Evaporation Of Seawater Research Articles

Experimental analysis of triangular solar distiller with a new form of absorber

To better improve the evaporation of seawater in solar distillers, and consequently boost the production of distillate, we suggest that the structure of the conventional absorber surface should be modified. The present work aims to study the thermal performance of the Triangular Solar Distiller (Henceforth, TSD) by using a new form of a Trapezoidal Absorber (Henceforth, TA). This new design (Henceforth, TSDTA) proves to reduce the influence of shadow created by the sloped sidewalls and the volume of seawater of the TSD. The experimental results obtained from the TSD are compared to those obtained from a conventional Triangular Solar Distiller equipped with a Plate Absorber (henceforth, TSDPA) under the same weather conditions of Sfax – a central-eastern town Tunisia. The findings show that the trapezoidal structure of the absorber increases the diurnal production of distillate by 22.73% as compared to the plate one. The thermal efficiency reaches a maximum value of 49% for the TSDTA and only 46% for the TSDPA during the daytime.

Enhanced dispersion of prussian blue via intercalation into layered double hydroxides for efficient solar seawater evaporation.

Prussian blue (PB) is favored for its photothermal absorption capability in solar vapor generation applications. However, the photothermal conversion efficiency of current PB-based devices is limited by the material's poor dispersion. Herein, we report a method of incorporating PB in the interlayers of layered double hydroxides (LDHs) to prevent its aggregation. The dispersion is further enhanced and stabilized by the addition of sodium dodecyl sulfate (SDS). The thermal and water stability of PB is improved due to the rigid structure of LDHs and interactions between layers and anions. Elemental analysis confirms that with the increase of molar ratio of Mg/Al and the introduction of SDS, concentrations of PB are decreased accordingly. As a result, the rate of solar vapor generation is increased by 35.9% for powders containing 50 mg of equivalent PB. Of note, converting this material into a three-dimensional structure of high rebound foam further enhances solar water evaporation rate, from 0.79 kg m-2 h-1 to 0.98 kg m-2 h-1, with only 20 mg of equivalent PB, increasing the corresponding photothermal conversion efficiency from 53.8% to 66.3%.

Conductive Metal-Organic Framework Nanosheets Constructed Hierarchical Water Transport Biological Channel for High-Performance Interfacial Seawater Evaporation.

Solar interfacial water evaporation shows great potential to address the global freshwater scarcity. Water evaporation being inherently energy intensive, Joule-heating assisted solar evaporation for addressing insufficient vapor under natural conditions is an ideal strategy. However, the simultaneous optimization of low evaporation enthalpy, high photothermal conversion, and excellent Joule-heating steam generation within a single material remain a rare achievement. Herein, inspired by the biological channel structures, a large-area film with hierarchical macro/microporous structures is elaborately designed by stacking the nanosheet of a conductive metal-organic framework (MOF), Ni3(HITP)2, on a paper substrate. By combining the above three features in one material, the water evaporation enthalpy reduces from 2455Jg-1 to 1676 J g-1, and the photothermal conversion efficiency increases from 13.75% to 96.25%. Benefiting from the synergistic photothermal and Joule-heating effects, the evaporation rate achieves 2.60kg m-2 h-1 under one sun plus input electrical power of 4W, surpassing the thermodynamic limit and marking the highest reported value in MOF-based evaporators. Moreover, Ni3(HITP)2-paper exhibits excellent long-term stability in simulated seawater, where no salt crystallization and evaporation rate degradation are observed. This design strategy for nanosheet films with hierarchical macro/microporous channels provides inspiration for electronics, biological devices, and energy applications.

A correlation of heat transfer for falling film evaporation on the horizontal tube with multiple-precision expansion method

The falling film evaporation of water and seawater outside the horizontal tube is experimentally investigated under non-boiling condition, and the effects of spray density, evaporation temperature, tube pitch, circumferential position and seawater salinity on the falling film evaporation are studied. A competitive mechanism, based on the analysis of liquid film, is proposed to analyze the critical Reynolds number of the spray water, ReΓ, and the dual effects of liquid film on heat transfer coefficient. The experimental data covers tube diameter D=19∼38 mm, tube pitch s/D=1.3∼2.25, evaporation temperature Tsat=50∼70 °C, spray Reynolds number ReΓ=118∼1979, and salinity S=0∼60 g/kg. By summing up a large number of experimental data, the heat transfer coefficient correlation applying both water and seawater falling film evaporation on horizontal tubes is proposed. The correlation is also compared with previous studies about water and seawater, which shows a better and wider adaptability to experimental conditions.

The Influence of Water Temperature on Seawater Evaporation in the Desalination Process

The Influence of Water Temperature on Seawater Evaporation in the Desalination Process

Design of High‐Performance Bilayer Solar Evaporator Using Graphene‐Coated Bamboo Prepared by Near‐Infrared Laser‐Induced Carbonization of Polystyrene

Solar seawater evaporation is a sustainable seawater desalination technology. However, how to convert low‐cost waste general plastics into highly efficient photothermal materials remains a challenge. By using the idea of “near‐infrared laser‐induced carbonization” at room temperature and in air atmosphere, polystyrene (PS) can be easily converted into graphene. Bismuth oxide (Bi2O3) catalyst is proven to efficiently convert laser energy into thermal energy and transmit it to the surrounding PS matrix, promoting carbonization. On this basis, by adjusting the catalyst content and the laser energy density per unit area, laser‐induced graphene (LIG) materials with high specific surface area, fast water transport, and high solar energy absorption efficiency can be obtained. Furthermore, the LIG materials are coated on the surface of natural bamboo with a capillary structure. This bilayer evaporation device has an evaporation rate of 1.51 kg m−2 h−1 and an energy conversion efficiency of 87.1% under irradiation of 1 sun. This work not only reveals the possibility of preparing high‐value‐added graphene materials from waste general‐purpose plastics, but also proves the application prospects of LIG materials in the field of solar seawater evaporation. This will provide a feasible approach for promoting the development of carbonization of waste general plastics.

Colloidal Plasmonic TiN Nanoparticles for Efficient Solar Seawater Desalination.

Transferring traditional plasmonic noble metal nanomaterials from the laboratory to industrial production has remained challenging due to the high price of noble metals. The development of cost-effective non-noble-metal alternatives with outstanding plasmonic properties has therefore become essential. Herein, we report on the gram-scale production of differently shaped TiN nanoparticles with strong plasmon-enabled broadband light absorption, including differently sized TiN nanospheres, nanobipyramids, and nanorod arrays. The TiN nanospheres and nanobipyramids are further coembedded in highly porous poly(vinyl alcohol) films to function as a photothermal material for solar seawater desalination. A seawater evaporation rate of 3.8 kg m-2 h-1 is achieved, which marks the record performance among all plasmonic solar seawater desalination systems reported so far. The removal percentage of phenol reaches 98.3%, which is attributed to the joint action of the excellent photocatalytic ability and the superhydrophilicity of the porous TiN-based composite film.

Passive interfacial photothermal evaporation and sky radiative cooling assisted all-day freshwater harvesting: System design, experiment study, and performance evaluation

The shortage of freshwater has become a great challenge for the sustainable development of human society. Desalination is considered to be the most practical way to provide a sustainable source of freshwater from seawater, but traditional solar desalination devices usually suffer from the shortcomings of low efficiency and nocturnal failure of freshwater harvesting. In this work, based on the judicious integration of solar-driven interfacial photothermal evaporation (IPTE) and sky radiative cooling (SRC), we design a novel all-day passive freshwater harvesting (FWH) system and carry out a systematic study on its FWH performance, including field experimental tests, performance modeling, and capacity predictions. During the daytime, the seawater is transported to the IPTE layer through the bionic plant water-drawing structure. The IPTE layer absorbs solar energy for seawater evaporation to increase the evaporation efficiency. Meanwhile, by utilizing the salt concentration difference for power generation, we achieve a 64.23% reduction in salt accumulation and a 7.69% enhancement in the seawater evaporation rate. At nighttime, the SRC coating cools the sloping surface and helps to harvest freshwater by condensing the moisture in the air. Outdoor experiment results and numerical prediction results confirm that the proposed system can passively produce freshwater during a 24-h day cycle in an uninterrupted manner, paving a bright future for freshwater resources at no active energy consumption.

Engineering of 0D/1D architectures in 3D networks over CDs/PPy-CPP biomass foam with high efficiency on seawater evaporation

Converting waste biomass into solar evaporator foam has been recognized as an effective strategy for waste recycling and solving the problem of water shortage, but problems of salt deposition and mechanical stability seriously hinder their practical application. Herein, this work proposes a sustainable and high mechanical strength biomass foam (CDs/PPy-CPP) evaporator with zero-dimensional/one-dimensional (0D/1D) hierarchical structure by hydrophilic carbon dots (CDs) and tubular polypyrrole (PPy) are seamlessly integrated into the outer surface of the three-dimensional (3D) carbonized pomelo peel (CPP) biomass foam. The evaporator achieved a high-efficient evaporation rate of up to 2.46 kg m−2 h−1 in 3.5 wt% NaCl solution at 1 sun irradiation, and similarly exhibited outstanding salient evaporation efficiency and resistance to salt deposition in 25 wt% NaCl solution, as well as prominent swage purification ability. Excellent photothermal conversion efficiency is demonstrated attributed to the 0D/1D structure in 3D networks of the CDs/PPy-CPP evaporator, as well as superior mechanical and water transport properties based on the multilayer mesh structure and microscopic water transport pores. The research intends to offer a low-cost, energy-efficient, and environmentally friendly approach to obtain multifunctional photothermal biomass foams and demonstrate the potential applications in seawater desalinization and swage purification.

In situ polymerization of three-dimensional polypyrrole aerogel for efficient solar-driven interfacial evaporation and desalination

Solar-driven interfacial evaporation (SIE) and desalination is a promising approach to mitigate the scarcity of freshwater resources. Here, a three-dimensional polypyrrole (3D PPy) aerogel was prepared by in situ polymerization of pyrrole to serve as an independent evaporator. The interconnected pore structure and super-hydrophilicity enabled PPy evaporators with rapid water transport to the top interface (< 5 s). The hydrogen interaction between polymer chains and water molecules induced large amount of intermediate water, thereby reducing the evaporation enthalpy of water in PPy aerogels. As a result, the optimized PPy aerogel attained an evaporation rate of 2.90 kg m−2 h−1 and an energy conversion efficiency of 114% under 1 sun irradiation. Moreover, the generated steam can be accelerated by the convection and an evaporation rate as high as 6.10 kg m−2 h−1 was realized at 2.5 m s−1. The rapid water transport also enabled PPy aerogel with high-efficiency of self-salt-discharge and efficient desalination for 3.5 wt% brine under 2.5 m s−1. In the outdoor SIE experiment, the excellent evaporation performance was achieved at 12:40 (7.04 kg m−2 h−1 under 74.2 mW cm−2 of solar intensity and 2.5 m s−1 of convective flow), and the cumulative evaporation of 41.50 kg m−2 for successive 9 h was obtained. After the evaporation of simulated seawater and heavy metal wastewater, the concentration of collected fresh water could be reduced about 2–3 orders of magnitude. This 3D PPy evaporation platform with high light absorption, porous structure, super-hydrophilic property, effective steam diffusion, and excellent salt resistance provides an effective way to develop advanced solar-driven water treatment technology.

Growth of phosphomolybdate-carbon hybrid nanorod array on carbon-fiber cloth with enhanced light-trapping and decreased water-evaporation enthalpy for constructing efficient salt-free hanging evaporator

Although numerous photothermal materials have been designed for solar-enabled water evaporation, their use in practical applications remains challenging due to their unsatisfactory photoabsorption, high vaporization enthalpy and serious salt crystallization phenomenon. To overcome these issues, herein we have reported the growth of phosphomolybdate-carbon (PMo12-C) hybrid nanorod arrays on carbon-fiber cloth (CFc) for constructing the efficient salt-free hanging evaporator. The optimized CFc/PMo12-C with nanorods (diameter: ∼0.5 μm, length: ∼1.8 μm) exhibits increased photo-absorption (93.1 %) in the range of 280–2500 nm due to nanorod-induced light-trapping effects, and they also have the decreased water-evaporation enthalpy (2066.7 kJ/kg, 36.8 °C) owing to the disorganization of the hydrogen bonds at nanorods/water interface. Subsequently, such CFc/PMo12-C is hanging between one high seawater-tank and one low empty-tank to construct the incline-hanging model evaporator, where seawater (3.5 wt% NaCl) can infiltrate and then flow from high to low along CFc/PMo12-C. Upon irradiation with sunlight (1.0 kW m−2), the evaporator exhibits a high evaporation rate (2.12 kg m−2 h−1). Even for high salt concentration (21.0 wt% NaCl solution), the hanging CFc/PMo12-C evaporator can retain an almost unchanged evaporation rate (∼2.1 kg m−2 h−1) and present excellent salt-resistant performance with 8 h irradiation. Therefore, this work not only offers a new approach for preparing PMo12-C hybrid nanorod array on CFc but also realizes the efficient continuous seawater evaporation without solid-salt accumulation.

Diagenetic evolution and effects on reservoir development of the Dengying and Longwangmiao formations, Central Sichuan Basin, Southwestern China

The deeply buried Lower Cambrian Longwangmiao Formation and Upper Ediacaran Dengying Formation from the Sichuan Basin, China, have a total natural gas reserve up to 3 × 1012 m3. The complex diagenetic evolution and their impacts on the present-day reservoir quality have not been systematically elucidated, hampering the current exploration. Crucially, the integration and comparation diagenetic study on these two formations, which may be able to shed new lights on reservoir formation mechanism, are yet to be systemically evaluated. By compiling geochemistry data, including carbonate U-Pb ages and petrophysics data, coupled with new petrology, trace elements, and strontium isotope data, of various types of diagenetic carbonates, this study aims to decipher the potential links between diagenesis and reservoir development of both formations. Intriguingly, similar diagenetic sequence, which contains five distinctive dolomite phases, is established in both formations. The matrix dolomite (D1) and early dolomite cement (D2) were likely formed by reflux dolomitization, as inferred by their nearly syn-depositional U-Pb ages and elevated δ18O caused by seawater evaporation. The subsequent moderate burial dolomite cement (D3) was most plausibly the product of burial compaction as indicated by its lighter δ18O and slightly younger U-Pb ages compared with D1 and D2. Whereas deep burial dolomite cements (D4 and D5) yield markedly depleted δ18O, elevated 87Sr/86Sr, along with much younger U-Pb ages and higher precipitation temperatures, suggesting that they were likely linked to hydrothermal fluids. Despite the wide occurrence of meteoric and organic acids leaching and thermochemical sulfate reduction, they may have only played a subsidiary role on these reservoirs development. Instead, superior reservoir quality is tightly linked to tectonics as inferred by higher reservoir quality closely related to the well-developed fractures and faults filled with abundant hydrothermal minerals. Notably, good reservoirs in both formations are mainly attributed to high permeability caused by tectonics. Hence, this new contribution emphasizes the crucial role of tectonics on spatially explicit reservoir prediction of deep to ultra-deep (up to > 8000 m) carbonates in the Sichuan Basin, as well as other sedimentary basin analogues in China.

Morph-genetic biomimetic multiscale porous hydrogels for high-efficient solar evaporation from seawater

Huge seawater resources are of utmost importance in addressing the increasing and severe water shortage worldwide. However, high-efficiently and sustainably extracting fresh water from seawater through solar evaporation remains a challenging task. Herein, we propose a novel approach based on the morph-genetic biomimetic concept, utilizing a cuttlebone-templated directional porous hydrogel (CTDPH). By etching away the cuttlebone (CaCO3) in the hydrogel network, we have developed a zwitterionic material that exhibits high-efficiency photo-thermal conversion, resistance to salt deposition, and super hydrophilicity, enabling high-efficiency solar evaporation. The resultant CTDPH demonstrates a high level of photo-thermal conversion efficiency, thanks to the incorporation of MXene (Ti3C2Tx) 2D nanosheets. By introducing polyzwitterions into the hydrogel matrix, the CTDPH achieves superhydrophilicity, greatly enhancing the transport of seawater. More importantly, the CTDPH possesses a penetrating oriented macro-porous structure, enabling rapid seawater transportation while effectively preventing salt crystallization. This prevents salt deposition on the surface of the hydrogel even during continuous 12-hour 1.0 sun irradiation. As a result, compared with the MXene-free gels and cuttlebone-reserved gels, this CTDPH can largely increase the seawater evaporating rate from 0.73 or 1.75 to 3.11 kg m-2h−1 under 1.0 sun irradiation. Furthermore, even after undergoing 10 cycles of seawater evaporation, the CTDPH still maintains 91.6% of its original solar evaporation rate (2.85 kg m-2h−1). The CTDPH emerges as a promising contender, offering both high efficiency and sustainability for solar evaporation from seawater, while simultaneously paving the way for innovative approaches to explore other materials and systems in the realm of solar evaporation.

Origin and evolution of deep lithium-rich brines in the southwest Jianghan Basin, central China: Evidence from hydrochemistry and stable isotopes

Lithium-rich brines from the upper Cretaceous and lower Eocene in the Jiangling depression, southwest Jianghan Basin were collected. In order to study the origin, evolution of the brines and the enrichment mechanism of lithium, the hydrochemical compositions and stable isotopes of the brines were tested and analyzed. The highest concentrations of potassium and lithium in the brine were 3.21 g/L and 97.85 mg/L, respectively. The brines of upper Cretaceous are mainly weakly acidic, while the lower Eocene brines are acid to alkalescent, and they are all Cl-Na type water. Compared with the ion trajectories of seawater evaporation, the brines showed enrichment of Cl, Ca, and Sr and depletion of Mg, which may be due to the dissolution of halite and water–rock interaction. The δD and δ18O compositions of the brines in both aquifers are similar, with δD values ranging from −51.4 to –33.0 ‰ and δ18O values ranging from −3.8 to 3.7 ‰. The data of δD and of δ18O indicate that the two aquifer brines originated from meteoric waters and experienced intense evaporation. The 87Sr/86Sr values (0.710144 to 0.712448) in the Upper Cretaceous brines are similar to the Paleocene sandstones, and the 87Sr/86Sr values (0.709982 to 0.710806) in the Lower Eocene brines are similar to the Paleocene anhydrite and glauberite. And the average content of lithium element in the upper Cretaceous brine is 54.38 mg/L, and the δ7Li values ranges from 10.2 to 14.1 ‰; the average content of lithium in lower Eocene brine is 23.81 mg/L, and the δ7Li values ranges from 17.7 to 21.9 ‰. The characteristics of 87Sr/86Sr and δ7Li indicate that the water–rock interaction between brine and silicate rock and the dissolution of halite lead to the enrichment of lithium in the brine of the two aquifers.

Efforts To Sustain Fresh Water Production in Order to Improve The Performance of Fresh Water Generator On The Mt. Rubra

Fresh water generator is an auxiliary aircraft aboard a ship that produces fresh water by evaporating seawater in the evaporator and the seawater is cooled by condensation in a distillation vessel or condenser (condenser), thus producing condensed water called condensate. Fresh water generator running optimally is one of the important factors to support ship operations, especially the results of the fresh water generator used for cooling systems and daily needs on board. This study aims to find out the causes of the problems and efforts that occur in the fresh water generator so that it can maintain fresh water production results in the fresh water generator. While data analysis is to identify the data set that has been obtained, so that the data can be analyzed and the purpose is analyzed in order to get a clearer picture in the preparation of this research both from the problems and the final results. It is hoped that this research research can produce ideas, solutions and appropriate problem solving, both in observing and dealing with the problems raised in this study. Based on research on fresh water production on fresh water generators in MT. Rubra has decreased from 19 tonnes/day to 12 tonnes/day. This is caused by the occurrence of salt deposits on the evaporator plate so that evaporation becomes late and the low pressure of sea water leading to the fresh water generator causes fresh water production to decrease

Biomimetic Seawater Evaporator Based on Organic 3D Light Capture and Suspension‐Protection Mechanism for In Situ Marine Cultivation

AbstractEfficient and durable seawater evaporation technologies are vital for expanding access to freshwater and developing novel irrigation systems. Here, a photothermal material termed as Y7, characterized by its fused‐ring, small‐molecule structure, and strong electron‐withdrawing end groups, is combined with an economical wood sponge. This combination is used to create a 3D solar desalination evaporator and to design a self‐circulating evaporative irrigation system. Mirroring the 3D light‐capture porous structure and underwater suspension of diatoms, this hydrophilic evaporator demonstrates efficient light absorption in the range of 300–1100 nm and excellent resistance to salt and photobleaching. With a mass of only 3 mg/3.14 cm2, the Y7‐evaporator realizes a solar‐energy‐to‐vapor conversion efficiency (η) of 91.7% and solar water evaporation rate (ṁ) of 1.62 kg m−2 h−1, marking a new record for purely organic evaporators. After the desalination process, the concentration of primary ions is reduced by five to six orders of magnitude. Based on these findings, an in situ self‐irrigation system is developed using seawater, which efficiently cultivates several plant species. The results present a novel seawater evaporation strategy rooted in enhanced photothermal effects and durability, suggesting potential applications in future self‐sustaining marine cultivation.

Solar-driven watersteam/brine production and brine-driven electricity generation by photothermal fabric coupled with osmotic membrane

The combination of solar-driven seawater evaporation and electricity generation has received increasing attention, and the traditional routes are based on the combination of the evaporator with thermogalvanic cells, thermoelectric or hydrovoltaic modules. But these combinations are relatively complex, and solid salt will crystallize during long-term seawater evaporation, limiting their practical applications. To solve the above problems, herein we have proposed a new kind of evaporation/electricity generation device by combining the photothermal fabric hanging-model evaporator and osmotic membrane-based generator. As a model of photothermal fabric, cotton fabric has been dyed with Chinese ink, and then the cotton-carbon fabric has high hydrophilicity and excellent photoabsorption efficiency (97.1%). Subsequently, the cotton-carbon fabric is set in an arc-shaped design between two seawater tanks for the construction of the hanging-model evaporator. Under the illumination of one sun, the evaporation rate of the hanging-model evaporator is as high as 1.94 kg m−2 h−1 without solid-salt accumulation, and the high-concentration brine (Na+ concentration: 1.07 ×105 mg L−1) can drip from the fabric bottom, realizing solar-driven watersteam and brine production with standing stability. Simultaneously, the brine is separated from the original seawater by a commercial cation exchange membrane, and two Ag/AgCl electrodes are used to construct an osmotic generator. It shows a high open voltage of 52 mV and the highest output power density of 116.52 mW m−2. Therefore, the present integration of the hanging-model evaporator and osmotic generator establishes a new path to continuously produce watersteam and brine under the sun and then to confer brine-driven electricity generation.

Evidence for enhanced aridification since 13 Ma in the Qom back-arc basin, Central Iran

The Iranian Plateau was once occupied by the Neotethys Sea, which connected with the Indian Ocean in the southeast and the proto-Mediterranean in the west during most of the Cenozoic era. However, the Neotethys Sea has undergone a stepwise retreat, and the Tethyan Seaway also closed in the Miocene driven by both Arabia-Eurasia collision and global eustatic sea-level drop. Changes in the land-sea distribution and uplift of the Zagros Mountain belt must have affected paleoclimatic changes in Iran. To date, a high-resolution paleoclimatic record is lacking for Iran. In this paper, we present new environmental magnetic and color parameter data for terrestrial sediments in the Qom back-arc basin, Central Iran from the middle to late Miocene (17–11.5 Ma). All of our parameters indicate an abrupt climatic change at ∼13 Ma. We suggest that the less reddish color and a shift in environmental magnetic parameters after ∼13 Ma implies weakened chemical weathering under a colder/drier climate. Enhanced aridification was mainly controlled by closure of the Tethyan Seaway and shrinkage of the Neotethys Sea after ∼13 Ma, which greatly reduced moisture transport to the downwind Central Iran by westerlies, whereas the rain shallow effect of the initially uplifted Zagros Mountain belt and reduced seawater evaporation related to lower sea-surface temperatures after the Mid-Miocene Climatic Transition only played minor roles. Therefore, our results provide a window to discuss relationships between plate tectonic movements, land/sea distribution, and climatic change in a tectonically active region during the late Cenozoic.

Boosting Water Evaporation by Construction of Photothermal Materials with a Biomimetic Black Soil Aggregate Structure.

Solar-driven interfacial evaporation is considered an efficient way to get fresh water from seawater. However, the low evaporation rate, surface salt crystallization, and low energy collection of the photothermal evaporation layer limit its further application in an outdoor freshwater field. And the aggregate structure design of the material itself is often ignored in solar-driven water evaporation. Black soil (BS), with a unique soil aggregate structure, is rich in tubular pores, which can be used for multilevel sunlight utilization and good capillary water transport. Based on the extraordinary photothermal properties and pumping capacity of BS, a reasonable unidirectional salt-collecting device is designed, which can realize long-term collection of mineral salts and continuous evaporation of seawater and generate electric energy in the continuous evaporation. Inspired by the unique aggregate structure, the photothermal material doping of halloysite and nigrosin will simulate the generation of this aggregate structure and retain a good water transport effect while obtaining multistage utilization of sunlight. The solar-driven evaporation rate of a nigrosin-halloysite solar steam generator is 1.75 kg m-2 h-1 under 1 kW m-2 mimic solar radiation; it can achieve stable salt leaching-induced voltage generation of 240 mV. This work demonstrates not only a solar evaporator that can continuously achieve desalination but also the design strategy of BS-like aggregate photothermal materials, which promotes the development of low-cost resource recovery and energy generation for practical outdoor seawater desalination.

Oriented porous hydrogel with excellent anti-salt and antibacterial properties for high-performance interfacial solar steam generation

In recent years, solar interfacial evaporation has drawn substantial attention in wastewater and seawater treatment, but it still requires intensive development in high-performance evaporators, particularly simultaneous with high anti-salt and antibacterial abilities to supply freshwater. In this work, a directionally channeled evaporator with excellent resistance to salt crystallization and microbial was designed and synthesized by using silver nanoparticles (AgNPs) / polydopamine (PDA) hydrogel via a simple freeze-dried method. The novel structure was proposed to enhance convection and accelerate water transport that prevents salt crystallization. PDA and AgNPs were deposited to achieve superb optical absorption, photothermal conversion and anti-biofouling ability. Therefore, the evaporation rate of the AgNPs-PDA hydrogel achieved 1.70 kg m−2 h−1 with a light-to-heat conversion efficiency of 90.3 %. Based on the efficient evaporation ability and especially structure of the AgNPs-PDA hydrogel, the evaporator presented a tolerance to high salt water and the stable evaporation performance of actual seawater evaporation during long-time application. Simultaneously, the addition of AgNPs endowed the AgNPs-PDA hydrogel evaporator with excellent antibacterial ability. Thus, these favorable properties endowed the special AgNPs-PDA hydrogel evaporator a great potential for obtaining efficient evaporation and simultaneously solving the fouling problem, especially to waterborne pathogens and salt crystallization in tanglesome applications.