Study On Fabrication And Performance Evaluation Of In-situ TiO₂ Hybridized Pvdf Ultrafiltration Membrane

Nowadays, water shortage and pollution is becoming global environment issue, which makes membrane technology more and more popular in the field of water treatment for its low consumption and high efficiency. And membrane separation has become a new remarkable water treatment technology in the 21 st century. However, membrane fouling accured in the actual operation restrains its widespread application. PVDF(polyvinylidene fluoride) as a kind of excellent membrane material has attracted much attention because it possesses lots of outstanding performances, such as thermal stability, chemical stability, mechanical propertyand radiation resistance etc. Nevertheless, the membrane made of PVDF is easily contaminated by the organics in the separation process due to its hydrophobic nature and low surface energy. In order to overcome membrane fouling and enhance its hydrophilic property, the authorsfocus on the modification of inorganic paticles and then hybridization of nanoparticlesinto the PVDF membrane.In this work, pure PVDF ultrafiltration membrane is prepared though phase inversion method employing PVDF as membrane material, DMAc as solvent and PVP as pore-forming agent. Theresearch introduces Ti O2 nanoparticles into the pure PVDF membrane by two methods: one is adding commercial Ti O2 nanoparticles immediately into the casting solution, the other is in situ formation of Ti O2 during phase inversion by adding TBT into casting solution. Various techniques, such as permeability experiments, contact angle goniometry, porosity, SEM, FTIR, XRD, XPS as well as AFM and TGA, were applied to characterizethe effects of modified membrane on the compression resistance, permeability, separation performance, anti-fouling performance and thermal stability. Simultaneously, we also investigated the influence of adding method and additive dose on the nanocomposite membrane structure in the phase inversion process.The permeability experiments showed that compared with PVDF-0 and PVDF-Ti O2 membrane, PVDF-TBT nanocomposite membrane had better permeability, separation performance and anti-fouling property. SEM and AFM were applied to characterize the surface morphology and cross-section structure, and the results revealed that PVDF-TBT nanocomposite membrane had more advanced poriosity and smoother surface, which improved the water flux dramatically and anti-fouling property to a certain extent. The TGA curves displayed that both the two kinds nanocomposite membrane had better thermal stability. The FTIR and XRD curves showed that theaddition of Ti O2 changed the crystal forms of PVDF, inducing the formation of β-PVDF.In the last, the raw water treatment performance of PVDF-TBT nanocomposite membrane was discussed. PVDF-TBT membrane had high separating effect for Al, Fe and Mn in the raw water, but was not good at removing TOC. The removal ratio of turbidity by PVDF-TBT could reach 80%. The PVDF-TBT membrane had higher flux in the raw water treatment compared with PVDF-0 and PVDF-Ti O2 membranes, which revealed that nanocomposite membrane prepared by in situ formation of Ti O2 had excellent performance in raw water treatment.