Photocatalytic Degradation of Carcinogenic N-Nitrosodiethylamine (NDEA) in Amine-Based CO₂ Capture Using Carbon Nitride under Visible Light

This study aimed to degrade Nitrosodiethylamine (NDEA), a carcinogenic compound formed during CO2 capture processes due to the use of amines. CO2 emissions are one of the major contributors to global warming, and although various techniques have been developed for carbon capture, amine-based technologies remain among the most effective. However, these systems lead to the formation of hazardous nitrosamines such as NDEA. In this study, NDEA degradation was investigated under visible light (sunlight simulator) using a photocatalyst in the presence of amines, i.e., Monoethanolamide (MEA) and Diethanolamine (DEA), to simulate real-time CO2 capture conditions. Carbon nitride (C3N4) was synthesized using the thermal condensation method from urea and utilized to enhance surface area and maximize light absorption for effective electron activation and pollutant removal. UV-Vi’s spectrophotometry was employed to monitor the degradation of NDEA in both catalytic and non-catalytic systems over a wavelength range of 325 nm to 1100 nm. The results indicated significant degradation with noticeable variations in absorbance due to the formation of intermediate products. A validated HPLC method using gradient elusion was further applied to quantify NDEA degradation and confirm the formation of multiple degradation products, indicating a complex degradation pathway. The findings demonstrate that while UV-Vis provides rapid monitoring of degradation trends, HPLC enables precise quantification and differentiation between NDEA and its byproducts. The study confirms that photocatalytic degradation using carbon nitride under visible light is an energy-efficient and effective approach for the removal of NDEA from amine-based CO2 capture.