Effects of ultrasound on the adsorption and desorption of chromium (Ⅵ) on activated carbon were studied. Results showed that within the range of experiment concerned

the adsorption ratio of chromium(Ⅵ) decreases with pH increasing regardless ultrasound application. However

with ultrasound

the equilibrium of the system moves to the direction in the decrease of adsorption

which becomes severe with the increase in pH. With ultrasound

as the initial Cr(Ⅵ) concentration increases from 20 mg·L-1 to 110 mg·L-1

the removal efficiency of Cr(Ⅵ) drops from 99.9% to 79.8%

while the equilibrium adsorption capacity increases from 3. 3 mg·g-1 to 15. 0 mg·g-1

which is similar to that without ultrasound. The adsorption ratio continuously increases until to an equilibrium without ultrasound

while

it appears a slight decrease after being quickly to the equilibrium

and then gradually increases to the equilibrium again in case with ultrasound. The desorption ratio of Cr(Ⅵ) is very small in distilled water regardless ultrasound application. While

the desorption can be greatly improved by the addition of NaOH

and this promotion effect is remarkable for the ultrasonic system.