Synthesis and characterization of nanocomposite ultrafiltration membrane (PSF/PVP/SiO2) and performance evaluation for the removal of amoxicillin from aqueous solutions

The presence of antibiotics in drinking water sources indicates the inefficiency of their removal using common water treatment process. Removal of these micro-pollutants from water requires more advanced and efficient processes. The purpose of this study was to synthesize a nanocomposite ultrafiltration membrane (Polysulfone/Polyvinylpyrrolidone/SiO2) and to evaluate for removal of amoxicillin from aqueous media. Ultrafiltration membranes were synthesized using phase inversion method. SiO2 nanoparticles (∼10-20 nm) were used in the range of 0 to 4 wt% as a hydrophilic agent for membrane modification. The characterizations of the membranes were determined using FTIR, water contact angle, AFM and SEM techniques. Also, the performance of synthesized membranes was evaluated in terms of pure water flux, amoxicillin separation efficiency and fouling parameters analysis. The results of FTIR analysis and contact angle measurement indicated that the hydrophilicity of nanocomposite membranes has increased significantly due to the presence of hydroxyl group in SiO2 structure. The results of AFM images also showed that with increasing the addition of nanoparticles, the average surface roughness of the synthesized membranes increased negligibly. Also, FE-SEM micrographs showed that with increasing SiO2 concentration, the porous structure of the membranes changes from a spongiform and tear-like to a canal-shaped, finger-shaped and macro-void structures. This change in the structure increased the porosity and then the membrane flux, so that the pure water flux was 6.6 L/m2.h for the unmodified membrane to 42.28 L/m2.h for the membrane with 3 wt% of nanoparticles. The evaluation of membrane performance showed that with increasing SiO2 nanoparticles from 0 to 4 wt%, the amoxicillin separation performance increased from 66.52% to 89.81%. In addition, the analysis of the membrane fouling parameters showed that the addition of SiO2 nanoparticles also improved the membrane resistance against fouling, so that the relative flux reduction ratio (RFR) from 57.03% (Rreversibler=9.9 and Rirreversible=47.13) for the unmodified membrane reduce to 22.89% (Rreversibler=16.10 and Rirreversible=6.79) for the modified membrane with 3 wt% of nanoparticles. The results of this study showed that the use of nanocomposite membranes is promising for the removal of biodegradable resistant pollutants such as amoxicillin antibiotics from water resources.