In this paper, the adsorption potential of activated carbon prepared by Ziziphus spina-christi lotus leaf for the removal of sulfate from aqueous solution was investigated. To this end, the effect of different parameters such as pH, contact time, temperature, adsorbent concentration, and initial sulfate ion concentration was investigated. The results indicated that the highest adsorption efficiency (84.5%) was obtained at pH 6, adsorbent concentration of 5 g/L, sulfate ion concentration of 20 ppm, 65 min and temperature of 45 °C. Also, the adsorption equilibrium study showed that the adsorption process follows the Langmuir isotherm model with the maximum adsorption capacity of 9.3 mg/g. In addition, the thermodynamic study showed that the adsorption process on the activated carbon surface was spontaneous. Moreover, the adsorption process was exothermic accompanied by a decrease in irregularity. Furthermore, the adsorption kinetic study indicated that the adsorption process follows the pseudo-second-order kinetic model.