What is the concentration threshold of nanoparticles within the membrane structure? A case study of Al2O3/PSf nanocomposite membrane

In this study the effects of Al2O3 nanoparticle concentration were investigated on the membrane structure/performance; the boundary of variations was detected, introduced as Nanoparticle Concentration Threshold (NCTh), and was used for forecasting the field of membrane application. For this purpose, Al2O3 nanoparticles with a size of 70nm and a concentration between 0 and 0.52Wt.% were added to the membrane matrix. Loading threshold of Al2O3 nanoparticles was evaluated and the properties of the nanocomposite membrane were compared up and sub the loading threshold. Rheometric analysis, contact angle measurement, SEM images, and filtration experiments showed that concentration threshold of Al2O3 nanoparticles was 0.39Wt.%. Based on their properties, the antifouling performance of those membranes possessing Al2O3 concentration below the threshold was evaluated in a membrane bioreactor (MBR). [Display omitted] •Al2O3/polysulfone nanocomposite membrane was synthesized via blending method.•Loading threshold of Al2O3 nanoparticles to polysulfone membrane was evaluated.•Membrane containing up and sub nanoparticle concentration threshold were compared.•sNCThMs are dense and of low permeation flux as well as high dye rejection.•uNCThMs are porous and of high permeation flux as well as low rejection.