Polyacrylamide/EDTA-modified chitosan/graphene oxide hydrogels as an adsorbent and supercapacitor for sustainable applications

Abstract

Due to high security and versatility, hydrogels have attracted great interest in sustainable applications such as wastewater treatment and energy storage. However, the poor adsorption capacity as an adsorbent and the low conductivity as an electrolyte seriously restrict the sustainable application of hydrogels. Here, we prepare nanocomposite hydrogels (PAAm/CS-EDTA/GO) by mixing ethylene diamine tetraacetic acid (EDTA)-modified chitosan (CS) and graphene oxide (GO) in crosslinking polymerization of acrylamide (AAm). Nanocomposite gives PAAm/CS-EDTA/GO hydrogel excellent mechanical properties (e.g., fracture energy of ∼1208 kJ∙m−3). EDTA, CS and GO support rich and special adsorption sites for the removal of metal ions and dyes. The addition of lithium chloride (LiCl) makes PAAm/CS-EDTA/GO/Li hydrogel have anti-freezing and anti-dehydration properties. Interestingly, the synergy of CS-EDTA and GO increases the conductivity of the hydrogel. The supercapacitor assembled by PAAm/CS-EDTA/GO/Li hydrogel electrolyte shows high capacitance and temperature tolerance. Our work provides a route for the rational development of adsorption materials and energy storage devices for sustainable applications.