Green synthesis of TiO2 nanoparticles using Cajanus cajan extract and their use in controlling the fouling of ultrafiltration PVDF membranes

Polyvinylidene fluoride (PVDF)/TiO2 composite ultrafiltration membranes were fabricated using different loadings of TiO2 NPs synthesized by the green route using an extract of Cajanus cajan. XRD analysis confirmed the synthesis of TiO2 nanoparticles of size 10 nm using Debye Scherrer's equation. High hydrophobicity of PVDF restricts its successful application due to fouling in the membrane. Therefore, composite membranes were prepared via the phase inversion route and characterized by contact angle and permeation tests. The BSA filtration experiments revealed that membrane with 0.5 wt% of TiO2 exhibits excellent hydrophilicity, permeation flux, high rejection ratio, and good antifouling performance. It was observed that the fouling characteristic of the membrane is governed by the surface roughness of the membrane, and with increasing loading of TiO2 the surface roughness decreases indirectly enhancing the antifouling property of membranes. The adsorption capacity of bovine serum albumin on the membrane surface decreased from 2.85 to 2.15 mg cm(-2) as the TiO2 loading increased from 0 to 0.02 g TiO2/g PVDF. Fouling was found due to cake formation in ultrafiltration and can be explained by Hermia's fouling model suggesting that the solutes are not deposited into the pores, which indicates that the fouling process is physically reversible.