Secrets of sediment: Using ion chromatography to analyze sediment formation in heating oils

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In a research study recently published, Kerkering and Andersson investigated the formation of sediments in various biogenic and fossil heating oils as well as blends of both over a storage period of two years.

While some of their findings confirm known phenomena such as the oxidation of the fatty methyl esters (FAMEs) in biodiesel, others were more startling. More precisely, the authors discovered evidence that the chemical composition of the fossil fraction in blended heating oils has a strong influence on the sediment formation rate.

To study the influence of long-term storage on different heating oils (biogenic, fossil, and a 10% blend) and to investigate the changes in their composition, the oils were stored for a period of 12–24 months at nearly ambient (40 °C) temperature and analyzed with different techniques (infrared spectroscopy, ion chromatography, size-exclusion chromatography, gas chromatography, and mass spectrometry) every 6 weeks.

Faced with the fact that one of the two blended heating oils investigated formed much more sediment than the other, the authors conclude that "the chemical composition of the fossil heating oil can influence the sediment formation rate […] suggesting that perhaps fuel additives may offer one route to reducing this rate". As to which compounds in fossil fuels exactly this effect can be attributed and why some blends are stable with respect to sediment formation and others are not are questions that need further investigation, as the authors point out in the conclusion of their article.

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