Decomposition of nitrosamines in aqueous monoethanolamine (MEA) and diethanolamine (DEA) solutions with UV-radiation

Abstract

CO2 capture based on chemical absorption using amine solutions is considered to be the most feasible way to remove CO2 from low pressure sources. However, amines, when exposed to nitrous oxides, may form nitrosamines which are known to be carcinogenic. In this work the destruction of two nitrosamines, NDELA (nitrosodiethanolamine) and NDMA (nitroso-dimethylamine), with UV-light is studied in a batch reactor at room temperature and at 45 °C. Additionally, the effect of UV-light on the degradation of MEA is investigated.

The results from this project clearly show that the rates of UV-induced decay of NDMA and NDELA are different. Additionally the efficiency of UV-light for decomposition of NDMA and NDELA depends on the type of solution. In dilute amine solutions (water wash solutions), the decay is much faster compared to more concentrated solutions. Colouring of the solutions, caused by degradation products, was found to decrease the effect of UV-light dramatically. A dynamic model for the reactor set-up used is developed and used for interpretation of the results. In all solutions the decay was found to be 1st order with respect to NDELA and NDMA concentrations.