Photocatalytic Removal of Toluene Vapour Pollutant from the Air Using Titanium Dioxide Nanoparticles Supported on the Natural Zeolite.

Background: The emission of volatile organic compounds (VOCs) in industrial and urban areas has adverse effects on the environment and human health. Toluene, the main pollutant among the VOCs, has wide applications in different industries such as plastics, adhesives, silicone sealant, paint, etc. This study aimed to remove of toluene from the air by using TiO2 nanoparticles supported on the natural zeolite using the photo-catalytic process. Methods: This is an experimental study that was conducted in 2017 in the Chemical Agents Laboratory of the Occupational Health Engineering Department at Jundishapur University in Ahvaz. Toluene vapour decomposition was carried out using UV/ZE, UV/TiO2, and UV/TiO2-ZE under continuous flows conditions. The effects of toluene initial concentration, retention time, and nanocomposite surface weight on toluene vapour decomposition were also investigated. Results: When UV/TiO2 and UV/TiO2-ZE systems are performed, increasing the initial toluene concentration reduces the efficiency of photocatalytic decomposition. The SEM images of TiO2-ZE catalyst show that zeolite pores were occupied by titanium dioxide nanoparticles. Moreover, the combination of titanium dioxide nanoparticles and zeolite has an incremental effect on toluene decomposition. Increasing retention time raises toluene decomposition, and the increased nanocomposite surface weight raises decomposition to the maximum level (70%) at 33.68 mg/cm2 weight and then decreases. Conclusion: The increasing toluene decomposition rate by using the TiO2-ZE nanocomposite can be due to the incremental effect of absorption and photocatalytic decomposition.

Photocatalytic activity of synthetic ZnO/WO3 nanocomposites immobilized on a Y-zeolite in removal of gas-phase styrene.

PURPOSE: The widespread use of styrene along with its harmful effects on human health has led to many studies on how to control and reduce its vapors in the workplace. In this study, efficient removal of styrene molecules in the gas phase was attempted by using Y-ZnO/WO3 hybrid photocatalysts. METHODS: ZnO/WO3 nanocomposites with different WO3 Wt% were prepared and immobilized on Y-zeolite. The samples' characteristics were evaluated using X-ray diffraction (XRD), energy dispersive X-ray spectrum (EDS), Brunauer-Emmet-Teller (BET) and field emission scanning electron microscopy (FESEM). RESULTS: The Y- ZnO/WO3 catalyst exhibits an improved photocatalytic activity as compared to Y-ZnO and Y-zeolite alone. This higher photocatalytic activity of the ZnO/WO3 supported on Y-zeolite can be attributed to a more efficient interaction of the ZnO/WO3 with the zeolite leading to higher adsorption capacities. Results reveal that the photocatalyst was highly photoactive in mineralizing styrene. The high activity can be attributed to the synergetic effects of strong UV, ZnO/WO3 nanocomposite and surface hydroxyl groups. The photocatalytic degradation reaction of styrene with the Y-ZnO/WO3 follows Langmuir-Hinshelwood kinetics. CONCLUSIONS: The results of this study indicate that this photocatalyst is suitable for the removal of styrene under UV light. The highest removal efficiency achieved was with Y-ZnO/WO3 at 2%.

Evaluation of airborne exposure to volatile organic compounds of benzene, toluene, xylene, and ethylbenzene and its relationship to biological contact index in the workers of a petrochemical plant in the west of Iran.

Nowadays, workers in petrochemical industry might be exposed to organic volatile compounds, including benzene, toluene, ethylbenzene, and xylene (BTEX). The aim of this study was to investigate the concentration of BTEX contaminations and the biological index in employees of petrochemical sites in the west of Iran. The study was conducted as a cross-sectional study on 30 stations and 60 inhalation and biological samples collected in winter and summer. The NIOSH 2549 and 1501 methods were used for sampling and analyzing the inhaled samples. Gas chromatography-mass spectrometry (GC-MS) equipped with flame ionization detector and high-performance liquid chromatography (HPLC) was used to measure the volatile contaminations. The results showed that the mean concentrations of benzene, toluene, and xylene were significantly different in summer and winter. Significant and strong correlations were observed between the concentrations of benzene, toluene, and xylene and the biological values (r > 0.7). Moreover, the concentration of benzene (ß = 0.836), toluene (ß = 0.718), and xylene (ß = 0.786) predicted the changes in their biological values. Given the hazardous concentrations of benzene and toluene in industrial plants and the correlation of the concentration levels and biological values, management and control strategies should be implemented to eliminate and reduce the pollutants and the effects.

Removal of ethyl benzene vapor pollutant from the air using TiO2 nanoparticles immobilized on the ZSM-5 zeolite under UVradiation in lab scale.

Ethyl benzene is a volatile organic compound that is used in the many industries, including Oil and Gas, Oil colored and Insecticides. Due to the toxic effects of this chemical substance control and elimination of this vapor is necessary. Photo catalytic degradation is a possible method to remove organic compounds from air. This study was performed to determine the efficiency of photo catalytic removal of ethyl benzene vapor using TiO2 nanoparticles immobilized on the ZSM-5 zeolite under UV radiation. This was an experimental study. The surface and volume of the pores of the bed were determined by the Bruner-Emmett-Teller (BET) method and Surface structure was determined by Scanning Electron Microscope (SEM), EDAX and X-Ray Diffraction (XRD). Dynamic air flow and different concentrations of ethyl benzene (25, 75 and 125 ppm) and flow rates (0.5, 0.7, and 1.0 L/min) were produced and the removal efficiency of ethyl benzene vapor were investigated using ZSM-5 and TiO2/ZSM-5/UV processes. The temperature and relative humidity were set at 25 ± 2°c and 35%. Evaluations for BET showed the specific surface areas decreased after loading TiO2 on ZSM-5. XRD and EDAX analysis and SEM images showed that zeolite structure was stabled and nanoparticles were successfully stabilized on Ze. The results showed that the highest removal efficiency (52%) by the process of TiO2/ZSM-5/UV (5 wt%) at concentration 25 ppm and flow rate 0.5 L/min respectively. The result of this study showed that the TiO2/ZSM-5catalyst may be a applicable and hopeful method to removal of ethyl benzene from air flow under UV irradiation.

The influence of ZnO-SnO2 nanoparticles and activated carbon on the photocatalytic degradation of toluene using continuous flow mode.

The present study examined the gas-phase photocatalytic degradation of toluene using ZnO-SnO2 nanocomposite supported on activated carbon in a photocatalytic reactor. Toluene was selected as a model pollutant from volatile organic compounds to determine the pathway of photocatalytic degradation and the factors influencing this degradation. The ZnO-SnO2 nanocomposite was synthesized through co-precipitation method in a ratio of 2:1 and then supported on activated carbon. The immobilization of ZnO-SnO2 nanocomposite on activated carbon was determined by the surface area and scanning electron micrograph technique proposed by Brunauer, Emmett, and Teller. The laboratory findings showed that the highest efficiency was 40% for photocatalytic degradation of toluene. The results also indicated that ZnO-SnO2 nano-oxides immobilization on activated carbon had a synergic effect on photocatalytic degradation of toluene. Use of a hybrid photocatalytic system (ZnO/SnO2 nano coupled oxide) and application of absorbent (activated carbon) may be efficient and effective technique for refinement of toluene from air flow.