Carbonyl and aromatic hydrocarbon emissions from diesel engine exhaust using different feedstock: A review

The depleting natural resources, primarily petroleum that has been the backbone of fuel industry is finding itself at loss to answer the questions of our future needs. This has led researchers to venture into the area of biodiesel since it is the next best contender to replace diesel in the immediate future. This is so because biodiesel has characteristics not only similar to diesel but also better in many respects, like biodegradability, renewability and better emission characteristics. Many authors have studied regulated emission characteristics. The results are in favour of biodiesels in terms of carbon monoxide, smoke, hydrocarbons (HC) and particulate matter (PM). The study in the area of unregulated emissions is, however, limited and inconsistent, even though they are considered carcinogenic and mutagenic in nature. Hence, for a better understanding of biodiesel and their emissions, it is necessary to examine their unregulated emissions as well. This paper consolidates and analyses data regarding carbonyl, polyaromatic hydrocarbons (PAHs) and their oxy and nitro derivatives of various biodiesels derived from various feedstock and their diesel and alcohol blends. The emission trends have also been studied for various parameters like engine speed, engine load, driving cycle etc.