Physicochemical characterization and possible applications of the waste biomass ash from oleoresin industries of India

Abstract

The oleoresin industries in India make use of the spice residue as boiler fuel and the combustion of this waste biomass generates tons of ash everyday. Herein the study we have carried out the characterization of this industrial waste ash in order to have a broad awareness of its properties in terms of toxicity, composition and possible utility. Techniques like XRF, ICP-AES, SEM–EDS, surface area, pore volume analysis, powder XRD, TG–DTA, FTIR and elemental analyses were used for the purpose. Ash collected from the grate fired furnace (bottom ash) as well the flyash deposited on the boiler walls and pipes were analyzed. Elemental analysis of the ashes indicates its potential as a crude fertilizer or cement replacement material. PXRD indicates the presence of several crystalline phases such as harrisonite (Ca(Fe3+,Mg)6(PO4)2(SiO4)2), aphthitalite ((K,Na)3Na(SO4)2, cryptomelane (KMn4+6Mn2+2O16), varulite (NaCaMn2+2.25Fe2+0.5Fe3+0.25(PO4)3), marokite (CaMn2O4), fersilicite (FeSi) in the flyash fraction and the phases magnetite (Fe3+2Fe2+O4), kalsilite (KAlSiO4), cryptomelane (KMn4+6Mn2+2O16), fukuchilite (Cu3Fe2+S8), walthierite (Ba0.5Al3(SO4)2(OH)6), and magnesite (Mg(CO3) in furnace ash. The amorphous nature of silica in the ashes is evident from the characteristic broad hump around 2θ=30. The iron rich fraction of the ash consists primarily of magnetite which leads to a greenish blue color on heating the ash above 650°C. This magnetite fraction if separated could find use as catalysts in organic reactions. SEM images indicate the ashes to be highly agglomerated and EDX data shows the surface of the ash particles covered with potassium oxide and carbon. The percentage of K seems to be higher in the flyash due to the volatility of the potassium compounds which is carried up by the air current. Even though the surface area of the as received ashes is negligible an acid treatment removes the surface adsorbed species and increases the surface area to 368m2/g making it an effective adsorbent.