Extraction of phenol from aqueous solution using ionic liquid-based emulsion liquid membrane

Abstract

The ionic liquid-based emulsion liquid membrane (ELM) has been developed to extract phenol from aqueous solution. The effects of ionic liquid type, internal NaOH concentration, Aliquat 336 concentration, liquid paraffin concentration, carrier type and concentration, homogenizer speed, volume ratio of emulsion to external phase, stirring speed and initial phenol concentration on extraction efficiencies of phenol have been studied. The results show that Aliquat 336 is the most preferred ionic liquid during extraction of phenol by ELM. The optimal experimental conditions during extraction of phenol are Aliquat 336 concentration of 4%, internal NaOH concentration of 378 mg·L-1, liquid paraffin concentration of 3%, 1-octanol concentration of 3%, homogenizer speed of 6500 r·min-1, volume ratio of emulsion to external phase of 1:1, stirring speed of 200 r·min-1, and initial phenol concentration of 1019 mg·L-1. The extraction efficiency of phenol by ionic liquid-based ELM could be above 94%. Orthogonal experiments show that during extraction of phenol by ELM, the order of importance of the four factors is volume ratio of emulsion to external phase>homogenizer speed>volume fraction of Aliquat 336>internal NaOH concentration. The recycled ionic liquid-based ELM with Span-80 have been demulsified by centrifuge successfully. The demulsification efficiency of ELM reaches nearly 100% in 20 min.