Sorption–desorption behavior of lateritic soils at low heavy metal concentrations

The increasing solid waste production and leachate-related contamination risks demand effective containment strategies, particularly in tropical regions where lateritic soils are widely considered for landfill liner applications. This study investigates the sorption and desorption behavior of five heavy metals (Cd, Cr, Cu, Mn, and Pb) in lateritic soils derived from quartzite, migmatite, and charnockite parent rocks in southwestern Nigeria. Batch equilibrium experiments were conducted using environmentally relevant metal concentrations (10–100 mg/L) to simulate landfill leachate conditions. Physicochemical characterization revealed acidic to near-neutral pH (4.61–6.73) and a wide range (4.55–14.44 meq/100 g) of cation exchange capacities (CEC), with quartzite derived lateritic soil (QDLS) and migmatite derived lateritic soil (MDLS) exhibiting more favorable geotechnical properties for containment applications despite their lower CEC. Adsorption efficiency increased with initial concentration and varied with parent rock type and metal species, with Cd consistently demonstrating the highest retention (up to 88.8% in MDLS), while Cu exhibited the weakest affinity. The observed selective adsorption sequence observed across all lateritic soils shows the influence of mineralogical composition in enhancing sorption capacity and contaminant attenuation. Sorption data were effectively described by both Freundlich and Langmuir isotherm models (R² ≥ 0.70 in 97% of cases), reflecting the heterogeneous nature of the soils, with Cd exhibiting the highest maximum adsorption capacities of 42.43 mg/g in charnockite derived lateritic soil (CDLS) and 33.38 mg/g in QDLS. Desorption experiments revealed partial reversibility, with hysteresis indices ranging from 1.000 to 1.356, indicating varying risks of metal remobilization. These findings suggest that lateritic soils, particularly those derived from quartzite and migmatite, are viable for landfill liner applications due to their strong metal-binding potential and low desorption tendencies, although their performance may be limited by partial desorption under acidic conditions. • Sorption–desorption of Cd, Cr, Cu, Mn and Pb at 10–100 mg/L. • Cd showed highest adsorption, Cu weakest across the soils. • Freundlich and Langmuir models confirm heterogeneous sorption. • Hysteresis index (1.00–1.36) indicates partial remobilization risk. • Parent rock controls metal retention performance.