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ABSTRACT. In this study, Ricinodendron heudelotii (akpi) shells are used as precursor to prepare activated carbon via chemical activation using phosphoric acid. The characterization of the obtained activated carbon is performed using X-ray diffraction (XRD), Boehm titration method and adsorption of acetic acid. The results show that the prepared activated carbon has a microstructure and a higher specific surface area (1179 m 2 /g), suggesting that the acid treatment has a significant positive influence on its sorption properties. The maximum adsorption capacity and pollutant elimination efficiency are found to be 43.48 mg/g and 90%, respectively. These results suggest that this low cost agent is an efficient tool to remove organic pollutants especially imidacloprid from wastewater.

Metallic Trace Elements (ETM) are naturally transported to the shallows by runoff. As the lowlands are exploited for market gardening, ETM can be found in the products of these crops and present risks of contamination for the populations. It is with this in mind that we decided to study the mobility of metallic trace elements in the soils of the market garden lowlands of the city of Daloa. To achieve this goal, nine (9) soil samples were taken from 3 sites at different depths (0 -15 cm, 15 to 30 cm and more than 30 cm). The determination of the water pH and of the organic fraction of the sediments were carried out according to ISO 10390 and NF ISO 10694 standards respectively. The ETM contents were obtained by an Atomic Absorption Spectrometer (AAS). The results obtained showed that the majority of the sediments studied are acidic. In addition, they contain a more or less large organic fraction of between 10 and 50%. In addition, our studies demonstrated a mobility of certain ETMs, in particular As, Cr, Hg and Zn, depending on the different sediment profiles studied. Also, Cd, Cr, Mg, Ni, Pb are linked to organic matter and to the clay fraction of the sediments. However, their mobility would be influenced by pH.