**4. Conclusions**

Removal of contaminants As(V), Fe(III), and Mn(II) from water by MgO-coated quartz sand was investigated. When placed in contact with model water solutions, MgO from the composite material dissolves, providing electrons for the reduction of present pollutant species. After 5 min of interaction of the MgO-coated quartz sand with 250 mL of model water solution with 200 μgL−<sup>1</sup> of As(V), 0.51 mgL−<sup>1</sup> of Fe(III), and 1.41 mgL−<sup>1</sup> of Mn(II), nearly 95% of the As(V) was removed. Final concentrations of arsenic, iron, and manganese in treated waters after 10 min of contact with active materials were very close to zero. The MgO-coated sand exhibited a strong ability to remove both ionic and colloidal forms of pollutants from treated waters. The removal process is based on redox and sorption processes on the surface and inside the pores of the active composite material.

**Author Contributions:** Conceptualization and methodology, V.S.C.; investigation, V.S.C. and N.M.P.; data curation, V.S.C. and N.M.P.; writing—original draft preparation, V.S.C.; review and editing, V.S.C. and J.N.J.; 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.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** Vesna S. Cvetkovi´c and Nataša M. Petrovi´c acknowledge the financial support for the investigation received from the Ministry of Education, Science, and Technological Development of the Republic of Serbia (Grant No. 451-03-68/2022-14/200026).

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


11. Shafaei, A.; Rezayee, M.; Arami, M.; Nikazar, M. Removal of Mn2+ ions from synthetic wastewater by electrocoagulation process. *Desalination* **2010**, *260*, 23–28. [CrossRef]

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### *Proceeding Paper* **Use of Hydrogels for Seawater Desalination Processes: A Patent Landscape Report †**

**Ahmed Fatimi**

> Chemical Science and Engineering Research Team (ERSIC), Department of Chemistry, Polydisciplinary Faculty of Beni Mellal (FPBM), Sultan Moulay Slimane University (USMS), Beni Mellal 23000, Morocco; a.fatimi@usms.ma † Presented at the 7th International Electronic Conference on Water Sciences, 15–30 March 2023; Available online: https://ecws-7.sciforum.net.

> **Abstract:** This patent landscape report encapsulates the state by introducing what has been invented concerning hydrogels for seawater desalination processes. As a result, 81 patent documents were found, and 62% of all patent documents have been published during the last three years. According to the findings, China was ranked as the first jurisdiction, and the most prolific patenting companies are from China and the United States, while William Marsh Rice University (United States) and Tianjin Polytechnic University (China) are the academic institutions leading the way. The patent classifications indicate that most inventions are intended for the treatment of seawater (e.g., desalination); processes specially adapted for manufacturing semi-permeable membranes for separation processes; and the treatment of water using ion-exchange sorbent compositions, dialysis, osmosis, or reverse osmosis. According to the knowledge clusters and expert driving factors in this patent landscape analysis, research and development are centered on methods and apparatus for desalination, which are the focus of the majority of patents, as well as macromolecular gels and synthetic macromolecular substances.

**Keywords:** seawater; desalination; hydrogels; patent landscape; innovation
