Investigating the performance of ELM systems in separating organic pollutants from industrial wastewater

Emulsion liquid membrane (ELM) is one of the processes widely used in industrial separation process. Extraction of benzoic acid from aqueous solutions by an emulsion type liquid membrane was investigated. The influence of two emulsion composition variables, namely the surfactant concentration, and organic phase to internal stripping phase ratio(VO/VI), as well as three process parameters, emulsion to external feed phase ratio (VE/VF), mixing speed of feed solution, and extraction time on the rates of extraction of benzoic acid, was experimentally studied. The emulsion liquid membrane consists of kerosene as solvent, Span 80 as surfactant, and NaOH as internal stripping phase. The role of a hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [BMIM]+[NTf2]− in increasing the stability of the emulsion membrane was also studied. The stability of emulsion containing 0.2% (v/v) of [BMIM]+[NTf2]− has significantly increased in comparison with that without ionic liquid. Approximately 99.7% of benzoic acid was extracted after only 5 min of contact with tested mixtures under the most favorable operating conditions.