Soil sorption of two nitramines derived from amine-based CO2 capture

Summary

Nitramines are potentially carcinogens that form from the amines used in post-combustion CO2 capture (PCCC). The soil sorption characteristics of monoethanol (MEA)- and dimethyl (DMA)-nitramines have been assessed using a batch experimental setup, and defined indirectly by measuring loss of nitramine (LC-MS/MS) from the aqueous phase (0.01 M CaCl2 and 0.1% NaN3) after equilibrium had been established with the soil (24 h). Nitramine soil sorption was found to be strongly dependent on the content of organic matter in the soil (r2 = 0.72 and 0.95, p < 0.05). Soil sorption of MEA-nitramine was further influenced by the quality of the organic matter (Abs254 nm, r2 = 0.93, p < 0.05). This is hypothesized to be due to the hydroxyl group on the MEA-nitramine, capable of forming hydrogen bonds with acidic functional groups on the soil organic matter. Estimated organic carbon normalized soil–water distribution coefficients (KOC) are relatively low, and within the same range as for simple amines. Nevertheless, considering the high content of organic matter commonly found in the top layer of a forest soil, this is where most of the nitramines will be retained. Presented data can be used to estimate final concentrations of nitramines in the environment following emissions from amine-based PCCC plants.