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Fresh water resources are depleting rapidly as the water demand around the world continues to increase. Fresh water resources are also not equally distributed geographically worldwide. The best way to tackle this situation is to use solar energy for desalination to not only cater for the water needs of humanity, but also to offset some detrimental environmental effects of desalination. A comprehensive review of the latest literature on various desalination technologies utilizing solar energy is presented here. This paper also highlights the environmental impacts of desalination technologies along with an economic analysis and cost comparison of conventional desalination methods with different solar energy based technologies. This review is part of an investigation into integration of solar thermal desalination into existing grid infrastructure in the Australian context.

The paper presents a multi-directional inclined compartmental basin solar desalination system with a unique design aimed at enhancing water purification through solar energy. The system consists of a central basin surrounded by four inclined compartmental basins, each equipped with a thick glass cover of 4 mm tilted at a 30° angle to facilitate condensation. Techniques such as one-step azimuth tracking are employed, where the entire setup is rotated 15° daily to optimize solar exposure, improving distillate productivity. The methodology includes the construction of basins with pyramid-like structures to concentrate solar energy, increase water temperature rapidly, and maintain it for prolonged periods. Experimental tests were conducted at different orientations (0°, 15°, 30°, 45°, 60°, 75°, and 90°), measuring yields across basins and analyzing the effects of solar radiation and temperature. This innovative system, leveraging azimuth tracking and optimized basin configurations, offers a supportable solution for potable water production in solar-rich areas. The study’s results show that the multi-directional solar desalination system achieved its highest yield of 20.305 liters/day at a 0° orientation, with Basin 1 (south-facing) producing 5.780 liters/day. Rotating the setup to different angles (e.g., 15°, 30°) yielded minor increases (up to 0.90%) in overall productivity due to optimized solar exposure. The findings confirm that one-step azimuth tracking enhances daily distillate production in solar-rich environments.

Because it is able to produce desalinated water directly using solar energy with minimum carbon footprint, solar steam generation and desalination is considered one of the most important technologies to address the increasingly pressing global water scarcity. Despite tremendous progress in the past few years, efficient solar steam generation and desalination can only be achieved for rather limited water quantity with the assistance of concentrators and thermal insulation, not feasible for large-scale applications. The fundamental paradox is that the conventional design of direct absorber–bulk water contact ensures efficient energy transfer and water supply but also has intrinsic thermal loss through bulk water. Here, enabled by a confined 2D water path, we report an efficient (80% under one-sun illumination) and effective (four orders salinity decrement) solar desalination device. More strikingly, because of minimized heat loss, high efficiency of solar desalination is independent of the water quantity and can be maintained without thermal insulation of the container. A foldable graphene oxide film, fabricated by a scalable process, serves as efficient solar absorbers (>94%), vapor channels, and thermal insulators. With unique structure designs fabricated by scalable processes and high and stable efficiency achieved under normal solar illumination independent of water quantity without any supporting systems, our device represents a concrete step for solar desalination to emerge as a complementary portable and personalized clean water solution.

In the field of desalination powered by renewable energies, the use of solar power cycles exhibits some favorable characteristics, such as the possibility of implementing thermal energy storage systems or a multi-generation scheme (e.g., electricity, water, cooling, hydrogen). This article presents a review of the latest design proposals in which two power cycles of great potential are considered: the organic Rankine cycle and the supercritical CO2 power cycle, the latter of growing interest in recent years. The designs found in the literature are grouped into three main types of systems. In the case of solar ORC-based systems, the option of reverse osmosis as a desalination technology is considered in medium-temperature solar systems with storage but also with low-temperature using solar ponds. In the first case, it is also common to incorporate single-effect absorption systems for cooling production. The use of thermal desalination processes is also found in many proposals based on solar ORC. In this case, the usual configuration implies the cycle’s cooling by the own desalination process. This option is also common in systems based on the supercritical CO2 power cycle where MED technology is usually selected. Designs proposals are reviewed and assessed to point out design recommendations.

Plastic waste caused by the extensive usage of face masks during COVID‐19 pandemic has become a severe threat to natural environment and ecosystem. Herein, an eco‐friendly approach to repurpose face mask waste for clean water production via solar thermal evaporation is proposed. By taking advantage of its interwind structure, face mask holds the promise to be an ideal candidate material for constructing photothermal evaporator. In‐situ surface modifications are performed successively with polyvinyl alcohol and polypyrrole to improve its wettability and solar absorption (97%). The obtained face mask‐based evaporator achieves significantly enhanced solar efficiency (91.5%) and long‐term salt‐rejection stability. The harvested clean water befits plant growing to enable farming on sea surface. A floating photothermal evaporation prototype is then developed to demonstrate autonomous solar ocean farming, with plants successfully cultivated over time. As such, the proposed strategy provides a promising solution towards ecological sustainability by tapping multiple benefits. This work presents an eco‐friendly way to recycle large amount of wasted face masks into solar absorbers for clean water production. A prototype of floating farm is further demonstrated, using recycled face mask to convert abundant seawater into portable water for plants irrigation. Plants can be well thrived, giving a promising solution to land soil crisis and polymer white pollution.

HighlightsMicro–nano water film enhanced interfacial solar evaporator enables a high evaporation rate of 2.18 kg m−2 h−1 under 1 sun.An outdoor device with an enhanced condensation design demonstrates a high water production rate of 15.9–19.4 kg kW−1 h−1 m−2.A multi-objective predictive model is established to assess outdoor water production performance.Interfacial solar evaporation holds great promise to address the freshwater shortage. However, most interfacial solar evaporators are always filled with water throughout the evaporation process, thus bringing unavoidable heat loss. Herein, we propose a novel interfacial evaporation structure based on the micro–nano water film, which demonstrates significantly improved evaporation performance, as experimentally verified by polypyrrole- and polydopamine-coated polydimethylsiloxane sponge. The 2D evaporator based on the as-prepared sponge realizes an enhanced evaporation rate of 2.18 kg m−2 h−1 under 1 sun by fine-tuning the interfacial micro–nano water film. Then, a homemade device with an enhanced condensation function is engineered for outdoor clean water production. Throughout a continuous test for 40 days, this device demonstrates a high water production rate (WPR) of 15.9–19.4 kg kW−1 h−1 m−2. Based on the outdoor outcomes, we further establish a multi-objective model to assess the global WPR. It is predicted that a 1 m2 device can produce at most 7.8 kg of clean water per day, which could meet the daily drinking water needs of 3 people. Finally, this technology could greatly alleviate the current water and energy crisis through further large-scale applications.

HighlightsA broad overview of MXenes and MXene-based nanomaterials in desalination is presented.Recent advancement in the synthesis of MXenes for applications in desalination is critically evaluated. Salt removal mechanisms and regeneration capability of MXenes are appraised.Current challenges and future prospect of MXenes in desalination are highlighted. Research directions are provided to safeguard the applications of MXenes in future desalination.MXenes, novel 2D transition metal carbides, have emerged as wonderful nanomaterials and a superlative contestant for a host of applications. The tremendous characteristics of MXenes, i.e., high surface area, high metallic conductivity, ease of functionalization, biocompatibility, activated metallic hydroxide sites, and hydrophilicity, make them the best aspirant for applications in energy storage, catalysis, sensors, electronics, and environmental remediation. Due to their exceptional physicochemical properties and multifarious chemical compositions, MXenes have gained considerable attention for applications in water treatment and desalination in recent times. It is vital to understand the current status of MXene applications in desalination in order to define the roadmap for the development of MXene-based materials and endorse their practical applications in the future. This paper critically reviews the recent advancement in the synthesis of MXenes and MXene-based composites for applications in desalination. The desalination potential of MXenes is portrayed in detail with a focus on ion-sieving membranes, capacitive deionization, and solar desalination. The ion removal mechanism and regeneration ability of MXenes are also summarized to get insight into the process. The key challenges and issues associated with the synthesis and applications of MXenes and MXene-based composites in desalination are highlighted. Lastly, research directions are provided to guarantee the synthesis and applications of MXenes in a more effective way. This review may provide an insight into the applications of MXenes for water desalination in the future.

Solar desalination is a promising strategy to utilize solar energy to purify saline water. However, the accumulation of salt on the solar evaporator surface severely reduces light absorption and evaporation performance. Herein, a simple and eco‐friendly method to fabricate a 3D gradient graphene spiral sponge (GGS sponge) is presented that enables high‐rate solar evaporation and zero liquid discharge (ZLD) desalination of high‐salinity brine. The spiral structure of the GGS sponge enhances energy recovery, while the gradient network structures facilitate radial brine transport and directional salt crystallization, which cooperate to endow the sponge with superior solar evaporation (6.5 kg m−2 h−1 for 20 wt.% brine), efficient salt collection (1.5 kg m−2 h−1 for 20 wt.% brine), ZLD desalination, and long‐term durability (continuous 144 h in 20 wt.% brine). Moreover, the GGS sponge shows an ultrahigh freshwater production rate of 3.1 kg m−2 h−1 during the outdoor desalination tests. A continuous desalination–irrigation system based on the GGS sponge for crop growth, which has the potential for self‐sustainable agriculture in remote areas is demonstrated. This work introduces a novel evaporator design and also provides insight into the structural principles for designing next‐generation solar desalination devices that are salt‐tolerant and highly efficient. A gradient graphene spiral sponge is demonstrated for solar desalination, which has a unique structure for energy recovery, radial brine transport, and directional salt crystallization. It exhibits excellent performance in solar evaporation (6.5 kg m−2 h−1), salt collection (1.5 kg m−2 h−1), freshwater production (3.1 kg m−2 h−1), durability (144 h), and zero liquid discharge desalination. This sponge can potentially enable continuous desalination–irrigation in remote areas for crop growth.

Solar‐driven interfacial evaporation is a promising technology for freshwater production from seawater, but salt accumulation on the evaporator surface hinders its performance and sustainability. In this study, we report a simple and green strategy to fabricate a three‐dimensional porous graphene spiral roll (3GSR) that enables highly efficient solar evaporation, salt collection, and water production from near‐saturated brine with zero liquid discharge (ZLD). The 3GSR design facilitates energy recovery, radial brine transport, and directional salt crystallization, thereby resulting in an ultrahigh evaporation rate of 9.05 kg m−2 h−1 in 25 wt% brine under 1‐sun illumination for 48 h continuously. Remarkably, the directional salt crystallization on its outer surface not only enlarges the evaporation area but also achieves an ultrahigh salt collection rate of 2.92 kg m−2 h−1, thus enabling ZLD desalination. Additionally,  3GSR exhibits a record‐high water production rate of 3.14 kg m−2 h−1 in an outdoor test. This innovative solution offers a highly efficient and continuous solar desalination method for water production and ZLD brine treatment, which has great implications for addressing global water scarcity and environmental issues arising from brine disposal. We report a novel three‐dimensional porous graphene spiral roll evaporator that enables zero liquid discharge evaporation from near‐saturated brine. This spiral roll structure facilitates energy recovery, radial brine transport, and directional salt crystallization, resulting in an outstanding average evaporation rate of 9.05 kg m−2 h−1, salt collection rate of 2.92 kg m−2 h−1, and water production rate of 3.14 kg m−2 h−1, which are the best performances reported so far.

Concentration of solar energy may be obtained by reflection, refraction, or a combination of the two. The collectors of a reflection system are designed to concentrate the sun’s rays onto a photovoltaic cell or steam tube. Refractive lenses concentrate light by having it travel through the lens. The sun’s rays are partially reflected and then refracted via a hybrid technique. Hybrid focus techniques have the potential to maximize power output. Fresnel lenses are an efficient tool for concentrating solar energy, which may then be used in a variety of applications. Development of both imaging and non-imaging devices is occurring at this time. Larger acceptance angles, better concentration ratios with less volume and shorter focal length, greater optical efficiency, etc., are only some of the advantages of non-imaging systems over imaging ones. This study encompasses numerical, experimental, and numerical and experimental studies on the use of Fresnel lenses in various solar energy systems to present a comprehensive picture of current scientific achievements in this field. The framework, design criteria, progress, and difficulties are all dissected in detail. Accordingly, some recommendations for further studies are suggested.