Graphene-oxide loading on natural zeolite particles for enhancement of adsorption properties

Multiple methods of grafting graphene oxide (GO) nanosheets to natural clinoptilolite-rich zeolite particles were developed in our laboratory. In this study, we have systematically characterized the GO coated particles prepared by various methods to select the most promising method for further research efforts. This study revealed that the most promising coating method was the clean-acid-treated zeolite particles followed by deposition of GO nanosheets onto the zeolite surface and mild thermal treatment of the particles. GO and its synergistic interaction in zeolite was attributed to electrostatic interactions, hydrophobic interactions and hydrogen bonds. Hydrophobic interactions are enhanced both due to dealumination of zeolite caused by the cleaning method followed by acid treatment and due to partial thermal deoxygenation of GO. This method provided a ten times larger surface area (from 10.55 m² g^-1 to 117.96 m² g^-1) and three times smaller pore diameter (from 81.91 Å to 30.68 Å), providing great particles for a variety of applications as adsorbents or catalysts.