HYDROMETALLURGY
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2016
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IF 2.29
Ying Zhang,Ting-an Zhang,Guozhi Lv,Guoquan Zhang,Yan Liu,Weiguang Zhang
In the present study, the mechanisms and thermodynamics of vanadium extraction by a mixture of bis-2-ethylhexyl phosphorous acid (D2EHPA) and 2-ethylhexyl phosphorous acid mono-2-ethylhexyl ester (EHEHPA) from sulfate medium were investigated. It was found that the maximum synergistic factors obtained at X D2EHPA = 0.2 and the reaction of the synergistic extraction is exothermical. Results showed that the mixture system in the presence of complexing agents exhibit a higher extraction efficiency and require a lower acid consumption during the stripping process of vanadium. Fourier transform infrared (FT-IR) spectroscopy showed that P–O–H and P O of the extractants are responsible for the synergistic extraction of VO 2 + species by cation exchange mechanism and some hydrogen bonds between EHEHPA and D2EHPA formed in the synergistic extraction system. With the slope analysis method, the reaction of the synergistic extraction was mainly predicted.
研究领域:
化学工程
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环境科学
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Yongchao Wang,Yahui Liu,Fancheng Meng,Jian Zhang,Shuai Zhao,Xile Tian,Lina Wang,Desheng Chen,Tao Qi
The significant chemical similarity between vanadium and chromium complicates the process of efficient extracting V(Ⅳ) from the solution containing Cr(Ⅲ) to prepare high-purity vanadyl sulfate electrolyte. In this study, the separation of vanadium and chromium with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA) was enhanced by increasing the concentration of SO 4 2− . Under the extraction equilibrium pH of 2.5, the extraction of Cr(III) was suppressed by increasing the concentration of SO 4 2− anions, which hardly affected the extraction efficiency of V(IV), achieving a separation factor as high as 5780.6 at SO 4 2− concentration of 1.75 mol·L −1 . Furthermore, after pretreatment of the water-leaching solution of sodium-roasted vanadium slag, extraction was carried out under the conditions of equilibrium pH of 1.8 and SO 4 2− concentration of about 2.00 mol·L −1 , and after stripping, the vanadyl sulfate electrolyte containing 2.12 mol·L −1 of vanadium and only 0.11 mg·L −1 of chromium was obtained. It was proved that Cr(Ⅲ) mainly extracted in the form of CrSO 4 + into organic phase by one EHEHPA dimer as [CrSO 4 (H 2 O)] + under higher SO 4 2− concentrations (e.g., ≥1.50 mol·L −1 ), while Cr(Ⅲ) was extracted by two EHEHPA dimers as Cr 3+ without SO 4 2− in the solution. Based on the density functional theory, the complex structures of Cr(III) were optimized and the energy changes of Cr(III) extraction reactions were calculated, indicating the complexation between SO 4 2− and Cr(III) under higher SO 4 2− concentrations resulting in the inhibition of Cr(III) extraction, and thus enhancing the separation of vanadium and chromium.
研究领域:
化学工程
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材料科学
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2025
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IF 9
Mengnan Yuan,Peng Cen,Chengliang Xiao
Due to their highly similar chemical properties, the separation of strontium and calcium has long been a great challenge. Although conventional saponification extraction enables Sr/Ca separation, it mainly suffers from inherent limitations including high-salinity wastewater generation and process complexity. This study developed a novel extraction approach utilizing ammonium citrate as a complexing agent in an EHEHPA/chloride system. Under optimized operational parameters (20 % EHEHPA, 0.02 mol/L AC, 30 min extraction duration, and 0.05 mol/L HCl for stripping), the system demonstrated remarkable separation performance with a separation factor reaching 161.5, which corresponded to a 27 times increase compared to saponification approaches. A four-stage cross-current extraction process yielded a strontium carbonate product with 91.06 % purity. Mechanistic studies indicated that the exceptional performance of this technology originated from the triple synergistic effects of ammonium citrate: robust pH buffering that stabilized the extraction system; selective coordination chemistry that dramatically increased the Sr 2+ /Ca 2+ reactivity differential; and interfacial activity modification that boosted mass transfer at the interface. This environmentally benign method can minimize the generation of ammonia‑nitrogen wastewater while operating under ambient conditions. Not only does it provide an innovative solution for greener recycling of strontium resources, it also offers valuable technical insights into the efficient separation of other similar metals.
研究领域:
湿法冶金
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分离科学
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环境工程
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资源回收
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无机化学
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产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2022
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IF 4.326
Xue Dong,Qiang Yan,Zhipeng Wang,Xiaogui Feng,Jing Chen,Chao Xu
Group separation of actinides (An, including U, Np, Pu, and Am) from lanthanides (Ln) is of great significance for nuclear resources recycling and long-term radiotoxicity reduction. But this task represents a big challenge due to the chemical complexity of the actinides. In the present work, we proposed a strategy for group An/Ln separation by oxidizing the actinides to hexavalent oxidation states and then selectively extracting them from lanthanides by a sterically hindered ligand, 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (EHEHPA). The intrinsic selectivity of EHEHPA to hexavalent actinides over trivalent/tetravalent lanthanides affords single-stage An/Ln separation factors in the range of 102–105, depending on the specific actinides or lanthanides. The selective mechanism of An(VI)/Ln(III/IV) was analyzed by means of UV–vis absorption and mass spectroscopies, which suggests that the Ln(III/IV)/EHEHPA and An(VI)/EHEHPA complexes possess similar metal/ligand stoichiometries but the former one may consist of more hydrophilic nitrate ion or water molecules, thus leading to high selectivity to An over Ln by EHEHPA.
研究领域:
核化学
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放射化学
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环境科学
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分析化学
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DOI
高影响因子
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