Carbonyl Compounds Emissions from Biodiesel Blends

Biodiesel is mostly made from vegetable oils and animal fats through transesterification reactions and are mainly as methyl esters. As a renewable, biodegradable and non-toxic fuel, biodiesel has been more and more applied to daily usage. Compared to diesel fuel, biodiesel combustion can be expected to produce less atmospheric pollutants such as CO, particular matters, and polycyclic aromatic hydrocarbons (PAHs). However, there is little study on carbonyl compounds emitted from biodiesel fuel till now. Though not regulated, carbonyl compounds are irritants to the eyes and respiratory systems, and some aldehydes are probable human carcinogens. In addition, carbonyl compounds contribute to ground level ozone formation, which is undesirable for areas under ozone non-attainment. In our study, carbonyl compounds emissions from petroleum diesel and biodiesel fuels were evaluated. A stationary generator is used to burn petroleum diesel fuel and a mixture of diesel and biodiesel at a ratio of 1:1 (B50) separately. The generator can work under different loads, from 0 kw, which stands for the idle condition, to 75kw, which represents the full load. The carbonyls are collected on cartridges coated with 2,4-dinitrophenylhydrazine (DNPH) by EPA TO-11A method and the samples are analyzed by high pressure liquid chromatography (HPLC). Formaldehyde, acetaldehyde and acetone are the common carbonyl pollutants from both petroleum diesel and biodiesel fuels and several more carbonyls are found in biodiesel samples. The total carbonyls emitted from biodiesel are also higher than petroleum diesel. Emissions for different operating conditions are also compared.