Synthesis of a novel composite nanofiltration membrane incorporated SiO2 nanoparticles for oily wastewater desalination

Abstract A novel composite nanofiltration membrane incorporated with silica nanoparticles was prepared by interfacial polymerization on polysulfone (PSF) ultrafiltration membrane. The silica nanoparticles (∼15 nm) were homogeneously dispersed in poly(amidoamine) (PAMAM) dendrimer aqueous monomers and incorporated in situ into the polyamide films. Series of tests including FTIR–ATR, AFM, XPS, etc. were performed to characterize the polyamide (PA)-SiO 2 membrane's morphologies, structure, physical and chemical characteristics, separation properties and permeability, etc. The results showed that silica loading into the PA membrane resulted in roughness and hydrophilicity promotion. The permeation performance for PA-SiO 2 membrane increased nearly 50% without loss of salt rejection rate by adding 1.0% (wt.) nano-SiO 2 nanoparticles in aqueous solution. The order of rejection to inorganic salts is Na 2 SO 4  > MgSO 4  > MgCl 2  > NaCl revealed both PA and PA-SiO 2 membrane were nagatively charged. The zeta potentials testing results indicated addition of SiO 2 will increase the negative charge quantities on the surface of PA-SiO 2 membrane for negatively charged hydroxyl groups and silanol-covered nano-SiO 2 surface. The value of molecular weight cutoff (MWCO) for PA-SiO 2 membrane was about 1000 g/mol and the additive of SiO 2 nanoparticles to PA membrane enlarges the pore size slightly. The PA-SiO 2 membrane had a higher stable flux and could remove nearly 50% salts when treated with oily wastewater in one-cycle filtration. Desalination of oily wastewater using the nacomposite PA-SiO 2 membrane is feasible.