Methanol/Ethanol/Butanol–Gasoline Blends Use in Transportation Engine—Part 2: Composition, Morphology, and Characteristics of Particulates

Spark ignition (SI) engines have a remarkable share in the passenger car segment in urban areas worldwide. Particulate matter (PM) emitted from these vehicles has an adverse health impact since it can penetrate deep into the lungs, leading to cardiovascular issues. In this study, a detailed physical, chemical, and morphological characterization of the PM emitted by a production-grade SI engine fueled with different alcohol–gasoline blends (gasohols), namely GM10 (10% methanol blended with gasoline, v/v), GE10 (10% ethanol blended with gasoline, v/v), and GB10 (10% butanol blended with gasoline, v/v) vis-à-vis baseline gasoline was performed. Results exhibited that gasohol-fueled engines emitted relatively lower particulate mass and numbers. Trace metal analysis was performed to explore the composition of PM, which showed that gasoline-fueled engines exhibited comparatively higher emissions of trace metals than gasohol-fueled engines. PM morphology was also investigated to evaluate the suitability of alcohol blending with gasoline, revealing that even a small fraction of alcohols blended with gasoline could alter the structure of particulates. This study successfully demonstrated that the large-scale implementation of gasohols in SI engines could reduce PM emissions and trace metals in the particulates. This study also showed the potential of gasohols to partially replace fossil fuels, which could be explored further for higher alcohol fractions.