Evaluation of the antifouling and photocatalytic properties of poly(vinylidene fluoride) plasma-grafted poly(acrylic acid) membrane with self-assembled TiO2.

Immobilization of TiO(2) is a promising approach that produces antifouling and photocatalytic membranes that could help advance wastewater treatment and re-use processes. In this study, poly(acrylic acid) (PAA) was plasma-grafted on commercial poly(vinylidene fluoride) (PVDF) to introduce functional groups on the membrane surface that can support the nanoparticles. It was found that plasma treatment at 100 W for 120 s followed by liquid grafting with 70% aqueous AA at 60°C for 2h maximized the number of TiO(2) binding sites. Membrane hydrophilicity was tremendously enhanced by the self-assembly of TiO(2), following a direct proportionality to TiO(2) loading. The membrane with 0.5% TiO(2) loading maintained the highest pure water flux and the best protein antifouling property. UV irradiation triggered the photodegradation of strongly bound foulants, but at least 1.5% TiO(2) and 30 min cumulative irradiation were necessary to completely recover the membrane's original performance. The TiO(2)-modified membranes removed 30-42% of 50mg/l aqueous Reactive Black 5 (RB5) dye. The fabricated membranes demonstrate huge potential for use in membrane reactors with high hydrophilicity, fouling mitigation, and photocatalytic capability.

Degradation of Reactive Black 5 dye using anaerobic/aerobic membrane bioreactor (MBR) and photochemical membrane reactor.

Three different types of advance treatment methods were evaluated for the degradation of Reactive Black 5 (RB5). The performance of two stage anaerobic SBR-aerobic MBR, anaerobic MBR with immobilized and suspended biocells and an integrated membrane photocatalytic reactor (MPR) using slurry UV/TiO(2) system were investigated. The results suggest that, nearly 99.9% color removal and 80-95% organic COD and TOC removal can be achieved using different reactor systems. Considering the Taiwan EPA effluent standard discharge criteria for COD/TOC, the degree of treatment achieved by combining the anaerobic-aerobic system was found to be acceptable. Anew, Bacilluscereus, high color removal bacterium was isolated from Anaerobic SBR. Furthermore, when this immobilized into PVA-calcium alginate pellets, and suspended in the anaerobic MBR was able to achieve high removal efficiencies, similar to the suspended biocells system. However, the immobilized cell Anaerobic MBR was found to be more advantageous, due to lower fouling rates in the membrane unit. Results from slurry type MPR system showed that this system was capable of mineralizing RB5 dyes with faster degradation rate as compared to other systems. The reactor was also able to separate the catalyst effectively and perform efficiently without much loss of catalyst activity.

Study the self cleaning, antibacterial and photocatalytic properties of TiO2 entrapped PVDF membranes.

The modified PVDF membranes were prepared by adding different amounts of TiO(2) particles (0-4 wt.%) into the casting solution. The TiO(2) entrapped PVDF membranes (0-4% PVDF/TiO(2)) were tested for its antibacterial property by using Escherichia Coliform (E. Coli), photoactive property using Reactive Black 5 (RB5) dye and self cleaning (antifouling) properties by fouling using 1% BSA solution. Results showed that TiO(2) addition significantly affects the pore size and hydrophilicity of the PVDF/TiO(2) membrane. This also improves the flux and permeability of modified PVDF/TiO(2) membrane. The results of antibacterial study showed that the composite PVDF/TiO(2) membrane removes E. Coli at a very faster rate than neat PVDF membrane and membrane with 4% TiO(2) possess highest antibacterial property. The RB5 dye removal using PVDF/TiO(2) occurs under UV by photolysis and photocatalysis mechanisms. The rate of RB5 dye color removal was faster as compared to the rate of aromatic ring structure. The resistance study showed 2% TiO(2) membrane having lower fouling resistance as compared to others. The fouling resistance caused by loosely bound protein (R(c)) was lower than the strongly bound protein (R(f)). The performance of fouled membranes flux and TMP can be recovered to its initial value by simple UV treatment.