Recovery of phenolic compounds from effluents by a microemulsion liquid membrane (MLM) extractor

A microemulsion liquid membrane (MLM) extractor was constructed for the separation and the concentration of phenolic compounds from pistachio peeling effluent water streams. The extraction efficiency was 64% for the MLM compared to 46% for the corresponding emulsion liquid membrane (ELM). The diameter of the dispersed phase droplets in the water-in-oil microemulsion was 136 nm; however, the droplet diameter in alkali (NaOH)-in-oil microemulsion (composing the interior and membrane phases of the MLM extractor) was even greater than those of the alkali-in-oil emulsion (composing the interior and membrane phases of ELM extractor). Storage modulus (G′) of the alkali-in-oil emulsion was significantly greater than the loss modulus (G″) whilst those of the alkali-in-oil microemulsion overlapped. Light microscopy images of the alkali-in-oil microemulsion demonstrated that hyper-droplets consisted of microdroplets probably originated from clustered nanoscalar droplets. Low-angle X-ray diffractometry results suggested that the number of ordered structures of surfactant molecules (reverse micelles) in the presence of a phenolic compound was higher in the membrane of the MLM extractor compared to that of the ELM.