铒在HBTMPTP-正庚烷/水溶液间的传质动力学

在(30±0.5)℃下,用层流恒界面池研究了铒在HBTMPTP-正庚烷-0.2mol/L(H,Na)Ac萃取体系中的传质动力学.测定了该体系的界面张力,考察了水相酸度、萃取剂浓度、氯离子浓度、温度和比界面对萃取速率的影响.实验表明,在本实验条件下,萃取过程属于扩散控制过程.Cyanex302中的杂质具有动力学的协萃作用.     

Extraction of Polonium from Aqueous Lactic Acid Solutions Using Dioctyl Sulphide, Cyanex 272, Cyanex 301 or Cyanex 302 in Toluene

The extraction of polonium from lactic acid (HLac) solutions has been studied with di-n-octyl sulphide (DOS), Cyanex 272, Cyanex 301 and Cyanex 302 extractants dissolved in toluene. For the extraction with DOS, the extracted species is most likely PoO(Lac)₂·3DOS. The results for Cyanex 272 also indicate extraction via a solvation mechanism rather than cation exchange. The extracted species is probably PoO(Lac)₂·2HA. The major species extracted with Cyanex 301 or Cyanex 302 do not contain any lactate molecules. The extracted species is most likely PoOA₂ at low extractant concentrations, while at higher concentrations an adduct complex of the type PoOA₂·2HA is formed. The extraction of polonium increases in the order Cyanex 272 < Cyanex 302 < DOS < Cyanex 301, which is the same order as the increase of the number of sulphur atoms in the reagents.     

Extractive separation of Th(IV), U(VI), Ti(IV), La(III) and Fe(III) from Zarigan ore

In this study, the effects of various extraction parameters such as extractant types (Cyanex302, Cyanex272, TBP), acid type (nitric, sulfuric, hydrochloric) and their concentrations were studied on the thorium separation efficiency from uranium(VI), titanium(IV), lanthanum(III), iron(III) using Taguchi^??s method. Results showed that, all these variables had significant effects on the selective thorium separation. The optimum separations of thorium from uranium, titanium and iron were achieved by Cyanex302. The aqueous solutions of 0.01 and 1 M nitric acid were found as the best aqueous conditions for separating of thorium from titanium (or iron) and uranium, respectively. The combination of 0.01 M nitric acid and Cyanex272 were found that to be the optimum conditions for the selective separation of thorium from lanthanum. The results also showed that TBP could selectively extract all studied elements into organic phase leaving thorium behind in the aqueous phase. Detailed experiments showed that 0.5 M HNO₃ is the optimum acid concentration for separating of thorium from other elements with acidic extractants such as Cyanex272 and Cyanex302. The two-stage process containing TBP-Cyanex302 was proposed for separation thorium and uranium from Zarigan ore leachate.     

Influence of the characteristics of soil and fly ash on the supercritical carbon dioxide extraction of dioxins.

Several investigations on the extraction of dioxins from soil and fly ash with supercritical fluid have been reported; however, few of them describe the influence of components on the extraction. We extracted dioxins from eight samples with different values of organic carbon content and surface area with supercritical CO(2) at a temperature of 463 K, a pressure of 40 MPa, and using 10% toluene as an entrainer. We researched the influence of the characteristics of soil and fly ash on supercritical CO(2) extraction of dioxins. The results revealed that the extraction efficiencies of PCDD/DFs and PCBs were high for all soil samples, while that of fly ash samples decreased with the increase in organic carbon content and surface area. The extraction efficiencies of dioxins from four standard samples, activated carbon, humic acid, alumina, and florisil, were also examined. The results revealed that the extraction efficiencies were strongly influenced by activated carbon like components present in the samples.     

Solvent extraction separation of iron(III) and aluminium(III) from other elements with Cyanex 302

A rapid method was developed for the solvent extraction separation of iron(III) and aluminium(III) from other elements with Cyanex 302 in chloroform as the diluent. Iron(III) was quantitatively extracted at pH 2.0-2.5 with 5 x 10(-3) M Cyanex 302 in chloroform whereas the extraction of aluminium(III) was quantitative in the pH range 3.0-4.0 with 10 x 10(-3) M Cyanex 302 in chloroform. Iron(III) was stripped from the organic phase with 1.0 M and aluminium(III) with 2.0 M hydrochloric acid. Both metals were separated from multicomponent mixtures. The method was applied to the separation of iron and aluminium from real samples.     

Designing supercritical carbon dioxide extraction of rice bran oil that contain oryzanols using response surface methodology

This study examines the supercritical carbon dioxide (SC-CO(2)) extraction of oryzanols contained rice bran oil from powdered rice bran. The extraction efficiencies and concentration factors of oryzanols, free fatty acids and triglycerides in the SC-CO(2) extracts were determined. With top-flow type SC-CO(2) extraction the total oil yield was 18.1% and the extraction efficiencies of oryzanols and triglycerides were 88.5 and 91.3% respectively, when 2750 g CO(2 )was consumed during the extraction of 35 g rice bran powder. The concentration factors of oryzanols and triglycerides in SC-CO(2)-extracted oil were higher than in the Soxhlet n-hexane extracted oil. SC-CO(2) extractions indicated that pressure can be used more effectively than temperature to enhance the extraction efficiency and concentration factor of oryzanols. A two-factor central composite scheme of response surface methodology was employed to determine the optimal pressure (300 bar) and temperature (313 K) for increasing the concentration of oryzanols in the SC-CO(2) extracted oil.     

Organophosphinic,phosphonic acids and their binary mixtures as extractants for molybdenum(VI) and uranium(VI) from aqueous HCl media

Extraction studies of uranium(VI) and molybdenum(VI) with organophosphoric, phosphinic acid and its thiosubstituted derivatives have been carried out from 0.1–1.0M HCl solutions. The extracted species are proposed to be UO₂R₂ and MoO₂ CIR on the basis of slope analysis for uranium(VI) and molybdenum(VI), respectively. The extraction efficiencies of PC-88A, Cyanex 272, Cyanex 301 and Cyanex 302 in the extraction of molybdenum(VI) and uranium(VI) are compared. Synergistic effects have been studied with binary mixtures of extractants. Separation of molybdenum(VI) from uranium(VI) is feasible by Cyanex 301 from 1M HCl, the separation factor log being 2.3.     

Extraction of neodymium(III) using binary mixture of Cyanex 272 and Cyanex 921/Cyanex 923 in kerosene

The extraction of Nd(III) using binary mixtures of Cyanex 272 (HA), Cyanex 921/Cyanex 923 (B) in kerosene from nitric acid medium has been investigated. The effect of aqueous phase acidity, extractant concentration, nitrate ion concentration and diluents on the extraction of Nd(III) has been studied. On the basis of slope analysis results, extracted species are proposed as Nd(NO₃)A₂·3HA and Nd(NO₃)₂·A·3HA·B using Cyanex 272 and its mixture with Cyanex 921/Cyanex 923, respectively. With the mixture of 0.1 M Cyanex 272 and 0.1 M Cyanex 923 in kerosene, the extraction of 0.001 M Nd(III) from 0.001 M HNO₃ solution was found to be 83.3 % whereas it was 73.3 % when 0.1 M Cyanex 921 used as synergist under same experimental conditions. The stripping data of Nd(III) from the loaded organic phase containing 0.1 M Cyanex 272 and 0.1 M Cyanex 921/Cyanex 923 with different acids indicated sulphuric acid to be the best stripping agent.     

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.     

Interfacial behavior of Cyanex 302 and kinetics of lanthanum extraction

In this paper, interfacial tension of Cyanex 302 is measured by a Sigma-701 tensiometer and the adsorption parameters are calculated according to the Gibbs and Szyszkowski adsorption isotherms. The interfacial adsorbed behavior of Cyanex 302 is investigated. The results demonstrate that the dimer is the predominant species in the bulk organic phase; however, the monomer is adsorbed at the interface and more interfacially active. The effects of aqueous pH, ion strength, and temperature on the interfacial activity of Cyanex 302 in heptane are discussed and explained in detail. The lower interfacial activity of Cyanex 302 in aromatic hydrocarbon than in aliphatic hydrocarbon has also been determined. The values of interfacial excess at the saturated interface increase in the order n-heptane>cyclohexane>toluene>benzene, which is consistent with the order of extractability of lanthanum by Cyanex 302 in these diluents. The interfacial activity data are used to discuss the kinetic mechanism of lanthanum(III) extraction. It is shown that an interfacial mechanism is very probable, and the extraction limiting step is the reaction between the Cyanex 302 molecules in the organic phase sublayer and the adsorbed intermediate complex.     

Liquid-liquid extraction of Th(IV) with Cyanex302

Summary Th(IV) was quantitatively extracted from 1 ^. 10^-3M HNO₃ using 1 ^. 10^-3M Cyanex302 in xylene and was stripped from the organic phase with 5M HCl. The effect of different parameters affecting the extraction was systematically studied to achieve optimum conditions for the extraction of thorium. Based on the data some separations of thorium from binary and complex mixtures and its recovery from monazite sand were achieved. The method is reproducible with a relative standard deviation of 0.4%.     

Cadmium(II) extraction from phosphoric media by bis(2,4,4-trimethylpentyl) thiophosphinic acid (Cyanex 302)

Cadmium extraction from phosphoric acid at different concentrations (0.7–8.8 M) by the commercial reagent Cyanex 302 in kerosene has been studied. Experimental results have been treated graphically and numerically and the formation of the species CdR₂(HR) in the organic phase has been proposed. The value of the equilibrium constant increases with the phosphoric concentration in the aqueous media. Small Cyanex 302 concentrations in the organic phase are enough to remove Cd(II) quantitatively from phosphoric acid solutions.     

Extraction of lead(II) from chloride solutions of nickel with mixtures based on tertiary amines

Extraction of lead(II) from chloride solutions of nickel with mixtures of tertiary amines with additions of 2-octanone and bis(2,4,4-trimethylpentyl)phosphinodithioic acid (Cyanex 301) in a diluent was studied. The influence exerted on the degree of the lead(II) extraction by the concentration of chloride ions and ratio of organic phase components was examined. Lead(II) can be virtually quantitatively extracted from concentrated chloride solutions with a mixture of 15% trialkylamine + 15% Cyanex 301, with the subsequent regeneration of the organic phase by its treatment with a concentrated HCl solution. The conditions of almost quantitative and selective extraction of lead from nickel raffinates of the cobalt production at the Kola Mining and Metallurgical Company were found.     

Experimental and mechanism studies on simultaneous desulfurization and denitrification from flue gas using a flue gas circulating fluidized bed

The oxidizing highly reactive absorbent was prepared from fly ash,industry lime,and an oxidizing additive M.Experiments of simultaneous desulfurization and denitrification were carried out in a flue gas circulating fluidized bed(CFB).The effects of influencing factors and calcium availability were also investigated on the removal efficiencies of desulfurization and denitrification.Removal efficiencies of 95.5%for SO2 and 64.8%for NO were obtained respectively under the optimal experimental conditions. The component of the spent absorbent was analyzed with chemical analysis methods.The results in- dicated that more nitrogen species appeared in the spent absorbent except sulfur species.A scanning electron microscope(SEM)and an accessory X-ray energy spectrometer were used to observe micro-properties of the samples,including fly ash,oxidizing highly reactive absorbent and spent absorbent.The simultaneous removal mechanism of SO2 and NO based on this absorbent was pro- posed according to the experimental results.     

Extraction of U(VI) with Cyanex 302

U(VI) was quantitatively extracted from 1·10⁻³M HNO₃ using 5·10⁻³M Cyanex 302 in xylene and was stripped from organic phase with 5M HCl. The optimum extraction conditions have been evaluated by studying parameters like acidity, effect of diluents, extractant concentration and period of equilibration. Based on this data, the separations of uranium from binary and complex metal mixtures and its recovery from uranmicrolite tailings (leachate) were successfully tested. Uranium can be determined with a relative standard deviation of 0.4%.     

A Sequential Extraction Method Measures the Toxic Metal Content in Fly Ash from a Municipal Solid Waste Incinerator

The purpose of this research was to develop an optimized pretreatment procedure for toxic metals (Pb, Cd, Zn and Cu) content in fly ash from a municipal waste incinerator. In addition, modified sequential extraction procedures were used to characterize the chemical composition of the fly ash samples. The sequential extraction resolved the fly ash elements into the following chemical forms: soluble, exchangeable, carbonate, oxide, organic, and silicate compounds. Certified reference city waste incineration ash (BCR.176) was used as target ash samples. A H₂O₂+HNO₃+HF mixed acid digestion solution with a low temperature evaporation procedure was selected as optimal for the fly ash digestion. The digested solution was analyzed by inductively coupled plasma mass spectrometry (ICP‐MS), which effectively determined the concentrations of the toxic metal elements in BCR.176. Except for Cd, the recovery of Pb, Zn, and Cu under H₂O₂+HNO₃+HF digestion and their sequential extraction procedures were higher than 95%. The relative standard deviations (RSD) for recoveries of the four elements were within 10%. Furthermore, the sequential extraction procedure's results provided information on the potential mobility of the studied elements. Most of the Cd was bound to water‐soluble and carbonate material in the fly ash samples. Most of the Pb, Zn, and Cu was released to carbonates and bound to organic matter in the fly ash samples.     

Dissolution Extraction of Uranium Oxides and Cerium Oxide with TBP-HNO3 Complex in Supercritical CO2

Dissolution extraction of uranium oxides, CeO2 and (U, Ce)O2 solid solution with TBP-HNO3 complex in supercritical CO2 (SC-CO2) was investigated. It is difficult to dissolve and extract directly UO2 pellets and CeO2 with TBP-HNO3 complex in SC-CO2. After UO2 pellets spontaneously turns into U3O8 powders under O2 flow and 600 °C, the extraction efficiency can reach more than 98%. For dissolution extraction of (U, Ce)O2 solid solution with TBP-HNO3 complex in SC-CO2 under 60 and 20 MPa, the extraction efficiency of U and Ce is 98.61% and 98.1% respectively.     

A new luminol chemiluminescence reaction using a tetravalent nickel-periodate complex as the oxidant

A modified sequential extraction procedure was developed and applied to characterize the species of metals in fly ash. Two fly ash samples were collected from a coal-fired thermal power plant located in the north of China. A sample was collected from the conventional pulverized coal (PC) combustor and another from the circulating fluidized bed (CFB) combustor. After extraction by the proposed sequential extraction procedure, the elements in the fly ash samples were divided into a water-extractable fraction (F1), an acid-soluble fraction (F2), a reducible fraction (F3), an oxidizable fraction (F4) and a residual fraction (F5). Except for Cu, V, Cd in the PC sample and V, Zn in the CFB sample, most of the other metals were present in the residual fraction (F5), which was very difficult to release into the environment. The fraction distribution patterns in the two samples were also compared. The results indicated that the distribution of metals in different fractions in fly ash samples were probably impacted by different combustion processes.     

Extraction of Polonium from Aqueous α-Hydroxyisobutyric Acid Solutions Using Dioctyl Sulphide, Cyanex 272, Cyanex 301 or Cyanex 302 in Toluene

A study of the extraction of polonium from aqueous solutions containing -hydroxyisobutyric acid (-HIBA) was performed with four different extractants, di-n-octyl sulphide (DOS), Cyanex 272, Cyanex 301 and Cyanex 302, dissolved in toluene. The extracted complex for DOS at low -HIBA concentrations is most likely PoO(-HIB)₂·2DOS, while at higher -HIBA concentrations there seems to be a solvating effect implicating an extracted complex of the type PoO(-HIB)₂(-HIBA)₂·2DOS. For the extraction of polonium with Cyanex 272 the results are inconclusive. The extracted complex is either PoOA₂ or PoO(-HIB)₂·2HA. For extraction with Cyanex 301 or Cyanex 302 the major extracted species does not contain any -HIBA molecules. The neutral species in both cases is PoOA₂, extracted at low extractant concentrations, while at higher extractant concentrations a complex of the type PoOA₂·xHA is extracted. The extraction of polonium increases in the order Cyanex 272 < DOS < Cyanex 302 < Cyanex 301.     

Separation Cd(Ⅱ), Fe(Ⅲ) and Zn(Ⅱ) from Eu(Ⅲ) in Sulfuric Acid with Cyanex302 by Using Microporous Hollow Fiber Membrane

With the development of chemical industry, refining and collecting valued material in dilute solutions or difficult separation systems has become one of important research aspects. In order to adapt to the demand of modem science and technology, separation Zn²⁺, Cd²⁺ and Fe³⁺ from Eu³⁺ solution to making Eu with high purity is necessary. Hollow fiber membrane (HFM) extraction, as a new separation technique, has many advantages^[1]. The extractant(commercial name as Cyanex302), bis(2,4,4-trimethylpentyl)monothiophosphinic acid, is a soft acid and so it is easy to extract transition elements^[2]. HFM extraction combined with a new extraction system, which had little consumption and no pollution and was a friend environment process.