Zeolite–carbon composites prepared from industrial wastes: (II) evaluation of the adaptability as environmental materials

Novel zeolite–carbon composites were fabricated by a combined process of calcination and carbonization at 600–850 °C in the N2 atmosphere followed by a hydrothermal treatment from industrial wastes of coal fly ash and sawdust mixtures in alkaline aqueous solutions. Adaptability of the resulting zeolite–carbon composites as high value-added environmental materials was evaluated. It was found that the composites consisted of micropores and mesopores with the ability to adsorb water vapor up to an amount of 20 mass% which was superior to some commercial zeolite building materials. The composites also demonstrated a capacity to absorb electromagnetic wave in the W-band frequency range (75–110 GHz) characterized as a reflection loss higher than 20 dB at the resonant frequencies. These results indicated that the zeolite–carbon composites were prominent candidates as environmental-friendly building materials for wall or flooring with adsorption abilities for water vapor as well as absorption and shielding effects of electromagnetic wave.