Environmental use of HCFA: Oil soil clean up

Abstract

The present study focuses on the evaluation of high calcium fly ash (HCFA), an inorganic waste material produced by electric power plants in large quantities. Properties of HCFA, such as mineralogical and chemical composition, fine particle size, porosity, floating ability and hydrophobicity makes its application in oil spill clean-up attractive. Its sorption capacity depends on its composition and the oil type. Its floating ability has a better result in thin oil spill layers, specifically its coarse fraction, which seems to outmatch due to its higher Si content. Hydrothermal treatment with NaOH solution, with or without a template (tetrapropylammonium bromide), despite the increase in porosity and the decrease in specific gravity, has rather reduced the hydrophobic character and therefore its affinity for oil. The change in Si/Al content by the addition of SiO2 has proved to ameliorate its sorption capacity, but not its floating ability. The application of a HCFA-oil mixture as road construction material seems to be encouraging. It contributes to the elimination of dust production during the paving of a road with gravel, and ameliorates the soil strength, which encourages its application in soil stabilisation.