Adsorption of Cd 2+ from aqueous solution onto composites based on powdered activated carbon and Maghnia clay adsorbents: experimental design, kinetic, equilibrium and thermodynamic study

ABSTRACTCadmium and other heavy metals in landfills pose significant health and environmental risks due to their leaching potential into soil and groundwater when in contact with water or moisture. In this study, we synthesised two composites, composite I (C(I)) and composite II (C(II)), using Algerian clay and coconut shell-derived activated carbon. These composites are intended for controlled landfill waste management. The components are mixed at varying mass percentages, effectively adsorbing cadmium (Cd2+) from aqueous solutions. We conducted a parametric adsorption study using an experimental design. Cd2+ removal is more effective with composite C(II), reaching a Qmax of 163 mg.g−1 and an improved R of 59% at 25°C, while C(I) achieves a Qmax of 131 mg.g−1 and an R of 47%. The pH study indicated significant adsorption in the pH range [6–8]. The experiment utilised a screening design to optimise Cd2+ adsorption and establish the response surface. The coded variable Xi ranged from −1 (low) to + 1 (high) such as pH (X1: 2–6), temperature (X2: 25–45°C), composite mass (X3: 0.5–2.5 g.L−1), stirring speed (X4: 20–180 Oscillation/min), equilibrium time (X5: 60–120 min), and initial solution concentration (X6: 25–225 mg.L−1). The optimal values for X1, X4, and X6 were found to be 6, 180 Oscillation/min, and 185 mg.L−1, respectively.KEYWORDS: Heavy metal removalsoil remediationenvironmental contaminantssustainable materialsscreening design Author contributionS.AIT HAMOUDI performed the experiment, discussed the results, and prepared the manuscript. L.NOURI and S.HEMIDOUCHE discussed the results and prepared the experimental design. N.KHELIFA discussed the results. A.KHELIFI, A.BOUDJEMAA, K.BACHARI. Funding and supervision and corrected the manuscript. All authors read and approved the final manuscript.Disclosure statementNo potential conflict of interest was reported by the author(s).Supplementary dataSupplemental data for this article can be accessed online at https://doi.org/10.1080/03067319.2023.2267450.