THE EXTRACTION EQUILIBRIUM MODEL AND SIMULATION OF COUNTERCURRENT SOLVENT EXTRACTION OF Gd-Tb-Dy-HCl-HEH(EHP)-KEROSENE SYSTEM

The extraction equilibrium mathematic models for gadolinium,terbium and dysprosium in HCl-1.5 mol/L HEH(EHP)system covering a relatively wide range of lanthanide concentration and acidity,have been developed.There are four independent variables and nine parameters.The average relative error is 4.56%.A computer program for the simulation of the counter current solvent extraetion process has also been written.Thus,the Gd,Tb and Dy concentrations in both aqueous and organic phase in eaeh stage as well as the aqueous acidity may be calculated.Product purities,distribution ratio and extraction factors may also be obtained thereby.The simulation results so obtained may serve as the referenee data for designing solvent ex- traction processes including those processes providing apart from the conventional outgoing organic stream, outgoing raffinate and an extra outgoing third exit stream either organic or aqueous.

Calculation of Extraction Equilibrium in Multi-Component System by Newton-Raphson Algorithm

Based on the extraction equilibrium and mass balances in countercurrent extraction systems, a novel method was studied for dealing with the extraction equilibrium and the mass distribution in a multi-component(gamma-component) system. The relationships of mass distribution (x(i), y(i), i = 1, ..., lambda) between two phases were expressed by 2 lambda dimensional simultaneous equations. These simultaneous equations can be converted to a one-dimension nonlinear equation, then it was solved by Newton-Raphson algorithm within a few number of iteration. Compared with the regular calculation method for the 2 lambda dimensional simultaneous equations, Newton-Raphson algorithm can decrease the number of iteration, increase the convergence of the equations and accelerate the speed of simulation. It was verified in many multi-component systems with satisfactory results. As an example, a five-component system is demonstrated in this paper.

Separation of cobalt and nickel by non-equilibrium solvent extraction

The separation of cobalt and nickel in the ammoniacal sulfate solution by non equilibrium solvent extraction with a phosphate (P303) as extractant was studied. In the experiment, the effects of equilibrium pH value in aqueous phase, contact time of the two phases, the air blowing time for feed liquor in the open beaker on percentage extraction of cobalt and nickel and percentage reextraction of nickel from the loaded organic phase with dilute H 2SO 4. etc were studied. The results showed that: Co(Ⅱ) can be oxidized to Co(Ⅲ) ammino complex by adding (NH 4) 2S 2O 8 or blowing air to the aqueous phase, and Co(Ⅲ) ammino complex is a kind of kinetically inert complex. Its extractive speed is very slow, while the nickel′s is much faster than that of cobalt. By controlling the contact time of the two phases, nickel can be separated from cobalt by non equilibrium solvent extraction. Then nickel was reextracted from the loaded organic phase with dilute H 2SO 4.

Extraction Equilibria of Trimellitic and [ 1,1′-Biphenyl]-2,2′-dicarboxylic Acid with 1-Octanol, 50%TBP, and 10%TRPO in Kerosene

To explore the feasibility of extracting aromatic acid products from oxidizing coal, two aromatic acids, trimellitic and [1,1′-biphenyl]-2,2′-dicarboxylic acid, were selected as the solutes, and the extraction equilibrium of the acids were studied with 1-octanol, 50% tributyl phosphate （TBP） in kerosene, and 10% trialkylphosphine oxide （TRPO） in kerosene. The results showed that the degree of extraction of [1,1′-biphenyl]-2,2′-dicarboxylic acid was larger than that of trimellitic acid for all of the solvent, and the extraction capacity with TRPO is more effective than the one with TBP. The extraction behavior of aromatic polyacid is different from that of carboxylic acid, and the reactive extraction function of aromatic acids with TBP and TRPO is not as effective as that of carboxylic acid. 1-octanol could be used to remove [1,1′-biphenyl]-2,2′-dicarboxylic acid from the mixture of trimellitic acid and [1,1′-biphenyl]-2,2′-dicarboxylic acid. Because the weak hydrogen bond association exists between -OH in 1-octanol and -COOH in aromatic acid, the extractive selectivity of [ 1, 1′-biphenyl]-2,2′-dicarboxylic to trimellitic acid depends on the stoichiometric ratio.

Selective extraction of In(Ⅲ),Ga(Ⅲ) and Zn(Ⅱ) using a novel extractant with phenylphosphinic acid

A new extractant, [N,N-di（2-ethylhexyl）aminolmethylphenylphosphinic acid （DEAPP）, was synthesized to de- velop the mutual separation techniques of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ）. The extraction selectivity for In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP was higher than that of the commercial phosphorus acid extractants such as D2EHPA and PC-88A. The extraction selectivity for metal ions in 1 mob L 1 aqueous ammonium nitrate solution with DEAPP was in the following order： In（Ⅲ） 〉 Ga（Ⅲ） 〉 Zn（Ⅱ）. These selective extraction behaviors indicate that the amino moiety of DEAPP plays an important role in the mutual separation of ln（Ⅲ）, Ga（Ⅲ） and Zn（ll）. The extraction equilibria of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP （ = HR） were expressed by the following reactions： In3＋ ＋ 2（HR）2 InR3（HR） ＋ 3H＋, Ga3＋ ＋ 1.5（HR）2 ＋ N- = GaR2（HR）（NO3） ＋ 2H＋, and Zn2＋ 4- 2（HR）2 ZnR2 （HR） 2 determined 4- 2H＋. The extraction equilibrium constants of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP were to be Kex, M = 1.7 × 104 [dm3.mol 1], 4.17 [（dm3.mol-1）s], and 1.55 × 10 2 [-], respectively.

SOLVENT EXTRACTION OF LANTHANIDES IN AQUEOUS NITRITE MEDIA BY CYANEX 302

Solvent extraction of trivalent lanthanides (except for Pm with Cyanex 302 [Bis (2,4,4-trimethylpentyl)monothiophosphinic acid] in heptane was studied at various aqueous pH values, extractant concentrations and different temperatures. Cyanex 302 shows pretty good behaviours on the extraction of lanthanides, especially when extracting heavy lanthanides. However,purified Cyanex 302 exhibits signi ficantly lower extractability to lanthanides than raw extractant. The roles ofdifferent components ofraw Cyanex 302 were discussed to understand the reason of good extractability of the raw extractant. The lanthanides extraction stoichiometry is discussed on the basis ofexperimental results, which can be expressed as follows:

Separation of nickel, cobalt and copper by solvent extraction with P204

Nickel, cobalt and copper were separated by solvent extraction with P204. The experimental results show that [Co(NH 3) 6] 3+ is an inert complex in extraction kinetics, therefore cobalt can be separated from nickel and copper by non equilibrium solvent extraction. Under the conditions of temperature 25?℃, contact time of two phases 10?min, phase ratio 1∶1, aqueous pH 10.10 and concentration of P204 20%, [Co(NH 3) 6] 3+ is hardly extracted by P204, while the percentage extractions of nickel and copper are 79.3% and 93.9% respectively. Nickel and copper are separated by equilibrium solvent extraction with P204. Under the conditions of temperature 25?℃, contact time of two phases 1?min, phase ratio 1∶1, equilibrium pH 4.01 and concentration of P204 20%, the separation factor of copper and nickel is 216.

Solvent extraction of lanthanum and cerium ions from hydrochloric acidic aqueous solutions using partly saponified 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester

In order to clarify the extraction process with saponified extractant, the solvent extraction experiments of rare earth elements(REEs), lanthanum and cerium, by using partly saponified 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester(EHEHPA, HL) from hydrochloric acidic solutions have been performed. The concentration of initial aqueous rare earth ion was in a range of 0.0010–0.1000 mol·L^(-1); EHEHPA in a range of 0.2877–0.8631 mol·L^(-1) with saponification rate of 0.3(mole fraction), and the initial aqueous p H in a range of 1.00–4.00. Firstly, the extracted species were determined by the saturation extraction capacity method. Secondly, according to the equilibrium aqueous pH values, the extraction processes were divided into three different categories: extraction with saponified EHEHPA, extraction with un-saponified EHEHPA, and hydrolysis process. Finally, for the first two processes, in order to predict the distribution ratio, two semi-empirical calculation models were developed with.The calculation results are in good agreement well with the experimental data.

Relative Basicity of Trioctylamine to Carboxylic Acid in Selected Organic Diluents

The relative basicity of trioctylamine （TOA）, pKa,BS, in protic polar diluent （1-octanol）, non-protic polar diluent [methyl iso-butyl ketone （MIBK）] and inert diluent （CCl4） were determined for 11 mono-carboxylic acids, and the dependence of PKa,BS on the nature of solute and diluent type was discussed. The results show that pKa,BS determined by half neutralization with the solute carboxylic acid is in the order of 1-octanol〉MIBK〉CCl4 for a fixed TOA concentration, and it increases with increasing acidity and hydrophobicity of the carboxylic acid. Compared with two parameters of the solute extracted （acidity and hydrophobicity）, pKa,BS is more sensitive to hydrophobicity of the acid. A mathematic equation representing relationship between the apparent extraction equilibrium （K11） and the system properties （PKa,BS and pKa） was proposed： 1g K11 = 2pKa,BS=pKa. It is proved that the extraction equilibrium of mono-carboxylic acids can be predicted by the above equation with reasonable accuracy.

Basic density, extractive content and moisture sorption properties of Pinus pinaster wood infected with the pinewood nematode, Bursaphelenchus xylophilus

The pinewood nematode（PWN）, Bursaphelenchus xylophilus, has become one of the most severe threats to pine forest worldwide. Nematodes, migrating through resin canals and feeding on the living cells, induce rapid metabolic changes in ray parenchyma cells, create cavitation areas, decrease xylem water content and oleoresin exudation, and cause necrosis of parenchyma and cambial cells. This study focused on the impact of PWN infection on technological parameters of wood and evaluated the impact of anatomic and biochemical incidences of tree defense reactions on basic density, extractive content and moisture sorption properties of Pinus pinaster wood.Samples of infected and uninfected wood were studied.The presence of nematodes reduced wood basic density by2 % and decreased the total content of extractives in infected wood as compared with uninfected（5.98 and8.90 % of dry wood mass, respectively）. Extractives in infected trees had inverse distribution along the trunk as compared with uninfected trees. The adsorption isotherms for infected and uninfected wood had similar positioning.We recorded differences（some statistically significant） in the equilibrium moisture content of infected and uninfected wood under varying environmental conditions. Despite the verified differences in wood basic density, extractive content and moisture sorption properties, the overall conclusion is that the PWN had a slight impact on these characteristics of wood.

Tailoring component incorporation for homogenized perovskite solar cells

Deep-level traps at the buried interface of perovskite and energy mismatch problems between the perovskite layer and heterogeneous interfaces restrict the development of ideal homogenized films and efficient perovskite solar cells(PSCs)using the one-step spin-coating method.Here,we strategically employed sparingly soluble germanium iodide as a homogenized bulk in-situ reconstruction inducing material preferentially aggregated at the perovskite buried interface with gradient doping,markedly reducing deep-level traps and withstanding local lattice strain,while minimizing non-radiative recombination losses and enhancing the charge carrier lifetime over 9μs.Furthermore,this gradient doping assisted in modifying the band diagram at the buried interface into a desirable flattened alignment,substantially mitigating the energy loss of charge carriers within perovskite films and improving the carrier extraction equilibrium.As a result,the optimized device achieved a champion power conversion efficiency of 25.24% with a fill factor of up to 84.65%,and the unencapsulated device also demonstrated excellent light stability and humidity stability.This work provides a straightforward and reliable homogenization strategy of perovskite components for obtaining efficient and stable PSCs.

A microextraction approach for rapid extraction and separation of Mn(Ⅱ) and Co(Ⅱ) using saponified D2EHPA system

In this paper,we proposed a microextraction approach for the extraction and separation of Mn(Ⅱ)and Co(Ⅱ)from sulfate solution simulating leachate of spent lithium-ion battery cathode materials using saponified di-(2-ethylhexyl)phosphoric acid system.The effects of the following operational variables were investigated:equilibrium pH,tri-«-butyl phosphate concentration,saponification rate,two-phase ratio and residence time.The results showcased that the microextractor can reach the extraction equilibrium within 20 s,thereby greatly reducing necessary extraction time comparing to that of conventional processes.The volumetric mass transfer coefficient showed 8-21 times larger than that of batch device.With the help of microextractor,95%of Mn(Ⅱ)was extracted with a single theoretical stage at a chosen two-phase ratio of 3:1,and the separation factor β_(Mn/Co) was as large as 65.5.In the subsequent stripping step,more than 99%of manganese from loaded phase was easily stripped under optimal conditions.The microextraction approach greatly enhances the mass transfer while enabling a continuous and controllable extraction process within a simple structure design.When extracting spent electrode material with microextractors,the comprehensive recovery of mangenese can reach 96%.The microextraction approach has a good applicability in the spent lithium-ion battery cathode materials recycling at both bench and industrial scales.

Association Mechanism Between Propionic Acid and Trioctylamine

Tertiary amines dissolved in diluents are attractive extractants for recovery of carboxylic acids from dilute aqueous solutions. Quantitative Fourier transform infrared (FTIR) analysis of organic solutions containing various concentrations of trioctylamine (TOA), n octanol, and propionic acid was carried out, and liquid liquid equilibrium was investigated using TOA in n octanol as the solvent. The fraction of ion pair association between TOA and propionic acid in the organic phase was quantitatively determined by FTIR. The apparent reactive extraction equilibrium constant, K 11 , was calculated using the quantitative FTIR spectrum and the equilibrium data. The results show that the fraction of ion pair association depends on diluent concentration, complex dissolution for propionic acid, and association between TOA and propionic acid. The K 11 based on quantitative FTIR has the same loading trend as that from the equilibrium data.