Degradation studies of herbicide isoproturon byusing heterogeneous solar photo fenton process (using fly ash)

Abstract

Pesticides carried over in surface waters and groundwater raise serious environmental concerns due to hazardous and bio cumulative affects that may impose to living organisms. In this respect, abatement of pesticide-induced micro-pollution requires the development of efficient technologies capable of dealing with toxic and bio recalcitrant species present at very low concentrations. Over the past few years, various AOPs have indeed been tested extensively for the degradation of several classes of pesticides. The incapability of conventional biological wastewater treatment to effectively remove many industrial toxic pollutants shows that new treatment systems are needed. Advanced oxidation processes can be used to treat pesticides but they are expensive so we can make them cost effective by using waste material as an alternate source of catalyst. In this context, fly ash can be used as iron source in photofenton reaction. Fly ash is a waste material originating in large quantities from modern power stations. Although it has been successfully used as a mineral admixture in concrete and brick production, there are still superfluous fly ashes in some countries, causing environmental and disposal problem. The utilization of fly ash for industrial wastewater treatment could be rewarding to both environment and economy. In our present studied we focus on use of fly as a catalyst in Fenton reaction which along with H2O2 helps in degradation of non biodegradable herbicide isoproturon. Experiments were performed in dark , UV light and sunlight to check the efficiency of the process. The effect of fly ash dosage , amount of H2O2, pH, initial concentration of isoproturon were studied. Solar photo fenton method was found to be effective and could yield better results than either UV fenton or dark fenton. Degradation of 92.2% was observed under optimum conditions (dosage of fly ash 1gm; H2O2 10mM; pH 2). Recycling studies were performed by separating the used fly ash from the system and little decrease in efficiency of fly ash was observed due to surface fouling. Actually metal oxide compounds in fly ash, such as iron and manganese, can combine with H2O2 to form a Fenton-like reagent and produce hydroxyl radical, which can oxidize persistent organic pollutants into small molecule compounds.