Efficient Vapor Generation Research Articles

3D printed Ti3C2@Polymer based artificial forest for autonomous water harvesting system

The escalating scarcity of freshwater resources presents significant challenges to global sustainability, demanding innovative solutions by integrating cutting-edge materials and technologies. Here we introduce an autonomous artificial forest (3D AF) for continuous freshwater acquisition. This system features a three-dimensional (3D) architecture incorporating a carbon nanofiber (CNF) network and MXene@polypyrrole (Ti3C2@PPy), enhancing surface area, light absorption, heat distribution, and surface wettability to improve solar vapor generation and fog collection efficiency. The autonomous operation is facilitated by an integrated photothermal actuator that adjusts to the day and night conditions. During daylight, the 3D AF tilts downward to maximize solar exposure for water evaporation, while at night, it self-adjusts to optimize fog particle collection. Notably, our device demonstrates the ability to harvest over 5.5 L m−2 of freshwater daily outdoors. This study showcases the potential of integrating advanced materials and technologies to address pressing global freshwater challenges, paving the way for future innovations in water harvesting.

Plant transpiration inspired biomass-derived solar evaporator for highly efficient solar vapor generation

The interface solar evaporation is an energy-saving and environmentally friendly method for seawater desalination and sewage purification. In this work, a biomimetic solar evaporator (ppy@AZL) inspired by plant transpiration was designed to achieve high efficient vapor generation. The ppy@AZL evaporator was made of zizania latifolia as raw material, has a cellulose skeleton with high water transport after alkalization and was decorated with photothermal polypyrrole to form bionic branches and leaves, and has excellent photothermal conversion performance. The evaporation performance and potential application of ppy@AZL evaporator in seawater desalination and sewage treatment were studied. The results indicated that the average evaporation rate of the ppy@AZL in simulated seawater (3.5 wt%) under the irradiation of one sun (1 kW m−2) was 2.239 kg m−2 h−1, and the photothermal conversion efficiency was 93.4 % in this work. In addition, the ppy@AZL evaporator has excellent evaporation rate of 2.668 kg m−2 h−1 in 9 h outdoor continuous evaporation experiment of simulated seawater (3.5 wt%), and can continuously and stably generate vapor. Therefore, this study provided a new solar evaporator with low-cost, simple preparation, better salt resistance, and high evaporation performance for seawater desalination and sewage treatment.

Pb-based metal organic framework as substrate: Chemical vapor generation-visual/smartphone colorimetric analytical system for sensitive and selective detection of sulfide ion in water and beers

A visual/smartphone colorimetric system was developed for the sensitive and selective detection of sulfide ion (S2−) using chemical vapor generation (CVG) as a gaseous sampling technique. S2− in samples were converted into H2S after the addition of H2SO4, which separated from the solution during CVG process, ensuring high efficiency of vapor generation (sensitivity) and eliminated interferences (selectivity). The H2S was subsequently reacted with Pb-BTC and PbS was thus formed, causing the test paper turned to black. It was utilized for the detection of S2− by visual/smartphone colorimetric system. Detectable limits of 0.05 μg/mL and 0.2 μg/mL were obtained under smartphone mode and visual mode, respectively. Furthermore, this colorimetric system was successfully used for the analysis of S2− in several beer samples and water samples, with recoveries ranging 97 %–111 %. This system represents a potential miniaturized, easy used and high-effective method for rapid and on-site detection of S2−.

Enhancing the efficiency of chemical vapor generation of zinc in a multimode sample introduction system

Enhancing the efficiency of chemical vapor generation of zinc in a multimode sample introduction system

Solar-powered flow-through catalytic evaporator for high-performance water desalination and synergistic pollutant degradation

Solar interfacial evaporation has been considered one of the most promising strategies to address freshwater scarcity. It is of great interest to explore means of expanding the utilization of solar interfacial evaporation for organic wastewater treatment to capture freshwater. To this end, it is proposed herein that a unidirectional flow-type solar-powered catalytic evaporator is fabricated as a unique integrated device with efficient vapor generation and organics degradation capability, giving rise to simultaneously achieving collection of freshwater and treatment of organics. Benefitting from the flow-through interfacial evaporation and the rational design of the high-performance array-type catalytic evaporative material composed of polydopamine (PDA)-coated CdS photocatalysts on carbon cloth (CC) substrate, the as-built solar-powered catalytic evaporator demonstrates excellent evaporation rate and organic treatment efficiency of 1.93 kg m−2 h−1 and 90.7 %, respectively, well exceeding those of the initial, un-designed evaporator (1.63 kg m−2 h−1 and 60.3 %). This work may provide a new strategy for the treatment of organic wastewater with versatility based on solar interfacial catalytic evaporation technology.

Design and fabrication of porous three‐dimensional Ag-doped reduced graphene oxide (3D Ag@rGO) composite for interfacial solar desalination

Solar-driven interfacial desalination technology has shown great promise in tackling the urgent global water scarcity crisis due to its ability to localize heat and its high solar-to-thermal energy conversion efficiency. For the realization of sustainable saline water desalination, the exploration of novel photothermal materials with higher water vapor generation and photothermal conversion efficiency is indispensable. In the current study, a novel 3D interconnected monolithic Ag-doped rGO network was synthesized for efficient photothermal application. The Ultraviolet–Visible-Near Infrared (UV–Vis-NIR) and FTIR analyses demonstrated that the controlled hydrothermal reduction of GO enabled the restoration of the conjugated sp2 bonded carbon network and the subsequent electrical and thermal conductivity through a significant reduction of oxygen-containing functional groups while maintaining the hydrophilicity of the composite photothermal material. In the solar simulated interfacial desalination study conducted using 3.5 wt.% saline water, the average surface temperatures of the 3D material increased from 27.1 to 54.7 °C in an hour, achieving an average net dark-excluded evaporation rate of 1.40 kg m−2 h−1 and a photothermal conversion efficiency of ~ 97.54% under 1 sun solar irradiance. In the outdoor real-world application test carried out, the surface temperature of the 3D solar evaporator reached up to 60 °C and achieved a net water evaporation rate of 1.50 kg m−2 h−1 under actual solar irradiation. The 3D interwoven porous hierarchical evaporator displayed no salt precipitation over the 54-h period monitored, demonstrating the promising salt rejection and real-world application potential for efficient desalination of saline water.

Solution cathode glow discharge coupled to atmospheric pressure chemical ionization for elemental detection of S and P in organic compounds

We report a post-plasma chemical ionization approach to evaluate solution cathode glow discharge (SCGD) for S and P elemental analysis. Here, the SCGD serves as a reactor to produce chemical vapors for S and P from organic compounds containing these elements, while a corona discharge operated in negative mode is used to ionize the products. The approach creates long-lived ions in atmospheric pressure, enabling direct investigation of chemical vapor products via mass spectrometric and ion mobility separations. The investigations indicate that SCGD converts S and P to H2SO4 and H3PO4, respectively. These species are then ionized as HSO4HNO3− and H3PO4NO3HNO3− via reactions with NO3HNO3− produced by corona discharge. The response factors for P among several small molecules varies within 10% of the average response from the compounds, suggesting a reasonable species-independent characteristic. The response factors for S show larger variations among compounds, indicating a higher dependence of chemical vapor generation efficiency on analytes' chemical structures. Detection limits of 15 and 29 ng/mL are achieved for P and S detection, respectively. These figures are limited by background equivalent concentrations and low ion flux in the utilized ion mobility-time of flight mass spectrometer, indicating potential for significant improvements. In particular, the specificity of clustering for S and P-containing ions produced in this approach suggest facile analysis of S and P using quadrupole-based mass spectrometers for improved analytical performance.

3D Vascular-structured Flame-retardant Cellulose-based photothermal aerogel for Solar-driven interfacial evaporation and wastewater purification

Solar-driven interfacial evaporation is recognized as a green and sustainable strategy to address the global freshwater problem. Efficient vapor generation relies on the creation of high-performance evaporators, which concentrate on improving solar energy conversion efficiency, water transport capacity and thermal localization. Herein, a functionalized cellulose aerogel with a novel three-dimensional vascular structure was designed by decorating the cellulose nanofiber with ZIF-67 and MXene (CZM3), which can be used as a solar-driven multifunctional evaporator. When exposed to 1 sun, the CZM3 aerogel demonstrated a high evaporation rate of 2.034 Kg·m−2·h−1 and an efficiency of 139.4 %, outperforming many advanced evaporators. What’s more, CZM3 aerogel maintained its stable water evaporation property after multiple test cycles. This was due to the hydrophilic vascular-like channels continuously transport water, while the photothermal materials encapsulated in CNF provide the power for water vaporization. Additionally, through the interfacial evaporation of CZM aerogel, the removal rates of salt ions (Na+, Mg2+, Ca2+ and K+) and heavy metal ions (Cu2+, Zn2+ and Cd2+) reached 98.2 %∼99.5 % and 81.6 %∼98.2 %, showing outstanding water purification ability. Contrary to the flammability of pure CNF, the peak heat release rate and total heat release of CZM3 aerogel were reduced by 75.2 % and 69.9 %, exhibiting superior fire safety. The high-performance evaporator designed in this work becomes a promising candidate material in the field of solar-driven water desalination and wastewater purification.

Ultraviolet assisted liquid spray dielectric barrier discharge plasma-induced vapor generation for sensitive determination of arsenic by atomic fluorescence spectrometry

In this study, a novel sensitive method for As determination by atomic fluorescence spectrometry was developed based on UV-assisted liquid spray dielectric barrier discharge (UV-LSDBD) plasma-induced vapor generation. It was found that prior-UV irradiation greatly facilitates As vapor generation in LSDBD likely because of the increased generation of active substances and the formation of As intermediates with UV irradiation. The experimental conditions affecting the UV and LSDBD processes (such as formic acid concentration, irradiation time, the flow rates of sample, argon and hydrogen) were optimized in detail. Under the optimum conditions, As signal measured by LSDBD can be enhanced by about 16 times with UV irradiation. Furthermore, UV-LSDBD also offers much better tolerance to coexisting ions. The limit of detection was calculated to be 0.13 μg L−1 for As, and the relative standard deviation of the repeated measurements was 3.2% (n = 7). The accuracy and effectiveness of this new method were further verified by the analysis of simulated natural water reference sample and real water samples. In this work, UV irradiation was utilized for the first time as an enhancement strategy for PIVG, which opens a new approach for developing green and efficient vapor generation methods.

The efficiency of Hg cold vapor generation and its influence on Hg isotope analysis by MC-ICP-MS

Non-quantitative Hg cold-vapor generation can compromise the accuracy of Hg isotope analysis, and it should be monitored and optimized by performing matrix separation, adopting the design of gas–liquid separators, and tuning the sample uptake rate.

An array structure of polydopamine/wood solar interfacial evaporator for high-efficiency water generation and desalination

Desalination of seawater using solar energy is an effective and environmentally friendly means to solve the chronic freshwater shortage problem. However, the low conversion rate of solar energy seriously affects the application of solar energy in the field of solar thermal conversion. In this regard, we present polydopamine (PDA) loaded woods with an array structure as solar interfacial evaporators for high-efficiency solar vapor generation. It was found that the solar interfacial evaporators made of PDA/wood composites demonstrated excellent solar absorption rate (up to 93%) and the highest solar vapor generation efficiency of 97.6% under one solar illumination. It is worth mentioning that in the simulated seawater experiments, the array structure showed outstanding salt-rejected performance in 3.5% and 20% NaCl solutions, mightily thanks to the original microporous channels of the wood and the artificial millimeter cut marks. Based on the above conditions, the efficiency of PDACW-7 × 7 in simulated seawater with different salinities (3.5 and 20 wt%) under 1 kW m −2 irradiation remained at about 96.1% and 81.9%. Therefore, due to the high light absorption rate and low cost, PDA/wood composites could have good prospect in the field of solar thermal conversion and seawater desalination. • The array structure of polydopamine/wood evaporators enhances light absorption and evaporation rate. • The evaporators show excellent light absorption and photothermal conversion efficiency. • The evaporators perform favorable desalination and salt-rejecting behaviors.

Vapor Generation of Rare-Earth Elements via Reaction with Tetrahydroborate: Chemical Identities and Mechanisms of Formation.

This technical note reports for the first time the simultaneous vapor generation of 16 rare-earth elements (REEs) via reaction with sodium tetrahydroborate (THB). Significant improvement in REE vapor generation efficiency was discovered in the presence of arsenazo III (ARS). Subsequent to a critical evaluation on the impacts of various experimental variables, including the concentrations of acids, THB, and ARS, blank-limited (reagent contamination and impurity from ARS) detection limits (LODs) in the range of 0.004-0.15 μg L-1 were achieved based on three times the standard deviation of the method blank by the proposed vapor generation inductively coupled plasma mass spectrometry (ICP-MS). The nature of released REE species was studied by various approaches and identified to be REE nanoparticles and REE-ARS chelates; a dual-route mechanism for the vapor generation of REEs was thereby proposed.

Flexible solar absorber using hydrophile/hydrophobe amphipathic Janus nanofiber as building unit for efficient vapor generation

Solar vapor generation has become a promising technology for water harvesting owing to the abundant and costless solar energy. However, there still remains great challenges to improve the usability of solar absorbers and realize high-efficient vapor generation. Herein, novel solar absorber is constructed using electrospun hydrophilic cellulose acetate/hydrophobic polyvinyl butyral amphipathic Janus nanofibers as substrate. Owing to the unique composition and structure, the electrospun Janus nanofibers film realizes the integration of water-pumping, thermal-resisting, self-floating, and salt-resisting functions in a monolayered film, which is desirable for designing solar absorbers. Highly efficient photothermal conversion material composed of carbon nanotubes, SiO2 nanoparticles and polydopamine is modified onto the surface of the Janus nanofibers film to obtain the solar absorber. With the solar absorber, a state-of-the-art water evaporation rate (2.398 kg m-2h−1) can be reached under 1 sun irradiation, and satisfactory reusability is guaranteed as well. Moreover, the solar absorber based on the Janus nanofibers film also shows promising desalination performance. The constructed solar absorber with excellent comprehensive performance provides potential strategy and new design philosophy for clean water generation.

Umbrella evaporator for continuous solar vapor generation and salt harvesting from seawater

Solar vapor generation, which uses photothermal materials to desalinate seawater by evaporation, is a promising technology to mitigate the water scarcity problem, but its performance is hindered by large heat leak and salt accumulation problems. Here we report an umbrella evaporator that achieves efficient vapor generation and salt harvesting concurrently via double-sided evaporation and reveal the salt nucleation, growth, and falling mechanism. The evaporator reaches an evaporation rate of 1.25 kg m −2 ·h −1 under ambient conditions, and its continuous operation for vapor and salt production from seawater is demonstrated. The salt mobility on the evaporation surface determines whether the salt could accumulate at the edge, which is influenced by water supply, solar intensity, salinity, and Mg 2+ and Ca 2+ contents.A simple salt creeping test on a glass slide is developed to determine whether and to what extent seawater needs to be pre-treated for continuous operation. • Umbrella evaporator achieves a high efficiency via double-sided evaporation • Central water supply results in salt accumulation at edges • Salt grows from the front by wicking water through its porous structures • Salt creeping behaviors indicate if Ca 2+ and Mg 2+ content is below the lower limit Solar evaporation could mitigate water stress problems, but challenges remain in structural improvement of devices, salt accumulation, and salt harvesting mechanisms. Ma et al. show an umbrella evaporator that achieves efficient vapor generation and salt harvesting concurrently via double-sided evaporation and reveal the salt nucleation, growth, and falling mechanism of salt harvesting.

Vertical porous MoS2/hectorite double-layered aerogel as superior salt resistant and highly efficient solar steam generators

Solar desalination which can produce freshwater by using green and renewable solar energy is considered as a promising strategy to mitigate water scarcity. However, in practical application, the crystallization and accumulation of salt will cause adverse impact on the water transportation, vapor generation efficiency, and long-term sustainable use of evaporator. Herein, we proposed a vertical porous MoS2/hectorite bi-layered aerogel for efficient solar steam generation with superior salt redissolution performances, excellent light absorption and outstanding local thermal effect. The top MoS2 layer functioned as efficient solar absorbers with excellent light absorption and photo-thermal conversion performances. For the bottom layer, the vertical water transport path and natural strong hydrophilicity of hectorite aerogel ensure stable water supply to the evaporation layer and prevent the accumulation of salt at the evaporation interface. The results show that the constructed superhydrophilic MoS2/hectorite bilayer aerogel has excellent self-driven salt removal performance, and can achieve self-cleaning within 30 min under extreme conditions simulating salt crystallization. In addition, the aerogels exhibited a steam generation rate of 1.32 kg m−2 h−1 and an evaporation efficiency of 85.99% under a light intensity of only 1 kW m−2. The superior performances of MoS2/hectorite double-layer aerogel, such as low cost, simple preparation, high strength and good salt resistance, make it suitable as portable evaporator for efficient solar interface desalination.

Flexible Solar Absorber Using Hydrophile/Hydrophobe Amphipathic Janus Nanofiber as Building Unit for Efficient Vapor Generation

Flexible Solar Absorber Using Hydrophile/Hydrophobe Amphipathic Janus Nanofiber as Building Unit for Efficient Vapor Generation

Flexible Solar Absorber Using Hydrophile/Hydrophobe Amphipathic Janus Nanofiber as Building Unit for Efficient Vapor Generation

Flexible Solar Absorber Using Hydrophile/Hydrophobe Amphipathic Janus Nanofiber as Building Unit for Efficient Vapor Generation

Flexible Solar Absorber Using Hydrophile/Hydrophobe Amphipathic Janus Nanofiber as Building Unit for Efficient Vapor Generation

Flexible Solar Absorber Using Hydrophile/Hydrophobe Amphipathic Janus Nanofiber as Building Unit for Efficient Vapor Generation

Narrow-Bandgap LaMO3 (M = Ni, Co) nanomaterials for efficient interfacial solar steam generation

Photothermal water evaporation provides a pathway towards a promising solution to global freshwater scarcity. Synergistic integration of functions in a material in diverse directions is a key strategy for designing multifunctional materials. Lanthanum-based perovskite complex oxides LaMO3 (M = Ni and Co) have narrow band gaps with a high absorption coefficient. These functionalities have not been appropriately explored for photothermal energy conversion. Here, we synthesized nanostructured metallic LaNiO3 and semiconducting LaCoO3 and used them to design interfacial solar steam generators. Effective light absorption capability over the entire solar spectrum of these materials leads to a photothermal efficiency of the order of 83% for both materials. Using a cone-shaped 3D interfacial steam generator with a LaNiO3 absorber, we achieved an evaporation rate of 2.3 kg m−2 h−1, corresponding to solar vapor generation efficiency of over 95%. To the best of our knowledge, this evaporation rate is higher than any oxide-based interfacial solar steam generator reported so far. Furthermore, we have also shown an effective way of using such evaporators for long-term seawater desalination.

Methanol-Enhanced Liquid Electrode Discharge Microplasma-Induced Vapor Generation of Hg, Cd, and Zn: The Possible Mechanism and Its Application.

Despite increased interest in microplasma-induced vapor generation (μPIVG) over the past several years, applications in real sample analyses remain limited due to their relatively low vapor generation efficiency and ambiguous mechanism. In this work, a novel method using methanol for significantly enhancing the liquid electrode discharge μPIVG efficiency was developed for the simultaneous and sensitive determination of Hg, Cd, and Zn by atomic fluorescence spectrometry (AFS). It is worth noting that the possible enhancement mechanism was investigated via the characterizations of volatile products by AFS, microplasma optical emission spectrometry, online gas chromatography, and gas chromatography-mass spectrometry, which involved the reductive species such as electrons, hydrogen radicals (·H), methyl radicals (·CH3), and other intermediates in the argon plasma adding methanol. Under the optimized conditions, the limits of detection of 0.007, 0.05, and 0.5 μg L-1 were obtained for Hg, Cd, and Zn, respectively, with relative standard deviations of 3.1, 3.7, and 5.2% for these elements, respectively. Vapor generation efficiencies of 90, 83, and 55% were achieved for Hg, Cd, and Zn, respectively, and improved 2.7-, 4.8-, and 7.9-fold, respectively, compared to those obtained in the absence of methanol. The accuracy and practicability of the proposed method were validated by the determination of Hg, Cd, and Zn in a certified reference material (CRM, Lobster hepatopancreas, TORT-3) and crayfish samples collected from three different provinces of China.