Solar-Assisted Direct Contact Membrane Sustainable Distillation for Desalination: An Integrated Bibliometric and Critical Review

Increasing freshwater scarcity has intensified the need for energy-efficient and sustainable desalination technologies, making solar-assisted Direct Contact Membrane Distillation (DCMD) an attractive solution due to its low-temperature operation, high salt rejection, and compatibility with renewable energy. The PRISMA 2020 framework was used to systematically review and analyze the literature published on Scopus during the period 1974–2026 from a bibliometric and critical technical perspective. The study combines bibliometric analysis with critical analysis of technological development to investigate the development of solar-assisted DCMD and its use for sustainable production of freshwater, which was not incorporated in previous reviews. The analysis identifies rapid research momentum since 2017, with China, the USA, Saudi Arabia, Australia and Turkey being major contributors, and shows how the research focus has shifted to include the use of membrane materials, integration with renewable energy, fouling prevention, temperature polarization and energy efficiency. Significant advances have been made, yet commercialization is severely hampered by wetting of membranes, thermal losses, and low numbers of pilot-scale validations and inadequate standardized testing of performance. The review highlights the major research gaps and future directions, such as the development of advanced membrane materials and advanced hybrid renewable energy systems, the use of artificial intelligence (AI) for process optimization, conducting a comprehensive techno-economic and life-cycle assessment, and pilot-scale demonstration over a long duration. The results offer a comprehensive plan for the further development of solar-assisted DCMD for reliable and sustainable water production.