Insertion of phenyl ethyleneglycol units on graphene oxide as stabilizers and its application for surfactant removal

The covalent functionalization of GO has been reported since it can provide specific anchoring centers to adsorption process. Many modifications on GO surface by grafting of arenediazonium salt are described in the literature, however, there are no reports about the insertion of TX-100 surfactant-like moieties. In this study a new GO derivative which has phenyl tetraethyleneglycol (PTEG) units attached as stabilizers was synthesized by grafting of arenediazonium salt. The PTEG moieties possess a structure similar to TX-100 and, consequently, can provide superior stability to GO in aqueous media. Furthermore, the presence of PTEG attached to GO can direct the micelle formation/adsorption on the nanomaterial surface by pi-stacking and hydrophobic interactions. GO-PTEG was characterized by SEM, TEM, TGA, XRD, Raman, FT-IR, CP/MAS C-13 NMR, XPS and Zeta potential, confirming the successful ethylene glycol insertion. The obtained zeta potential measures suggest that GO-PTEG suspension was more stable than those with pristine GO. The Synthesized GO-PTEG was applied to non-ionic (TX-100) and cationic (DTAB) surfactant removal from water. In order to optimize the adsorption process, the influence of following parameters was evaluated: time, temperature, sonication, pH, surfactant concentration and nanomaterial loading. The experimental kinetic data could be fitted with a pseudo-second order model and the adsorption process could be better described by Frumkin adsorption isotherms for both surfactants. The TX-100 and DTAB maximum removal capacities achieved by GO-PTEG were 1689 and 713 mg/g, respectively. These results were superior to those by GO and other materials, suggesting that the GO-modification improved the adsorption process.