Intensified reactive extraction of 4-hydroxypyridine with di(2-ethylhexyl) phosphoric acid in 1-octanol by using tributyl phosphate

The efficient separation of amphoteric organic compounds from dilute solutions is of great importance in the industrial field. In the present work, the reactive extractions of 4-hydroxypyridine(4-HP) with tributyl phosphate(TBP), di(2-ethylhexyl) phosphoric acid(D2EHPA) and TBP + D2EHPA dissolved in 1-octanol were investigated, respectively. The influences of the initial concentrations of TBP, D2EHPA and TBP + D2EHPA on distribution ratio(D) were discussed, as well as the reactive extraction mechanism were proposed. The obvious intensification effect was observed when the mixture of TBP and D2EHPA was used as extractant. The best extraction conditions were found to be of the molar ratio of D2EHPA and TBP at 2:1 and the equilibrium aqueous pH at 3.50-4.50. D values increased with the increase of the total concentration of TBP and D2EHPA in 1-octanol. Especially, the analysis on the extraction mechanisms clearly indicate(i) TBP in 1-octanol shows negligible reactive extraction toward 4-HP,(ii) D2EHPA in 1-octanol exhibits moderate extraction effect by forming 4-HP:D2EHPA(1:1) and 4-HP:2D2EHPA(1:2) type complexes, while(iii) D2EHPA in TBP/1-octanol demonstrates the maximum distribution ratio with the 4-HP:D2EHPA(1:1) type complex domination. The discussion provides new insights on the mechanism and opens a new way for the intensified extraction of amphoteric organic compounds by using the mixture of multiple extractants in the diluent.

Maslinic acid supplementation prevents di(2-ethylhexyl)phthalate-induced apoptosis via PRDX6 in peritubular myoid cells of Chinese forest musk deer

Chinese forest musk deer(FMD),an endangered species,have exhibited low reproductive rates even in captivity due to stress conditions.Investigation revealed the presence of di(2-ethylhexyl)phthalate(DEHP),an environmental endocrine disruptor,in the serum and skin of captive FMDs.Feeding FMDs with maslinic acid(MA)has been observed to alleviate the stress response and improve reproductive rates,although the precise molecular mechanisms remain unclear.Therefore,this study aims to investigate the molecular mechanisms underlying the alleviation of DEHP-induced oxidative stress and cell apoptosis in primary peritubular myoid cells(PMCs)through MA intake.Primary PMCs were isolated and exposed to DEHP in vitro.The results demonstrated that DEHP significantly suppressed antioxidant levels and promoted cell apoptosis in primary PMCs.Moreover,interfering with the expression of PRDX6 was found to induce excessive reactive oxygen species(ROS)production and cell apoptosis in primary PMCs.Supplementation with MA significantly upregulated the expression of PRDX6,thereby attenuating DEHP-induced oxidative stress and cell apoptosis in primary PMCs.These findings provide a theoretical foundation for mitigating stress levels and enhancing reproductive capacity of in captive FMDs.

Tb(III) Transport in Dispersion Supported Liquid Membrane System with D2EHPA as Carrier in Kerosene

The transport of Tb（III） in dispersion supported liquid membrane（DSLM） with polyvinylidene fluoride membrane（PVDF） as the support and dispersion solution including HCl solution as the stripping solution and di（2-ethylhexyl） phosphoric acid（D2EHPA） dissolved in kerosene as the membrane solution, has been studied. The effects of pH value, initial concentration of Tb（III） and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on the transport of Tb（III） have also been investigated, respectively. As a result, the optimum transport conditions of Tb（III） were obtained, i.e., the concentration of HCl solution was 4.0 mol/L, the concentration of D2EHPA was 0.16 mol/L, the volume ratio of membrane solution to stripping solution was 30：30 in the dispersion phase and pH value was 4.5 in the feed phase. Ionic strength had no obvious effect on the transport of Tb（III）. Under the optimum conditions, the transport percentage of Tb（III） was up to 96.1% in a transport time of 35 min when the initial concentration of Tb（IIl） was 1.0× 10 -4 mol/L. The diffusion coefficient of Tb（III） in the membrane and the thickness of diffusion layer between feed phase and membrane phase were obtained and the values were 1.82×10 -8 m2/s and 5.61 um, respectively. The calculated results were in good agreement with the literature data.

二(2-乙基己基)二硫代次膦酸对硝酸溶液中Am^(3+)和Eu^(3+)的萃取

以正十二烷作稀释剂,研究了二(2-乙基己基)二硫代次膦酸(D2EHDTPA)对HNO_3溶液中Am^(3+)和Eu^(3+)的萃取行为.考察了酸度、萃取剂及NO-3浓度和皂化度对萃取的影响.在考察的pH范围(2. 5～4. 5)内,D2EHDTPA萃取Am^(3+)和Eu^(3+)的分配比(D)随pH值增大而增加; p H=3. 65时,分离因子(SF_(Am/Eu))值达到最大(4000).随D2EHDTPA浓度的增加,D_(Am)和D_(Eu)值均增加.斜率分析表明,D2EHDTPA萃取Am^(3+)和Eu^(3+)主要形成3∶1和2∶1型的萃合物. NO_3^-未直接参与D2EHDTPA对Am^(3+)和Eu^(3+)的萃取反应. D2EHDTPA经NaOH皂化后,萃取能力显著增强,SF_(Am/Eu)值提高到104量级,萃取容量约为理论值的60%.此外,使用高分辨质谱、红外光谱和等温微量热滴定方法研究了D2EHDTPA与Eu^(3+)的配位化学行为,得到了金属离子与配体的组成比、络合物稳定常数以及配位热力学参数ΔH,ΔS和ΔG值.

Selective removal of iron(Ⅲ) from highly salted chloride acidic solutions by solvent extraction using di(2-ethylhexyl) phosphate

Metal ions including Fe^(3+),Ca^(2+),Mg^(2+),Ni^(2+),Co^(2+) and Cu^(2+) are commonly found in the leaching solution of laterite-nickel ores,and the pre-removal of Fe^(3+) is extremely important for the recovery of nickel and cobalt.Di(2-ethylhexyl)phosphate acid(D2EHPA)showed high extraction rate and selectivity of Fe^(3+) over other metal ions.The acidity of the aqueous solution is crucial to the extraction of Fe^(3+),and the stoichiometry ratio between Fe^(3+) and the extractant is 0.86:1.54.The enthalpy for the extraction of Fe^(3+) using D2EHPA was 19.50 kJ/mol.The extraction of Fe^(3+)was ≥99% under the optimized conditions after a three-stage solvent extraction process.The iron stripping effects of different reagents showed an order of H_(2)C_(2)O_(4)>NH_(4)HCO_(3)>HCl>NaCl>NaHCO_(3)>Na_(2)SO_(3).The stripping of Fe was ≥99% under the optimized conditions using H_(2)C_(2)O_(4) as a stripping reagent.

Combination of on-line preconcentration by di(2-ethylhexyl) phosphoric acid resin in the presence of complexing agent with microwave plasma-atomic emission spectrometry for the determination of rare earths

The adsorption of rare earths,lanthanum,cerium,neodymium,and yttri um by di(2-ethylhexyl) phosphoric acid(D2EHPA) resin in the presence of a compl exing agent,EDTA,was investigated. Flow injection was selected as the injectin g method. Various parameters,sample pH,sample loading time,sample flow rate,EDTA concentration,EDTA flow rate,eluent concentration,and eluent flow rate,were studied and optimized. Under the optimum conditions,the method allowed the determination of rare earths with detection limits of 1.09 μg/L(lanthanum),3 .31 μg/L(cerium),2.05 μg/L(neodymium),and 1.25 μg/L(yttrium) . High repea tabilities were obtained for all the four rare earths(RSD【5%) . The proposed met hod was applied to the determination of the rare earths in water samples with a recovery range of 95.8%-103.3%.

Separation of Eu(Ⅲ) with supported dispersion liquid membrane system containing D2EHPA as carrier and HNO_3 solution as stripping solution

The Eu（III） separation in supported dispersion liquid membrane （SDLM）, with polyvinylidene fluoride membrane （PVDF） as the support and dispersion solution containing HNO3 solution as the stripping solution and Di（2-ethylhexyl） phosphoric acid （D2EHPA） dis- solved in kerosene as the membrane solution, was studied. The effects ofpH value, initial concentration of Eu（III） and different ionic strengths in the feed phase, volume ratio of membrane solution and stripping solution, concentration of HNO3 solution, concentration of carrier, different stripping agents in the dispersion phase on the separation of Eu（III） were also investigated, respectively. As a result, the optimum separation conditions of Eu（III） were obtained as the concentration of HNO3 solution was 4.00 mol/L, concentration of D2EHPA was 0.160 mol/L, and volume ratio of membrane solution to stripping solution was 30：30 in the dispersion phase, and pH value was 5.00 in the feed phase. Ionic strength had no obvious effect on the separation of Eu（III）. Under the optimum conditions studied, when initial concentration of Eu（III） was 1.00× 10^-4 mol/L, the separation rate of Eu（III） was up to 94.2% during the separation period of 35 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The results were in good agreement with the literature data.

Separation of Trivalent Samarium through Facilitated Stripping Dispersion Hollow Fiber Liquid Membrane Using p204 as Mobile Carrier

The separation of Sm（III） through stripping dispersion hollow fiber liquid membrane system （SDHFLM） containing feed phase adding acetate buffer solution and dispersion solution with HC1 solution as the stripping solution and membrane solution of di（2-ethylhexyl） phosphoric acid （p204） dissolved in kerosene, has been studied. A set of factors were studied, including pH value, initial concentration of Sm（III） and different ionic strength of feed phase, volume ratio of membrane solution and stripping solution （O/W）, HC1 concentration, carrier concentration, different stripping agents of dispersion phase on Sm（III） separation. Experimental results indicate that the optimum separa- tion conditions of Sm（III） were obtained as that HC1 concentration was 4.00 tool/L, p204 concentration was 0.150 mol/L, and volume ratio of membrane solution and stripping solution （O/W） was 1.00 in the dispersion phase, and pH value was 4.60 in the feed phase. Ionic strength had no obvious effect on separation of Sm（III）. When initial Sm（III） concentration was 1.00 × 10^-4 mol/L, the separation rate of Sm（III） was up to 93.5% in 85 min. The kinetic equation was developed in terms of the law of mass diffusion and the theory of interface chemistry. The modeled results were in good agreement with the experiment data.

Study on a novel flat renewal supported liquid membrane with D2EHPA and hydrogen nitrate for neodymium extraction

The Nd（III） extraction in flat renewal supported liquid membrane（FRSLM）,with polyvinylidene fluoride membrane and renewal solution including HNO3 solution as the stripping solution and di（2-ethylhexyl） phosphoric acid（D2EHPA） dissolved in kerosene as the membrane solution,was investigated.The effects of pH in the feed phase,volume ratio of membrane solution to stripping solution,concentra-tion of HNO3 solution and concentration of carrier in the renewal phase on extraction of Nd（III） were also studied,respectively.As a result,the optimum extraction conditions of Nd（III） were obtained when concentration of HNO3 solution was 4.00 mol/L,concentration of D2EHPA was 0.100 mol/L,and volume ratio of membrane solution to stripping solution was 1.00 in the renewal phase,and pH was 4.60 in the feed phase.When initial concentration of Nd（III） was 2.00×10-4 mol/L,the extraction percentage of Nd（III） was up to 92.9% in 75 min.

A comparative investigation into floatability of bastnaesite with three di/trialkyl phosphate surfactants

Flotation separation and recovery of rare earth minerals(REM) have returned to an important position due to the growing strategy demand for rare earth elements(REE).In this paper,a comparative investigation into the floatability of bastnaesite((Ce,La)FCO3) was conducted by using three di/trialkyl phosphate collectors,di(2-ethylhexyl) phosphate(DEHPA),dibutyl phosphate(DBP) and tributyl phosphate(TBP).The density functional theory(DFT) computation recommends that the chemical activity of the three phosphate collectors is in order of DEHPA≥ DBP >> TBP,and their hydrophobization assuggested by the IgP(oil-water partition coefficient) value is in the order of DEHPA> TBP> DBP.The micro-flotation indicates that the preferable pH values for flotation of bastnaesite with the three phosphate collectors are 7.0-8.0,and DEHPA achieves much higher flotation recovery of bastnaesite,followed by DBP,and then TBP,which coincides with their reactivity and hydrophobicity,the two prerequisites for froth flotation.The contact angle,zeta potential,Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS) deduce that DEHPA likely reacts with the Ce(Ⅲ)atoms of bastnaesite interface through its O atom(s) of the P(=O)-O-group to generate the Ce-O-P bonds,and its two 2-ethylhexyl groups orient outside for attaching bubbles,resulting in flotation enrichment of bastnaesite.Furthermore,this investigation offers a novel strategy for developing collectors in selective beneficiation of REM.

A preliminary study of polymer inclusion membrane for lutetium(Ⅲ)separation and membrane regeneration

This paper reports on the selective transport of Lu(Ⅲ)from La(III)and Sm(III)through a polymer inclusion membrane(PIM)composed of 40 wt%di(2-ethylhexyl)phosphinic acid(P227)and 60 wt%poly(vinylidene fluoride)(PVDF).Basically,the changes in surface morphology,thickness and water contact angle of this PVDF-based PIM containing P227(P227@PVDF PIM)with different polymer concentrations were investigated.By solvent extraction experiments,it is found that Lu(Ⅲ)can be selectively extracted from La(Ⅲ)and Sm(Ⅲ)at pH 1.5 in hydrochloric acid solution.According to this result,P227@PVDF PIM was used to selectively transport Lu(Ⅲ)from hydrochloric acid feed solution containing similar concentration of La(Ⅲ)and Sm(Ⅲ).The recovery factor of Lu(III)is 91% after 36 h,and about 5%of Sm(Ⅲ)was also transported through the PIM.The concentration of La(III)in the feed solution and the stripping solution does not change.Furthermore,to overcome the ubiquitous decline of transport efficiency caused by the loss of carrier or the damage of membrane structure after long-term use of PIMs,a process for regenerating PIMs was first proposed and implemented.By comparison of the regenerated PIM with the normal PIM,there is almost no difference in the SEM image,ATR-FTIR spectrum and Lu(III)transport efficiency.It is expected that P227@PVDF PIMs have the potential to be applied to the grouped separation of rare earth elements(REEs),and this study also can be as an inspiration for the further study on the PIMs regeneration process.