Absorption behavior of graphene nanoplates toward oils and organic solvents in contaminated water

Abstract

In this work, graphene nanoplates (GNPs) were successfully prepared via direct chemical exfoliation from natural graphite. The properties of prepared GNPs were investigated using scanning electron microscopy and X-ray diffraction. The resultant GNPs had a low bulk density of 0.015 g mL-1, C content of 99.6%, a lateral diameter of 5-15 μm, and thickness of <15 nm, respectively. The absorption capacity of the GNPs for a range of oils and organic solvents including pump oil, polydimethylsiloxane oil (PDMS), dioctyl phthalates (DOP) oil, olive oil, bean oil, mazut oil, xylene, ethanol, and ethylene glycol (EG) was evaluated. The effects of the sorption conditions such as the absorption time (sorption kinetics), temperature, and aging manner (static, stirring, and ultrasonic) on the absorption capability of the GNPs were also investigated. It could be seen that the GNPs revealed extremely high absorption capacities for oil and organic solvents, reaching 21-42 times their own weight only after 2 min of absorption at room temperature, which were found to be much higher than those shown by various commercially available absorbents.