Hydrophobic and oleophilic amine-functionalised graphene/polyethylene nanocomposite for oil–water separation

Abstract

An efficient approach was developed for the fabrication of graphene-based material for oil/water separation. GO prepared by graphite oxidation with strong oxidants possesses several hydrophilic moieties including epoxy, hydroxyl, and carboxylic acids. The hydrophobic dodecyl amine-functionalised GO (DDA-GO) was synthesised via nucleophilic substitution and amidation reactions between the amino group of DDA and the epoxy and carboxylic acid group on GO surface. Further modification of the DDA-GO with low density polyethylene (LDPE) through solution mixing method synergistically enhanced its surface hydrophobicity and oil/water separation efficiency. The water contact angle (WCA) of the synthesised DDA-GO/LDPE absorbents reached 153 ±2.4°, thus showing superhydrophobicity. Absorption experiments conducted with silicone oil, engine oil, diesel, THF, cyclohexane, and other selected organic solvents showed that the DDA-GO/LDPE was an efficient absorbent with the capacity of absorption of 38.5–78 times its own weight, and a separation efficiency of up to 98% was also attained. The oil-loaded sorbent was simply squeezed in order to expel up to ≈97% of sorbed liquids. The recyclability experiment further displayed good recyclability and desirable regeneration for practical application.