**4. Conclusions**

Activated carbons with a well-developed porosity were prepared from *Stipa tenacisssima* leaves by chemical activation with phosphoric acid at different activation conditions. Generally, increasing the activating agent to STLs ratio from 1 to 3 increased the surface area and, especially, the total pore volume. The obtained results confirm that a 450 ◦C activation temperature and an impregnation ratio of 2 are suitable for obtaining an activated carbon with a surface area of 1503 m2/g and pore volume of 0.59 cm3/g. The synthesized activated carbons R1-500, R2-500, and R3-500 showed a good adsorption capacity for atenolol removal. The maximum adsorption capacities reached the value of 110 mg/g and showed a similar adsorption capacity as the commercial activated carbon from Darco. The equilibrium and adsorption kinetics results were satisfactorily fitted to Freundlich and Langmuir models and also to the second-order kinetic adsorption equation. Consequently, our findings suggest that a good quality activated carbon could be easily produced by onestep chemical activation with phosphoric acid from cheaper and sustainable raw materials such as *Stipa tenacisssima* leaves, and suitable for the elimination of pharmaceutical drugs and further environmental applications.

**Author Contributions:** N.M.: investigation, formal analysis, writing—original draft preparation; I.M.: methodology, writing—review and editing, formal analysis; S.B.: formal analysis, writing review and editing; D.C.-A. and F.J.V.G.: formal analysis, reviewing and editing; N.B.-S. and O.C.: conceptualization, project administration, supervision, reviewing and editing. All authors discussed the results and commented on the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Acknowledgments:** The authors thank the Ministry of Higher Education and Scientific Research of Algeria for the internship and the University of Alicante for their cooperation.

**Conflicts of Interest:** The authors declare no conflict of interest.
