Separation of Drugs by Commercial Nanofiltration Membranes and Their Modelling.

Pharmaceutical drugs have recently emerged as one the foremost water pollutants in the environment, triggering a severe threat to living species. With their complex chemical nature and the intricacy involved in the removal process in mind, the present work investigates the performance of commercially available polyamide thin-film composite tubular nanofiltration (NF) membranes (AFC 40 and AFC 80) in removing polluting pharmaceutical drugs, namely caffeine, paracetamol and naproxen. The structural parameters of the NF membranes were estimated by water permeability measurements and retention measurements with aqueous solutions of organic, uncharged (glycerol) solutes. The effect of various operating conditions on the retention of solutes by the AFC 40 and AFC 80 membranes, such as applied transmembrane pressure, tangential feed flow velocity, feed solution concentration and ionic strength, were evaluated. It was found that the rejection of drugs was directly proportional to transmembrane pressure and feed flow rate. Due to the size difference between caffeine (MW = 194.9 g/mol), naproxen (MW = 230.2 g/mol) and paracetamol (MW = 151.16 g/mol), the AFC 40 membrane proved to be efficient for caffeine and naproxen, with rejection efficiencies of 88% and 99%, respectively. In contrast, the AFC 80 membrane proved to be better for paracetamol, with a rejection efficiency of 96% (and rejection efficiency of 100% for caffeine and naproxen). It was also observed that the rejection efficiency of the AFC 80 membrane did not change with changes in external operating conditions compared to the AFC 40 membrane. The membrane performance was predicted using the Spiegler-Kedem model based on irreversible thermodynamics, which was successfully used to explain the transport mechanism of solutes through the AFC 40 and AFC 80 membranes in the NF process.

Removal of micropollutants from water by commercially available nanofiltration membranes.

The current work is focused on the use of nanofiltration in the removal of micropollutants, specially drugs (diclofenac and ibuprofen) and heavy metal (zinc sulphate and zinc nitrate) from wastewater. The commercially available nanofiltration (NF) membranes (AFC 80, AFC 40, AFC 30) were characterised by demineralised water and the ability of the membranes to reject drugs and zinc(II) was subsequently examined. The influence of the operating conditions on the rejection and the permeate flux was evaluated. The operating conditions tested included the transmembrane pressure (5-30 bar); the effect of the feed concentration on the heavy metals rejection (50-200 mg L-1); the effect of ionic strength on the diclofenac and ibuprofen rejection (0-10 g L-1 NaCl) and the volumetric flow rate (5-15 L min-1). It has been shown that increasing the transmembrane pressure increases the intensity of the permeate flow and rejection. Drugs rejection also increases with increasing bulk feed flow rates; however, decreases with increasing ionic strength (NaCl concentration in feed). Experimental data indicated that concentration polarisation existed in the membrane separation process. The stable permeation flux and high rejection of drugs and heavy metals indicated the potential of NF for the recovery of drugs and zinc(II) from wastewater.

New monodisperse magnetic polymer microspheres biofunctionalized for enzyme catalysis and bioaffinity separations.

Magnetic macroporous PGMA and PHEMA microspheres containing carboxyl groups are synthesized by multi-step swelling and polymerization followed by precipitation of iron oxide inside the pores. The microspheres are characterized by SEM, IR spectroscopy, AAS, and zeta-potential measurements. Their functional groups enable bioactive ligands of various sizes and chemical structures to couple covalently. The applicability of these monodisperse magnetic microspheres in biospecific catalysis and bioaffinity separation is confirmed by coupling with the enzyme trypsin and huIgG. Trypsin-modified magnetic PGMA-COOH and PHEMA-COOH microspheres are investigated in terms of their enzyme activity, operational and storage stability. The presence of IgG molecules on microspheres is confirmed.