Reduction of graphene oxide with L-lysine to prepare reduced graphene oxide stabilized with polysaccharide polyelectrolyte

An environmentally friendly approach to reduce graphene oxide (GO) with L-lysine (L-Lys) was developed by using carboxymethyl starch (CMS) as a stabilizing agent and a stable suspension of reduced graphene oxide (RGO) was obtained. UV visible absorption spectroscopy was used to monitor the deoxygenating process and the factors that affect the GO reduction, such as the ratio of GO/L-Lys, the temperature and pH were optimized. The reduction of the GO was verified by Fourier transform infrared spectroscopy, X-ray diffraction, thermo-gravimetric analysis, Raman spectroscopy and X-ray photoelectron spectroscopy. Ordered porous RGO/CMS foams were prepared by a unidirectional freeze-drying method (UFDM) and used as absorbents for copper ions. Since L-Lys and CMS are natural and edible chemicals, this approach provides a green method to produce stable RGO from GO on a large scale. The nontoxic biodegradable RGO/CMS foams show potential applications for metal ions removal from wastewater.