Chemical-grafting of graphene oxide quantum dots (GOQDs) onto ceramic microfiltration membranes for enhanced water permeability and anti-organic fouling potential

Abstract

In this work, graphene oxide quantum dots (GOQDs) with an average size of around 3.8 nm were prepared by facile hydrolysis of citric acid. Subsequently, GOQDs were immobilized onto the (3-aminopropyl) triethoxysilane (APTES) functionalized alumina membrane surface by covalent bonding. The effects of GOQDs on the surface properties including the pore size, hydrophilicity and surface roughness, as well as water permeability and anti-organic fouling properties of ceramic membranes were systematically studied. The ceramic membranes modified by GOQDs could remain a porous structure with reduced surface roughness and improved hydrophilicity. Notably, the surface modification by GOQDs slightly decreases the average pore size from 200.8 nm to 191.3 nm, and the uniformity in pore size is improved at the same time. As a result, the GOQDs modified ceramic membranes show improved water permeability with an enhanced pure water flux (~30%) and reduced membranes resistance (~15%). Importantly, GOQDs modified ceramic membranes show much higher pure water flux and lower filtration resistance both before and after the static adsorption experiment, which compare favorably with those unmodified ones. In addition, the GOQDs modified ceramic membranes also show improved fouling resistance in HA solution under submerged conditions.