Role of various factors affecting the photochemical treatment of N-nitrosamines related to CO₂ capture

ABSTRACT

Post-combustion CO₂ capture using amine solvents is the most feasible method of reducing anthropogenic CO₂ emissions, which are the largest contributor to global warming. The formation of carcinogenic N-nitrosamines (i.e. by-products) can hinder the industrial application of this technology. In this study, the effects of direct UV photolysis (N-nitrosamine concentration and amines) and advanced oxidation processes (UV/H₂O₂ and UV/O₃) on the three specific N-nitrosamines that are commonplace in amine-based CO₂ capture (i.e. N-nitrosodiethylamine (NDEA), N-nitrosodiethanolamine (NDELA), and N-nitrosomorpholine (NMOR)) were examined. A significant decrease in the photodegradation rate constants was observed for NDEA (1.02 × 10⁰ to 2.94 × 10⁻¹ min⁻¹), NDELA (1.52 × 10⁰ to 3.32 × 10⁻¹ min⁻¹), and NMOR (1.93 × 10⁰ to 2.20 × 10⁻¹ min⁻¹) as their concentrations increased within 1–50 mg/L. This is the first report of a significant increase in the degradation rate constants of N-nitrosamine with an increase in amine concentrations (i.e. monoethanolamine, diethanolamine, and morpholine) within 10–200 mM. The photodegradation rate constants increased as the molar ratio of H₂O₂ to N-nitrosamine increased to 20, but then decreased at molar ratios beyond this. O₃ had a negligible effect on the photodegradation of N-nitrosamines.

GRAPHICAL ABSTRACT

KEYWORDS:

• N-nitrosamine
• photodegradation
• hydrogen peroxide
• ozone
• CO₂ capture

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20142010201810) through POSCO E & C.