Photocatalytic Degradation of a Gaseous Organic Pollutant

Abstract

A simple and effective method to demonstrate the phenomenon of photocatalytic degradation of a gaseous organic pollutant was developed. Titanium dioxide (anatase) was used as the photocatalyst, and sunlight was found to be an effective light source for the activation of TiO2. The organic pollutant degrade in this demonstration was a common indoor air pollutant, dichloromethane. The TiO2 powder was suspended in a 3:7 ethanol/water solution, and then coated on microscopic slides. The slides together with appropriate indicators were place in 250-mL conical flasks. A small amount of the volatile dichloromethane solvent was injected into each flask, and the flasks were sealed with a piece of parafilm. Some of the flasks were exposed to direct sunlight, and some were kept in the dark. The degradation products of dichloromethane were carbon dioxide, water, and hydrogen chloride. Formation of the acidic HCl gas could be monitored easily by two indicators, the universal pH paper and ammonia. The universal pH paper would change color from green to red in the presence of HCl and H2O, while HCl would react with ammonia to form a white fume. The results of this demonstration showed that both TiO2 and light were required in this photocatalytic degradation process.

Properties of Semiconductors: Synthesis of Oriented ZnO for Photoelectrochemistry and Photoremediation

“…Band bending occurs near the interface as the band energies in the solid match solution energetics. As electrons drop to lower energy levels, they will move away from the interface into the solid and holes will move toward the interface to create hydroxyl radicals 11 that oxidize solution species such as methylene blue (Figure 9).…”

Photocatalytic Hydrogen Production over CdS Nanomaterials: An Interdisciplinary Experiment for Introducing Undergraduate Students to Photocatalysis and Analytical Chemistry

“…The concept and study of photocatalysis have also received increasing emphasis in undergraduate chemistry courses recently. Many teaching experiments and reactors about heterogeneous photocatalytic degradation and oxidation of pollutants have been reported, which help students to understand the basic chemistry, concepts, and extensive applications of semiconductors and photocatalysis. − For instance, Tatarko et al and Chen et al designed a cheap photocatalytic reactor and a simple parallel photochemical reactor for the remediation of the azo dye Congo Red and methylene blue in water for undergraduate students, respectively. , Boffa et al prepared sol–gel-derived TiO 2 powders for the photodegradation of toluidine blue in solution using UV–vis light, thus effectively introducing undergraduate students to materials chemistry . Pitcher et al described a simple demonstration of photocatalysis using the photodegradation of 2,6-dicholorophenolindophenol sodium salt (DCIP) over the commercially available TiO 2 .…”

Laboratory Experiments on the Electrochemical Remediation of the Environment. Part 8. Microscale Simultaneous Photocatalysis

“…It has been shown in the literature that such phenomena are electrochemical in nature (3,4) and are under intense study for application in the environmental remediation arena where they are globally called photocatalysis. Chemical educators have thoroughly discussed the corresponding theory and designed several experimental routes in this Journal to help students learn and understand the photocatalytic oxidation processes (5)(6)(7)(8)(9). In this article we extend this experimental approach to show the simultaneous oxidation of an organic species as well as the reduction of a metal ion.…”