Effect of silver nanoparticle (AgNP) location in nanocomposite membrane matrix fabricated with different polymer type on antibacterial mechanism

Biofouling is one of the most serious problems for membrane processes and the nanocomposite membranes having silver nanoparticle have been used widespread to control it. Silver nanoparticles (AgNP) can prevent the capability of bacteria permanently attaching to the membrane surface. However this mechanism depends on the location of AgNP into membrane matrix. The location of AgNP can change depending on the polymer type and phase inversion parameters. This study demonstrates the effect of polymer types on AgNP location into membrane matrix. Polysulfone (PS), polyethersulfone (PES) and cellulose acetate (CA) polymers were used for fabrication of flat-sheet bare and nanocomposite membranes. The location of AgNP in membrane matrix was determined according to viscosity measurements of dope solutions, AFM, SEM-EDS and contact angle analysis. It was found that AgNPs should mostly accumulate onto the top and skin layers of PES and PS nanocomposite membranes while it settled down the sublayer of CA nanocomposite membrane. The location of AgNP into membrane matrix changed to the bacteriostatic effects of nanocomposite membranes because the interaction between AgNP and bacteria depends on the release of ionic silver from AgNP embedded in membrane. The nanocomposite membranes which stored AgNP at surface had the best antibacterial properties.