Solubility of Naphthalene in the Top Phase of Polyethylene Glycol and Ammonium Sulfate Aqueous Two-Phase Systems

Inthis study, the solubility of naphthalene was used to demonstratethe dissolubility of three top aqueous two-phase systems (ATPSs) comprisingpolyethylene glycol (PEG) 1000, PEG 1500, and PEG 2000, respectively,mixed with ammonium sulfate (NH4)(2)SO4. First, the liquid-liquid equilibrium data were obtainedfor the three individual ATPSs. Under the condition of 1 mg naphthalenein a 1 mL individual top phase of the ATPSs at 298 K, the measureddissolubilities with compositions of 20 wt % ammonium sulfate and20 wt % PEG 1000, 1500, and 2000 against naphthalene were 4.19, 4.80,and 5.04 mmol & BULL;L-1, respectively. It was demonstratedthat the dissolubility of naphthalene in the top phase of ATPS positivelycorrelates with the contents of PEG, salt, and both (PEG and salt),with average correlation coefficients of 0.9817, 0.9978, and 0.9588,respectively. The dissolubilities of the top phases of the three ATPSsagainst naphthalene were compared and revealed to be within 98-163%of those of 13 selected common solvents, indicating that their performancecan be further fine-tuned. The results obtained in this study highlightcharacteristics of the ATPSs that render them suitable for use assolvents, in addition to their well-known use as separation candidates.