Membrane processes are major breakthrough for the removal of organic pollutants in water remediation. The separations of solutes depend on nature of the membranes and solutes. The separation performance depends on the nature of the solutes (i.e., molecular volume, polarity, and hydrophobicity) for the same membrane. As 4-chlorophenol is of more dipolemoment compared to 2-chlorophenol, the orientation of the molecule enables it pass through the pores of the membrane, which is of negatively charged and thus separation order follows: 2-chlorophenol > 4-chlorophenol. Hydrophobicity factor also supports the order. Addition of sodium dodecyl sulfate (SDS) to chlorophenol solution shows remarkable increase in separation performance of the membrane. The improvement in separation is 1.8 and 1.5 times for 4- and 2- chlorophenol consecutively in case of 0.0082 M SDS (lcmc = 0.0082 M) in the solution. 4-chlorophenol has better attachment tendency with SDS because of its relatively more hydrophobic nature and thus reflects in performance i.e. the separation performance of 4-chlorophenol with SDS through the membrane is better compared to 2-chlorophenol.

The advancement of membrane research closely relates to the activities of ‘immobilization of enzymes’. The modification of polymeric membrane surfaces according to tailor-made specifications is considered an art and useful in this arena. In this study, lipase is immobilized on Polyvinyl alcohol photomodified Polysulfone (PS–PVA) membranes. The maximum immobilization (1.48 mg/cm2) for PS–PVA membranes is achieved. The amount of immobilized lipase directly relates on the PVA content on the membrane. Scanning Electron Microscope and X-ray diffraction patterns show the evidences of lipase immobilization on membranes. The hydrolytic performances of lipase immobilized PS and PS–PVA–glu membranes for olive oil are studied. The free fatty acid (FFA %) and acid value (AV) parameters are determined by titrimetic analysis (1.53 and 3.04 for PS–PVA–glu) and compared with esterification GC-mass analysis data. The K m and V max values are 105 mM and 0.9 mM/min for lipase immobilized on PS–PVA–glu and 153.8 mM and 0.51 mM/min for lipase on PS. The reusability feature shows the lipase immobilized on PS–PVA–glu matrix have better stability (10.7% decrease) compared to lipase immobilized on PS matrix (33.3% decrease) after five cycles.

Removal of pentachlorophenol from water is investigated using the surfactant-enhanced cross-flow membrane filtration technique in which anionic surfactant; sodium dodecyl sulfate (SDS) is the carrier of pentachlorophenol. The separation performances are studied by varying SDS concentrations (≪critical micelle concentration, CMC). The association between pentachlorophenol and SDS leads to increase their effective size of the feed solutes and thus results the improvement in separation performances of the membrane. The performance is co-related with the separation of markers (glucose and sucrose) as well as salt rejection of the membrane. SDS, in feed induces the charge due to its polar head and thus separation improves due to electrostatic repulsion of membrane and associated molecule. The higher hydrophobicity of pentachlorophenol is also the factor. The study reveals that there is better improvement in pentachlorophenol separation upon addition of SDS for the thin film composite membrane which is of more permeability.