Shortage Of Freshwater Resources Research Articles

Dual-Interface Solar Evaporator with Highly-Efficient Thermal Regulation via Suspended Multilayer Design.

Facing the increasing global shortage of freshwater resources, this study presents a suspended multilayer evaporator (SMLE), designed to tackle the principal issues plaguing current solar-driven interfacial evaporation technologies, specifically, substantial thermal losses and limited water production. This approach, through the implementation of a multilayer structural design, enables superior thermal regulation throughout the evaporation process. This evaporator consists of a radiation damping layer, a photothermal conversion layer, and a bottom layer that leverages radiation, wherein the bottom layer exhibits a notable infrared emissivity. The distinctive feature of the design effectively reduces radiative heat loss and facilitates dual-interface evaporation by heating the water surface through mid-infrared radiation. The refined design leads to a notable evaporation rate of 2.83kg m-2 h-1. Numerical simulations and practical performance evaluations validate the effectiveness of the multilayer evaporator in actual use scenarios. This energy-recycling and dual-interface evaporation multilayered approach propels the design of high-efficiency solar-driven interfacial evaporators forward, presenting new insights into developing effective water-energy transformation systems.

Preparation and properties of a metal-organic frameworks polymer material based on Sa-son seed gum capable of simultaneously absorbing liquid water and water vapor

Atmospheric water harvesting (AWH) technology has attracted significant attention as an effective strategy to tackle the global shortage of freshwater resources. Work has focused on the use of hydrogel-based composite adsorbents in water harvesting and water conservation. The approaches adopted to make use of hygroscopic inorganic salts which subject to a “salting out” effect. In this study, we report the first use of modified UIO-66-NH2 as a functional steric cross-linker and Sa-son seed gum was used as polymeric substrate to construct super hygroscopic hydrogels by free radical copolymerization. The maximum water uptake on SMAGs (572 cm3·g−1) outperforms pure UIO-66-NH2 (317 cm3·g−1). Simultaneously, our first attempt to use it for anti-evaporation applications in an arid environment (Lanzhou, China) simulating sandy areas. The evaporation rate of the anti-evaporation material treated with 0.20 % super moisture-absorbent gels (SMAGs) decreased by 6.1 % over 64 h period under natural condition in Lanzhou, China. The prepared material can not only absorb liquid water but also water vapor, which can provide a new way for water collection and conservation technology. The design strategy of this material has wide applications ranging from atmospheric water harvesting materials to anti-evaporation technology.

High anti-corrosive and Scalable CDs/BCN heterostructure photocatalysts for efficient H2 production in natural seawater

Photocatalytic natural seawater-derived splitting to produce hydrogen is one of the most potential strategies to alleviate the shortage of freshwater resources and energy crisis. Nevertheless, the complicated composition of natural seawater poses substantial challenges to the activity and stability of photocatalysts. Here, we report on the fabrication of carbon dots (CDs) and B elements co-modified carbon nitride (i.e. CDs/BCN) via precursor-mediated supramolecular self-assembly and subsequent NaBH4-assisted thermal reduction as well as its implementation as seawater-derived H2 production. The fabricated CDs/BCN exhibits the flaky porous structure capable of providing more transport channels for the generated gases (e.g. H2) and precipitates (e.g. Mg(OH)2, Ca(OH)2) during the seawater splitting process. Benefitting from cooperation of CDs and B elements i.e. the inhibited recombination of electron-hole pairs as well as the extended optical absorption range of CN, the optimal CDs/BCN-2 under visible-light irradiation exhibits the high H2 production rate up to 10369 μmol g-1 h-1 in natural seawater. The proven satisfactory reusability and the corresponding structural stability demonstrate the excellent corrosion resistance of CDs/BCN-2 in natural seawater. Additionally, CDs/BCN-20 photocatalyst synthesized via 20-fold precursor amplification procedure still displays efficient photocatalytic performance of 9022 μmol g-1 h-1, indicating its potential for industrial applications.

Application of VIC-WUR model for assessing the spatiotemporal distribution of water availability in anthropogenically-impacted basins

Climate change, rapid increase in population, and urbanization have given rise to over-exploitation and shortage of freshwater resources. Acquiring accurate representations of fresh water availability is therefore crucial to sustainable development. Based on the underlying hydrological processes and storage types, fresh water can be divided into blue and green water components. Hence, quantification of the spatio-temporal distribution of blue and green water requires estimating the components of terrestrial water cycle. In this study, a framework is proposed to evaluate the water scarcity using the blue and green water concept. In this framework, the Wageningen Institute and Research (WUR) version of the Variable Infiltration Capacity Model (VIC) is employed to simulate terrestrial water cycle. Compared to VIC model, VIC-WUR model employs additional modules to account for sectoral water demands, return flows, and groundwater withdrawals, however, very limited number of its applications have been reported so far. The Divandareh-Bijar (DBJ) basin in west of Iran is selected because it has experienced severe anthropogenic alterations in the past three decades. To address precipitation and parameter uncertainty, the VIC-WUR model is separately calibrated for three precipitation datasets. As a part of this framework, the calibrated model is used to simulate blue and green water components and their corresponding scarcity metrics for the first time. According to the results, blue and green water resources in the DBJ are relatively scarce. The results also highlight the importance of considering anthropogenic impacts on the spatiotemporal dynamics of green and blue water resources. Additionally, quantification of the uncertainty in blue and green water components can help produce more reliable estimations for intelligent management of water resources. The ANalysis Of VAriance (ANOVA) method is therefore used to quantify the contribution of three major factors, including precipitation inputs, model parameters, and the interaction of these two, on the uncertainty of calculated water scarcity metrics. Structural uncertainty is implicitly addressed through the use of the modified version of the VIC model. The results indicate seasonality of these contributions for the two metrics under investigation and the differences in relative contribution of different sources to the overall uncertainty. The proposed framework could be employed to identify water stress in various spatiotemporal scales across the globe.

Chloride binding mechanism in seawater-mixed UHPC

The rapid development of marine concrete structures and the sharp shortage of freshwater resources contribute to the wide investigation of seawater-mixed ultra-high-performance concrete (SWUHPC). However, few studies have investigated the chloride ions (Cl-) binding mechanism of SWUHPC. Herein, the chloride binding experiments and molecular dynamics (MD) simulation were carried out to reveal the physically and chemically bound Cl- mechanisms of SWUHPC. The results of the experiments clearly demonstrate that the addition of silica fume (SF) led to a significant decrease in the capacity of Cl- binding. Conversely, the incorporation of metakaolin (MK) resulted in a marked increase in the content of chemically bound Cl-. Furthermore, it is revealed through MD simulations that the amount of physically bound Cl- heavily depends on the Ca/Si ratio of C-S-H. A higher Ca/Si ratio results in a stronger electrostatic effect of the C-S-H surface on Cl-, which increases the physical binding of Cl- via Ca-Cl bonds. In addition, it is found that Al[6] and Ca in the interlayer region of C-A-S-H formed the main structure layer (Ca4Al2(OH)122+) of Friedel’s salt, and then chemically adsorbed Cl- in the pore solution. These findings provide novel nanoscale insights regarding the physically and chemically bound Cl- mechanisms of SWUHPC.

Multi‐Dimensional Bionic Micro‐Nanostructure Surface for Controllable Fog Harvesting: from Fabrication to Application

AbstractWith the rapid growth of the population and the development of the economy, the shortage of freshwater resources has become a worldwide problem. Utilizing fog harvesting provides a practical solution to relieve the water shortage problem for residents in arid regions. This review summarizes the typical fog harvesting phenomena in nature in detail, the construction methods, fog harvesting performance, and the action mechanism of different biomimetic micro‐nano structures from one‐dimensional (1D), two‐dimensional (2D), and three‐dimensional (3D) perspectives. The influence of surface micro‐nano structure and wettability on water harvesting performance is analyzed. Finally, the challenges and future development directions of multi‐scale micro‐nano surface controllable water harvesting technology are summarized and prospected, which provides a good idea for the design of bioinspired micro‐nanomaterials and promotes water harvesting from scientific research to practical application.

Superhydrophobic Bulgy Windmill for Synchronous Efficient Fog Collection and Power Generation.

The shortage of freshwater resources is a serious problem faced by mankind in the 21st century. To maximize the acquisition of freshwater resources, numerous fog collectors have been constructed. In the process of fog collection accompanied by the movement of the wind, the mechanical energy brought about by the wind is often ignored. Based on this, inspired by beetles and origami art, we designed a windmill installation with a bump on the edge. Droplets nucleate at the windmill bulge and accelerate the transport process under the action of centrifugal force. This leads to quick fog collection and reduces the secondary evaporation rate of freshwater resources. The fog collection efficiency can reach 2.8 times that of the original sample. Moreover, the windmill can convert mechanical energy into electricity while collecting fog, and the operating voltage of a single windmill can reach 0.85 V. After the array, the amount of fog collected by the windmill and the power generation voltage can be increased by multiple times, which realizes the efficient use of energy and provides a new idea for the design of an efficient fog collector in the future.

A comprehensive review on adsorptive removal of azo dyes using functional materials

Abstract The shortage of freshwater resources caused by azo dye pollution is an acute global issue, which has a great impact on environmental protection and human health. Therefore, the use of new strategies for designing and synthesizing green, efficient, and economical materials for the removal of azo dyes is required. Among the various methods for removal of azo dyes, adsorption by using advanced functional materials, including nanomaterials, metal oxides, metal oxides–polymer composite, biomaterials, and porous materials, have attracted significant attention over the past few years because of their capabilities of brilliant removal efficiency, high selectivity, quick response, reversibility, flexibility in operation, and less harmful by-products. In this review, we report the adsorption of azo dyes and general design principles underlying the above-mentioned functional materials and, in particular, highlight the fundamental mechanisms and effect of various environmental conditions; also, current challenges and opportunities in this exciting field have been emphasized, including the fabrication, subsequent treatment, and potential future applications of such functional materials.

Highly efficient freezing desalination technology: Parameters optimization and model configuration

Seawater desalination has become an available route to reduce the shortage of freshwater resources. Lower energy consumption and suitable operational conditions make freezing crystallization a green technique in the desalination area. Herein, we coupled the sweating intensification with the freezing crystallization to reach a highly efficient desalination performance. Under the trajectory of the freezing temperature and time: 259.15 K and 150 min, the sweating temperature, heating rate, and sweating time: 272.15 K, 0.5 K/min, and 120 min, the desalination ratio exceeds 70 %. Meanwhile, we established the theoretical models to expound the intrinsic correlations of process variables and target parameters, to visualize the impurity migration. Two kinetic models are proposed to analyze temperature effects on the crystal layer growth, sweating melt flow, and inclusion entrapment. Next, the fractal slice model is proposed to describe the complex microstructure of the crystal pillar. The thermal coefficients are deduced based on the fractal theory, where the larger porosity is against thermal conduction. Finally, we discussed the kinetic and porosity effects on the impurity migration and desalination performance, and established a boundary layer model to correlate the separation efficiency with process kinetic and impurity distribution successfully.

Response of Soil Fungal Community to Biochar Application Under Different Irrigation Water Salinity

Saline water irrigation can alleviate the shortage of freshwater resources in the northwest arid zone, but long-term saline water irrigation can damage the soil fungal community structure. To alleviate the harm caused by salinity, biochar is used as a soil amendment to improve the soil fungal community structure. To investigate the intrinsic link between biochar application and the structural diversity of fungal communities in saline soils, two irrigation water salinity levels were set:0.35 dS·m-1 (fresh water) and 8.04 dS·m-1 (saline water). At each irrigation water salinity, two levels of biochar application were set:0 t·hm-2 (no application) and 3.7 t·hm-2 (application). High-throughput sequencing results showed that compared to that under fresh water irrigation, saline water irrigation increased fungal community species diversity and decreased fungal community species richness; biochar application under saline water irrigation reduced soil fungal community species diversity and species richness. The dominant fungal phyla in the soils of each treatment were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, Glomeromycota, Rozellomycota, and Cysticercales, and the dominant genera were Gibberella, Chaetomium, Sarocladium, Stachybotrys, and Fusarium. Compared to that under freshwater irrigation, saline water irrigation significantly increased the relative abundance of Basidiomycota and Chytridiomycota and significantly decreased the relative abundance of Ascomycota and Rozellomycota. The application of biochar under saline irrigation significantly increased the relative abundance of Ascomycota and Sarocladium but significantly decreased the relative abundance of Basidiomycota, Chaetomium, and Fusarium. LEfSe analysis showed that under the condition of no biochar application, saline irrigation reduced the number of potential biomarkers of fungal communities, whereas the application of biochar under the condition of saline irrigation increased the number of potential biomarkers of fungal communities. These results indicated that the application of biochar can improve the saline soil environment and fungal community structure and provide a theoretical basis for reasonable brackish water irrigation and soil fertilization in arid areas.

Highly Efficient and Durable P, Ru-CeO2 Self-supporting Electrodes Toward Industrial-level Hydrogen Production

The electrolysis of seawater has become a preferred method for hydrogen production since the current shortage of freshwater resources, offering an effective strategy to address the energy crisis. Nevertheless, this...

Janus membrane with asymmetric wettability for efficient oil/water separation

The rapid development of society and industry as well as the frequent occurrence of oil spills cause the shortage of fresh water resources, which not only affects human safety and life, but also impedes the world-wide sustainable development. To address these challenges, novel membrane materials with unique wettability properties have gained significant attention, particularly in the field of oil/water separation. In this research, we modified the hydrophobic PET fabric to achieve superhydrophilic characteristics using impregnation method. Subsequently, we electrospun hydrophobic PVDF fibers onto the superhydrophilic fabric surface, and PVDF/Ca10(PO4)6(OH)2@PET Janus membrane with asymmetric wettability was obtained. The membrane has an excellent unidirectional liquid transport capacity, and can effectively separate heavy oil or light oil, the separation efficiency is more than 90 %. The results also show that the Janus membrane can be used under alkaline conditions and has satisfactory tensile resistance and re-use performance. This work provides a new idea for Janus membrane design and effectively improves the application potential of the Janus membrane in the field of oil/water separation.

Multifunctional graphene/Ag hydrogel with antimicrobial and catalytic properties for efficient solar-driven desalination and wastewater purification

The increasing shortage of freshwater resources needs to be addressed urgently. Solar-driven desalination and wastewater purification are efficient and green methods to obtain freshwater resources. However, it is still a challenge to obtain efficient, stable, salt-resistant, antimicrobial, and antifouling evaporators. To address this challenge, in this study, polyacrylamide-based reduced graphene oxide hydrogels with a porous structure were synthesized in situ by a one-step radiative reduction method, and silver nanoparticles were introduced on this basis. Graphene/silver composite hydrogel (ArG-Ag) exhibits fast water transport, thermal localization, and low enthalpy of water evaporation, achieving an excellent evaporation rate of 3.089 kg m-2h−1 (one sun) and an evaporation efficiency of 122.7 %, as well as good mechanical stability, salt resistance, and salt ion purification after 8 cycles of evaporation. The ArG-Ag evaporator exhibits 99 % 24 h bacterial inhibition against E. coli and 210-day long-term mold resistance, effectively resisting biological contamination of seawater. In this study, multifunctional evaporators with integrated high efficiency evaporation performance, salt resistance, antimicrobial, antifungal, antifouling, and catalytic properties are proposed, which are expected to be used for seawater desalination and wastewater purification.

Evaluation of Furrow Irrigation System on Head Cabbage Yield and Water Use Efficiency in Arbegona Woreda, Ethiopia

Available fresh water resources are subjected to an ever-increasing pressure due to extensive agricultural water demand for irrigated lands. A long-term perspective in shortage of fresh water resources, especially in arid and semi-arid area, highlights an urgent solution for innovative irrigation strategies and agricultural water management. The experiment was conducted in Arbegona district, Sidama region of Ethiopia. This experiment was conducted to evaluate and demonstrate of Alternative, Fixed and Conventional furrow irrigations on Head Cabbage yield and water use efficiency. To achieve this objective the treatment were three furrow irrigation method (Conventional, Alternate and Fixed furrow) laid out in a random complete block design (RCBD) with three replications. The result shows that there is no significant difference between alternative and conventional furrow irrigation on Head cabbage yield. But, fixed furrow irrigation system reduces the yield significantly. The maximum yield (48407kg/ha and 43840kg/ha) was obtained from conventional and alternate furrow irrigation method, respectively. The minimum yield (35242kg/ha) was obtained under fixed furrow irrigation. Furrow irrigation method has no significant effect on plant height, head weight and head diameter of head cabbage. The highest water use efficiency was obtained from alternate furrow irrigation and shows significant difference between the other treatments. Therefore, to save water, labour and time without significant yield reduction alternate furrow irrigation is recommended in water scarce area of Ethiopia.

A Fe-Ni-MOF-74@bamboo photothermal evaporator for efficient solar steam generation

Solar-driven interfacial steam generation is considered as a promising technology to solve the shortage of fresh water resources by using inexhaustible solar energy. In this field, the challenge comes from the design of an interfacial evaporator with high performance in photothermal conversion, water activation (low evaporation enthalpy) and water delivery ability. Herein, a composite evaporator was prepared by in-situ composition of bamboo and Fe-Ni-MOF-74 and subsequently simple carbonization. In this evaporator, bamboo ensures that water quickly reaches the evaporation interface, and rich hydrophilic groups have the function of activating water molecules. Fe-Ni-MOF-74 enhances photothermal effect due to bimetallic coordination. In addition, the hydrophilic feature and the pore structure strengthen the water activation and water absorption capacity. Meanwhile, carbonization under mild conditions compensates for the light absorption. As an outcome, the evaporator achieves high evaporation rate (3.61 kg m−2 h−1), high solar-vapor conversion efficiency (153 %), low evaporation enthalpy (1.517 kJ g−1), good stability in saline water and antibacterial function. Furthermore, both seawater and wastewater purified by the evaporator comply with drinking water standards. In the outdoor experiment, the evaporator can collect water of 4.01 kg m−2 during one daylight. The result highlights great potential of bamboo and MOF composite evaporator for producing fresh water using solar energy.

Natural multiscale channeled salt resistant solar evaporator for efficient and long-term water desalination

Solar steam evaporation exhibits great potential in solving the global shortage of freshwater resources. However, salt accumulation at the top photothermal conversion surface has severely limited the desalination efficiency and stability of solar desalination systems. Herein, we demonstrated a nature-inspired salt resistant bilayered evaporator by using a slight delignificated tree root as bottom substrate and decorated graphene oxide layer as the top absorber surface. The naturally design of tree root inherently exists multilevel vertical channels interconnected porous microstructures. This distinctive structure of tree root allows ultra-high-speed water transport capability and rapid multi-directional salt exchange, enabling it to possess anti-salt-accumulation properties for solar steam generation. This designed tree root-based evaporator effectively prevented salt accumulation while maintaining a fast and stable evaporation rate, which exhibited an evaporation rate of 1.60 kg m−2 h−1 with excellent long-term stability in a high-salinity brine (21 wt%) under 1 sun irradiation. Taking the unparalleled advantages, our designed tree root-based evaporator obtained by a facile fabrication method represents a high-efficacy and stable fresh water production platform for practical applications in water purification.

Graphene aerogel-doped CoFe2O4/MoS2 sheets for magnetic oil absorption and the degradation of contaminants

In recent years, oil spills and the discharge of industrial organic wastewater have not only damaged society and the economy, but also have had a negative impact on the human environment. The composition of oily wastewater is complex and hazardous. It mainly comprises insoluble organic substances and unsaturated aliphatic hydrocarbons. It exists in the form of oil–water mixtures, freely suspended emulsions, and stable emulsions containing surfactants. The shortage of fresh water resources and how to effectively separate oil and water present serious challenges to the scientific community. In this study, we designed a graphene aerogel with magnetic oil-absorbing functionality, which not only has emulsion-breaking functionality, but also can repeatedly adsorb organic pollutants. More importantly, it exhibits a strong Fenton catalytic effect and can effectively degrade pollutants. The aerogel designed in this research integrates adsorption, catalysis and degradation, and exhibits excellent purification of wastewater containing pollutants such as dyes, antibiotics and aromatic hydrocarbons, providing a novel insight into the treatment of oily wastewater.

T-shape solar evaporator constructed with natural wood and Ti2O3 nanoparticles for water evaporation and desalination

Desalination by solar-driven interfacial evaporation is considered as an effective green way to solve the shortage of fresh water resources. However, traditional interfacial evaporation systems are subject to heat loss. In this work, we designed and constructed a T-shape solar evaporator by using natural wood as a support and black Ti2O3 nanoparticles (NPs) with a narrow band-gap as a photothermal conversion material. As a T-shape support, natural wood with good hydrophilicity, well-arranged hierarchical channels and low thermal conductivity not only hinders the loss of conducted heat to water, but also ensures a high rate of moisture transport. As the top solar energy absorption layer for thermal localization and salt collection, horizontal wood surface coated by Ti2O3 NPs has a total solar absorption capacity of 93.6% over the full spectrum. A colorless acid-catalyzed silica sol (ACSS) as a binder is introduced in order to improve the adhesion of Ti2O3 NPs on the wood surface. The horizontal wood is connected vertically with another piece of wood for transporting water and providing thermal insulation. The constructed T-shape evaporator achieves a water evaporation rate of 2.33 kg/m2/h for pure water under 1 sun irradiation. In a desalination experiment, the water evaporation rate is 0.31 kg/m2/h and the salt recovery rate is stable up to 50 h at 31.13 g/m2/h. This work may provide new insights into the design and construction of low-cost, environmentally friendly and efficient solar evaporators for seawater desalination.

Atmospheric Water Harvesting in Microporous Organic Polymers Constructed from Trazine and Benzimidazole Units

AbstractPorous materials‐assisted atmospheric water harvesting (AWH) approaches are attractive for addressing the severe shortage of freshwater resources. Herein, ionothermal polymerization approach was employed to realize four porous organic polymers (FJU‐CTFs) with strong hydration stability and low skeleton density for atmospheric water harvesting. The materials exhibited ultra‐high water vapor adsorption capacity (1108 cm3 g−1), s‐type adsorption isotherms, and rapid filling of water vapor in the pores of the materials under low humidity conditions. It has the characteristics of atmospheric water harvesting from the air at lower humidity (30 %–40 %) and narrow temperature (30–35 °C). A total of 30 times of water adsorption‐desorption cycles showed the excellent working ability and hydrolytic stability of FJU‐CTFs, which provided new solutions for the application of porous materials in AWH and expanded new material types.

Recent Advances and Challenges of Metal‐Based Materials for Solar Steam Generation

AbstractGlobal energy and environmental problems are becoming increasingly prominent, and the shortage of freshwater resources has been plaguing many countries and regions in the world. Solar steam generation (SSG) has emerged as a green, low‐cost and efficient strategy for freshwater production, which has attracted enormous attention in recent years. Furthermore, various photothermal materials and structural designs for the preparation of efficient SSG systems have been widely reported. Among them, metal‐based photothermal materials are abundant, and the exploration on metal‐based SSG systems is one of the important research directions. In this review, the basic concepts and design objectives of current metal‐based SSG systems are first introduced, as well as advances in the recent development of metal‐based photothermal materials, including photothermal mechanisms, and preparation methods. The evaluation criteria of the SSG system are further described. Then the development of metal‐based SSG systems is summarized in terms of structural design, functional modules (light absorption, thermal management, water transport, salt rejection, etc.), and potential applications (wastewater treatment, sterilization and other fields). Finally, the main challenges and future prospects of metal‐based SSG systems in basic research and practical applications are emphasized.