l-Proline Based Aqueous Biphasic System: Design and Application To Isolate the Alkaline Earths

Abstract

An aqueous biphasic system (ABS) was obtained after mixing an amino acid (l-proline) solution (5 mol·kg–1) with a 0.90 g·g–1 solution of nonionic surfactant (Triton X-100). The phase diagram of the system was constructed at 296 K. The system was found to work in a more efficient and economic way when the surfactant is enriched with a cosolute, isoamyl alcohol in a ratio of 2:1. The addition of isoamyl alcohol results in a decrease in density of the surfactant phase, much below the density of a dilute solution of proline (0.1 mol·kg–1). This results in very low consumption of the amino acid for the design of the ABS. The tolerance of the ABS toward changes in pH and concentrations have been found to improve drastically in the presence of the cosolute. When sodium alginate is used as a complexing agent, the developed system shows a pH-dependent separation for the alkaline earth metal ions Mg2+, Ca2+, Sr2+, and Ba2+ from one another. Detection of these metal ions after their separations has been achieved with eriochrome black T (EBT; for Mg2+ at pH 9.5) and arsenazo III (for Ca2+, Sr2+, and Ba2+ at pH 7.2) using absorption spectrometry. As different pH values are suitable for the complexation and extraction of different alkaline earths, it is possible to have a sequential separation of the individual elements from a mixture as and when required.

Block copolymer as a novel functional phase in an aqueous biphasic system for species selective iodine extraction

“…24,25 Aqueous solutions of PPG-PEG-PPG #2000 (30%) and Natartrate (1.2 M) were taken as the stock solutions to obtain the binodal curve. 24,25 Aqueous solutions of PPG-PEG-PPG #2000 (30%) and Natartrate (1.2 M) were taken as the stock solutions to obtain the binodal curve.…”

“…Phase diagram of this new copolymer-based ABS was constructed by the simple turbidimetric titration method. 24,25 Aqueous solutions of PPG-PEG-PPG #2000 (30%) and Natartrate (1.2 M) were taken as the stock solutions to obtain the binodal curve. The detailed Experimental method is described as per our earlier reports.…”

“…The detailed Experimental method is described as per our earlier reports. 24,26 By convention, the component predominantly in the bottom phase was plotted in the abscissa (Na-tartrate for our system), and the component predominantly in the top phase was plotted as the ordinate (PPG-PEG-PPG #2000 for our system).…”

Comparison of Salt Cations in the Design of Nonionic Surfactant Based Aqueous Biphasic Systems: Application in Polyphenol Separations

“…Binodal data points were obtained from the biphasic compositions of the mother solutions of Brij 35 (30%)/Na 2 SO 4 (2 M), MgSO 4 (1.4 M), and ZnSO 4 (1.4 M) systems. The experimental procedure followed herein is described in our earlier reports. , Binodal curves were obtained by plotting weight percentages of Brij 35 and sulfate salts. The composition of the bottom phase (salt rich phase) was plotted in the abscissa and that in the top phase (surfactant rich phase) was plotted as the ordinate.…”

Phase separation in aqueous systems for realizing virtually significant extractions

“…The phase diagrams of our proposed PVP-based ABSs were constructed by the simple turbidometric titration method. 25,[29][30][31][32][33] Binodal curves were obtained for the biphasic compositions of PVP (40%)/Na-tartrate (1.8 M) and PVP (30%)/TX (30%) systems. For this purpose, the initial weight of the blank centrifuge tube was recorded.…”