<p>Research on samarium (Sm) adsorption is significant due to the potential applications of metal–organic frameworks (MOFs) in environmental cleanup and separation technologies. This study aimed to evaluate the effectiveness of three MOFs: MOF-808, MOF-808-SO₄, and MOF-808-PO₄ under varying conditions. Key parameters investigated during the adsorption tests included pH, temperature, sorbent mass, initial concentration and contact time. The results showed a decreasing trend in adsorption capacity as follows: MOF-808-PO₄ exhibited the highest efficiency, followed by MOF-808-SO₄, with MOF-808 demonstrating the least effectiveness. Under the specified experimental conditions, MOF-808-PO₄ emerged as the most efficient adsorbent for samarium removal. Thermodynamic analysis indicated that the adsorption process is both exothermic and spontaneous. Furthermore, the experimental data were best described by the Langmuir isotherm model and adhered to pseudo-second-order kinetics. This research offers novel insights into the application of modified MOFs for the selective removal of samarium ions from wastewater, addressing a critical need in environmental remediation and industrial processes. By providing a comprehensive comparison of the adsorption efficiencies of these three MOFs under controlled conditions, this study systematically examines the influence of key factors such as pH, temperature, sorbent mass, initial concentration, and contact time, while also elucidating the underlying mechanisms of the adsorption process.</p> Graphical Abstract <p></p>