The phase behavior of n-ethylpyridinium tetrafluoroborate and sodium-based salts ATPS and its application in 2-chlorophenol extraction

Abstract In this paper, the aqueous two-phase systems (ATPS) containing n-ethylpyridinium tetrafluoroborate ([EPy]BF4), sodium-based salts, and water were studied and the extraction efficiency of 2-chlorophenol was measured to study the ATPS performance in extracting phenolic compounds. The binodal curves of [EPy]BF4 + sodium carbonate (Na2CO3) ATPS and [EPy]BF4 + sodium dihydrogen phosphate (NaH2PO4) ATPS have been determined at 308.15 K, 318.15 K, and 328.15 K and atmospheric pressure. After getting good correlation with Merchuk equation, the binodal curves together with gravimetric method were used to calculate the tie-lines data. Furthermore, the reliability of tie-lines data was verified using Othmer-Tobias and Bancroft equations. Then, the salt influence and temperature influence on the phase behavior were discussed and the results show the salt-outing ability of Na2CO3 is better than NaH2PO4. With the aim of studying the ATPS performance in extracting phenolic compounds, extraction efficiency for 2-chlorophenol at different temperatures were studied and the results show that [EPy]BF4 + Na2CO3 ATPS is preferred than [EPy]BF4 + NaH2PO4 ATPS in applications.