盐湖卤水萃取提锂及其机理研究

本文以磷酸三丁酯(TBP)为萃取剂,煤油为稀释剂,在FeCl₃存在的条件下,选择性萃取盐湖卤水中的锂。系统研究了相比、萃取剂组成、铁锂比等对锂萃取率的影响,及洗涤、反萃取工艺条件。得到最佳工艺条件为：萃取相比V_O/V_A为1.5,TBP质量分数为75%,c_Fe³⁺/c_Li⁺=2,c_H⁺=0.02 mol·L^-1,萃取时间为20 min;洗涤相比V_O/V_A为15;反萃取相比V_O/V_A为20。并运用红外与核磁方法分析研究,表明是TBP上的P=O双键与LiFeCl₄金属配合物的配位水分子产生氢键作用而使金属配合物与TBP结合。     

Determination of technetium-99 in environmental samples: A review

Due to the lack of a stable technetium isotope, and the high mobility and long half-life, ⁹⁹Tc is considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. ⁹⁹Tc is also an important tracer for oceanographic research due to the high technetium solubility in seawater as TcO₄⁻. A number of analytical methods, using chemical separation combined with radiometric and mass spectrometric measurement techniques, have been developed over the past decades for determination of ⁹⁹Tc in different environmental samples. This article summarizes and compares recently reported chemical separation procedures and measurement methods for determination of ⁹⁹Tc. Due to the extremely low concentration of ⁹⁹Tc in environmental samples, the sample preparation, pre-concentration, chemical separation and purification for removal of the interferences for detection of ⁹⁹Tc are the most important issues governing the accurate determination of ⁹⁹Tc. These aspects are discussed in detail in this article. Meanwhile, the different measurement techniques for ⁹⁹Tc are also compared with respect to advantages and drawbacks. Novel automated analytical methods for rapid determination of ⁹⁹Tc using solid extraction or ion exchange chromatography for separation of ⁹⁹Tc, employing flow injection or sequential injection approaches are also discussed.     

The enthalpies of mixing of organophosphate esters with hydrocarbons

Heats of mixing were obtained calorimetrically at 298°K for each of the phosphate esters tri-n-butylphosphate (TBP), bis(2-ethylhexyl)phosphate [(H)DE-HP], and di-n-butylphosphate [(H)DBP] withn-dodecane and with 1,3-diethylbenzene. These data and data from the literature on Gibbs free energies and heats of mixing of the phosphate esters with decane, hexane, and benzene are interpreted according to a nonideal associated mixture model. This takes into account the size effect, nonspecific (regular-type) interactions, and association to dimers, which is partial for TBP and complete for the acidic esters, which in turn associate further to trimers and possibly higher oligomers. The enthalpies of mixing with the aliphatic hydrocarbons involve two parameters, one describing the association and the other the nonspecific interaction, and independently obtained quantities. The enthalpies of mixing with the aromatic hydrocarbons require further parameters, involving the mutual interactions, which could not be calculated.     

Isomorphic substitution of boron in ZSM-5 type zeolites using TBP as template

A series of B-ZSM-5 samples has been synthesized using ethyl silicate (ES) ester-40, orthoboric acid and tetrabutylphosphonium (TBP) cation template and characterized by XRD, FT-IR, SEM and chemical analysis. It is observed that boron content in the initial reaction mixture influences the crystallization time and the morphology of the crystals. The migration of boron from framework upon calcination is enhanced as the boron content in the framework is increased. The test reaction of 1-hexene is under the profound influence of temperature on conversion and on the formation of primary products trans-2-hexene (t-2H), cis-2-hexene (c-2H) and 3-hexene. The ratios of the selectivity of c-2H to t-2H and 2-hexene to 3-hexene increased with decreasing temperature and decreasing boron content in the framework. Skeletal isomerization products started forming from 250°C as secondary products and increased with further increase of temperature.     

Facilitated Transport of Penicillin G by Bulk Liquid Membrane with TBP as Carrier

The facilitated transport of penicillin G from aqueous solutions to the stripping phase through bulk liquid membrane (BLM) containing TBP in 3% iso-octanol and n-butyl acetate was studied. Na₂CO₃ solution was used as the stripping phase. Experiments were performed as a function of stirring rate, TBP concentration and type of diluent in the liquid membrane phase, pH, and initial penicillin G concentration in the feed phase, Na₂CO₃ concentration in the stripping phase, etc. The results showed that the BLM process could carry out the simultaneous separation and concentration of penicillin G from dilute aqueous solutions, and arise “up-hill” effect due to the characteristic of non-equilibrium mass transfer. The diffusion of penicillin G complex in the liquid membrane phase played an important role in BLM process. The mass transfer mechanism of BLM for this system was also discussed.     

Improvements in the selection of real components forming a substitute mixture for petroleum fractions

Complex mixtures, particularly petroleum fractions, usually need to be suitably modeled before providing the simulation and other types of chemical engineering calculations. The most convenient way is to describe the original mixture by a substitute mixture. The formerly published approach based on the employment of substitute mixtures of real components can be improved in order to get a closer match between the behavior of the original and substitute mixtures. In the first phase of the algorithm, a new concept of a band around the characterization curves brings wider possibilities for the selection of real components into the substitute mixture. The second phase, which is used to determine the composition of the substitute mixture, can be also improved by considering the global or bulk properties of the original mixture if available. Typically, some of the properties e.g. liquid density, molecular mass and PNA (Paraffinic/Naphthenic/Aromatic carbon) analysis can be measured and used to improve the adjustment of the composition. The improved algorithm is illustrated by an example.     

TBP萃淋树脂分离ICP-MS测定八氧化三铀中的钍和锆

采用TBP萃淋树脂萃取色层分离,ICP–MS法测定U_3O_8中痕量杂质元素Th和Zr。U_3O_8样品先经硝酸溶解,再用盐酸转化成氯化铀酰,以TBP萃淋树脂作为固定相,6 mol/L盐酸作为流动相,使铀与待测杂质元素Th和Zr进行分离,用ICP–MS测定淋洗液中杂质元素Th和Zr的含量。Th和Zr的检出限分别为0.008 5μg/L和0.068μg/L,线性方程分别为y=55.789x–0.001 2和y=23.889x–0.001 7,线性相关系数r2=1。测定结果的相对标准偏差均小于5%(n=5),加标回收率在96%~103%之间。用该法测定U_3O_8标准物质,测定结果与标准值一致。该法操作简便,分离快速,测定结果准确、可靠。     

近红外光谱法测定30%TBP/正十二烷中硝酸含量

核燃料后处理工艺控制分析中,有机相中硝酸含量是一项重要的控制参数。通过研究TBP/正十二烷介质中硝酸的近红外光谱,将有机相样品的傅立叶变换近红外光谱与偏最小二乘回归法相结合,建立了含铀后处理有机相样品中硝酸浓度的测量方法。建立的定量校正模型的最佳校正标准偏差(RMSEC)、预测标准偏差(RMSEP)以及相关系数(r)分别为0.011,0.014,0.999。方法检出限为0.05 mol/L,测量结果的相对标准偏差不大于4%(n=6)。采用近红外分析法与滴定法对模拟样品进行测量,对测量结果进行t检验,结果表明两种方法的测定结果无显著性差异。所建方法无需样品预处理,可直接测量,分析速度快,结果准确,具有一定的实用性。     

Room temperature phosphorescence in the liquid state as a tool in analytical chemistry

A wide-ranging overview of room temperature phosphorescence in the liquid state (RTPL¹) is presented, with a focus on recent developments. RTPL techniques like micelle-stabilized (MS)-RTP, cyclodextrin-induced (CD)-RTP, and heavy atom-induced (HAI)-RTP are discussed. These techniques are mainly applied in the stand-alone format, but coupling with some separation techniques appears to be feasible. Applications of direct, sensitized and quenched phosphorescence are also discussed. As regards sensitized and quenched RTP, emphasis is on the coupling with liquid chromatography (LC) and capillary electrophoresis (CE), but stand-alone applications are also reported. Further, the application of RTPL in immunoassays and in RTP optosensing—the optical sensing of analytes based on RTP—is reviewed. Next to the application of RTPL in quantitative analysis, its use for the structural probing of protein conformations and for time-resolved microscopy of labelled biomolecules is discussed. Finally, an overview is presented of the various analytical techniques which are based on the closely related phenomenon of long-lived lanthanide luminescence. The paper closes with a short evaluation of the state-of-the-art in RTP and a discussion on future perspectives.     

不同稀释剂中TBP萃取醋酸的研究

研究了不同稀释剂中ＴＢＰ对醋酸的萃取，其萃取能力在不同稀释剂中按甲苯〉苯〉环己烷〉煤油〉四氯化碳〉氯仿〉甲基异丁基酮的顺序变化，求出了萃取反应的焓变，建立了萃取平衡常数与稀释剂物理参数间的经验方程，并用红外光谱对萃取机理进行了研究。