Analysis, Characterization and Bleaching Properties of Smectite From Iliri Road Swelling Clays in North Eastern Uganda, Leached in Different Acids

Clay from Iliri was activated using hydrochloric and sulfuric acid of differing concentrations. The chemical compositions of the raw clay and clay activated at different acid concentrations were analyzed to investigate the extent of cation dissolution. From the results, the clays were classified as sodium bentonite mixed with feldspars, illite, kaolinite and plagioclase. When cotton and sunflower oil was bleached at 90°C the optimal time was 25 minutes using1% clay activated with 20% acid, the bleaching efficiency obtained were 90 and 80% for hydrochloric and sulfuric acid leached clays respectively. Clay leached in 20% hydrochloric acid bleached to the same level as that leached in 30% sulfuric acid. The equilibrium data was analyzed using Freundlich and Langmuir adsorption isotherms and the former was found to provide a better fit for the data. The values of the Freundlich constant, n, for cotton-seed oils were larger than sunflower oils because the extent of bleaching differed. The values of k increased with increase in strength of the acid used to the clay. Iliri clay contained montmorillonite. The clay was made of 40–50% smectite, 20–30% feldspars and plagioclase showing they formed from alkaline intrusive granitoids in basic medium. The presence of iron, aluminium, and silicon in approximate percentages of 11, 18 and 60% respectively indicated that the clay was montmorillonite. The IR spectrum absorption peaks at 3600, 3454, 526 and 466cm-1 among others were due to Al-Al-OH, Mg-OH-Al, Si-O-Al and Si-O-Si deformations respectively indicated presence of smectites in the clay. DTA showed peaks at temperatures of 100, 250 and 650°C due to presence of smectites.