“Synergistic Effects of Sonolysis and Photocatalysis in Degradation of Some Nitroaromatic Compounds in Industrial Wastewater”

Abstract

ABSTRACT

Metal oxychlorides of Fe, Cu, Bi and Zn were prepared and tested in heterogeneous Fenton degradation of 20 ppm of 2-nitrophenol or nitrobenzene in the presence of ultrasonic (US, 20 kHz), ultraviolet (UV, 6 W), and US/UV coupled irradiations. The different experimental conditions including the catalysts dosages, hydrogen peroxide concentration, pH value, temperature, pollutant concentration and irradiation time were optimized and the reusability of the tested metal oxychlorides was investigated as well. The degradation capability of 2-NP or NB follows the order US/UV> UV > US. The rate constant of degradation using sonophotocatalytic system was even higher than the sum of rates of individual systems due to its synergistic performance. The rate constant of degradation followed the same order of mentioned metals oxychloride. The mechanism proposed considers a major role of produced hydroxyl radicals while the difference in band gap energy was emphasized in case of Bi and Zn oxychlorides.