硫酸体系中P507浸渍树脂吸附Cd(Ⅱ)的研究

选用2-乙基已基膦酸单(2-乙基已基)酯(P507)为萃取剂,HZ818大孔树脂为载体,以干法浸渍技术制备了P507浸渍树脂.研究了吸附平衡时间、溶液pH和树脂用量对硫酸体系中该浸渍树脂吸附Cd(Ⅱ)的影响.静态吸附实验表明,吸附过程符合准二级动力学模型.采用0.5mol/L的盐酸溶液可将吸附在树脂上的Cd(Ⅱ)洗脱下来.     

2-乙基己基磷酸单(2-乙基己基)酯萃淋树脂分离-火花源质谱法测定高纯氧化镱中痕量稀土杂质

本文采用萃取色谱法以2-乙基已基膦酸单(2-乙基已基)酯(P_507)萃淋树脂为固定相,以HCI-NH_4CI体系为淋洗液,研究了99.999%~99.9999%的高纯Yb_2O_3中稀土杂质和Yb基体的分离条件,将杂质淋洗液富集于复合螯合剂-活性碳上,经灼烧灰化后制成样品电极,进行质谱测定.测定下限达 0.01~0.05 μg/g,可用于高纯 Yb_2O_3中杂质的测定.回收率在80%以上.     

钴(Ⅱ)在二-(2-乙基己基)膦酸/CHCl3支撑液膜体系中的传输

钴(Ⅱ)在二-(2-乙基己基)膦酸/CHCl3支撑液膜体系中的传输;液膜分离     

2-乙基己基膦酸单(2-乙基己基)酯-H2SO4-钴(Ⅱ)、镍(Ⅱ)萃取体系中所形成的配合物研究

制备了一元酸性磷(膦)酸酯类萃取剂(HL)二(2-乙基已基)磷酸(P-204)和2-乙基已基膦酸单(2-乙基已基)酯(P-507)与钴(Ⅱ)、镍(Ⅱ)的配合物。通过元素分析、水含量测定、热重分析、红外和电子光谱及磁矩测定就二种萃取剂与钴、镍配合物的组成、性质和立体构型进行了比较研究。结果表明,二种配体所形成的配合物是相似的。深兰色的钴配合物CoL_2为四面体构型。棕色的镍的无水配合物NiL_2和绿色的含水配合物NiL_2·2H_2O对均为八面体构型。四面体钴配合物中键的共价性程度大于八面体的镍配合物。     

镧系元素三元协萃规律研究——AAC类(P507-PMBP-TOA)协萃Eu~(3+)和Tb~(3+)机理

本文论述了2-乙基己基膦酸单2-乙基已基酯(P507)、1-苯基3-甲基4-苯甲酰基吡唑啉酮-5(PMBP)与三辛胺(TOA)的甲苯溶液,从盐酸底液中萃取铕和铽的机理。该体系属于螯合、离子缔合AAC类,并根据实验数据得到了该体系的一元、二元和三元萃取平衡常数。     

液膜富集技术与分光光度法测定痕量稀土

在分析化学中用液膜富集痕量物质是一个新课题,而关于痕量稀土的液膜富集方法,迄今报道甚少。为此,我们研究了液膜萃取富集分离ppb级稀土的方法,并提出了稀土的分组富集方法,从而提高了分光光度法测定稀土的灵敏度。 (一)主要试剂 兰113A(单丁二酰亚胺)作为液膜的表面活性剂,P507(2-乙基己基膦酸单2-乙基     

在硫酸盐体系中用二-(2-乙基己基)磷酸萃取钴(Ⅱ)镁的研究

二-(2-乙基己基)磷酸是一种良好的萃取剂,对它的研究也较多。但用二-(2-乙基已基)磷酸萃取钴(Ⅱ)和镁的机理除了Baes作了些工作外,以后的工作就很少了。我们在前一工作的基础上又研究了二-(2-乙基已基)磷酸的煤油溶液从硫酸钠和硫酸铵溶液中萃取钴(Ⅱ)镁的萃取机理及介质、酸度、温度对萃取的影响。     

溶剂萃取过程动力学研究(Ⅱ)——HEH(EHP)从硫酸盐溶液中萃取Zn(Ⅱ)

本文以苯为稀释剂,考察了2-乙基己基膦酸单2-乙基己基酯(HEll(EHP),P_(507)从硫酸盐溶液中萃取Zn(Ⅱ)的动力学过程。 (一)实验 1.HEH(EHP)按铜盐法提纯,纯度为99.26％.其余主要试剂为A.R.级. 2。自制恒温恒界面反应池,两相分别搅拌,方向相反,以SZGB-11光电转速传感器测定两相搅拌速度,使之基本相等。根据需要可更换反应池内筒调节界面积大小。     

钴(Ⅱ)-2-乙基己基膦酸单(2-乙基己基)酯固体萃合物成键特性和构型的研究

2-乙基己基膦酸单(2-乙基己基)酯(简写HEH(EHP)或P_(?07))是一种工艺性能优良的金属萃取剂,广泛应用于稀土分组及钴镍等金属的分离。对其萃取金属的性能和平衡的研究已有报道。研究萃合物的成键特性及空间构型,对于深入了解萃取机理有     

金属离子提取的支撑型液膜稳定性:膜材料研究进展

支撑液膜是一种结合膜材料与萃取体系的高效率分离技术.然而在使用过程中,溶剂与萃取载体从多孔支撑体中流失和多孔膜材料在有机相载体中不稳定,导致支撑液膜通量的衰减或选择性降低,支撑液膜表现为不稳定,目前尚未见工业化的成功案例.本文简要介绍了支撑液膜不稳定机理,从膜材料角度,综述了提高支撑液膜稳定性的方法.重点介绍了液膜凝胶...     

Transport of U(VI) from sulphuric acid medium across supported liquid membrane (SLM) containing di-(2-ethylhexyl) phosphoric acid (D2EHPA)/n-dodecane as a carrier

This paper reports on the supported liquid membrane (SLM) based transport studies of U(VI) from sulphate medium using di-(2-ethylhexyl) phosphoric acid/n-dodecane as carrier. Polytetrafluoroethylene membrane was used as solid support and H₂SO₄ as receiver phase. The effects of various parameters such as receiver phase concentration, feed acidity, carrier concentration, U(VI) concentration, membrane thickness and membrane pore size on U(VI) transport had been investigated. With increase in H₂SO₄ concentrations and pH of feed solution there is an increase in U(VI) transport across the SLM. Similarly with increase in membrane thickness the U(VI) transport decrease whereas in case of pore size variation reverse results are obtained. The membrane thickness variation results showed that the U(VI) transport across the SLM is entirely diffusion controlled and the diffusion coefficient the D _(o) was calculated as 1.36 × 10^?7 cm² s^?1. Based on optimized condition, a scheme had been tested for selective recovery of U(VI) from ore leach solution containing a large number of other metal ions.     

Kinetics of europium(III) transport through a liquid membrane containing HEH(EHP) in kerosene

Coupled transport of Eu(III) ions through a bulk liquid membrane containing mono(2-ethylhexyl)2-ethylhexyl phosphonate [HEH(EHP)] in kerosene has been examined. The influences of the carrier concentration, the HCl concentration in the stripping solution, the pH in the feed solution and the temperature were investigated. The transport of the Eu(III) ions is coupled by counter-transport of protons. The kinetics of the Eu(III) transport could be analyzed in the formalism of two consecutive irreversible first order reactions. The pseudo-first order apparent rate constants of the interfacial transport of the Eu(III) species are determined, varying temperature. The activation energy values are 14.0±1.0 and 54.0±3.4 kJ mol⁻¹ for extraction and stripping, respectively.     

Mechanistic study of active transport of silver(I) using sulfur containing novel carriers across a liquid membrane

This work studies the mechanism of active transport of silver(I) through an immobilized liquid membrane (ILM) containing thiourea derivatives having sulfur as donor atoms, namely (N-(N′,N′-diethyl thiocarbamoyl)N″-phenylbenzamidine (TCBA) and 1,6-diethylcarbamoyl imino)-1,6-diphenyl-2,5 dithiahexane (TCTH) dissolved in cumene as mobile carrier. An uphill transport model has been described and equations have been derived taking into account aqueous boundary layer diffusion and liquid membrane diffusion as simultaneous controlling factors. In the present model, various separate cases were discussed using carrier TCBA and TCTH considering the possibility of each chemical species and evaluating diffusional membrane resistance for lower and higher concentration of extractants. The diffusion coefficients were observed to decrease with increase in the extractant concentration ranging from 1.0×10⁻⁷ to 3.5×10⁻⁶ mol cm⁻³. Plotting [Ag]₀−[Ag]_t vs. time resulted in a slope of [L₀]A/Δ_oV taking into account both complexing species, AgL and AgNO₃L, in the membrane. The validity of this model was evaluated with experimental data and found to be well in agreement with theoretical values. The mass transfer coefficient (Δ⁻¹_a), the diffusion coefficient of the metal carrier species (D_o) and the thickness of the aqueous boundary layer were calculated from the proposed model for TCBA and TCTH. The mathematical equation was derived to correlate the permeability flux with support characteristics such as porosity, tortuosity and thickness.     

Facilitated transport of Am(III) through a flat-sheet supported liquid membrane (FSSLM) containing tetra(2-ethyl hexyl) diglycolamide (TEHDGA) as carrier

Facilitated transport of Am(III) in nitric acid medium using tetra(2-ethyl hexyl) diglycolamide (TEHDGA) in n-dodecane as carrier was studied. It was aimed at finding out the physico-chemical model for the transport of Am(III) using TEHDGA/n-dodecane as carrier under various experimental parameters like feed acidity, carrier concentration, varying strippant, varying membrane pore size, etc. The feed acidity and carrier concentrations were varied from 1 M to 6 M HNO₃ and 0.1 M to 0.3 M TEHDGA/n-dodecane, respectively. The transport of Am(III) increased with increase in feed acidity and carrier concentration reaching maximum at 3 M HNO₃ and 0.2 M TEHDGA/n-dodecane, respectively. Several stripping agents were tested and 0.1 M HNO₃ was found to be the most suitable stripping agent for this system. Almost quantitative transport of Am(III) was observed at about 180 min with feed acidity of 3 M HNO₃, 0.1 M HNO₃ as strippant and 0.2 M TEHDGA/n-dodecane as carrier. The pore size of the membrane support was varied from 0.20 μm to 5 μm and the permeation coefficient increased with increase in pore size up to 0.45 μm (2.43 × 10⁻³ cm/s), and then decreased with further increase in pore size. The plot between permeation coefficient vs. (membrane thickness)⁻¹ was linear which showed that the Am(III) transport was membrane diffusion limited. The membrane diffusion coefficient calculated from the graph was found to be 1.27 × 10⁻⁶ cm²/s and its theoretical value was 1.22 × 10⁻⁶ cm²/s. The stability of the carrier against leaching out of the membrane support as well as the integrity of membrane support was studied over a period of 30 days and was found to be satisfactory within the studied time period.     

Kinetic Study of Mercury(II) Transport through a Bulk Liquid Membrane Using Cyanex 301 as Carrier

A kinetic study of Hg(II) ions transport through a bulk liquid membrane (BLM) was investigated. The commercially available liquid bis(2,4,4‐trimethyl(pentyl) dithiophosphinic acid) (Cyanex 301) was employed as mobile carrier. The influences of the carrier concentration in the liquid membrane, HNO₃ concentration in the feed phase, type of organic solvent, composition of the receiving phase, and stirring speed on mass transfer were studied. Various solvents including CH₂Cl₂, CHCl₃, C₂H₄Cl₂ and CCl₄ were used as organic membrane. Among the solvents, CHCl₃ provided the superior results. The kinetic parameters (k₁, k₂, R_m^max, t^max, J_d^max, and J_a^max) were calculated for the interface reaction assuming two consecutive, irreversible first‐order reactions. The analysis of Hg(II) accumulation in liquid membrane and the rate‐controlling step under different experimental conditions were elucidated. The experiments demonstrated that Cyanex 301 is an appropriate carrier for Hg(II) transport through liquid membrane.     

Modelling of mass transfer in facilitated supported liquid membrane transport of copper(II) using MOC-55 TD in Iberfluid

The transport of copper(II) through a supported liquid membrane using MOC-55 TD (oxime derivative), dissolved in Iberfluid, as a carrier has been studied. A physico-chemical model is derived to describe the transport mechanism which consists of: diffusion process through the feed aqueous diffusion layer, fast interfacial chemical reaction and diffusion through the membrane. The experimental data can be explained by mathematical equations describing the rate of transport. The mass transfer coefficient was calculated from the described model as 2.8×10⁻³ cm s⁻¹, the thickness of the aqueous boundary layer as 2.6×10⁻³ cm⁻¹ and the membrane diffusion coefficient of the copper-containing species as 1.2×10⁻⁸ cm² s⁻¹.     

Carrier‐Mediated Transport of Hg(II) through Bulk and Supported Liquid Membranes

The transport of Hg (II) ions from an aqueous solution into an aqueous receiving solution through bulk and supported liquid membranes containing a calix[4]arene derivative 1 as a carrier was examined. The kinetic parameters of bulk liquid membrane studies were analyzed assuming two consecutive, irreversible first‐order reactions. The influence of temperature, stirring rate, carrier concentration and solvent on the kinetic parameters (k₁, k₂, R_m ^max, t_max, J_d ^max, J_a ^max) has also been investigated. The membrane entrance rate, k₁, and the membrane exit rate, k₂, increased with increasing temperature and stirring rate. The activation energy values are calculated as 4.87 and 48.63 kj mol^?1 for extraction and reextraction, respectively. The values of calculated activation energy indicate that the process is diffusionally controlled by species. Also, the transport behavior of Hg²⁺ from aqueous solution through a flat‐sheet supported liquid membrane has been investigated by the use of calix[4]arene derivative 1 as carrier and Celgard 2500 as the solid support. A Danesi mass transfer model was used to calculate the permeability coefficients for each parameter studied. The highest values of permeability were obtained with 2‐nitrophenyloctyl‐ether (NPOE) solvent and the influence was found to be in the order of NPOE>chloroform>xylene.     

Preparation and characterization of Pd-Ag alloy composite membrane with magnetron sputtering

A Pd-Ag (24 wt%) alloy composite membrane was prepared by the magnetron sputtering. A γ-Al_2O_3 membrane was synthesized by the sol-gel method and used as substrate of the Pd-Ag alloy film. The process parameters of the magnetron sputtering were optimized as a function of the compactness of the Pd-Ag alloy film. The best membrane with a thickness of 1 μm was produced with a sputtering pressure of 2.7 Pa and a substrate temperature of 400℃. The membrane had an H_2/N_2 permselectivity of 51.5--1000 and an H_2 permeation rate of 0.036--1.17×10~(-5)cm~3/cm~2·s· Pa, depending on operating conditions.     

Air gap membrane distillation of sucrose aqueous solutions

In this paper results obtained with air gap membrane distillation (AGMD) using sucrose aqueous solutions are shown. The role of the relevant process parameters has been investigated experimentally (the flow rate through the cell, the feed initial concentration, the type of membrane, the air gap thickness, etc.). Equations have been proposed to estimate the intermediate temperatures for the air gap configuration. The fluxes given by different gas stagnant film diffusion models showed good agreement with the experimental results over the entire range of temperatures studied. Also a model which accounts for the thermal diffusion phenomenon was used. From the fits of the experimental flux data to the theoretical equations, the diffusion coefficient of the water vapour–air mixture, D_AB, and the thermal diffusion coefficient, K_T (only in the last case), were obtained and the results were analysed. For the D_AB coefficient higher values than the tabulated ones have been obtained, although of the same order of magnitude, and still higher when the thermal diffusion is considered.     

Liquid-supported membranes in chromium(VI) optical sensing: transport modelling

Flat sheet liquid-supported membranes (FSLSM) containing Aliquat 336 as a carrier have been evaluated as sample interface in an optical sensor for Cr(VI) monitoring. A model describing the transport mechanism of Cr(VI) through the membrane is reported. The model considers a diffusion process through a feed aqueous diffusion layer, a fast interfacial chemical reaction and a diffusion of ALQHCrO₄ and (ALQ)₂CrO₄ species through the membrane (Aliquat 336, ALQ). The mathematical equations describing the transport rate are derived and they correlate the membrane permeability coefficient to diffusional and equilibrium parameters as well as to the chemical composition of the system, i.e. extractant concentration in the membrane phase and acidity in the feed phase. The experimental data are explained by the derived equations and the diffusion resistances to mass transfer are evaluated. The influence of other experimental parameters, such as stirring speed in the feed phase and nature of the diluent and stripping agent on the transport is also discussed. Experiments with optical detection demonstrate the suitability of liquid-supported membranes (LSM) containing ALQ as interfaces for optical sensing.