The objective of this study is to convert agricultural residues, particularly cocoa pod shells from the Ivory Coast, into low-cost bioadsorbents. In this context, biochar can be produced from agricultural residues for use in removing water pollutants. The main question was whether the adsorption efficiency of biochar produced from this biomass can be improved by physical activation with carbon dioxide (CO2). To this end, an assessment was made of the effectiveness of raw and activated biochar in adsorbing cadmium (Cd2¿) from an aqueous solution under conditions close to those of drinking water (pH = 6 and temperature = 22 ± 1 °C). The results of the adsorption indicated that raw biochar, obtained by pyrolysis of cocoa pod shell biomass at 400°C, was more effective at removing Cd2¿ (removal rate = 72.0 ± 1.1% and adsorption capacity = 14.4 ± 0.3 mg/g) than activated biochar, which was produced by pyrolysis of the same biomass at 900°C followed by activation with CO2 at 800°C (removal rate = 65.3 ± 1.8% and adsorption capacity = 13.0 ± 0.4 mg/g). The experiment indicates that the chemical surface properties of adsorbents significantly influence the adsorption of Cd2¿, while physical properties have a minor impact. This study revealed that raw biochar pyrolysed at 400 °C was more efficient than activated biochar in adsorbing Cd2¿, thus offering an easily available, environmentally friendly, and inexpensive adsorbent for improving drinking water quality. Therefore, it is not systematically necessary to activate biochar to be effective in removing pollutants from water.