**1. Introduction**

For humans, animals, agriculture, and many different sectors, including agrifood and pharmaceutics, pure water is a necessary raw material. Owing to climate change and the increase in population, the demand and needs of people are also growing rapidly, which has resulted in problems such as water availability. With the current shortage of such material,othersourcesoralternativestoimprovethecurrentresourcesareneeded[1].

As an alternative, seawater desalination could help to overcome this issue in waterstressed countries. The process implies the use of membranes to remove salt compounds and obtain fresh water, which is necessary for human health and the better functioning of society [2]. In sea basins, for example, the continuous exposure of agriculture to saline water causes soil salinity, which directly affects the morphology, physiology, and metabolism of plants and/or fruits (i.e., poor or no yields, reduced root growth, reduced nutritional status, and so on) [3].

Despite significant advances in desalination technology, seawater desalination continues to consume more energy than traditional fresh water treatment technologies [2]. A novel approach for seawater desalination using hydrogels is currently being explored by researchers around the world [4]. The fundamental benefit of the hydrogel-based process is that it does not require a membrane because the hydrogel surface itself serves as the interface, as well as the high water uptake that such materials can offer. In practical applications, a dry hydrogel is swollen in the seawater, and the hydrogel with absorbed seawater is squeezed to obtain fresh water [5].

Hydrogels are polymer-based materials that can be created from a large number of synthetic polymers, polysaccharides, proteins, or hybrid polymers [6]. The three-dimensional

**Citation:** Fatimi, A. Use of Hydrogels for Seawater Desalination Processes: A Patent Landscape Report. *Environ. Sci. Proc.* **2023**, *25*, 11. https:// doi.org/10.3390/ECWS-7-14184

Academic Editor: Lampros Vasiliades

Published: 14 March 2023

**Copyright:** © 2023 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

structure of these hydrogels remains in equilibrium in an aqueous medium owing to the balance between the elastic forces of the crosslinked macromolecular network and the osmotic forces of the liquid [7]. Furthermore, the chemical composition and the crosslink density of such materials determine the swelling and permeability properties of the structure [8].

Through the innovation and improvement of raw materials (such as polymers and biopolymers), chemical synthesis, formulation, and chemical engineering related to the desalination process, hydrogels for seawater desalination processes are developing quickly. This is also supported by the rise in the number of patent applications submitted in this field of study and development each year.

This study presents a patent landscape report on innovative and emerging seawater desalination technologies based on hydrogels. A landscape report is a family of techniques for studying the information present in and attached to patents in a specific area [9–12]. It is established as a tool for research planning in accordance with the criteria for patent analysis [13–16]. The results are then examined by responding to specific queries, such as who, what, and where queries regarding patenting patterns.
