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Reactive extraction of L‐valine with di(2‐ethylhexyl) phosphate acid

Bai, Huihua, Guo, Kaixuan, Chen, Xue, Chang, Zhixian, Li, Deliang
Journal of chemical technology and biotechnology 2016 v.91 no.12 pp. 3096-3102
aqueous solutions, equations, ion exchange, pH, phosphates, valine
BACKGROUND: Reactive extraction is a promising technique for the recovery of amino acids from aqueous solutions. The reactive extraction of L‐valine with di(2‐ethylhexyl) phosphate acid (D2EHPA) has been studied in this work. An expression for the equilibrium distribution ratio (D) was proposed to describe the experimental data. RESULTS: The diluents, equilibrium pH value (pHₑq), the concentration of L‐valine and D2EHPA were found to be the key factors that affected D. The highest D was observed at pHₑq around 2.6 with 1‐octanol as diluent. D value increased with increase of the concentration of D2EHPA. In contrast, with increase of the concentration of L‐valine, D value decreased. The extraction mechanism was analyzed using Fourier infrared spectra. The reactive extraction mechanism of L‐valine with D2EHPA was mainly via proton‐transfer and ion‐exchange process. By fitting the experimental data, (1:1) complex of L‐valine with D2EHPA was deduced. The comparison of theoretical D values with the experimental data verified the reliability of the proposed mechanism equations. CONCLUSIONS: L‐valine was efficiently extracted from aqueous solutions using D2EHPA in 1‐octanol, which provides preliminary practical information and theoretical basis for the separation of L‐valine, as well as its purification and recovery. © 2016 Society of Chemical Industry