Comparative study of the variability in the compositions and the effect of milling time on coal fly ash and wood fly ash nanoparticles

Industrial and domestic fly ashes (FA) also known as coal fly ash (CFA) and wood fly ash (WFA) respectively has been causing environmental menaces but in recent times they are gaining potential applications in various industries varying from Construction, processing, activated carbon, filler and reinforcement, agriculture to water purifications, to mention but a few due to its availability and low cost. There is every need to place these two fly ashes and weigh their compositions. In this study, the chemical and elemental compositions of both coal fly ash and wood fly ash are compared. The physiochemical and Morphological Characteristics of the milled and unmilled nano fly ashes were determined using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD), and X-Ray Fluorescence (XRF) analyses. The milling times were taken at 0, 20, 40 and 60 mins and 0 min taken when sieved with 75μm size ASTM standard before milling. The crystal phases detected by the XRD in WFA are rhombohedral, hexagonal, cubic and tetragonal while that of CFA are hexagonal, orthorhombic, rhombohedral and anorthic. XRD analysis shown that the most dominant crystalline in wood fly ash were calcite (CaC03), quartz (SiO²), Sylvite (KCl), Lime (CaO), maghemite-Q (?-Fe2O3), nitratetine (Na(NO3)) and magnetite (Fe3O4) phases; while in coal fly ash were Quartz (SiO²), Mullite (Al₂.32Si0.68O4.84), Sillimanite (Al₂(SiO4)O, Calcite high (CaCO3), Hematite (Fe2O3), Microcline (KAlSi3O8). The particles size got increased from 75μm to average diameter of 200nm. Morphological characteristics revealed that the surface of nano obtained shows that wood fly ash nanoparticles (WFA-NPs) has more irregular shape, rough and uneven compared to coal fly ash nanoparticles (CFA-NPs). As revealed by EDX the elemental composition that are present in Wood fly ash nanoparticles are Ca, K, Mg, Si, Al and Fe while that of coal fly ash nanoparticles are Si, Al, Ca, Fe, Ti and Mg. The overall effects of the grinding process showed that there are tremendous reductions in both the particle and crystallite size of CFA-NPs and WFA-NPs as well as great improvement in the metallurgical and mechanical properties of the two samples with respect to milling time when compared to unmilled samples.