Solar Water Purification Research Articles

Vermiculite-derived MgFe nanosheet-enhanced hydrogel with dual photothermal and photocatalytic Fenton functions for solar water purification

The rapid expansion of industrial activities and urbanization has exacerbated environmental and water pollution. Solar water evaporation is a promising technique for water purification. Herein, an innovative dual-functional hydrogel that combines photothermal conversion with photocatalytic degradation was successfully prepared. The composited hydrogel (MF/CNTs-1) achieves a high-water evaporation rate of 2.23 kg·m−2·h−1 under 1 sun irradiation. Furthermore, two-dimensional MgFe nanosheets synthesized via alkali etching of vermiculite can generate highly reactive radicals through photo-Fenton reaction, facilitating efficient pollutants degradation. This dual-functional evaporator harnesses solar energy to enhance both water purification and pollutant degradation, providing valuable insights into designing vermiculite-derived materials for comprehensive water treatment and sustainable water purification.

Unlocking desalination’s potential: Harnessing MXene composite for sustainable desalination

Amidst freshwater scarcity, desalination is an effective solution, elevating pure water to a paramount commodity. Researchers actively pursue cost-effective alternatives to traditional desalination methods, with solar steam-based technologies now-a-days. Herein we report the synthesis of hierarchical photothermal absorber consisting of Ti3C2Tx decorated polypropylene fiber (PPF) composite and further used for solar desalination applications. Ensuring system stability amidst temperature fluctuations, pH variations, and mechanical stresses is pivotal for optimal desalination and wastewater treatment performance. Seamless integration of components is imperative to achieve this. Structurally, the Ti3C2Tx MXene@PPF composite evaporator showcases impressive metrics, such as high evaporation rate of 4.63 kg m-2h−1 along with a remarkable solar-evaporation efficiency of 93.48 % when tested under 1 sun illumination. Moreover, the composite absorber exhibits good mechanical stability, exceptional chemical stability even under harsh conditions (such as acid and alkali environments), outstanding salt tolerance and maintained a consistent evaporation rate over extended durations. Also, the absorber achieves good mechanical properties. These findings underscore the Ti3C2Tx MXene@PPF composite evaporator’s potential as a groundbreaking material for solar steam generation, offering high efficiency and cost-effectiveness. Beyond saline water desalination, its salt-preserving attributes and filtration capabilities position it as a promising alternative for wastewater treatment. This study presents an innovative and scalable solar water purification system applicable to a diverse range of water contaminants and manufacture in a cost-effective way.

Bi-functional hydrogen tungsten bronze/carbon composite catalysts towards biomass conversion and solar water purification

We presented a novel bi-functional catalyst composed of HxWO3 and carbon composites, which exhibits excellent catalytic activity in biomass conversion and has the ability to effectively purify water via a wide range of wavelengths in the light spectrum. The HxWO3/carbon composites were effectively produced from commercially available monoclinic tungsten trioxide (WO3) and polypropylene (PP) powders to a single-step mechanochemical reaction employing high-energy ball milling. We systemically investigated how different synthesis parameters, such as rotation speed, processing duration, and ball diameter, affect the mechanochemically-induced phase transformation to either tetragonal or cubic HxWO3 during planetary ball milling. The crystal phase of HxWO3 was controllable by altering the total impact energy in the ball milling. In addition, real-time monitoring of the pressure increment inside the pot and evaluation of the evolved gas revealed the degassing behavior through the oxidative degradation of PP assisted by WO3. The CV and Rietveld analysis proved that HxWO3 exhibited significant enhancement by two orders of magnitude in the rate of H+ diffusion compared to monoclinic WO3. This enhancement would be attributed to the expansion of a mechanically-formed tunnel along the a-axis, which facilitates the migration of H+ ions. The HxWO3/carbon composites performed approximately 12-fold higher efficiency in generating soluble solids (glucose and furfural derivatives) compared to untreated WO3 through the catalytic hydrolysis of cellulose, owing to the enhanced Brønsted acidity. Moreover, the composite particles showed broad light absorption in the UV–Vis–NIR range and demonstrated a considerable enhancement of over three orders of magnitude in the photocatalytic degradation of methyl orange pollutants when exposed to NIR and visible light.

When cellulose nanocrystals meet graphene oxide: Structurally enhanced aerogels for efficient solar steam generation and water purification

Pollution, population growth, and climate change are intensifying global freshwater shortages. Traditional methods of collecting freshwater, such as rainwater harvesting and sewage treatment, have high energy consumption, limiting their implementation in underdeveloped regions. On the other hand, solar-driven seawater evaporation offers a promising solution, purifying water using naturally abundant solar energy. Reduced graphene oxide (rGO) is considered as a strong candidate for this purpose due to its broad spectral absorption. However, its hydrophobicity hinders its direct use in solar steam generators. Here, we report the preparation of a series of cellulose nanocrystal (CNC)-rGO aerogels (CGAs) through a one-pot hydrothermal gelation process, followed by unidirectional freeze-drying. The introduction of CNCs enhances the hydrophilicity and structural stability of the resulting CGAs. The CGAs also feature uniform and unidirectional channels that promote efficient water transport, as confirmed by scanning electron microscopy (SEM) and X-ray microtomography (XMT). The CGAs have an optimized water evaporation rate of 1.80 kg m−2 h−1 under 1 sun irradiation, with 90 % solar-to-vapor energy efficiency. Moreover, durability and seawater desalination tests provide additional evidence for the practicality of CGAs in water purification. It is anticipated the implementation of CGAs will expedite the application of solar steam generators in practical scenarios.

Solar-Driven Evaporator With "Starburst Turbine" Design Featuring Directional Salt Crystallization, Antibacterial, and Catalytic Multifunctionality for Efficient Water Purification.

Facing the global challenge of water scarcity, solar-driven desalination is considered a sustainable technology for obtaining freshwater from seawater. However, issues such as uncontrolled salt crystallization and bacterial contamination limit its efficiency and practicality. This study proposes an innovative solar-driven evaporator designed to address these challenges using optimized shape design and advanced photothermal materials. Based on finite element analyses, cylindrical evaporators with a "Starburst Turbine" shape are designed and fabricated, achieving directional salt crystallization and a record-breaking water collection rate of 3.56kg m-2 h-1 and an evaporation rate of 4.57kg m-2 h-1 under one sun illumination. During continuous 60-h illumination tests, the evaporator maintained a stable evaporation rate, attributed to its excellent directional salt crystallization capability. Additionally, the evaporator demonstrates superior photodynamic antibacterial performance and photocatalytic degradation of organic pollutants. Under one sun illumination for 1 h, it achieves 100% sterilization of S. aureus and E. coli, and a 95.4% degradation of methylene blue (MB), demonstrating its potential to purify various wastewater types. These findings underscore the significant scientific and practical value of integrating antibacterial and photocatalytic functions into solar water purification materials, providing a sustainable solution to global water scarcity challenges and environmental protection.

High-performance solar water purification enabled by controlled water convection in integrated porous aerogel multistage distiller

The employment of solar multistage distillers possessing thermal localization and energy cycle properties for saltwater desalination exhibits significant potential in fulfilling the increasing worldwide need for freshwater. In order to prevent salt crystallization on evaporators, most evaporators, however, excessively boost brine exchanging in distiller while ignoring heat loss during water convection. Here, we introduce an interesting porous aerogel-based multistage distiller (PAMS) that effectively suppresses heat loss during saltwater exchanging by controlling the water absorption rate through pore structure devising. This allows us to optimize the balance between evaporation, water transport, and salt-crystallization resistance. Finally, PAMS can reach a remarkable evaporation rate of 5.93 kg m−2h−1 and a high water-collection rate of 4.03 kg m−2h−1 under one solar irradiation thanks to the adjustable balance. Besides, PAMS exhibits impressive long-term stable antibacterial properties, which enhances the anti-biofouling and increases its reliability as a source of freshwater for ocean farm.

Full-spectrum plasmonic semiconductor with stabilized oxygen vacancies enables VOCs purification for durable clean water capture

To mitigate health risks associated with volatile organic compounds (VOCs) in solar-driven water evaporation, we developed Au/WO2.72 material with full-spectrum absorption capabilities and dual photothermal and photocatalytic properties. Injecting hot electrons from Au nanoparticles (NPs) into WO2.72 preserves oxygen vacancies, thus maintaining the plasmonic effect and significantly reducing hot electron relaxation. This leads to enhanced purification of VOCs. The MF-Au/WO2.72 water evaporator, constructed on a melamine–formaldehyde (MF) substrate, demonstrated a water evaporation rate of 1.36 kg m-2 h−1 and stability over 6 h daily for 12 days under one sun irradiation. Importantly, it achieved a 92.9 % removal efficiency for phenol VOCs. Outdoor experiments validated its effectiveness in organic wastewater purification and seawater desalination, highlighting its potential for efficient and clean water production by simultaneously removing VOCs during the evaporation process. This work provides valuable insights into utilizing plasmonic-coupling materials for solar water purification.

Solar driven kaolin-based hydrogels for efficient interfacial evaporation and heavy metal ion adsorption from wastewater

Solar evaporation technology holds great promise for desalination and wastewater treatment due to its low energy consumption and sustainability. However, simultaneously removing contaminants from bulk water during the evaporation process remains challenging. In this work, we developed a clay-based hydrogel evaporator which exhibits efficient photothermal evaporation and heavy metal ion adsorption. The prepared Kaolin/CNTs/PAM hydrogel (KCAH) demonstrated approximately 99.8% light absorption in the wavelength range of 250–2,500 nm and achieved an evaporation rate of 2.99 kg m−2 h−1 under one sun illumination. It maintained over 99% desalination efficiency and exhibited good cycling stability in simulated seawater with different salinities, and its performance was verified in heavy metal ion and organic dye wastewater. Additionally, during the photothermal synergistic adsorption tests for Mn2+ ion, the KCAH achieved an evaporation rate of 2.74 kg m−2 h−1 and an adsorption capacity of 94.5 mg g−1. In the outdoor test, it is shown that the KCAH system’s daily water production was 4.85 kg m−2, with Mn2+ adsorption capacity of 265.37 mg g−1. In summary, this solar evaporator boasts high evaporation performance and excellent adsorption capabilities, making it a promising option for solar water purification, especially for heavy metal ion wastewater treatment.

Intercalation of V2O5 and Polypyrrole into a Graphene Oxide Layer: A Hybrid Multifunctional Photothermal Structure for Efficient Solar Evaporation, Water Purification, Disinfection, and Power Production.

Development of a hybrid multifunctional photothermal structure with multifunctional capabilities is deliberated as an effective approach for harvesting abundant solar energy for sustainable environmental applications. Achieving enhanced solar to thermal conversion efficiency utilizing a suitably designed, environmentally compatible thermal management structure however remains a significant challenge. Herein, we report the intercalation of V2O5 and polypyrrole into a graphene oxide layer to design a hybrid photothermal assembly (PPy-V2O5-GO) and its multifunctional proficiencies. The hybrid photothermal structure demonstrated synergistic photothermal conversion, buoyant porous structure sustaining water transmission, and efficient steam release. V2O5 and polypyrrole-intercalated optimized graphene oxide structure attained an evaporation rate of 1.9 kg m-2 h-1 with a conversion efficiency of 92% under 1 sun solar radiation. At maximum, the assembly's surface temperature hit 64 ± 2 °C, suggesting its suitability as a solar water purifier. Outdoor experiments suggest the evaporator assembly's capability to accumulate a total output of 15 kg m-2 over a single day. Cell viability investigations revealed strong antimicrobial properties of PPy-V2O5-GO against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, eliminating nearly all under 1 sun, making it a potential candidate for photothermal therapy. Furthermore, when combined with a commercial thermoelectric module, the framework displayed exceptional photothermal conversion efficiency, hinting at its potential for electrical power generation. The integration of PPy-V2O5-GO with a Bi2Te3-based thermoelectric module significantly boosted the thermoelectric generator's performance, offering an enhanced power output of 2.8 mW and a high power density of 1.24 mW/cm2, making them suitable for off-grid or remote-area application. Overall, the PPy-V2O5-GO photothermal assembly's stability, lack of leaching, effectiveness in producing pure water from seawater, antimicrobial efficacies, and recyclability make it an excellent choice for sustainable water treatment and power generation.

Assessment of Theoretical and Test Performance Considerations of Concentrated Solar Water Purification System “Parabosol” in Underserved Regions

Water is a fundamental human right and a prerequisite for sustainable development because it is an essential element of existence. Notwithstanding, a huge part of the world’s population continues to face challenges in accessing clean and safe drinking water. This situation is particularly pronounced in arid and underdeveloped regions where there is a global water crisis that is a huge threat to human health, economic development, and environmental stability. Designed with solar energy, the award-winning “Parabosol” enhances water evaporation and purifies it simultaneously. Parabosol does not require any expensive machines or complicated infrastructural frameworks, making it both cost-effective and efficient for such vulnerable communities. Transporting it easily allows for quick deployment in remote areas during emergencies, ensuring a clean, dependable water supply for basic household use. This innovative measure, which reduces the risk of waterborne diseases and increases access to safe water resources within communities, could greatly contribute to public health promotion efforts. It is intended for daily performance that corresponds to the minimum needs of one family unit (no less than 35 L per person). The processing capacity of each station varies between 120 and 180 L of water per day (depending on geographical and environmental conditions), depending on geographical and meteorological (solar radiation values) factors. However, experimental values are around 250 L. Parabosol illustrates a novel model with its distinctive design and functionality, highlighting the critical role of clean energy in the development of a more sustainable and resilient future. Additionally, unlike macrosystems that require a substantial initial investment and ongoing operating costs, Parabosol is a portable solution that has the potential to address the issue of clean water scarcity in the future.

A Portable Solar Water Purifier with Reverse Osmosis and Ultra Violet Disinfection System

A Portable Solar Water Purifier with Reverse Osmosis and Ultra Violet Disinfection System

Selection of ideal emissivity spectrum for radiative cooling and its application in water harvesting

Radiative cooling, a novel cooling technology for condensation water harvesting without energy input, offers a promising solution to the water scarcity. According to the actual locations and atmospheric conditions, selecting the ideal radiative cooling spectrum is crucial to achieve improved condensation efficiency. In this work, we analyze the condensation rate and condensation power in the southern, middle and northern China with three ideal radiative cooling emitters, namely, 4-infinite, single-window, and double-window emitter. Depending on variations in temperature, relative humidity, or the heat transfer coefficient, an optimal emitter can be selected based on the calculated boundary conditions and differences in condensation rate. Meanwhile, three multilayer design of 4-infinite emitter, double-window emitter and single-window emitter are developed using the memetic algorithm. Their emissivity aligns well with the impedance theory. They are then applied to a case study that assesses condensed water collection in Hangzhou, utilizing real-time atmospheric and environmental data in the whole year. Regarding the all-day dew collection, the average daily water generation per week in Hangzhou can be up to 256.94 mLm−2. For the solar water purification, the average condensation rate throughout the year is 1.956 Lm−2hour−1 withh=10Wm−2K−1. Our findings demonstrate that the multilayer design significantly enhances the water harvesting. Hence, our research provides valuable insights for selecting suitable ideal radiative coolers for water harvesting in specific atmospheric conditions and geographical locations.

Nanostructured ZnO‐CQD Hybrid Heterostructure Nanocomposites: Synergistic Engineering for Sustainable Design, Functional Properties, and High‐Performance Applications

AbstractHybrid nanocomposites integrating nanostructured zinc oxide (ZnO) and carbon quantum dots (CQDs) with designed heterostructures possess exceptional optical and electronic properties. These properties hold immense potential for advancements across diverse scientific and technological fields. This review article investigates the synthesis, properties, and applications of ZnO‐CQD heterostructure nanocomposites. Recent breakthroughs in fabrication methods are examined, including hydrothermal, microwave‐assisted, and eco‐friendly techniques. Key preparation methods such as sol‐gel, co‐precipitation, and electrochemical deposition are discussed, emphasizing their role in controlling heterostructure formation. This review analyses the impact of heterostructures on optical and electronic properties, such as fluorescence, photoluminescence, and photocatalytic activity. Synergistic interactions between ZnO and CQDs within heterostructures are highlighted, demonstrating how they lead to substantial performance improvements. Applications of ZnO‐CQD heterostructures span solar cells, LEDs, photodetectors, water purification, antimicrobial treatments, gas sensing, catalysis, biomedical imaging, drug delivery, environmental sensing, and energy storage. Insights are provided into refining synthesis methods, enhancing characterisation techniques, and broadening the application landscape. Challenges like stability are addressed, along with strategies for optimised performance and practical implementation. This comprehensive review offers a thorough understanding of ZnO‐CQD heterostructure nanocomposites, emphasising their significance within materials science and engineering. By addressing core concepts and future directions, it lays a foundation for continued innovation in this dynamic field.

Electrothermal-assisted all-weather solar steam generator based on hydrogel implantation strategy

Using solar energy to treat sewage is a feasible scheme to alleviate the shortage of water resources and reduce carbon emissions. However, the fluctuation of sunlight intensity poses a great challenge to the stability of the treatment process, which hinders its application in the actual water treatment scene. Herein, based on the adhesion of hydrogel, an electrothermal-assisted all-weather solar steam generator with sandwich structure was synthesized through hydrogel implantation strategy, in which polyacrylamide hydrogel with thermal grease-modified heating wires was implanted as the middle heat conduction layer, the photothermal evaporation layer as the upper layer and the waste heat evaporation layer as the bottom layer. The electrothermal assisted solar evaporator (EASE) perfectly achieves the superposition of photothermal and electrothermal effects, and can achieve high interfacial water evaporation performance under extremely low auxiliary working voltage. Applying a low voltage of 2 V to both ends of the evaporator can achieve a high evaporation rate of 4.58 kg m−2h−1 under 1 solar irradiation, which is similar to the sum of the evaporation rate under only 1 solar illumination (2.22 kg m−2h−1) and a 2 V voltage input (2.26 kg m−2h−1). More interestingly, the suitable thickness of the hydrogel layer not only ensures the transfer of heat between layers, but also weakens the heat loss caused by the water flow effect. The implantation strategy ensures the stability of the water structure and inhibits the hydrogen reaction of electrolytic water in the electrothermal process. This work provides an important theoretical and practical reference for the preparation of all-weather solar interface water purification equipment.

Solar Water Purifier Machine

The Solar Water Purifier Machine (SWPM) is an innovative device designed to provide clean, potable water using solar energy, particularly in remote or disaster affected areas. This paper explores the design, functionality, and effectiveness of the SWPM, highlighting its potential impact on communities lacking access to safe drinking water. The study includes a detailed analysis of the components, the working mechanism, and a comparison with traditional water purification methods. Additionally, it examines the environmental benefits and economic feasibility of deploying SWPMs in various regions . The purified water is then stored in a tank for later use. The machine is designed to be low cost, portable, and easy to operate, making it ideal for use in areas where access to clean water is limited. The solar powered operation ensures sustainability and reduce the carbon footprint, making it an environmentally friendly solution for water purification.

A self-floating integrated hydrogel evaporator with efficient salt resistance and thermal localization for efficient solar water desalination

Solar-driven interfacial evaporation technology was considered a promising way to effectively alleviate the global freshwater crisis. However, it is still a major challenge to design evaporators with efficient thermal management, salt resistant and self-floating ability to realize efficient clean water production. Here, we design a double-layer hydrogel evaporator with self-floating system. The evaporator is prepared from expanded polystyrene board, poly (vinyl alcohol), polyvinylpyrrolidone, agar and conductive carbon black. The structural design of the evaporator improves water transport capacity of the evaporation system and effectively reduces heat loss, so that the evaporator has efficient salt resistance and thermal localization. The evaporator demonstrates an outstanding evaporation rate and evaporation efficiency of 2.77 kg m-2h−1 and 94.25 % under 1 kW m−2 illumination. Additionally, the evaporator exhibits good stability in the 10-cycle solar evaporation experiment. Furthermore, the evaporator exhibits excellent salt resistance in 3.5 wt% NaCl solution during continuous evaporation for 9 h at 1 kW m−2 illumination. Moreover, the purification rates of the organic wastewater 4-nitrophenol and methylene blue by the evaporator reached 99.8 % and 100 %, respectively. This evaporator has stable and efficient capability of solar water purification, providing a new way for large-scale solar desalination and water purification.

Bioinspired magnetically generated bilayer aerogel with vertically aligned pores: Efficient solar evaporation and water purification for crop production

Facing the challenge of freshwater scarcity, solar evaporation technology with interfacial heating is considered to be a technology that uses solar energy to sustainably obtain fresh water through evaporation and condensation processes. However, the construction of a solar-driven evaporation system capable of consistently, efficiently, and steadily producing pure water under sunlight is pivotal yet challenging. In this work, inspired by mushrooms, a magnetic-generated double‑layered solar evaporator is designed for efficient water evaporation. With the thermal management of the aerogel and the vertical arrangement of the water channels, this evaporator overcomes the trade-off between water delivery and heat management that has long plagued traditional evaporators. In addition, the presence of cold evaporation breaks the long-existing photothermal efficiency of traditional solar evaporation cannot exceed the limit of 100 %. With this structure, an evaporation rate of 1.966 kg m−2 h−1 and a solar-to-vapor energy efficiency of 120.6 % are achieved under irradiation of 1 sun. The mung beans are irrigated with pure water obtained by evaporation to germination. The work provides a new direction for manufacturing evaporators and key insights into addressing water scarcity and the use of water.

Jellyfish-inspired sustainable and facile porous zwitterionic hydrogel sponge for efficient solar thermal desalination and water purification

Solar thermal desalination (STD), as a type of eco-friendly desalination and water purification technology is instrumental in mitigating the issue of water scarcity globally. Nevertheless, technology challenges persist for accomplishing a multi-purpose, high evaporation rate combine with low-cost and durability. In this research, we glean inspiration from marine jellyfish to propose a novel design for a solar evaporation device that is low-cost, easy to deployment and high efficiency. The evaporator incorporated carbon black for broad spectrum solar absorption, pristine cotton textile capillary action could maintain a sufficient water provision for continuous steam generating. Notably, the zwitterionic hydrogel exhibited excellent salt resistance and water activation properties, promoting water evaporation and enhancing the long-term stability of the evaporator effectively. Under one solar irradiance of 1 kW m−2, the evaporator raised an outstanding evaporation rate of 2.158 kg m-2h−1 and the energy efficiency was 88.71 %. Besides, it demonstrated broad applicability in purifying complex contaminated water sources and could obtain clean water from them. It was anticipated that this evaporator could be an effective solution for alleviating water source shortage especially for economically stressed regions. This research provided novel insights and potential applications for the expansion of STD technology in areas such as renewable energy utilization, off-grid desalination and waste water treatment. Furthermore, it offered guidance and inspiration for future in-depth research of the water-energy-climate nexus.

Can the Interfacial Solar Vapor Generation Performance Be Really “Beyond” Theoretical Limit?

AbstractThe interfacial solar vapor generation (ISVG) process is an environmentally friendly approach that utilizes solar to produce steam, which can solve the water shortage. Despite many previous research studies, claims beyond the theoretical limit have risen due to limitations in the efficiency of converting solar to vapor and the rate of solar evaporation, which are still being debated. Energy losses remain even under ideal conditions, which means that the efficiency of the system will never be ≥100%. This review primarily analyzes the theoretical values of evaporation rate and energy efficiency in the ISVG process. Utilizing a theoretical formula for energy distribution, the factors contributing to the current exceedance of conversion efficiency and evaporation rate are scrutinized. By examining various strategies, such as the reduction of vaporization enthalpy for photothermal materials and the utilization of environmental energy for evaporation, these studies seek to enhance evaporation efficiencies, but they ignore the problem of the theoretical limit of evaporation. Therefore, this review emphasizes misconceptions about efficiencies beyond theoretical limits and aims to guide researchers to provide plausible explanations for such breakthroughs under specific conditions, alongside established reference conditions. Ultimately, this study lays a solid theoretical foundation for practical solar water purification.

Robust and Elastic Thermoresponsive Hydrogels with High Swelling Properties for Efficient Solar Water Purification

Robust and Elastic Thermoresponsive Hydrogels with High Swelling Properties for Efficient Solar Water Purification