Self-healing stable polymer hydrogel for pH regulated selective adsorption of dye and slow release of graphene quantum dots

Abstract

Developing composite hydrogels with excellent self-healing ability and reasonable mechanical strength is extremely challenging. Herein, to overcome this difficulty, we identify the importance of balancing the ratio between the components of a composite hydrogel based on graphene oxide and poly(acrylic acid-acrylamide) [GO_xAAM]. The gel exhibits enhanced mechanical strength, excellent self-healing ability, and extraordinary swelling capacity (a swelling ratio of 732) at room temperature and neutral pH. Further, the dye adsorption of the composite hydrogel has been investigated. The hydrogel could selectively adsorb organic cationic dyes (methylene blue vs. rhodamine B) from contaminated water with remarkable efficiency (90–95%). The kinetics investigation suggests that the dye adsorption on this composite hydrogel follows a pseudo-second-order model. The reusability of the hydrogel has been demonstrated by repeating the adsorption–desorption process over 10–14 cycles with almost identical results in the adsorption efficiency. Moreover, the hydrogel is utilized as a solvent-induced slow release source for graphene quantum dots (GQDs). The results taken together suggest that the (GO_xAAM) composite gel can be a promising candidate for developing multifunctional gel materials.