Sonocatalyzed decolorization of synthetic textile wastewater using sonochemically synthesized MgO nanostructures.

ABSTRACT

The present study focused on the synthesis of nanostructured MgO via sonochemical method and its application as sonocatalyst for the decolorization of Basic Red 46 (BR46) dye under ultrasonic irradiation. The sonocatalyst was characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray microanalysis (EDX). In the following, the sonocatalytic removal of the dye under different operational conditions was evaluated kinetically on the basis of pseudo first-order kinetic model. The reaction rate of sonocatalyzed decolorization using MgO nanostructures (12.7 × 10(-3) min(-1)) was more efficient than that of ultrasound alone (2.0 × 10(-3) min(-1)). The increased sonocatalyst dosage showed better sonocatalytic activity but the application of excessive dosage should be avoided. The presence of periodate ions substantially increased the decolorization rate from 14.76 × 10(-3) to 33.4 × 10(-3) min(-1). Although the application of aeration favored the decolorization rate (17.8 × 10(-3) min(-1)), the addition of hydrogen peroxide resulted in a considerable decrease in the decolorization rate (9.5 × 10(-3) min(-1)) due to its scavenging effects at specific concentrations. Unlike alcoholic compounds, the addition of phenol had an insignificant scavenging effect on the sonocatalysis. A mineralization rate of 7.4 × 10(-3) min(-1) was obtained within 120 min. The intermediate byproducts were also detected using GC-MS analysis.