**2. Methods**

Patent data for this study were extracted from the Lens online database using different keyword searches in patent titles, abstracts, and claims [17]. Title, abstract, and claim keyword searches are common tools for patent extraction [9–12]. The search was then filtered to include only patent documents (i.e., patent applications, granted patents, and three limited patents) until 2022, and the information was extracted according to patent document type, patent family, publication date, patent applicant, patent owner, patent jurisdiction, legal status of patents, and patent classification [13–16].

### **3. Results and Discussion**

### *3.1. Documents Type and Patent Families*

A total of 81 patent documents were collected between 1985 and 2022 that concern the use of hydrogels for seawater desalination processes. The selection includes 66 patent applications, 12 granted patents, and 3 limited patents. With 57 simple families and 57 extended families, it was confirmed that 57 patent documents covering the same technical subject were published at different times in the same country or in different countries or regions.

#### *3.2. Publication Date of Patent Documents*

Based on the earliest priority date, it is possible to precisely assume that 1985 is considered the starting year of patenting of hydrogels for seawater desalination [18]. Thirtyone patent documents were published between 1985 and 2019; however, 62% of all patent documents have been published during the last three years. Furthermore, 2022 was the year with the maximum recorded number of patent documents and patent applications, with 16 and 15, respectively, while 2011 was the year with the maximum number of granted patents, with a total of five (Figure 1).

**Figure 1.** Publication dates of patent documents related to the use of hydrogels for seawater desalination processes.

### *3.3. Patent Applicants and Owners*

The patent applicant is the person or organization that has filed a patent application. On the other hand, the patent owner is the organization with rights to the property of the granted patent [15].

The top 10 applicants for patent documents related to the use of hydrogels for seawater desalination processes until 2022 are displayed in Figure 2. The list includes natural persons and organizations (i.e., companies and academic institutions). The companies "Kraton Polymers US LLC" (Houston, TX, United States) and "Baoshan Iron & Steel CO LTD" (Shanghai, China) are the most prolific patenting companies, with nine and four patent documents, respectively, while William Marsh Rice University (Houston, TX, United States) and Tianjin Polytechnic University (Tianjin, China) are the academic institutions leading the way, with four patent documents each. On the other hand, different natural people are the lead applicants, with four or three patent documents.

**Figure 2.** Applicants (top 10) of patent documents related to the use of hydrogels for seawater desalination processes.

Table 1 presents the owners of patent documents related to the use of hydrogels for seawater desalination processes until 2022. The ownership of the rights to the property of the patent concerns eight owners: four companies and four academic institutions. Three of them are, at the same time, already applicants according to the top 10 applicants.


**Table 1.** Owners of patent documents related to the use of hydrogels for seawater desalination processes.

#### *3.4. Jurisdictions and Legal Status of Patents*

Patent jurisdictions correspond to the countries in which the patent is protected through the appropriate patent office at which the patent application is filed. When a patent application is filed, it is examined by the appropriate patent office (e.g., the China National Intellectual Property Administration (CNIPA), the Moroccan Office of Industrial and Commercial Property (OMPIC), the United States Patent and Trademark Office (USPTO), and so on), and a decision is delivered according to the specific patentability criteria that an invention must meet. Finally, a claimed invention through a patent application becomes a granted patent in one or more designated countries if it is qualified for patent protection [13].

For patent documents related to the use of hydrogels for seawater desalination processes, the jurisdictions of patent documents until 2022 are presented in Figure 3. China, through the CNIPA, encompasses 45 patent documents, with a patent contribution per document total of 55.56%. The United States, through the USPTO, encompasses 23 patent documents, with a patent contribution per document total of 28.4%. On the other hand, the global system for filing patent applications, known as the Patent Cooperation Treaty (PCT) and administered by the World Intellectual Property Organization (WIPO), encompasses seven patent documents, with a patent contribution per document total of 8.64%.

**Figure 3.** Jurisdictions of patent documents related to the use of hydrogels for seawater desalination processes.

Moreover, these jurisdictions of patent documents related to the use of hydrogels for seawater desalination processes ensure the following five legal statuses:


### *3.5. Patent Classifications*

As a technology indicator in a specific area, the patent classifications help inventors and researchers to categorize claimed inventions and retrieve different patent documents. The International Patent Classification (IPC) is the most widely used hierarchical system in the form of codes. It divides all technology areas into a range of sections, classes, subclasses, groups, and subgroups [13].

For patent documents related to the use of hydrogels for seawater desalination processes, the top 10 IPC codes until 2022 are presented in Table 2. The patent classifications reveal that most IPC code corresponds to C02F103/08, with 29 patent documents. It concerns the treatment of seawater using the desalination process. The IPC codes related to hydrogels and presented into these top 10 correspond to B01J13/00 and C08J3/075, which are categorized for colloid chemistry and macromolecular gels, respectively.

**Table 2.** IPC codes (top 10) of patent documents related to the use of hydrogels for seawater desalination processes.


### **4. Conclusions**

The novel approach for seawater desalination using hydrogels was successfully explored by researchers around the world. Inventors proposed various claimed inventions through this innovation. In this study, a patent landscape report was proposed regarding patent document types, patent families, publication dates, patent applicants, patent owners, patent jurisdictions, the legal status of patents, and patent classifications. Therefore, this research reveals that China and the United States are leading the way in innovation, and the most prolific patenting organizations are companies and universities. On the other hand, most inventions are intended for the treatment of seawater using desalination processes specially adapted for manufacturing semi-permeable membranes for separation processes, and the research and development are based on macromolecular gels and synthetic macromolecular compounds.

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

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

**Informed Consent Statement:** Not applicable. **Data Availability Statement:** The data presented in this study are available within this article content.

**Acknowledgments:** The author acknowledges the Cambia Institute for the Lens patent dataset used in this study.

**Conflicts of Interest:** The author declares no conflict of interest.
