Photocatalytic removal of xylene as a pollutant in the air using ZnO-activated carbon, TiO₂ -activated carbon, and TiO₂ /ZnOactivated carbon nanocomposites

Abstract

Background: Today, advances in different areas of science and technology along with their application in industries have led to an increase in dangerous pollutants which can resist biodegradation. Volatile organic compounds (VOCs) are regarded as important factors of air pollution in closed environments. Xylene is one of these compounds which is produced in mass quantities and widely used in industries, therefore, the removal of this compound is necessary. One of the available technologies for removing this compound is photocatalytic degradation. The present study aimed to determine the efficiency of photocatalytic removal of xylene as a pollutant in air using TiO2 -ZnO nanoparticles and TiO2 -ZnO composite coated on activated carbon under ultraviolet radiation. Methods: In this experimental study, after coating of the nanoparticles on activated carbon, the produced catalysts with a specific surface area were characterized using Brunauer-Emmett-Teller (BET) surface area and porosity analysis, scanning electron microscope (SEM), and the type and percentage of the main elements present in the bed were determined using energy dispersive x-ray spectroscopy (EDS). The tests were carried out at laboratory scale and ambient temperature. In order to produce polluted air containing 100 ppm xylene vapor at a specific flow rate and concentration, a dynamic concentrator system was used. The removal of xylene was investigated under continuous flow mode. Results: The results of the specific surface area using BET analysis and SEM images showed that nanoparticles were well coated on activated carbon. According to the results of the photocatalytic removal, the efficiencies of photocatalytic removal of xylene by AC/ZnO 5%, AC/TiO2 15%, and AC/3TiO2 /1ZnO were 80.1, 89, and 95.1%, respectively. Conclusion: According to the results, the use of ZnO-TiO2 nanocomposite on activated carbon can be an appropriate method for the photocatalytic removal of xylene from polluted air.

Synthesis, characteristics, and photocatalytic activity of zinc oxide nanoparticles stabilized on the stone surface for degradation of metronidazole from aqueous solution

“…Thus, generation of hydroxyl radicals on the surface of catalyst for degradation of metronidazole is limited. Also, with increasing metronidazole concentration, the radiation photons, which react with catalyst surface, are prevented and screened off, therefore, the production of hydroxyl radicals is delayed and the degradation of metronidazole is decreased (8,(41)(42)(43)(44)(45)(46). Sobana et al investigated photocatalytic degradation of acid red 18 by ZnO nanoparticles and found that by increasing the concentration of acid red 18, the removal efficiency decreased, which is consistent with the results of this study (47).…”

Air pollution remediation using synergetic coupling of AC/TiO2 filter for benzene gas removal: regeneration and reuse of spent activated carbon after the treatment process

“…These results are in agreement with that obtained by Andriantsiferana et al [10], which studied the tartrazine treatment with novel TiO2 composite deposited on the AC porous surface, and the performance results indicated that the removal efficiency of phenolic pollutant was kept for several cycles of treatment. Rangkooy et al [15] also used AC/TiO2 in the filter to remove the pollutants from the air, with a removal efficiency reached 90%. Hence, the predominant conclusion is that the synergistic effect is due to the simultaneous occurrence of TiO2 onto the AC support media, leading to carbon adsorption and finally, photo-oxidation.…”

Photocatalytic removal of Malachite green dye from aqueous solutions by nano-composites containing titanium dioxide: A systematic review

“…Electrons oxidize oxygen molecules to produce peroxide radicals. This radical, combined with ambient hydrogen, produces hydroxyl radicals that play an important role in photocatalytic activity (23).…”

“…But today, researchers are increasingly using efficient methods, which are economically sustainable technologies for treating colored effluents (18)(19)(20). Today, the photocatalyst process is used as a simple and efficient method to remove organic pollutants and dyes from industrial effluents and has been shown to play a significant role in environmental control by decomposing organic pollutants (21)(22)(23). The photocatalytic technique is superior to traditional purification techniques.…”