Ultrasound-induced destruction of low levels of estrogen hormones in aqueous solutions.

The removal of estrogen hormones from water and wastewater is of importance due to their adverse effects toward ecosystems and potential risks to human health. The ultrasound-induced destruction of estrogen compounds in aqueous solutions is studied in a batch reactor using a 1.1 W/mL sonication unit and in a continuous flow reactor using a 2.1 W/mL sonication unit. The estrogen compounds of interest are 17alpha-estradiol, 17beta-estradiol, ethinyl estradiol, estrone, equilin, gestodene, levonorgestrel, and norgestrel. Effects of process variables such as temperature, pH, and pressure are examined. The degradation of estrogens follows pseudo first-order kinetics. The reaction likely takes place in the interfacial region where supercritical environment is produced upon cavity implosion and in the bulk solution with radical species. Low solution pH is more favorable for destruction of estrogens. A kinetic degradation model is developed to predict the destruction of estrogen compounds. Low solution temperature shows favorable destruction of estrogens. Increasing the fluid pressure is detrimental to reaction efficiency.