In this research, the performance of a new biosorbent prepared using low-cost oak shell waste materials for consecutive removal of particular cations and chromate anions from aqueous solutions was studied. The adsorbent impregnated with Pb²⁺, Ag⁺, Ba²⁺, and Sr²⁺ was used to remove chromate anions by the formation of an appropriate insoluble precipitate. The biosorbent was characterized by FTIR, XRD, SEM, TG-DTG, and VSM techniques. The adsorption capacities of 133.84, 53.12, 50.12, and 40.39 mg g⁻¹ were obtained for chromate for the samples containing Pb²⁺, Ag⁺, Ba²⁺, and Sr²⁺ cations, respectively. The chromate uptake was inversely proportional to the k_sp of the chromate precipitate and increased with the cation content of the adsorbent. The adsorption process was kinetically fast and the equilibrium was established within 10 min. The experimental data were analyzed by the Langmuir, Freundlich, Sips, and Redlich-Peterson isotherm models. The data were fitted to the Langmuir isotherm, indicating that chromate was adsorbed homogeneously on the adsorbent surface.