Investigation of characterization and biofouling properties of PES membrane containing selenium and copper nanoparticles

Selenium and copper nanoparticles exhibit superior antioxidant activity, unique properties, and great potential applications that make them very attractive for developing new composite materials. In this study, polyethersulfone (PES) ultrafiltration membrane was modified by dispersing nano-sized selenium (nSe) and copper (nCu) particles uniformly in a PES solution (18% polymer weight) and casted by a phase inversion process. Membranes with four different weight ratios of nSe and nCu to PES of 0.002, 0.010, 0.030, and 0.050 were tested. Selenium nanoparticles were prepared by the reduction of aqueous sodium selenite solution with freshly prepared glucose solution. The method was capable of producing spherical selenium nanoparticles in a size range of about 150-175nm, under ambient conditions. The synthesized nanoparticles can be separated easily from the aqueous solutions by a high-speed centrifuge and can be re-dispersed in an aqueous medium by an ultra-sonicator. The effects of temperature, time, and stirring rate on the size of the selenium nanoparticles were studied. In addition, nanoscale particles of metallic copper clusters were prepared by sonochemical reduction of copper(II) hydrazine carboxylate Cu-(N₂H₃COO)₂.2H₂O complex in an aqueous medium. Reduction process takes place under an argon atmosphere over a period of 2-3h and the size of copper nanoparticles was about 90-105nm. The synthesized selenium and copper nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and particle size distribution techniques. Moreover, Se/PES and Cu/PES blend membranes were also characterized using contact angle goniometer, scanning electron microscopy (SEM), and permeation tests. Anti-fouling performance was examined using activated sludge as a biological suspension. The protein rejection study was also carried out using the bovine serum albumin (BSA) solution. The morphology and permeation properties of the blend membranes were found to be dependent on the amounts of nanoparticles. Compared to neat PES membrane, the 0.05 Cu/PES membrane exhibited highest protein rejection ratio (86.3%). However, the Se/PES membranes showed better antifouling performance (lower flux decline). The blending membranes with nanoparticles are considered to be suitable for the prevention of biofouling.