Enhanced removal of ethanolamine from secondary system of nuclear power plant wastewater by novel hybrid nano zero-valent iron and pressurized ozone initiated oxidation process

Abstract

Monoethanolamine (shortly ethanolamine (ETA)), usually used as a corrosion inhibitor, is a contaminant of wastewater from the secondary cooling system of nuclear power plants (NPPs) and is not readily biodegradable. We conducted various experiments, including treatments with nano zero-valent iron (nZVI), nano-iron/calcium, and calcium oxide (nFe/Ca/CaO) with ozone (O₃) or hydrogen peroxide (H₂O₂) to reduce the concentration of ETA and to decrease the chemical demand of oxygen (COD) of these wastewaters. During this study, wastewater with ETA concentration of 7465 mg L^-1 and COD of 6920 mg L^-1 was used. As a result, the ETA concentration was reduced to 5 mg L^-1 (a decrease of almost 100%) and COD was reduced to 2260 mg L^-1, a reduction of 67%, using doses of 26.8 mM of nZVI and 1.5 mM of H₂O₂ at pH 3 for 3 h. Further treatment for 48 h allowed a decrease of COD by almost 97%. Some mechanistic considerations are proposed in order to explain the degradation pathway. The developed hybrid nano zero-valent iron-initiated oxidation process with H₂O₂ is promising in the treatment of ETA-contaminated wastewaters.

Keywords: Ethanolamine (ETA); Nano zero-valent iron; Nuclear power plant wastewater; Oxidation process; Pressurized ozonation.