English

Abstract

The objective of this work was to investigate the influence of the thermal treatment of alluvial clay on the ad-sorption capacity of Pb(II) and Fe(II) to reduce clogging during adsorption phenomenon. The chemical, X- ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscopy (TEM) analysis of the alluvial clays reveal that the main mineral present is smectite, kaolinite and quartz. Cation exchange capacity (CEC) and specific surface area of the raw clay fraction are 62 meq/100 g and 104 m2/g respectively. The mains oxydes of alluvial clay fraction<50µm are SiO2, Al2O3 and Fe2O3.The adsorbent used in this work is the alluvial clay, that after splitting has been thermally treated at 300°C and 600°C, the natural clay properties does not completely disappear until 300°C and 600°C. This study shows that the losses are about 3% for the heat treatment at 300°C (A300) and 5% for the heat treatment at 600°C (A600) after fractionation of Alluvial clays. The adsorption equilibrium is reached in five minutes, whatever the pH, temperature and the molar ratio of the solution. The pH is increased the removal increases as seen from plots of 2, 4 and 6 which gave removals as high as 92.15μmol/g and 100.6 μmol/g to Pb(II) and 92.68 μmol/g and 110.5 μmol/g to Fe(II) respectively. The temperature is decreased the removal increases as seen from plots of 50°C, 40°C and 30°C which gave removals as high as 99.8 μmol/g and 100.3 μmol/g to Pb(II) and 98.9 μmol/g and 100.3 μmol/g to Fe(II) respectively. While, the adsorption capacity was increased as decreasing the temperature. So, it is be recognized that adsorption mechanism should be physical adsorption. The adsorption process of Pb(II) and Fe(II) are best described by the second-order equation. However, the adsorption isotherms could be well fitted by the Freundlich equation, proves the surface heterogeneity of thermally treated Alluvial Clay. Key words: Adsorption, agitated reactor, thermally treated alluvial clay, Cameroon.