Oxidation of estrone by permanganate: Reaction kinetics and estrogenicity removal

Permanganate was used as an oxidant to control estrone in the present study. Kinetics was determined at pH 2.5-9.4 and temperature 15–40°C for the reaction of estrone with potassium permanganate. It was found that the reaction is second-order overall and first-order with respect to both estrone and permanganate. The second-order rate constant for the reaction at pH 5.8 and 25°C is 44.45 L mol-1 s-1. The reaction rate first decreased with the increase of pH in the range of 2.5-6.6 and then increased greatly with the increase of pH in the range of 6.6-9.4. In addition, the rate constant exponentially increased with the increase of reaction temperature. Removal of estrogenicity was also investigated during the degradation of estrone using yeast estrogen screen (YES). Results show that the estrogenicity increased in the initial 15 min of reaction and then decreased fast, with a removal rate of 73.8% within the 30 min of reaction. Results also demonstrate that the reaction rate between estrone and permanganate is faster in natural water background than in the ultra-pure water system. Permanganate oxidation is therefore a feasible option for removal of estrone in drinking water treatment processes. However, the contact time must be enough in order to remove estrone without causing the increase of estrogenicity.