Desorption of metal ions from activated carbon in the presence of ultrasound

The aim of the present work is to explore the effects of ultrasound on desorption of metal ions from activated carbon. The desorption of Cu(II), Mn(II), Hg(II), and Cr(VI) from activated carbon in the absence and the presence of ultrasound is investigated. Desorption studies are performed under various conditions of temperature and intensity. Results indicate that ultrasonic irradiation considerably improves the desorbed amount and the rate of desorption. The amount of desorbed metal ions increases with increasing temperature and ultrasound intensity. The addition of ethanol to the desorption system leads to an enhancement of the desorption rates, especially in the presence of ultrasound. Acidification of the regenerating solution to pH 1 leads to an enhancement of the desorption of Cu(II). This improvement is more obvious in the presence of ultrasound. Modeling of desorption kinetics shows that ultrasound enhances surface diffusivity. This can be attributed to the phenomena induced by acoustic cavitation: acoustic vortex microstreaming, high-speed microjets, high-pressure shock waves, and intense localized heating.