Stability investigation of graphene oxide–silver nanoparticles composites in natural reservoir water

Abstract

Many capping agents like citrate, PVP (polyvinylpyrrolidone) and PEG (polyethylene glycol) have been applied for stabilizing silver nanoparticles (AgNPs) in waters, and other work has also been conducted to investigate the influences of physicochemical properties of aqueous solutions on the important aspects of AgNPs behaviours. Herein, we successfully synthesized graphene oxide (GO)–AgNPs composite and investigated its stability in natural reservoir water (NRW) for the first time. The effects of physicochemical properties like pH, electrolytes, humic acid (HA) and bacteria in solutions were addressed. What's more, the stability of GO–AgNPs composite in NRW was studied over a period of 7 days with natural light exposure and compared to the stability of commercial citrate capped AgNPs (citrate–AgNPs). Using transmission electron microscopy, surface plasmon resonance (SPR) spectra and ζ-potentials measurements, we explained the mechanisms behind the stability of GO–AgNPs composite and the aggregation of citrate–AgNPs. We demonstrated that physicochemical properties like pH, electrolytes, HA and bacteria exhibit negligible effects on the GO–AgNPs composite which has good stability in NRW without Ag release. As GO is a widely used carbon based material, GO–AgNPs composite is of great significance in broadening the applications of AgNPs in water purification and many others fields.