Comparison of Extraction Capacities Between Ionic Liquids and Dichloromethane

Abstract

Extraction capacities between ionic liquids (1-butyl-3-methylimidazolium hexafluorophosphate, that is, C 4, and 1-hexyl-3-methylimidazolium hexafluorophosphate, that is, C 6) and dichloromethane were compared with respect to the extraction of 4-Nonylphenol (NP) and 4-tert-Octylphenol (OP) from water samples under different conditions. The results indicated that the extraction time leading to equilibrium was less in dichloromethane (20 min) than in ionic liquids C 4 and C 6 (60 min). When the pH in water increased from 1 to 13, the extraction efficiency of the ionic liquid C 4 decreased from 72% to 35% for OP and from 61% to 34% for NP, the extraction efficiency of the ionic liquid C 6 decreased from 68% to 25% for OP and from 56% to 28% for NP, and the extraction efficiency of dichloromethane decreased from 75% to 44% for OP and from 72% to 48% for NP. From the results of salt-out effect, it was concluded that the salt-out effect on the ionic liquids was less significant than that on dichloromethane. The extraction efficiencies were also influenced by the OP and NP concentrations and they decreased as the analyte concentration increased from 10 μg/l to 100 μg/l. The extraction capacities of dichloromethane (37.5 μg/l) on analytes were higher than those of ionic liquids (20 μg/l-30μg/l). The extraction efficiency of ionic liquids and dichloromethane increased as temperature rose from 25°C to 55°C. Similar extraction properties were found in ionic liquids and dichloromethane when used to extract organic chemicals, that is, their extraction efficiency could be affected by acidity, temperature, and analyte concentrations.