Synergistic role of Ag nanoparticles and Cu nanorods dispersed on graphene on membrane desalination and biofouling

We propose a new membrane of cellulose acetate/graphene/Ag nanoparticles and/or Cu nanorods (CA/G/Ag-Cu) composite, which improved the membrane desalination and biofouling simultaneously using membrane technology. The membrane was prepared from casting polymer dope solution containing 25 wt.% in acetone as solvent with different concentrations of graphene dispersed on it Ag:Cu at 18 °C. The membrane was then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and further tested for the separation of saline solutions (5 g/L and 10 g/L NaCl) by reverse osmosis system. The release of silver- and copper-nanoparticles from the membrane was monitored in a batch experiment by an atomic absorption spectrophotometer (AAS). The biofouling effects of addition G/nano-(Ag-Cu) on membrane performance were investigated against Gram +ve and Gram −ve bacterial test organisms. Membranes were assayed with an agar culture medium and by immersing in bacterial suspension. Bacterial activities were observed by inhibition zones formation and investigating biofilm formation by SEM. The reference membrane (without additions) had no antibacterial activity and bacterial growth was found on the membrane surfaces, while CA/G/nano-(Cu-Ag) membrane had shown antibacterial activity. Permeability tests showed a vast improvement of water flux and salt rejection.