Investigation of Photocatalytic Oxidation and Wet Absorption in a Combined System for Removal of Nitrogen Oxides

Abstract

Background: One of the important achievements of the past decade was the rapid growth of industries and accordingly production of various chemical compounds.Objectives: This study presents a combined system of photocatalytic oxidation and absorption solution to remove nitrogen oxides from polluted air flow. Materials and Methods:The experimental system used in this study comprised a pollutant gas source, mixing chamber, photocatalytic oxidation reactor, wet absorption system, and finally a system for measuring nitrogen oxides. Firstly, by using photocatalytic property, nitrogen oxide was converted to nitrogen dioxide. Then, absorption system was used to absorb nitrogen dioxide into the sodium hydroxide solution. Results: Experimental results have shown that output of nitrogen oxide removal in the initial concentration of 200 ppm was 44% in the beginning of the process and then fixed at 15% during the rest of the process. Also, by changing the amount of zinc oxide nanoparticles from 4 to 8 mg/cm 2 , no considerable change was observed in the conversion rate of nitrogen oxide. In addition, while

Removal of toluene vapors from the polluted air with modified natural zeolite and titanium dioxide nanoparticles

“… 8 9 10 In the photocatalytic process, a catalyst with the proper band gap such as zinc oxide or titanium dioxide and light source (usually ultraviolet (UV)) is used to convert organic compounds into benign and odorless constituents – water vapor (H 2 O) and carbon dioxide (CO 2 ). 10 11 12 Titanium dioxide (with three crystalline phases: anatase, rutile and brookite), a white powder that has a photocatalytic and super-hydrophilic, is used in water and wastewater treatment, air pollution and buildings. 12 13 Features such as low price, availability, chemical stability and lack of toxicity make the titanium dioxide as the most appropriate photocatalyst.…”

“… 10 11 12 Titanium dioxide (with three crystalline phases: anatase, rutile and brookite), a white powder that has a photocatalytic and super-hydrophilic, is used in water and wastewater treatment, air pollution and buildings. 12 13 Features such as low price, availability, chemical stability and lack of toxicity make the titanium dioxide as the most appropriate photocatalyst. 14 Photocatalytic oxidation by having advantages such as an activity at ambient temperature and low pressure, low cost and low power consumption in comparison with other methods, has introduced as one of the promising alternatives for treating a wide range of volatile organic compounds in the recent years.…”