Decomposition of Commercial Available Monocrotophos in Aqeous Solution of tio2 by Sonophotocatalysis

Abstract

Environmental Protection Agency (E.P.A.,1990) estimates aboutmore than 600 million pounds of pesticides enter the environment each year in the environment. Pesticides are included in a broad range of organic micro pollutants that have ecological impacts. Different categories of pesticides have different types of effects on living organisms and these different type of pesticides has a property of bioaccumulation in the environment. Mainly pesticides are not completely degraded during conventional treatment technology due to low biodegradability. Field surveys shows that due to not complete mineralization, some amount of pesticides are released in aquatic environment and mix into ground water and used as a source of drinking water. So there is a clear need to set up the emerging alternative technologies that can deal with highly concentrated and toxic nonbiodegradable pesticides. So recently considerable interest has been shown by researchers towards the degradation of pesticides by advanced oxidation process such as photocatalysis, sonolysis, sonophotocatalysis,. These technique are basically very ecofriendly and time consuming technology and most basic advantage of these technology is completely destruction of any toxic compounds into nontoxic ending products and it can be easily carried out at room temperature and atmospheric pressure.

Basic principle behind of these technology is production of OHº radical which has high oxidation potential and mainly its nonselective property. These OHº radical can easily react with the toxic compound due to its high potential capability and change into nontoxic ending products. Photocatalysis itself is a very advance technique which has large potential for the degradation of any complex organic matter. But if the two modes of irradiations (photocatalysis and sonolysis) are used in combination, degradation would be enhance because sonolysis process improve the mass transfer and surface area. In this present work, we are investigating the sonophotocatalytic degradation of commercially used pesticide Monocrotophos. Titanium dioxide (TiO2) was used as Photocatalyst. Experiments were performed in slurry mode in UV light and at optimized condition. The process is optimized by varying different parameters like catalyst concentration, operating pH, H2O2 conc., Initial pollutant conc. in photocatalytic experiment In photocatalytic experiment, 92% degradation was found under the optimized catalyst concentration of 1gL-1, pH 4 and oxidant concentration of 0.375mgL-1 within 2 hoursand 80% mineralization was achieved in 6 hours. In sonophotocatalytic experiment, 97 % degradation was found under same optimized condition after running of 2 hours and 88% mineralization was achieved in 6 hours. Positive result of the synergy effect shows that combined effect has more valuable in comparison of both individuals treatment. So the results of Sonophotocatalytic degradation of monocrotophos compound showed that it could be used as efficient and environmental friendly technique for the complete degradation of recalcitrant organic pollutants