Use of Lomo-Nord Shales in Ivory Coast for the Adsorption Treatment of Humic Acid Extracted from Leachate from the Akouédo Landfill

The environmental pollution caused by the mismanagement of household waste dumps and their leachate in developing countries has led researchers to explore adsorption treatment processes using shales from Côte d'Ivoire. To carry out this study, mineralogical characterization by X-ray Diffraction and Infrared of the shales was required prior to treatment. Using humic acid extracted from the leachates, adsorption tests were carried out using batch adsorption tests, and the optimum adsorption parameters were determined and modeled. The results of the mineralogical characterization revealed the presence of certain minerals. Batch adsorption treatment using slate from Côte d'Ivoire showed that the optimum concentration of slate to use was 30 g/L for a concentration of 15 mg/L humic acid. The duration of agitation at equilibrium was 60 minutes, with a maximum adsorption rate of 92 %. The effect of pH on the adsorption of humic acids showed that, in general, the evolution of adsorption rates was inversely proportional to the increase in pH. The highest yields were obtained at pH levels between 3.5 and 5.5. The results of the influence of the initial concentration of humic acids showed an increase in adsorption efficiency with the increase in the initial concentration up to 100 mg/L. The pseudo-second order model better described the adsorption of humic acid on the shale; it is accompanied by intra-particle diffusion, therefore by a contribution of active sites inside the pores.