Degradation of 17β-estradiol by combined ultrasound/KMnO4 in an aqueous system

Abstract

Estrogenic compounds in drinking water resources pose potential threats to human health. Treatment technologies are recommended to effectively remove these compounds in order to supply safe drinking water to the public. In this study, single ultrasound and combined ultrasound/KMnO4 were adapted to reduce 17β-estradiol (E2) in aquatic systems. The effects of combined ultrasound/KMnO4 were compared with ultrasound because KMnO4 has an oxidative enhancement effect on ultrasound. The results showed that the E2 removal rate increased with increasing reaction time and power but decreased with solution temperature. The process of ultrasound could degrade small quantities of E2 by approximately 47.7% at the relatively optimal conditions of 270W ultrasound power, 25°C, and 180 min reaction time. Compared with pure ultrasound, an obvious enhancement effect was observed after the introduction of KMnO4. The residual E2 concentration decreased with increasing KMnO4 dosage and irradiation time, and the removal efficiency of E2 was greater than 99.6% when the reaction reached 30 min with 5 mg L−1 KMnO4. A good correspondence with pseudo-first-order kinetics was found in each process. It was demonstrated that the degradation reaction rate constants of E2 in ultrasound, KMnO4, and ultrasound/KMnO4 treatment were 0.0037, 0.0247, and 0.0647 min−1, respectively. Characterized by high efficiency and rapid effect, combined ultrasound/KMnO4 treatment has great potential for future application. The non-purgeable organic carbon index indicated that the degradation products of E2 under ultrasound were mineralized.