CHARACTERISATION OF LIGNITES THEIR EXTRACTED HUMIC ACIDS:SUITABILITY FOR SOIL BENEFICIATION/CONDITIONING

This research gives attention to the non-energy use of Lignite samples collected from Ohordua town of Edo State and Azagba-Ogwashi in Delta State. A total of six composite Lignite samples,from ten sampled points were subjected to analytical study, with a view to determining their humic content and properties for use in soil beneficiation and conditioning.Proximate and Ultimate analytical technique was used to characterize the lignite from which humic acid was extracted under alkaline condition, and precipitated using acidic medium of 6M HCl.X-Ray Diffraction and X-Ray Fluorescence analytical methods were employed to determine the mineralogical and elemental composition of the samples respectively,while Ultra-Violent visible spectroscopy was used for organic characterization of the humic acid.Proximate analyses of the Lignite show percentage composition of Ohordua and Azagba-Ogwashi Lignite respectively,Fixed Carbon (65.22 wt% and 67.16wt%),Moisture Content (26 wt% and 25.4wt%) and Ash (5.02 wt% and 4.5 wt%).Ultimate analyses shows Hydrogen (6.60 wt% and 6.22wt%), Nitrogen (1.34 wt% and 1.19wt%,) Sulphur (0.77 wt% and 0.70wt%), Oxygen (26.07 wt% and 24.73 wt%), for Ohordua and Azagba-Ogwashi respectively.The analytical results suggest the existing lignite with varying thickness is of Lignite rank. The Ultimate analyses of the extracted Humic acid show Carbon (57.5wt% and 55.8wt%)%, Hydrogen (5.1 wt% and 3.9wt%), Nitrogen (2.5 wt% and 1.1wt%), Sulphur (Nil and 0.3wt%) and Oxygen (34.9 wt% and 38.9wt%,) for Ohordua and Azagba-Ogwashi, respectively.The mineralogical composition in the lignite samples shows Kaolinite was the main clay mineral identified. Non clay minerals such as anorthite, drierite, yeelimite, spurite, belite, wollastonite, hematite, pyrite, bauxite and quartz were detected.For Ultra-Violent visible spectroscopy characterization of the Humic Acid, E2/E3 and E4/E6 absorption values for Ohordua (21.69 and 4.50) respectively, while Azagba-Ogwashi reveal (19.39 and 4.6) respectively. The humic substance has percentage aromaticity values of 33.90% and 34.06%, total acidity has 10.4% and 10.1%, COOH has 3.4% and 3.3%, Phenolic has 7.0% and 6.8% and acidity ratio has 0.49% and 0.48%, for Ohordua and Azagba-Ogwashi, respectively which depicts the Humic Acid has a high degree of Humification and a very good total acidity ratio. Results from this research indicate that the Lignite from both locations are similar in geochemistry, mineralogy and organic properties. Although,humification is high in both samples, Ohordua Lignite with lesser aromaticity and E4/E6 ratio, higher E2/E3 ratio and higher acidity ratio is more suitable for soil beneficiation and conditioning than that of Azagba-Ogwashi.