<p>New granulated adsorbent Al₂O₃ containing 0.25% graphene oxide (GO) was synthesized by spray drying, and the adsorption of diclofenac from aqueous solutions was studied. Diclofenac adsorption was carried out at room temperature at different pH values and adsorption times. The mechanism of diclofenac adsorption obeys the Langmuir model. The adsorbate molecules tend to cover homogeneous surface sites by a monolayer, and the adsorbate—adsorbate interactions are negligible in the range of low and medium surface coverages. The maximum adsorption capacity of the Langmuir monolayer was 29.67 mg g⁻¹. The obtained results show that the Al₂O₃—0.25 vol.% GO adsorbent is suitable for the production of adsorbents for additional purification of wastewater from diclofenac.</p>