Influence of TiO2 charge and BSA-metal ion complexation on retention of Cr (VI) in ultrafiltration process

Abstract

TiO 2 nanoparticles (NPs), functionalized poly vinyl chloride (PVC) and polysulfone (PSf) were assembled together in different compositions to fabricate composite membranes with potential application in Cr (VI) and antifouling treatment. Here, TiO 2 nanoparticles were synthesized via sol-gel process and Poly vinyl chloride chemically altered with 4-amino benzoic acid. Functionalized PVC was blended uniformly throughout PSf matrix rendering the yellowish-orange color and porous structure giving better productivity. TiO 2 NPs were studied for optimum concentration to provide the excess charge for Cr (VI) rejection. SEM images revealed the porous finger like structure within the membranes and the molecular weight cutoff confirmed the ultrafiltration nature of the membranes. Composites showed good wetting behavior with contact angle (between 67 and 76°) and swelling behavior (≈50–79%). Cr (VI) aqueous rejection and the key parameters namely pressure, pH, filler TiO 2 concentration and BSA protein were studied in detail. Maximum of 87 ± 5% rejection of Cr (VI) was obtained with productivity of 6.5 L/m 2 h at 100 kPa pressure in acidic medium. While the antifouling experiments indicated incorporation of TiO 2 NPs increased the flux recovery ratio, presence of BSA protein in feed solution showed binding effects with Cr 2 O 7 2− anions. The membranes showed good reusability for continuous 3 cycles maintaining the rejection efficiency above 70 ± 5% at the end of 3rd cycle. • Work reports the effect of TiO 2 NPs on performance of 4-amino benzoic acid/PSf membranes. • Presence of BSA feed and interaction between Cr (VI) ions on membrane performance is deliberated. • Complexation between BSA protein and Cr 2 O 7 2− ions lead to increased rejection efficiency with time. • The composite membranes showed improved rejection of Cr (VI) throughout the whole pH range owing to TiO 2 NPs.