THE EXTRACTED COMPLEX FORMED BY MONO (2-ETHYLHEXYL)-2-ETHYLHEXYL PHOSPHATE WITH DIVALENT Mn

In order to clarify the mechanism and the complex formed in the extraction of divalent Mn by alkylphosphonic acid monoester, the solid complex has been prepared by mono (2-ethylhexyl)-2-ethylhexyl phosphate, HEH(EH)P, HA with divalent Mn. The elemental analysis, magnetic susceptibility and thermogravimetry have been determined for the solid complex of HEH(EH)P-Mn(II) and the infrared spectrum has been carried out in comparison to the extractant HEH(EH)P. The extracted compound has also been studied by electronic and electron spin resonance spectroscopy in octane solvent and solid state at room temperature. On the basis of the measurements, it is concluded that the structure of the solid polymeric species MnA_2 is in a tetrahedral arrangement.

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.

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.

Enhanced CO_2 adsorptive performance of PEI/SBA-15 adsorbent using phosphate ester based surfactants as additives

In this study,a series of polyetherimide/SBA-15： 2-D hexagonal P6 mm,Santa Barbara USA（PEI/SBA-15） adsorbents modified by phosphoric ester based surfactants（including tri（2-ethylhexyl）phosphate（TEP）,bis（2-ethylhexyl） phosphate（BEP） and trimethyl phosphonoacetate（TMPA））were prepared for CO2 adsorption.Experimental results indicated that the addition of TEP and BEP had positive effects on CO2 adsorption capacity over PEI/SBA-15.In particular,the CO2 adsorption amount could be improved by around 20% for 45PEI-5TEP/SBA-15 compared to the additive-free adsorbent.This could be attributed to the decrease of CO2 diffusion resistance in the PEI bulk network due to the interactions between TEP and loaded PEI molecules,which was further confirmed by adsorption kinetics results.In addition,it was also found that the cyclic performance of the TEP-modified adsorbent was better than the surfactant-free one.This could be due to two main reasons,based on the results of in situ DRIFT and TG-DSC tests.First and more importantly,adsorbed CO2 species could be desorbed more rapidly over TEP-modified adsorbent during the thermal desorption process.Furthermore,the enhanced thermal stability after TEP addition ensured lower degradation of amine groups during adsorption/desorption cycles.