A Layered Chitosan/Graphene Oxide Sponge as Reusable Adsorbent for Removal of Heavy Metal Ions

Along with the growing severity of environment problem and energy crisis, it is inevitable to develop novel materials, which are contributed to the removal of hazardous pollutants from contaminated water. Herein, we reported a facile method for the preparation of free-standing chitosan/graphene oxide(CS/GO) composite sponges with low density, where CS/GO mixtures were first synthesized by the homogeneous reaction of chitosan and graphene oxide in aqueous acetic acid solution; then CS/GO sponges were obtained by lyophilizing the suspension, which were prefrozen at −20 °C and in liquid nitrogen successively. The obtained layered sponge showed good water-driven shape memory effect and was a good adsorbent of Co 2+ and Ni 2+ with a large adsorption capacity of 224.8 and 423.7 mg/g, respectively. Importantly, the successive adsorption-desorption studies employing CS/GO sponge indicated that the composite could be regenerated by HCl solution and reused in more than five cycles with regeneration efficiency beyond 80%. Also, the resultant sponge was explored as an exceptionally adsorbent for the removal of organic dye ( e.g. , methylene blue, MB).