Microwave-assisted synthesis of polyacrylamide-aminated graphene oxide hybrid hydrogel with improved adsorption properties

Few layers graphene oxide (GO), graphene oxide functionalized with diethylenetriamine (GO-DETA) and the hybrid of graphene oxide-diethylenetriamine and polyacrylamide (GO-DETA/PAM) hydrogel with high adsorption of methylene blue were prepared using microwave-assisted methods. TGA and XPS analysis were performed to confirm DETA molecules incorporation on GO and to identify an in-situ acrylamide polymerization with no usual chemical cross-linkers. The morphology and structure of the graphene derivative materials and hybrid gel were evaluated by TEM and SEM images. The obtained GO-DETA sheets played an important role as a cross-linker agent during the polymerization of PAM to form the hybrid GO-DETA/PAM. The results obtained showed that the GO-DETA influenced the swelling behavior and thermal properties of PAM, as well as improved its Tg, presenting a more stable PAM network in saline conditions. The hybrid hydrogel significantly improved the capacity to adsorb methylene blue (maximum adsorption capacity 205.4 mg g(-1)), compared to the neat PAM (maximum adsorption capacity 51.5 mg g(-1)). This feature demonstrates how this novel material can be used in the removal of emerging contaminants in water, for example, using a fast and reproducible synthetic method and lower quantities of adsorbent.