The adsorption of water-soluble ionic liquids on graphene oxide of different oxygen content

Abstract

With the large-scale study and application of graphene and ionic liquids (ILs), it was imperative to clarify their interaction mechanism with the environment. The graphene oxides (GO) with different oxygen content were obtained using electron beam irradiation and chemical reduction. Then, batch adsorption experiments were preformed to understand the adsorption behavior of ILs on GO with different oxygen content. Experimental results show that the adsorption capacity of ILs on GO depends strongly on the oxygen level of graphene and the ionic strength of the solution, GO of rich and poor oxygen presented better performance at high and low ionic strength, respectively, which is owing to the formation of chemical bonds between ILs and oxygen groups on GO. Moreover, ILs possess aromaticity and cationic properties, both of which favor the adsorption of ILs on GO. Competitive adsorption of two ILs on GO with poor oxygen content was observed; but it was found that one IL could promote the adsorption of the other ILs on GO of rich oxygen content, which could be attributed to the properties of ILs and GO. This work may advance the understanding of the adsorption behavior of ILs on graphene oxide and find a possible way to remove ILs in the environmental systems.