization constants determined were significantly lower than those reported in prior literature, possibly due to the effect of water in the literature values.     

Combining CMPO and HEH[EHP] for Separating Trivalent Lanthanides from the Transuranic Elements

Combining octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) into a single process solvent for separating transuranic elements from liquid high-level waste is explored. The lanthanides and americium can be co-extracted from HNO₃ into 0.2 mol/L CMPO + 1.0 mol/L HEH[EHP] in n-dodecane. The extraction is relatively insensitive to the HNO₃ concentration within 0.1–5 mol/L HNO₃. Americium can be selectively stripped from the CMPO/HEH[EHP] solvent into a citrate-buffered N-(2-hydroxyethyl)ethylenediaminetriacetic acid solution. Separation factors >14 can be achieved in the range pH 2.5–3.7, and the separation factors are relatively insensitive to pH—a major advantage of this solvent formulation.     

Transport Behaviour of La~（3＋） with Hollow Fiber Sandwich Liquid Membrane Extraction System

ＴｒａｎｓｐｏｒｔＢｅｈａｖｉｏｕｒｏｆＬａ~（３＋）ｗｉｔｈＨｏｌｌｏｗＦｉｂｅｒＳａｎｄｗｉｃｈＬｉｑｕｉｄ　ＭｅｍｂｒａｎｅＥｘｔｒａｃｔｉｏｎ　ＳｙｓｔｅｍＺｈｕＧｕｏｂｉｎ（朱国斌）；ＬｉＪｉｅ（李洁）（ＤｅｐａｒｔｍｅｎｔｏｆＣｏｍｍｏｄ?..     

An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 2. Flowsheet Test with Actinide-spiked Simulant

An Advanced TALSPEAK (trivalent actinide–lanthanide separations by phosphorus-reagent extraction from aqueous complexes) counter-current flowsheet test was demonstrated using a simulated feed spiked with radionuclides in annular centrifugal contactors. A solvent comprising 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP] or PC88A) in n-dodecane was used to extract trivalent lanthanides away from the trivalent actinides Am³⁺ and Cm³⁺, which were preferentially complexed in a citrate-buffered aqueous phase with N-(2-hydroxyethyl)ethylenediamine-N,N´,N´-triacetic acid (HEDTA). In a 24-stage demonstration test, the trivalent actinides were efficiently separated from the trivalent lanthanides with decontamination factors >1000, demonstrating the excellent performance of the chemical system. Clean actinide and lanthanide product fractions and spent solvent with very low contaminations were obtained. The results of the process test are presented and discussed.     

An Advanced TALSPEAK Concept Using 2-Ethylhexylphosphonic Acid Mono-2-Ethylhexyl Ester as the Extractant

A method for separating the trivalent actinides and lanthanides is being developed using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) as the extractant. The method is based on the preferential binding of the actinides in the aqueous phase by N-(2-hydroxyethyl)ethylenediamine-N,N’,N’-triacetic acid (HEDTA), which serves to keep the actinides in the aqueous phase while the lanthanides are extracted into an organic phase containing HEH[EHP]. The process is very robust, showing little dependence upon the pH or the HEH[EHP], HEDTA, and citrate concentrations over the ranges that might be expected in a nuclear fuel recycling plant. Single-stage runs with a 2-cm centrifugal contactor indicate that modifications to the process chemistry may be needed to increase the extraction rate for Sm, Eu, and Gd. The hydraulic properties of the system are favorable to application in centrifugal contactors.