Comparing ZSM5, TiO2/ZSM5, UV/ ZSM5, and UV/TiO2/ZSM5 Processes in Removal of Styrene from Synthetic Air Current

Background and purpose: Styrene, one of the most important compounds of VOCs, causes some health concern. In current study, the ability of ZSM5, TiO2/ZSM5, UV/ ZSM5, and UV/TiO2/ZSM5 methods was investigated in removing styrene from air synthetic current. In order to synthesize the zeolite and TiO2-coated zeolite, the sol-gel and saturation methods were employed, respectively. In this study, the effect of the type of removal process, saturation time and initial pollutant concentration were investigated on the removal of styrene in a photoreactor. Phocheck device with direct reading system was applied to determine the output concentration. Also, SEM, XRD, EDX, and BET analyses were used to characterize the chemical and physical properties of ZSM5, and TiO2/ZSM5. SEM analysis showed that zeolite has a crystal form, and TiO2 successfully covered the surface of this compound. In addition, the EDX analysis demonstrated that a great part of zeolite structural includes Al and Si constituents. The XRD pattern showed the presence of attached TiO2 in the zeolite structure. BET analysis revealed that the surface area of zeolite decreased when TiO2 was coated on its surface. The order of increase in removal efficiency was as follows: UV/TiO2/ZSM5 > ZSM5> TiO2/ZSM5. The saturation time of ZSM5 and TiO2/ZSM5 in the 300 ppm concentration was 370 and 280 min, respectively, while the outlet concentration in the UV/TiO2/ZSM5 method was fixed at 74% removal efficiency after elapsing 310 min. The increment of time exposure and initial styrene concentration also led to decrease in removal efficiency. In this study application of UV/TiO2/ZSM5 process provided a higher efficiency of the styrene removal than that of TiO2/ZSM or ZSM5 in the same time.