Efficient removal of estrogenic compounds in water by MnIII-activated peroxymonosulfate: Mechanisms and application in sewage treatment plant water

In this paper, the degradation of three endocrine-disrupting chemicals (EDCs): bisphenol A (BPA), 17 beta-estradiol (E2) and 17 alpha-ethinylestradiol (EE2) by manganite (gamma-MnOOH) activated peroxymonosulfate (PMS) was investigated. Preliminary optimisation experiments showed that complete degradation of the three EDCs was achieved after 30 mM of reaction using 0.1 g L-1 of gamma-MnOOH and 2 mM of PMS. The degradation rate constants were determined to be 0.20, 0.22 and 0.15 min(-1) for BPA, E2 and EE2, respectively. Combining radical scavenging approaches, Electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) analyses, we revealed for the first time that about 40% of EDCs degradation can be attributed to heterogeneous electron transfer reaction involving freshly generated Mn(IV), and 60% to sulfate radical degradation pathway. The influence of various inorganic ions on the gamma-MnOOH/PMS system indicated that removal efficiency was slightly affected by chloride and carbonate ions, while nitrate and nitrite ions had negligible impacts. The application of gamma-MnOOH/PMS system in real sewage treatment plant water (STPW) showed that degradation rate constants of EDCs decreased to 0.035-0.048 min(-1 )and complete degradation of the three EDCs after 45 mM. This study provides new insights into the reactivity of combined gamma-MnOOH and PMS, and opens new ways for the application of Mn-bearing species in wastewater treatment technologies.

Automated summary

This study investigated the degradation of three endocrine-disrupting chemicals by gamma-MnOOH activated peroxymonosulfate, showing that 40% of the degradation can be attributed to heterogeneous electron transfer reaction with freshly generated Mn(IV) and 60% to sulfate radical degradation pathway. The system showed complete degradation of EDCs after 30mM of reaction with specific conditions. The application of this system in real sewage treatment plant water showed decreased degradation rate constants of EDCs, providing new insights into the reactivity of combined gamma-MnOOH and PMS.