Preparation Of Ag-nTiO₂/PVC Blended Ultrafiltration Membrane And Its Antibiofouling Performance Study

In order to improve the antibacterial property of the polyvinyl chloride ?PVC?ultrafiltration membranes, the Ag-nTiO₂/PVC ultrafiltration membranes was prepared with phase inversion method.In this research, we investigated the optimal preparation method of the modified membrane, prepared the membrane module and tested its anti-pollution capacity in the water treatment process.Based on the optimized preparation conditions, we prepared the modified membrane with following contents: the content of polymer polyvinyl chloride ?PVC?was 12%; polyvinylpyrrolidone ?PVP? content was 6%; the modified nanoparticles Ag-nTiO₂ concentration was 1% and Tween80 concentration was 0.4%.Various techniques such as scanning electron microscopy ?SEM?, atomic force microscopy ?AFM?, electronic tensile test machine, contact angle goniometry as well as permeability experiments and antibacteria experiments were applied to characterize the modified membrane for analysis of the morphology, permeability, anti-fouling performance and the anti-fouling mechanism of the modified membranes. The results indicated that the strength, hydrophilicity, flux, rentention property and antifouling property of the modified membrane were improved in certain degree . With 1.0 wt. %addition of Ag-nTiO₂ nanoparticles in the casting solution, the contact angle of the modified membrane was sharply decreased to 20%. And the water flux is increased 40% in accrodingly.The additives had less effect on the porosity of the modified membrane, while the retention capacity of membranes is enhanced simultaneously after addition of Ag-nTiO₂. All cases showed that the addition of Ag-nTiO₂ nanoparticles in the casting solution can improve the PVC membrane antibacterial property.Moreover, the experimental results illustrated that the mechanical strength increased with increasing thickness of membrane. But the thicker membrane led to the lower membrane flux. We prepared a kind of composite membrane of which there is a support layer on the bottom covered with a thin layer of ultrafiltration membrane to improve the mechanical strength and flux of the membrane. Compare to homogeneous membrane, the composite membrane showed higher mechanical strength and membrane flux.Long-term filtration of water was investigated with the membrane modules with the unmodified and modified membranes. The results showed that compared with unmodified membrane, the water flux of the modified membrane was increased by 40%, and the water flux reduction was decreased by 5% and the removal ratio of UV254 reached to 22%, respectively.