AbstractThis study investigates the potential of utilizing spent coffee grounds (SCG) treated with Ca(OH)2 as an adsorbent for the removal of lead (Pb(II)) ions from aqueous solutions. The SCG was subjected to sequential treatments, including washing, drying, sieving, and immersion in Ca(OH)2 solutions of varying concentrations. Adsorption experiments were conducted under different conditions to evaluate the efficiency of the adsorbent, including variations in contact time, solution pH, adsorbent dosage, temperature, and initial Pb(II) ion concentration. Characterization of the SCG before and after treatment was performed using Fourier transform infrared spectroscopy. The results revealed significant changes in the structural properties of the SCG after treatment with Ca(OH)2, leading to enhanced adsorption performance. The adsorption experiments demonstrated that the efficiency of Pb(II) ion removal was influenced by factors such as contact time, solution pH, adsorbent dosage, temperature, and initial Pb(II) ion concentration. Optimal conditions for maximum adsorption efficiency were identified as a contact time of 270 min, pH 6, adsorbent dosage of 1 g, and temperature of 313 K, resulting in a maximum adsorption capacity qmax of 18.69 mg g−1. The highest desorption rate was observed using HNO3, measured at 90.6%. The reusability efficiency of the adsorbent material was 87.98% in the first use, decreased to 75.41% after five reuses, and further reduced to 39.96% after ten reuses, indicating a decline in performance with repeated use. These findings highlight the potential of SCG as an effective and environmentally friendly adsorbent for the removal of potentially toxic elements from aqueous solutions.