Waste are in the limelight: cost-effective waste materials for sustainable solar desalination

Solar-based desalination is one of the sustainable methods of obtaining clean water from contaminated water. Recent advances in the production of highly efficient photothermal absorbers have increased their evaporation rate. Improved solar absorption (> 94%) and lowered heat loss are two distinct advantages over traditional solar desalination systems (TSDS). This review emphasizes the novelty of exploring waste materials, cost-effectiveness, and their potential for reuse in solar desalination. The focus is primarily on waste materials derived from (i) urban/residential sources, (ii) plant-based biochar, and (iii) ocean-derived biomass. By incorporating these waste materials into the process, we aim to enhance sustainability, reduce environmental impact, and promote the efficient utilization of resources in this emerging field. Furthermore, the results on evaporation rate, photothermal efficiency, productivity of the absorbers under practical conditions and their durability, economic feasibility, desalination performance for wastewater, methods for increasing freshwater productivity, and future prospects are discussed. The CI/CS hydrogel synthesized from cuttlefish produces at a maximal rate of 4.1 kg m⁻² h⁻¹ under artificial sun illumination. The CNT-coated Juncus effuses absorber produces 20.3 L/day under natural solar irradiation. In traditional solar desalination systems, the freshwater productivity of 5.9 L/m².day was achieved with waste wicks and a solar collector. It shows that adequate freshwater production in TSDS requires a second thermal energy source, such as a phase change material (PCM) or solar collector.