Recovery of various phenols and phenylamines by micellar enhanced ultrafiltration and cloud point separation

Abstract

The recovery of organic pollutants by micellar enhanced ultrafiltration and cloud point technique was studied. It was found that micellar enhanced ultrafiltration and cloud point technique enable high recovery of some organic pollutants without using any hydrocarbon solvents. The cloud point technique gives higher recovery than ultrafiltration. Appropriate surfactants having low critical micelle concentration and low cloud point must be used. Oxyethylated fatty acid methyl esters are the most appropriate for cloud point separation as, having ester groups, they are quickly hydrolyzed in sewage systems. CTAB and SDS are appropriate for ultrafiltration. The recovery of pollutants in both considered techniques can be estimated from the micelle binding constants or from linear solvation free energy relationships according to the Abraham model. The efficiency of separation increases with an increase of pollutant hydrophobicity and excess molar refraction. Hydrogen bond acidity of pollutants improves separation from systems containing nonionic surfactants and CTAB but it does not affect separation in the presence of SDS. Hydrogen bond basicity and dipolarity of pollutants decrease the recovery. The derived models enable the selection of pollutants which can be efficiently removed from aqueous streams by the cloud point technique and micellar enhanced ultrafiltration.