Physico-chemical characterization of agro-waste sugarcane bagasse ash from three brazilian sugarcane mills and obtaining biosilica from ash

Abstract

The interest in transforming biomass into new sources of energy and new materials has been encouraging studies around the world. The ash resulting from the burning of straw and sugarcane bagasse, for example, is a material rich in silica. In the present study, samples of fly ash and bottom ash from sugarcane residues were collected in three different mills (Cerradinho Iracema and Guaíra), located in regions where the soils are classified as oxisols. The ashes were characterized by XRD, EDX, ICP-OES, SEM, FTIR spectroscopy and TGA/DTG techniques. Most ash samples showed silica as the main constituent (42-69%) and silica in crystalline form in all. Biosilica was obtained from ash samples using alkali extraction and acid precipitation. The physical and chemical properties of the extracted biosilica are described. The biosilica samples have amorphous phases and purity ranged from 93 to 97 wt.%. The results showed that the different origins of sugarcane residue ash used as raw material did not affect the quality of the extracted biosilica.