Facile preparation of zeolite-activated carbon composite from coal gangue with enhanced adsorption performance

A composite structure of the zeolite and activated carbon is successfully synthesized through CO2 activation followed by the hydrothermal synthesis method using coal gangue as the raw material. The zeolite-activated carbon composite is used as an adsorbent for the removal of heavy metal ions and macromolecular organics. The integrative adsorption property of the composite could be improved by adding a certain amount of powdered coal into coal gangue as the extra carbon source. The specific surface area of a so-prepared composite is 669.4 m2/g, which is much larger than that of the pure NaA type zeolite (249.3 m2/g). As a result, the zeolite-activated carbon shows high adsorptive efficiencies for Cu2+ (92.8%) and Rh-B (94.2%). The thermodynamic and kinetic processes for adsorption of Cu2+ and Rh-B onto pure zeolite and zeolite-activated carbon are also investigated systematically. The mechanistic study of zeolite-activated carbon indicates that the uniform micropores in zeolite are suitable for the adsorption of heavy metal ions and the multilevel porous structure of activated carbon could accommodate macromolecular organics. The high value-added product prepared from coal gangue is a good alternative to treat industrial waste water.