Adsorptive Volatile Organic Removal from Air onto NaZSM-5 and HZSM-5: Kinetic and Equilibrium Studies

Abstract

Because of their adverse effects, such as their toxicity and carcinogenicity, volatile organic compounds (VOCs) are the most important and common pollutants produced by urbanization and industrial processes that contaminate air and water streams. VOCs, commonly originating from many industrial syntheses, and their derivatives, especially halogen, produce an unpleasant odor in the air when present in excess. All the issues related to VOCs make them a severe threat to whole ecosystems and environments as well as humans. Globally growing environmental awareness and knowledge have resulted in strict regulations to control VOC emissions into the air. It is necessary for each component of emitted VOCs to be controlled or removed from the air. NaZSM-5 and HZSM-5, having high ratios of SiO2/Al2O3 (50), which are necessary for good adsorbents of organics, were prepared. Characterization of the prepared materials was done by XRD, SEM, FTIR, N2 adsorption, NH3-TPD, 27Al-NMR, and TGA analysis. The adsorptive removal of VOCs from the air by Na-ZSM-5 and H-ZSM-5 was explored. These adsorption materials were tested with respect to the adsorption capacity, renewability, and selectivity for benzene, toluene, ethylbenzene, and xylene. The effects of the contact time, adsorbent dose, and initial concentration of pollutant on the adsorption process were also studied. Finally, the adsorption data were applied to Langmuir, Freundlich, and Temkin isotherms and two different kinetic models.