Experimental and numerical investigation of the effect of liquid temperature on the sonolytic degradation of some organic dyes in water
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Date
2016
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Publisher
Elsevier
Abstract
This paper presents a comprehensive experimental and numerical investigation of the effects of liquid
temperature on the sonochemical degradation of three organic dyes, Rhodamine B (RhB), Acid orange
7 (AO7) and Malachite green (MG), largely used in the textile industry. The experiments have been
carried out for an ultrasonic frequency of 300 kHz. The obtained experimental results were discussed
using a new approach combining the results of single-bubble event and the number of active bubbles.
The single-bubble event was predicted using a model that combines the bubble dynamics with chemical
kinetics occurring inside a bubble during the strong collapse. The number of active bubbles was predicted
using a method developed in our previous work. The experiments showed that the degradation rate of the
three dyes increased significantly with increasing liquid temperature in the range 25–55 C. It was predicted
that the main pathway of pollutants degradation is the attack by OH radicals. The simulations
showed that there exists an optimum liquid temperature of about 35 C for the production of OH inside
a bubble whereas the number of active bubbles increased sharply with the rise of the liquid temperature.
It was predicted that the overall production rate of OH increased with increasing liquid temperature in
the range 25–55 C. Finally, it was concluded that the effect of liquid temperature on the sonochemical
degradation of the three dyes in aqueous phase was controlled by the number of active bubbles in the
range 35–55 C and by both the number of bubbles and the single bubble yield in the range 25–35 C.