Selenocarrageenan-inspired hybrid graphene hydrogel as recyclable adsorbent for efficient scavenging of dyes and Hg2+ in water environment.

It remains a real challenge to treat the industrial wastewater containing hardly-decomposed dyes and heavy metal ions. Herein, an environment-friendly hybrid hydrogel is prepared by a simple mixing of selenocarrageenan (SeCA) and graphene oxide (GO) under heating and stirring for 5 min without any other reagent. Such a selenocarrageenan hybrid graphene hydrogel (SeCA-GH) without volume shrinkage exhibits excellent adsorption capacity and selective binding to dyes and Hg2+. The maximum adsorption capacity of methylene blue and Hg2+ on SeCA-GH is 168 mg g-1 and 331 mg·g-1 at 25 °C, respectively. Furthermore, the adsorption characteristics of SeCA-GH are investigated in detail, including saturated adsorption capacity, adsorption isotherm, and kinetic adsorption process. Notably, SeCA-GH can be easily regenerated and reused for multiple cycles without release of SeCA and GO. SeCA-GH as recyclable adsorbent offers a promising candidate for sustainable, affordable, and efficient removal of dyes and Hg2+ in water environment.