HDEHP萃取Ga（Ⅲ）的动力学

用生长液滴法研究了ＨＤＥＨＰ在盐酸介质中萃取Ｇａ（Ⅲ）的动力学，结果表明，萃取反应速率取决于发生在界面区域内两步连续反应Ｇａ３＋＋Ａｉ－＝ＧａＡｉ２＋ＧａＡｉ２＋＋Ａｉ－＝ＧａＡ２＋ｉ研究了阴离子表面活性剂ＳＤＳ、ＡＢＳ对ＨＤＥＨＰ萃取Ｇａ（Ⅲ）的影响，二者均不改变ＨＤＥＨＰ萃取Ｇａ（Ⅲ）的分配比，但使其正向萃取初始速率降低，原因是表面活性剂与萃取剂在界面上发生了竞争吸附；其次是表面活性剂的加入导致了界面膜上分子排列更致密和界面膜增厚，产生了更大的传质阻力。     

Au-impregnated polyacrylonitrile (PAN)/polythiophene (PTH) core-shell nanofibers with high-performance semiconducting properties

FETs based on Au-impregnated polyacrylonitrile (PAN)/polythiophene (PTH) core-shell nanofibers have been fabricated and exhibit high mobility (～2.0 cm(2) V(-1) s(-1)).     

Preparation of porous ultrafine polyacrylonitrile (PAN) fibers by electrospinning

A facile method for the preparation of porous ultrafine nanofibers was demonstrated. The PAN/NaHCO₃ composite nanofibers were electrospun, and then NaHCO₃ was removed by a selective dissolution and reaction with the solution of hydrochloric acid (10 wt%). The obtained PAN fibers showed highly porous surfaces after the extraction of NaHCO₃. The structure and properties of ultrafine PAN nanofibers were characterized by Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), and thermogravimetry (TG). The results indicated that NaHCO₃ could be introduced into the PAN solution and successfully electrospun. CO₂ is released and pores are formed on the fibers. The morphology image of the fibers was detected by scanning electron microscope (SEM) and showed that many pores aligned the nanofibers. Copyright © 2008 John Wiley & Sons, Ltd.     

Morphology control of polyacrylonitrile (PAN) fibers by phase separation technique

Based on the constructed theoretical ternary phase diagrams of water/dimethyl sulfoxide (DMSO)/polyacrylonitrile (PAN) terpolymer system, the phase separation behavior for PAN fibers preparation was investigated. Theoretical ternary phase diagrams were determined by the extended Flory‐Huggins theory. To investigate the temperature dependence of theoretical ternary phase diagrams, all binary interaction parameters at different temperatures were determined accurately and thoroughly revisited. From numerical calculations, it was found that a small quantity of water was needed to induce phase demixing. Meanwhile, the cloud point data of the system for more dilute PAN terpolymer solutions were determined by cloud point titration, and the cloud point data for more concentrated PAN terpolymer solutions were calculated by Boom's linearized cloud point (LCP) curve correlation. Furthermore, the morphology of PAN fibers was investigated by using scanning electron microscopy (SEM). With increasing the concentration of PAN terpolymer solutions as well as the quenching depth, the morphology of PAN fibers turns from large open channels to small bead‐like structures, accompanying with a reduction of the porosity of PAN fibers. Judging from our investigation, it was clear that the final morphology of PAN fibers was mainly determined by phase separation in fiber‐forming process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 261–275, 2009     

Extraction mechanism of Tc(IV) by Di-(2-ethylhexyl)phosphoric acid (HDEHP)

Journal of Radioanalytical and Nuclear Chemistry - Di-(2-ethylhexyl)phosphoric acid, HDEHP, is a well-known extractant used for metal ion extraction in an industrial scale and for research work....     

Electrokinetic and permeation characterization of hydrolyzed polyacrylonitrile (PAN) hollow fiber ultrafiltration membrane

PAN membrane and hydrolyzed PAN membranes with the same pore size were used to investigate the relationship between the electrokinetic property and permeation performance by streaming potential measurement and ion exchange technology. SEM and FT-IR/ATR spectra were employed to analyze the reaction and the presence of the amide groups. The thickness of the polyacrylic acid (PAA) layer on the membrane surface measured by ion-exchange titration technology increased with the reaction time, and that on membrane hydrolyzed for 50 min could reach 10.8 nm. Streaming potential measurement was used to study the influence of the carboxylic and nitrile group on the membrane surface on their separation property. Zeta potential measured in pure water had close relationship with the permeation property. This measurement also proved that there was a maximum zeta potential between zero and the concentration tested. For the ionization or dissociation of the carboxylic group on the membrane surface, treated membranes had a more flexible zeta potential range than that of the untreated membrane in the pH range of 3–9. They were all negative in pure water and 1 g·L⁻¹ KCl solution, while the membranes hydrolyzed for 30 min and 50min had IEPs at pH 5.5 and 6.1 in 1 g·L⁻¹ MgCl₂ solution. Special inflection points of all the membranes were observed in AlCl₃ solution for the positive colloid structure of Al(OH)₃.     

稀释剂对二（2—乙基己基）磷酸萃取镧（Ⅲ）的影响

二（２－乙基己基）磷酸从硝酸介质中对Ｌａ（Ⅲ）的萃取对不同稀释剂其平衡常数为；正己烷＞环己烷＞四氯化碳＞甲苯＞氯仿＞甲异丁酮，萃取平衡常数与稀释剂的极性参数Ｓ间呈线性关系。     

Extraction and separation of antimony(III) and (V) by a liquid cation-exchanger HDEHP

A systematic investigation was carried out on the extraction of Sb(III) and (V) with HDEHP from various acidic, neutral and alkaline solutions. Antimony(III) is best extracted from neutral or slightly acidic solutions, and the E values are nearly the same in the forward and backward extractions. Antimony(V) extraction is high only from concentrated HCl and HClO₄, and the E values are much larger in the backward direction. Extraction and separation of Sb(III) and (V) was studied as a function of acidity, alkalinity, anion and water-miscible organic additives in the aqueous phase, as well as the diluent used and HDEHP molarity. Separation factors obtained for Sb(III) and (V) were higher than when using isopropyl ether as solvent, which was hitherto used for this purpose.     

Extraction chromatographic separation of thorium (IV) with tri-n-octylphosphine oxide (TOPO)

Thorium was extracted from a mixture of nitric acid and NaNO₃ of 0.01M each at pH 2.2 on a column of silica gel coated with TOPO. Thorium was separated from alkalis, alkaline earths, chromium, iron, cobalt, nickel, zinc, cadmium, mercury, lead, trivalent rare earths, platinum group metals, chloride, phosphate and acetate in binary mixtures by selective extraction of thorium. Thorium was separated from cerium (IV), zirconium, uranium and molybdenum by selective elution of thorium with 0.01M H₂SO₄. The method was extended for the analysis of thorium in monozite ore.     

Process optimization and empirical modeling for electrospun polyacrylonitrile (PAN) nanofiber precursor of carbon nanofibers

Ultrafine fibers were spun from polyacrylonitrile (PAN)/N,N-dimethyl formamide (DMF) solution as a precursor of carbon nanofibers using a homemade electrospinning set-up. Fibers with diameter ranging from 200 nm to 1200 nm were obtained. Morphology of fibers and distribution of fiber diameter were investigated varying concentration and applied voltage by scanning electric microscopy (SEM). Average fiber diameter and distribution were determined from 100 measurements of the random fibers with an image analyzer (SemAfore 5.0, JEOL). A more systematic understanding of process parameters was obtained and a quantitative relationship between electrospinning parameters and average fiber diameter was established by response surface methodology (RSM). It was concluded that concentration of solution played an important role to the diameter of fibers and standard deviation of fiber diameter. Applied voltage had no significant impact on fiber diameter and standard deviation of fiber diameter.     

Extraction spectrophotometric determination of maneb with 1-(2'-pyridylazo)-2-naphthol (PAN)

A rapid, sensitive, simple and selective spectrophotometric method has been developed for the determination of micro-quantities of maneb (manganese ethylenebisdithiocarbamate) after extraction of the manganese-PAN complex in isobutyl methyl ketone (MIBK). The complex absorbs strongly at 550 nm. Beer's law is obeyed over the concentration range 0.37-3.75 microg/ml. The molar absorptivity was found to be 4.1 x 10(4) l. mole(-1) . cm(-1). The developed method has been applied to the determination of maneb in commercial formulations, synthetic mixtures, grain and in the presence of various other dithiocarbamates.     

Extraction and separation of141Ce and153Gd with HDEHP

Studies on liquid-liquid extraction of trace level cerium and gadolinium,¹⁴¹Ce and¹⁵³Gd, from HCl and HNO₃ media with liquid cation exchanger, HDEHP reveal that a quantitative separation of the elements from an admixture of the two radioisotopes can be achieved with 0.1% HDEHP and 0.01N HCl. The condition is also valid for separation of trace amount of¹⁵³Gd from bulk or macro quantity of cerium.     

Reversed phase chromatographic separation of zirconium,niobium and hafnium tracers with HDEHP

Effective separation of the congeneric pair of elements, zirconium and hafnium and also niobium which was in admixtures with zirconium as daughter in its isotopic form were achieved through reversed phase column and paper extraction chromatographic procedures using di-(2-ethylhexyl)phosphoric acid (HDEHP) as the liquid exchanger. In reversed phase column chromatographic separation, the tracers,⁹⁵Zr,⁹⁵Nb and^175,181Hf, were extracted by HDEHP impregnated on kieselguhr and were sequentially eluted with 6N H₂SO₄+xN oxalic acid+H₂O₂(where x=0.1, 0.5 and 2). Similarly, in reversed phase paper chromatographic study in which a coating of HDEHP on Whatman No. 1 chromatographic paper was used as stationary phase, the mobile phase, 18N H₂SO₄+0.1N oxalic acid + H₂O₂, helped in separating the elements with favorable separation factors. Under the optimal conditions, the separation and decontamination of the elements in both methods were found to be quantitative, as verified by -spectrometric studies.     

Organic semiconductors-coated polyacrylonitrile(PAN) electrospun nanofibrous mats for highly sensitive chemosensors via evanescent-wave guiding effect

We report the first use of organic semiconductors（OSCs）-coated PAN nanofibrous mats as highly responsive fluorescence quenching-based chemosensors for 2,4,6-trinitrotoluene（TNT） and H₂O2 detection in vapor phase.Conjugated polymers,poly（triphenylaminealt-biphenylene vinylene）（TPA- PBPV）,and small organic molecules,1 -boronic-ester pyrene and 1,6-bisboron-ester pyrene,were coated onto the nanofibers fabricated by electrospinning.By introducing the nanofibers structure,a 9-fold fluorescence intensity enhancement and a 14-fold sensitivity enhancement were achieved,which could be attributed to its high area-to-volume ratio,excellent gas permeability,and more importantly,the evanescent-wave effect occurred once the diameters of the fibers were small enough.Since the organic semiconductors coated onto the nanofibrous mats could be replaced by other functional materials,the nanofibers-enhanced detection strategies could be extended to more general domains including chemical and environmental detection.     

A novel methodology for designing thermal processes in order to optimize stabilization of polyacrylonitrile (PAN) fibers

The aim of this work is to describe a novel methodology for optimizing the stabilization of polyacrylonitrile (PAN) fibers, through designing of proper thermal treatment. The methodology is based on a set of design rules and the procedure for implementing them, utilizing the time‐temperature‐transition (TTT) and the maximum permittable stress (max.stress) plots. The proposed approach is implemented in order to optimize the stabilization of commercial PAN fibers, resulting in a series of multistage thermal treatments. The changes of both physical and chemical structures of PAN during the progress of the multistage treatments were investigated and showed that the fibers were progressively converted into completely stabilized material; this gradual transformation permitted improvement of fiber annealing and minimized the effect of the decomposition reactions. The proposed methodology can be universally applied for achieving the global optimum of the stabilization process for any PAN precursor.     

Extraction and separation of Th(IV) and U(VI) from nitric acid media using PIA-8 and HDEHP

Extraction behavior of Th(IV) and U(VI) has been investigated with bis(2-ethylhexyl) phosphinic acid (PIA-8) and bis(2-ethylhexyl) phosphoric acid (HDEHP) from nitric acid media in toluene. The optimum conditions for extraction of these metals have been established by studying various parameters like acid concentration, pH, reagent concentration, diluents and shaking time. The extraction of Th(IV) was found to be quantitative with 0.3-2.5M HNO₃ by 2.5^.10^-2M HDEHP and in the pH range 0.1-2.5 with 2.3^.10^-2M PIA-8 in toluene. U(VI) was completely extracted in the acidic range of 0.1-2.0M HNO₃ with 2.2^.10^-2M HDEHP and in the pH range of 1.0-3.0 with 2.0^.10^-2M PIA-8 in toluene. The probable extracted species have been ascertained by log D-log c plot as UO₂ R₂ ^.2HR with both the reagents and Th (NO₃)₂R₂ ^.2HR with PIA-8 and Th (NO₃)₃R^.3HR with HDEHP, respectively. Temperature dependence of the extraction equilibrium is examined by the temperature variation method. Separation of U(VI) and Th(IV) was also carried out from commonly associated metals.     

Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers prepared by atmospheric plasma treatment and electrospinning

Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheric plasma treatment and electrospinning. Atmospheric helium plasma treatment was first used to reduce the AgNO₃ precursor in pre-electrospinning solutions into metallic silver nanoparticles, followed by electrospinning into continuous and smooth nanofibers with Ag nanoparticles embedded in the matrix. SEM, TEM, and EDX spectra were used to study the structure and surface elemental composition of the nanofibers. Silver nanoparticles, with diameters ranging between 3 and 6 nm, were found to be uniformly dispersed in the nanofiber matrix. The Ag/PAN nanofibers exhibited slow and long-lasting silver ion release, which provided robust antibacterial activity against both Gram-positive Bacillus cereus and Gram-negative Escherichia coli microorganisms.     

Extraction of certain actinide and lanthanide elements from different acid media by polyurethane foams loaded with di(2-ethylhexyl)phosphoric acid (HDEHP)

The extraction of uranium(VI) from an aqueous HNO₃ phase into an organic phase consisting of a polyurethane foam immobilizing a solution of di(2-ethylhexyl)phosphoric acid (HDEHP) in o-dichlorobenzene has been investigated at varying concentrations of nitric acid and HDEHP. The mechanism of the extraction is discussed on the basis of the results obtained. The aggregation number of HDEHP immobilized on the foam was obtained from the analysis of data obtained for the extraction of cerium(III) from acidic perchlorate solutions of constant ionic strength.     

Extraction of certain actinide and lanthanide elements from different acid media by polyurethane foams loaded with di(2-ethylhexyl)phosphoric acid (HDEHP)

Except for conditions of low acidity and low ratios of di(2-ethylhexyl)phosphoric acid (HDEHP) to U(VI) the data obtained for the distribution of U(VI) between sulfuric acid solutions and polyurethane foams loaded with solutions of HDEHP in nitrobenzene could be analyzed by the equation: log (4.36 D_u)=log K+1.43 log (C_d–4C_u)/(C_H)^1.4+log f_u where the polymerization number of HDEHP is about 2.8, D_u is the distribution ratio, and f_u=[UO ₂ ²⁺ ]_(aq)/[UO₂]_(aq) indicating that the extraction proceeds via the formation of a 14 UO₂:HDEHP complex. At both low acidity and HDEHP/U(VI) ratio a UO₂-HDEHP polymer is formed.     

Extraction of certain actinide and lanthanide elements from different acidic media by polyurethane foams loaded with di-(2-ethylhexyl)phosphoric acid (HDEHP)

The extraction of cerium(III) from weakly acidic chloride solutions by HDEHP-nitrobenzene-loaded polyurethane foams could be analyzed quantitatively in terms of the equation: log(9.056 D_c)=log K_c+2.14 log (C_d?6C_c)+3 pH+log f_c where D_c is the distribution ratio of cerium(III) between the foam and aqueous phases, C_d and C_c are the total HDEHP and Ce(III) concentrations on the foam, respectively, log f_c=[Ce³⁺]_(sq)/[ΣCe(III)]_(aq), and K_c is the equilibrium constant of the equation: Ce _(aq) ³⁺ +2.14(HX)_2.8(o) ? ? CeX₆·H_3(o)+3H _(aq) ⁺ . Values of K_c under the different extraction conditions tested are given.