Environmental impact of amines

The process of post combustion CO2-capture by chemical absorption relies on large scale use of chemicals, typically amines in aqueous solution. In such operations, emissions of amines may occur through the cleaned exhaust gas, as degraded solvent and as accidental spills. It is thus important that the chemicals used have low or no environmental effects. To check this, standard ecotoxicity and biodegradability tests for a marine environment were performed on more than 40 amines, including both solvents already in use for CO2-removal and new promising chemicals. The results form a database for environmental risk assessment of common absorption solvents and will be used to correlate chemical structure of the solvents to degradation and toxicity data for use in solvent screening. Some of the solvents used for carbon capture, have been shown to have low biodegradability. The tertiary amines which have been tested do not degrade easily, while the amino acids tested both have low toxicity and degrade easily. The fate estimation model EPI Suite (TM) [US EPA, Washington DC, USA] has also been used to estimate the biodegradation and toxicity of the chemicals. It was compared to the experimental results to investigate if this tool could be used for future solvent screening. For the biodegradability the predictions showed agreement with 48% of the tested compounds, while for ecotoxicity the predictions showed agreement with 66%. (C) 2008 Elsevier Ltd. All rights reserved.