Determination of Filtration Performances of Nanocomposite Hollow Fiber Membranes with Silver Nanoparticles

This study is focused on identifying the relationship between structural properties and filtration performance of membranes with and without AgNPs. For this purpose, Ag nanoparticles (AgNPs) (0, 0.2, 0.4, 0.8 wt%) were embedded into hollow fiber (HF) membranes by using the blending method. The dry-wet phase inversion method was used for the fabrication of HF membranes. Successful embedding of AgNPs into the HF membrane matrix was confirmed by different analytical techniques such as scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX), water contact angle (CA), electrokinetic analyzer for zeta-potential measurement, and dynamic mechanical analyzer for mechanical stability. Model solutions (protein and real activated sludge) were used for the determination of filtration performance of pristine and nanocomposite membranes. AgNPs reduced the CA value of pristine membrane from 94°±1° to 69°±2°. From SEM-EDX measurement, it was realized that the dual-layer structure was obtained as well as finger-like pores were increased when AgNPs were added. In addition, AgNP concentration increment increased the pore size at the outer surfaces of the HF membranes. EDX measurement showed existence of AgNP throughout the outer surface of the membranes. Similar to these results, addition of AgNP increased permeability of membranes from 120 L/m²·h·bar to 212 L/m²·h·bar. According to the model solution filtration results, AgNP improved both protein and activated sludge filtration performances of membranes regarding rejection properties. Besides, AgNPs increased mechanical stabilities of HF membranes. Considering all results, it was concluded that HF membranes with embedded AgNPs having finger-like dual-layer cross-section structure, highly hydrophilic surface, mechanical strength, pore size, and low fouling properties are suitable, especially for membrane bioreactor systems.