The potential of Euphrates poplar (EP) leaves, a plentiful agricultural waste, as a sustainable adsorbent for wastewater treatment is examined in this work. FTIR, FESEM, and XRD were used to characterize activated carbon (AC) derived from EP leaves by carbonizing them at 400°C for 3 hours. Brunauer found a surface area of 3.77 m²/g using the Brunauer–Emmett–Teller (BET) technique. Methylene blue (MB) adsorption trials showed that with an ideal contact time of 60 minutes, the removal efficiency exceeded 91%. Temperature and pH significantly affected the adsorption process, and the addition of EP nanoparticles enhanced dye uptake. According to kinetic modeling, the Temkin isotherm (R²= 0.904) provided the most accurate equilibrium fit, while the pseudo-second-order model (R²= 0.999) best explained the adsorption behavior. Positive ΔS° values indicated greater unpredictability at the solid-solution interface, and thermodynamic parameters confirmed that the adsorption was endothermic and spontaneous. These results demonstrate that Euphrates poplar leaves are an economical and environmentally beneficial adsorbent for dye removal, providing a viable alternative for wastewater treatment applications.