Inhibition of bacterial adhesion on cellulose acetate membranes containing silver nanoparticles

Membrane fouling is one of the major drawbacks that changes polymeric membrane performance. Biofouling has a series of effects, such as to reduce membrane permeability, to increase energy costs and to decrease membrane lifetime. Cellulose acetate (CA) membranes, containing different amounts of β-cyclodextrin stabilized silver nanoparticles (AgNP-β-CD), were prepared by dispersing the pre-synthesized nanoparticle (28 nm mean diameter) in CA casting solution. These membranes were obtained by phase-inversion process, in order to achieve both antibacterial properties and biofouling resistance. The typical crystal structure of the AgNP-β-CD, before and after being dispersed in CA membranes, was detected by X-ray diffraction. Field emission electron microscopy images showed membranes with finger-like morphology and atomic force microscopy images showed the presence of nanoparticles in the membrane top surface. The results indicated that the presence of AgNP-β-CD did not influence the membrane thermal degradation but increased the water flux through the membrane. The antibacterial activity of the membranes containing AgNP-β-CD (CA-Ag) was evaluated against E. coli and S. aureus using the plate count method. The results showed that almost 100 % of the E. coli and S. aureus viable cells were inhibited after 12 h of contact with CA-Ag membranes. In addition, the CA membranes were able to prevent more than 90 % E. coli biofilm formation. Based on the results, CA membranes prepared with AgNP-β-CD can be potentially applied as anti-biofouling filtration membranes for water treatment and wastewater recovery.