Glyphosate removal from water by functional three-dimensional graphene aerogels

Three-dimensional carboxymethyl chitosan (CM-CS)-graphene aerogels (CM-CS@GA) were prepared through an integration strategy of a carboxylation process and freeze drying technology for efficient glyphosate removal from water. The structure, surface properties, morphology and crystal phase of the prepared CM-CS@GA composites were characterised using SEM, TEM, XRD, FT-IR and BET. The adsorption behaviour of glyphosate in aqueous solution on CM-CS@GA was systematically investigated. The results show that with the advantages of high surface area, and abundant hydroxyl and carboxyl groups of CM-CS@GA, glyphosate can be easily and rapidly extracted from the water. The adsorption equilibrium of CM-CS@GA for glyphosate correspond to a Langmuir isotherm, the maximum adsorption capacity can reach to 578.0 mg g(-1), and the novel adsorbent exhibited a better glyphosate removal efficiency in solutions with low pH. The exhausted CM-CS@GA composites could be regenerated by NaOH solution for repeated use without any significant capacity loss, where the adsorbed glyphosate was effectively desorbed into the solution. These results provide evidence to further validate that CM-CS@GA composites would be of considerable potential in the removal of glyphosate from contaminated waters.