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Solar-driven evaporation has been proposed as an efficient way to harvest solar energy for water treatment and desalination. However, the complex preparation process and the degradation of photothermal absorbers restrict their practical applications in solar thermal technology. Herein, a solar-assisted fabrication of three-dimensional dimpled MoS2 membrane (DMM-SA) with an open macroporous (1-2 μm) network is fabricated by folding and overlapping nanosheets under solar illumination. DMM-SA exhibits superior water permeability (334-461 LMH/bar) and extraordinary chemical and structural stability. Compared to the 1T and mixed-phase DMM-SA samples, 2H-DMM-SA floating on the water surface generates high heat localization and achieves high evaporation efficiencies of 83.8 ± 0.8% and 91.5 ± 1.1% at 1 and 3 sun illumination, respectively. After multiple illumination and regeneration cycles, 2H-DMM-SA presents high water evaporation and salt rejection performance. After desalination, the salinity level of permeate water is far below the World Health Organization (WHO) standard. Numerical simulations verify that the inner spaces between two nanosheets and the nanochannels contribute to the high bulk water and vapor fluxes during desalination. The facile and efficient design of 3D 2H-DMM-SA provides a novel avenue for seawater utilization by harvesting solar energy.

A purely chemical method is demonstrated to treat a variety of biomass wastes for extracting cellulose nanofibrils (CNFs) with a consistent property. By hydrothermal reaction, carbon dots (CDs) can be easily grafted on the surface of CNFs to act as photo-thermal agents and enable fast water evaporation rate at 2.5 kg m-2h-1 with about 96.45% solar-to-vapor efficiency under one sun irradiation. This derives from good hydration ability of this system, which lowers the evaporation enthalpy. Moreover, this system not only adsorbs dye contaminants effectively by the formation of hydrogen bonds, but also possesses long-term antifouling solar desalination by means of rationally drilled millimeter-sized channels. Given the sustainable biomass resources and scalable fabrication process, this work offers a promising strategy towards construct low-cost evaporators with the excellent water purification performance.

As communities grow, greater demands are placed on water supplies, wastewater services, and the electricity needed to power the growing water services infrastructure. Water is also a critical resource for thermoelectric power plants. Future population growth in the United States is therefore expected to heighten competition for water resources. Especially in arid U.S. regions, communities may soon face hard choices with respect to water and electric power. Many parts of the United States with increasing water stresses also have significant wind energy resources. Wind power is the fastest-growing electric generation source in the United States and is decreasing in cost to be competitive with thermoelectric generation. Wind energy can potentially offer communities in water-stressed areas the option of economically meeting increasing energy needs without increasing demands on valuable water resources. Wind energy can also provide targeted energy production to serve critical local water-system needs. The U.S. Department of Energy (DOE) Wind Energy Technologies Program has been exploring the potential for wind power to meet growing challenges for water supply and treatment. The DOE is currently characterizing the U.S. regions that are most likely to benefit from wind-water applications and is also exploring the associated technical and policy issues associated withmore » bringing wind energy to bear on water resource challenges.« less

Abstract Atmospheric water generators (AWGs) produce potable water from the moisture in the air, providing a potentially viable water source in austere locations or emergency response scenarios. In this study, the operating constraints of three existing commercially available AWG devices are investigated, compared to historical weather data from across the continental United States. Utilizing linear regression modeling and weather station data for the years of 1985–2019, the monthly and spatial trends of energy demand to produce water from these devices are estimated. Energy and water production efficiencies for the devices are highly dependent on environmental conditions with relative humidity (RH) and temperature as the two driving factors. Publicly available manufacturer specifications for each AWG system were modeled to predict yield and specific energy consumption (SEC). A spatial analysis depicts the change in SEC in kilowatt-hours per liter (kWh l−1) across the country at a monthly scale. SEC for refrigeration AWG ranged between 0.02 and 3.64 kWh l−1 and solar driven sorption was between 3.19 and 5.29 kWh l−1, significantly larger than conventional water treatment energy demands. Additionally, the results are synthesized based on the Köppen–Geiger climate classification system, to approximate projected water production and energy demand for each environment, with arid climates demanding larger energy consumption per unit volume of water produced. Excluding arid and cold climate classes, solar powered refrigeration devices have the potential to operate more efficiently than solar driven sorption due to advances in photovoltaic solar panel technology, but still require more energy than alternatives.

Interfacial solar steam generation (ISSG) is considered as an excellent seawater desalination technology because of its electricity-independent nature, low cost, and portability. However, improving the water evaporation efficiency, simplifying the fabrication process, and reducing the overall cost of the evaporator are still challenging. Here, an efficient and sustainable solar water evaporator is fabricated with carbonized ginkgo biloba leaves as the structural basis of photothermal materials. The combination of the abundant capillary channels in ginkgo leaves paired with polyacrylamide (PAM) hydrogel accelerates water transportation and solar-driven evaporation. The fabricated evaporator shows excellent photothermal conversion capability and evaporates water at 2.39 kg m-2 h-1 under 1 sun irradiation. In addition, the device exhibits remarkable stability in simulated seawater and can effectively realize seawater desalination or sewage treatment. As a result, the system is promising for future highly efficient solar evaporation due to its environmental protection and low cost.

An ion-concentration-polarization-assisted photocatalytic reactor can enhance the water purification performance by inducing the nonlinear electric field that inhibits the recombination of photoexcited electrons and holes.

In the context of global climate crisis and growing world population there is the urgent need for viable technical solutions to harvest energy from alternative, renewable and continuous sources and to recover pure water at affordable costs. Herein, we capitalize on the study of direct contact membrane distillation technology treating hypersaline solutions simulating reverse electrodialysis outgoing mixed streams, in the logic of valorising the otherwise environmentally threating brine, in an integrated system operating at the water-energy nexus. Experimental results in terms of transmembrane water flux and dissolved salts rejection, indicate that DCMD is a feasible option to treat feed solutions with concentrations as high as 228 g L􀀀 1 total dissolved solids, while recovering pure water from brines which are practically impossible to be dewatered through reverse osmosis. Specific thermal energy consumptions and gain to output ratios, calculated under different feed compositions and flow rates for polypropylene and polyvinilidenefluoride membranes, indicated the possibility to tailor the thermal energy requirements of the MD stage by controlling the ratio between the streams at different salinity that are partially mixed in the RED unit and to potentially adapt it to the available amount of heat.

AbstractProducing affordable freshwater has been considered as a great societal challenge, and most conventional desalination technologies are usually accompanied with large energy consumption and thus struggle with the trade‐off between water and energy, i.e., the water–energy nexus. In recent decades, the fast development of state‐of‐the‐art photothermal materials has injected new vitality into the field of freshwater production, which can effectively harness abundant and clean solar energy via the photothermal effect to fulfill the blue dream of low‐energy water purification/harvesting, so as to reconcile the water–energy nexus. Driven by the opportunities offered by photothermal materials, tremendous effort has been made to exploit diverse photothermal‐assisted water purification/harvesting technologies. At this stage, it is imperative and important to review the recent progress and shed light on the future trend in this multidisciplinary field. Here, a brief introduction of the fundamental mechanism and design principle of photothermal materials is presented, and the emerging photothermal applications such as photothermal‐assisted water evaporation, photothermal‐assisted membrane distillation, photothermal‐assisted crude oil cleanup, photothermal‐enhanced photocatalysis, and photothermal‐assisted water harvesting from air are summarized. Finally, the unsolved challenges and future perspectives in this field are emphasized. It is envisioned that this work will help arouse future research efforts to boost the development of solar‐driven low‐energy water purification/harvesting.

Reusing polluted water through various decontamination techniques has appeared as one of the most practical approaches to address the global shortage of clean water. Rather than relying on single decontamination mechanism, herein we report the preparation and utilization of paper-based composites for multifunctional solar-driven clean water generation that is inspired by the multiple water purification approaches in biological systems. The reduced graphene oxide (rGO) sheets within such composites can efficiently remove organic contaminants through physical adsorption mechanism. Under solar irradiation, the floating rGO composites can instantly generate localized heating, which not only can directly generate clean water through distillation mechanism but also significantly enhance adsorption removal performance with the assistance of upward vapor flow. Such porous-structured paper-based composites allow for facile incorporation of photocatalysts to regenerate clean water out of contaminated water with combined adsorption, photodegradation, and interfacial heat-assisted distillation mechanisms. Within a homemade all-in-one water treatment device, the practical applicability of the composites for multifunctional clean water generation has been demonstrated.