Sonochemical Degradation of Phenol in the Presence of Inorganic Catalytic Materials

Abstract

Degradation of phenol in its aqueous solutions, using various techniques, including ultrasound, have been examined and discussed to better understand the mechanisms involved therein and the advantages as well as the disadvantages associated with the use of inorganic catalytic materials. IntroductionSonochemical degradation of organic molecules [1], employing cavitational effect is not new. Many simple [2] and complex molecules [3] from modest to very high toxicity levels, polluting the aquatic life and the environment have been successfully reduced to relatively non-toxic or lesser harmful species, if not degraded completely by the ultrasound. Although the degree of degradation and the duration of sonication varied considerably, depending upon the nature of moieties, but the sonochemical degradation undergoes either without the addition of extra chemicals or involves the minimum amounts of non-toxic chemicals such as photocatalyst TiO 2 , Fenton's reagent etc., hence can be termed as a green technology. The purpose of this article is to review the sonochemical degradation of phenol, under different experimental conditions and in the presence of several other active chemicals to understand better the mechanisms involved in all such processes.Phenol is an important chemical, from the point of its industrial and commercial applications, but is of great environmental apprehension due to its toxicity. Its chemical name is hydroxybenzene which is more acidic compared to aliphatic alcohols hence is also known as carbolic acid [4]. At ambient temperature and pressure it is a hygroscopic crystalline solid, which is colourless when pure [5] but