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Xiangqian Fan, Yang Yang, Xinlei Shi et al.
Advanced Functional Materials · 2020
A solar‐thermal water evaporation structure that can continuously generate clean water with high efficiency and good salt rejection ability under sunlight is highly desirable for water desalination, but its realization remains challenging. Here, a hierarchical solar‐absorbing architecture is designed and fabricated, which comprises a 3D MXene microporous skeleton with vertically aligned MXene nanosheets, decorated with vertical arrays of metal–organic framework‐derived 2D carbon nanoplates embedded with cobalt nanoparticles. The rational integration of three categories of photothermal materials enables broadband light absorption, efficient light to heat conversion, low heat loss, rapid water transportation behavior, and much‐improved corrosion and oxidation resistance. Moreover, when assembling with a hydrophobic insulating layer with hydrophilic channel, the MXene‐based solar absorber can exhibit effective inhibition of salt crystallization due to the ability to advect and diffuse concentrated salt back into the water. As a result, when irradiating under one sun, the solar‐vapor conversion efficiency of the MXene‐based hierarchical design can achieve up to ≈93.4%, and can remain over 91% over 100 h to generate clean vapor for stable and continuous water desalination. This strategy opens an avenue for the development of MXene‐based solar absorbers for sustainable solar‐driven desalination.
Keyuan Xu, Chengbing Wang, Zhengtong Li et al.
Advanced Functional Materials · 2020
Solar‐driven interfacial desalination (SDID), which is based on localized heating and interfacial evaporation, provides an opportunity for developing environmentally friendly and cost‐effective seawater thermal desalination. However, localized heating and rapidly generated interfacial steam may cause salt to accumulate on the evaporator's surface and block the channel of steam evaporation. Salt accumulation inevitably reduces the light absorption and service period of the solar absorber, resulting in a significant decrease in evaporation efficiency over time. Salt accumulation makes it difficult to produce SDID devices with high energy efficiency and long‐term stability for large‐scale use in remote poverty‐stricken areas. Therefore, the exploration of novel and effective strategies for addressing salt accumulation through both material design and structural engineering has attracted more attention in recent years. This review presents an overview of the state‐of‐the‐art advancements in salt‐resistant photothermal evaporation and discusses the critical issues for achieving salt mitigation SDID, focusing on the classification of salt mitigation strategies based on photothermal evaporation configurations, the basic mechanism of salt mitigation, and the architectural design of photothermal materials. Finally, the important challenges and prospects of SDID are discussed to providing a meaningful roadmap to efficient salt mitigation SDID.
M. Al‐Obaidi, Rana H. A. Zubo, F. Rashid et al.
Energies · 2022
Solar energy, amongst all renewable energies, has attracted inexhaustible attention all over the world as a supplier of sustainable energy. The energy requirement of major seawater desalination processes such as multistage flash (MSF), multi-effect distillation (MED) and reverse osmosis (RO) are fulfilled by burning fossil fuels, which impact the environment significantly due to the emission of greenhouse gases. The integration of solar energy systems into seawater desalination processes is an attractive and alternative solution to fossil fuels. This study aims to (i) assess the progress of solar energy systems including concentrated solar power (CSP) and photovoltaic (PV) to power both thermal and membrane seawater desalination processes including MSF, MED, and RO and (ii) evaluate the economic considerations and associated challenges with recommendations for further improvements. Thus, several studies on a different combination of seawater desalination processes of solar energy systems are reviewed and analysed concerning specific energy consumption and freshwater production cost. It is observed that although solar energy systems have the potential of reducing carbon footprint significantly, the cost of water production still favours the use of fossil fuels. Further research and development on solar energy systems are required to make their use in desalination economically viable. Alternatively, the carbon tax on the use of fossil fuels may persuade desalination industries to adopt renewable energy such as solar.
Abdul Najim
npj Clean Water · 2022
Freeze desalination (FD) has several benefits compared to vaporization-based and membrane-based desalination methods. The FD process needs approximately 1/7th of the latent heat required by the vaporization-based desalination processes. The involvement of sub-zero temperature in FD reduces the risk of corrosion and scaling. This paper reviews the advances in FD methods involving stand-alone and hybrid methods that operate with and without utilizing the energy released during the re-gasification of liquefied natural gas. Moreover, the paper discusses the future focus areas for research and development to make FD a commercially feasible technology. Potable water was produced from brackish water and seawater by FD wherein the nucleation was achieved by ice seeding, the mixing of rejected salt from ice into the liquid phase was controlled appropriately, growth of ice crystals was slow, and liquid subcooling was maintained at approximately 4 K. The post-treatment of obtained ice is needed to produce potable water if the process is instigated without ice seeding. The plant capacity of stand-alone progressive FD was higher than the stand-alone suspension FD of seawater. The integration of the falling-film, fractional thawing, and block FD method showed significantly improved plant capacity than the stand-alone suspension FD method. The energy consumption of stand-alone PFC and SFC-based desalination with latent heat recovery was reported close to the reverse osmosis (RO) method. The hybrid (integration of the suspension FD method with membrane distillation) FD method utilizing LNG cold energy consumed less energy than the conventional RO method.
Zhuoyi Li, Xu Ma, Danke Chen et al.
Advanced Science · 2021
Though evaporation‐driven electricity generation has emerged as a novel eco‐friendly energy and attracted intense interests, it is typically demonstrated in pure water or a very low salt concentration. Integrating evaporation‐driven electricity generation and solar steam desalination simultaneously should be more promising. Herein, a polyaniline coated metal‐organic frameworks (MOFs) nanorod arrays membrane is synthesized which inherits the merits of both polyaniline and MOFs, demonstrating nice stability, good interfacial solar steam desalination, and evaporation‐driven electricity generation. Moreover, an integrated system based on this hybrid membrane achieves good interfacial solar‐heating evaporation and prominently enhanced evaporation‐driven electricity generation under one sun. Notably, the realization of effective seawater desalination and efficient evaporation‐driven electricity generation simultaneously by the non‐carbon‐based materials is reported for the first time, which provides a new alternative way for cogenerating both freshwater and electricity by harvesting energy from seawater and solar light.
N. Dhakal, S. G. Salinas-Rodríguez, Jamal Hamdani et al.
Membranes · 2022
Rapid population growth and urbanization are two main drivers for the over-abstraction of conventional freshwater resources in various parts of the world, which leads to the situation of water scarcity (per capita availability <1000 m3/year). Predictions based on the World Bank projected population data and the FAO AQUASTAT database for freshwater availability show that by 2050, 2 billion people living in 44 countries will likely suffer from water scarcity, of which 95% may live in developing countries. Among these, the countries that will likely be most strongly hit by water scarcity by 2050 are Uganda, Burundi, Nigeria, Somalia, Malawi, Eritrea, Ethiopia, Haiti, Tanzania, Niger, Zimbabwe, Afghanistan, Sudan, and Pakistan. Currently, these countries have not yet established desalination to meet their freshwater demand. However, the current global trend shows that membrane-based desalination technology is finding new outlets for supplying water to meet growing water demand in most of the water-scarce countries. These 14 water-scarce countries will demand an additional desalination capacity of 54 Mm3/day by 2050 in order to meet the standard of current municipal water demand and to compensate for the withdrawal of renewable resources. Case studies from India, China, and South Africa have highlighted that other countries may apply the strategy of using desalinated water for industrial users. Moreover, challenges to the widespread adoption of desalination exist such as expense, significant energy use, the need for specialized staff training, the large carbon footprint of facilities, environmental issues such as greenhouse gas emission (GHGs), chemical discharge, and operational problems such as membrane fouling.
Mustafa Omerspahic, H. Al-Jabri, S. A. Siddiqui et al.
Frontiers in Marine Science · 2022
At a time when worldwide water shortage is increasing, seawater is being viewed as an inexhaustible supply of freshwater via the process of seawater desalination. As a result, seawater desalination is becoming more popular, especially in areas where freshwater is scarce, such as the Middle East and North Africa (MENA), which accounts for half of all global saltwater desalination activities. To enhance the efficiency of saltwater desalination, thermal and membrane-based desalination technologies are continually being developed and hybridized systems established. Brine is an unavoidable product of seawater desalination and is commonly disposed of in oceans and seas, where it has negative effects on the surrounding marine environment and its biodiversity due to the resultant increased salinity and temperature, as well as the presence of chemicals. Furthermore, the quality and amount of brine are influenced by several parameters, including the input quality and quantity, the desalination process, and the discharge method. The intensity of brine’s influence on the marine biota is determined by a number of factors; nevertheless, marine species differ in their tolerance to brine’s effects. Desalination technology is improving to maximize water recovery and reduce the volume of brine produced, with the objective of eventually reaching zero liquid discharge and limiting harmful effects on the marine environment. Meanwhile, proper systems for analyzing the effects of seawater desalination facilities on the marine ecology must be implemented. This review study will look at all of the factors that determine the physicochemical features of desalination brine, with a focus on its impact on marine chemistry and biodiversity. More crucially, the most cutting-edge brine management methods will be investigated for long-term desalination and a healthy marine ecosystem.
Youhong Guo, Xingyi Zhou, Fei Zhao et al.
ACS Nano · 2019
Precisely controlled distribution of energy in solar-to-thermal energy conversion systems could allow for enhanced energy utilization. Light absorbing hydrogels provide a means for evaporating water by using solar energy, yet targeted delivery of solar thermal energy to power the water evaporation process remains challenging. Here we report a light-absorbing sponge-like hydrogel (LASH) that is created by in-situ gelation of a light absorbing nanoparticle-modified polymer leading to synergistic energy nanoconfinement and water activation. By means of experimental demonstration and theoretical simulation, the LASH presents record high vapor generation rates up to ~3.6 kg m-2 h-1 and stable long-term performance under one sun (1 kW m-2) irradiation. We investigate the energy confinement at the polymer-nanoparticle interphases and the water activation enabled by polymer-water interaction to reveal the significance of such effects for high-rate solar vapor generation. The water vaporization enabled by LASHs can remove over 99.9% of salt ions in seawater through solar water desalination. The fundamental design principle, scalable fabrication route and superior performance offer possibilities for portable solar water purification, industrial solar-powered water treatment and other advanced solar thermal applications.
Xiangyang Dong, Y. Si, Chaoji Chen et al.
ACS Nano · 2021
Sufficient and clean freshwater is still out of reach for billions of people around the world. Solar desalination from brine is regarded as one of the most promising proposals to solve this severe crisis. However, most of the reported evaporators to date still suffer from the decreasing evaporation rate caused by salt crystallization accumulated on their surface. Here, inspired by the vascular tissue structure, transpiration, and antifouling function of reed leaves, we design biomimetic hierarchical nanofibrous aerogels with parallel-arranged vessels and hydrophobic surfaces for highly efficient and salt-resistant solar desalination. Foldable vessel walls and flexible silica nanofibers give the reed leaf-inspired nanofiber aerogels (R-NFAs) excellent mechanical properties and enable them to withstand repeated compression. Besides, the R-NFAs can efficiently absorb sunlight (light absorption efficiency: 94.8%) and evaporate the brine to vapor, similar to reed leaves (evaporation rate: 1.25 kg m-2 h-1 under 1 sun). More importantly, enabled by the hydrophobic surfaces and parallel-arranged vessels, the R-NFAs can work stably in high-concentration brine (saturated, 26.3 wt %) under high-intensity light (up to 6 sun), demonstrating potent salt resistance. It is expected that R-NFAs with combined antisalt pore and surface structures will provide a designed concept for salt-resistant solar desalination.
Yang Yang, Ruiqi Zhao, Tengfei Zhang et al.
ACS Nano · 2018
Harvesting solar energy for desalination and sewage treatment has been considered as a promising solution to produce clean water. However, state-of-the-art technologies often require optical concentrators and complicated systems with multiple components, leading to poor efficiency and high cost. Here, we demonstrate an extremely simple and standalone solar energy converter consisting of only an as-prepared 3D cross-linked honeycomb graphene foam material without any other supporting components. This simple all-in-one material can act as an ideal solar thermal converter capable of capturing and converting sunlight into heat, which in turn can distill water from various water sources into steam and produce purified water under ambient conditions and low solar flux with very high efficiency. High specific water production rate of 2.6 kg h-1 m-2 g-1 was achieved with near ∼87% under 1 sun intensity and >80% efficiency even under ambient sunlight (<1 sun). This scalable sheet-like material was used to obtain pure drinkable water from both seawater and sewage water under ambient conditions. Our results demonstrate a competent monolithic material platform providing a paradigm change in water purification by using a simple, point of use, reusable, and low-cost solar thermal water purification system for a variety of environmental conditions.
Meichun Ding, Hao Lu, Yongbin Sun et al.
Advanced Science · 2022
Superelastic, arbitrary‐shaped, and 3D assembled clay/graphene aerogels (CGAs) are fabricated using commercial foam as sacrificial skeleton. The CGAs possess superelasticity under compressive strain of 95% and compressive stress of 0.09–0.23 MPa. The use of clay as skeletal support significantly reduces the use of graphene by 50%. The hydrophobic CGAs show high solvent absorption capacity of 186–519 times its own weight. Moreover, both the compression and combustion methods can be adopted for reusing the CGAs. In particular, it is demonstrated a design of 3D assembled hydrophilic CGA equipped with salt collection system for continuous solar desalination. Due to energy recovery and brine transport management promoted by this design, the 3D assembled CGA system exhibits an extremely high evaporation rate of 4.11 kg m−2 h−1 and excellent salt‐resistant property without salt precipitation even in 20 wt% brine for continuous 36 h illumination (1 kW m−2), which is the best reported result from the solar desalination devices. More importantly, salts can be collected conveniently by squeezing and drying the solution out of the salt collection system. The work provides new insights into the design of 3D assembled CGAs and advances their applications in continuous solar desalination and efficient oil/organic solvent adsorption.
G. Ni, S. H. Zandavi, Seyyed Morteza Javid et al.
Energy & Environmental Science · 2018
Although desalination technologies have been widely adopted as a means to produce freshwater, many of them require large installations and access to advanced infrastructure. Recently, floating structures for solar evaporation have been proposed, employing the concept of interfacial solar heat localization as a high-efficiency approach to desalination. However, the challenge remains to prevent salt accumulation while simultaneously maintaining heat localization. This paper presents an experimental demonstration of a salt-rejecting evaporation structure that can operate continuously under sunlight to generate clean vapor while floating in a saline body of water such as an ocean. The evaporation structure is coupled with a low-cost polymer film condensation cover to produce freshwater at a rate of 2.5 L m−2 day−1, enough to satisfy individual drinking needs. The entire system's material cost is $3 m−2 – over an order of magnitude lower than conventional solar stills, does not require energy infrastructure, and can provide cheap drinking water to water-stressed and disaster-stricken communities.
Miaomiao Zou, Yu Zhang, Zheren Cai et al.
Advanced Materials · 2021
Solar‐driven water evaporation has been considered a sustainable method to obtain clean water through desalination. However, its further application is limited by the complicated preparation strategy, poor salt rejection, and durability. Herein, inspired by superfast water transportation of the Nepenthes alata peristome surface and continuous bridge‐arch design in architecture, a biomimetic 3D bridge‐arch solar evaporator is proposed to induce Marangoni flow for long‐term salt rejection. The formed double‐layer 3D liquid film on the evaporator is composed of a confined water film for water supplementation and a free‐flowing water film with ultrafast directional Marangoni convection for salt rejection, which functions cooperatively to endow the 3D evaporator with all‐in‐one function including superior solar‐driven water evaporation (1.64 kg m‐2 h‐1, 91% efficiency for pure water), efficient solar desalination, and long‐term salt‐rejecting property (continuous 200 h in 10 wt% saline water) without any post‐cleaning treatment. The design principle of the 3D structures is provided for extending the application of Marangoni‐driven salt rejection and the investigation of structure‐design‐induced liquid film control in the solar desalination field. Furthermore, excellent mechanical and chemical stability is proved, where a self‐sustainable and solar‐powered desalination–cultivation platform is developed, indicating promising application for agricultural cultivation.
Xuezhen Feng, Renji Zheng, Caiyan Gao et al.
Nature Communications · 2022
Ultrathin two-dimensional (2D) metal oxyhalides exhibit outstanding photocatalytic properties with unique electronic and interfacial structures. Compared with monometallic oxyhalides, bimetallic oxyhalides are less explored. In this work, we have developed a novel top-down wet-chemistry desalination approach to remove the alkali-halide salt layer within the complicated precursor bulk structural matrix Pb0.6Bi1.4Cs0.6O2Cl2, and successfully fabricate a new 2D ultrathin bimetallic oxyhalide Pb0.6Bi1.4O2Cl1.4. The unlocked larger surface area, rich bimetallic active sites, and faster carrier dynamics within Pb0.6Bi1.4O2Cl1.4 layers significantly enhance the photocatalytic efficiency for atmospheric CO2 reduction. It outperforms the corresponding parental matrix phase and other state-of-the-art bismuth-based monometallic oxyhalides photocatalysts. This work reports a top-down desalination strategy to engineering ultrathin bimetallic 2D material for photocatalytic atmospheric CO2 reduction, which sheds light on further constructing other ultrathin 2D catalysts for environmental and energy applications from similar complicate structure matrixes. Ultrathin two-dimensional metal oxyhalides show excellent photocatalytic properties with unique electronic and interfacial structures. Here, the authors develop a top-down desalination strategy to engineer ultrathin bimetallic two-dimensional material for photocatalytic atmospheric carbon dioxide reduction.
Zhangxin Wang, Thomas Horseman, Anthony P. Straub et al.
Science Advances · 2019
We review recent advances, limitations, and prospects of solar-thermal desalination for sustainable, low-cost water production. Solar-thermal desalination (STD) is a potentially low-cost, sustainable approach for providing high-quality fresh water in the absence of water and energy infrastructures. Despite recent efforts to advance STD by improving heat-absorbing materials and system designs, the best strategies for maximizing STD performance remain uncertain. To address this problem, we identify three major steps in distillation-based STD: (i) light-to-heat energy conversion, (ii) thermal vapor generation, and (iii) conversion of vapor to water via condensation. Using specific water productivity as a quantitative metric for energy efficiency, we show that efficient recovery of the latent heat of condensation is critical for STD performance enhancement, because solar vapor generation has already been pushed toward its performance limit. We also demonstrate that STD cannot compete with photovoltaic reverse osmosis desalination in energy efficiency. We conclude by emphasizing the importance of factors other than energy efficiency, including cost, ease of maintenance, and applicability to hypersaline waters.
B. A. Sharkh, Ahmad A. Al-Amoudi, M. Farooque et al.
npj Clean Water · 2022
The ocean has often been announced as a sustainable source of important materials for civilization. Application of the same extraction processes to desalination concentrate, rather than to unconcentrated seawater, will necessarily be more energetically favorable, so the expansion of seawater desalination in recent decades brings this dream closer to reality. However, there is relatively little concrete commercial development of ‘concentrate mining’. This review assesses the technical and economic prospects for utilization of commercially viable products from seawater. The most important technologies for economic use of products from desalination plant concentrate are technologies for more economic separation and technologies for more economic concentration. The most promising separation technologies are those, such as nanofiltration, which separate brine into streams enriched/depleted in entire classes of constituents with minimal input of energy and reagents. Concentration is becoming more economic due to rapid advances in Osmotically-Assisted RO technology. Despite very active research on many aspects of desalination concentrate utilization, it is likely that commercial development of the non-NaCl components of desalination brine will depend on the available market for NaCl, as the challenges and costs of extracting the other mineral components from bitterns in which they are highly enriched are so much less than those faced in direct treatment of brines.
Yaoxin Zhang, T. Xiong, Dilip Krishna Nandakumar et al.
Advanced Science · 2020
The past few years have witnessed a rapid development of solar‐driven interfacial evaporation, a promising technology for low‐cost water desalination. As of today, solar‐to‐steam conversion efficiencies close to 100% or even beyond the limit are becoming increasingly achievable in virtue of unique photothermal materials and structures. Herein, the cutting‐edge approaches are summarized, and their mechanisms for photothermal structure architecting are uncovered in order to achieve ultrahigh conversion efficiency. Design principles to enhance evaporation performance and currently available salt‐rejection strategies for long‐term desalination are systematically investigated. The guidelines to utilize every component in solar desalination systems for simultaneous in situ energy generation are also revealed. Finally, opportunities and challenges for future works in this field are also discussed and concluded.
Lei Wu, Z. Dong, Zheren Cai et al.
Nature Communications · 2020
Solar-driven water evaporation represents an environmentally benign method of water purification/desalination. However, the efficiency is limited by increased salt concentration and accumulation. Here, we propose an energy reutilizing strategy based on a bio-mimetic 3D structure. The spontaneously formed water film, with thickness inhomogeneity and temperature gradient, fully utilizes the input energy through Marangoni effect and results in localized salt crystallization. Solar-driven water evaporation rate of 2.63 kg m−2 h−1, with energy efficiency of >96% under one sun illumination and under high salinity (25 wt% NaCl), and water collecting rate of 1.72 kg m−2 h−1 are achieved in purifying natural seawater in a closed system. The crystalized salt freely stands on the 3D evaporator and can be easily removed. Additionally, energy efficiency and water evaporation are not influenced by salt accumulation thanks to an expanded water film inside the salt, indicating the potential for sustainable and practical applications. Solar-driven water evaporation technology still faces main challenges of limited efficiency and salt fouling. Here the authors achieve high energy efficiency and evaporation rate under high salinity through an energy reutilizing strategy based on interfacial water film inhomogeneity on a biomimetic structure.
Julianne Rolf, Tianchi Cao, Xiaochuan Huang et al.
Environmental Science & Technology · 2022
Inorganic scaling caused by precipitation of sparingly soluble salts at supersaturation is a common but critical issue, limiting the efficiency of membrane-based desalination and brine management technologies as well as other engineered systems. A wide range of minerals including calcium carbonate, calcium sulfate, and silica precipitate during membrane-based desalination, limiting water recovery and reducing process efficiency. The economic impact of scaling on desalination processes requires understanding of its sources, causes, effects, and control methods. In this Critical Review, we first describe nucleation mechanisms and crystal growth theories, which are fundamental to understanding inorganic scale formation during membrane desalination. We, then, discuss the key mechanisms and factors that govern membrane scaling, including membrane properties, such as surface roughness, charge, and functionality, as well as feedwater characteristics, such as pH, temperature, and ionic strength. We follow with a critical review of current characterization techniques for both homogeneous and heterogeneous nucleation, focusing on the strengths and limitations of each technique to elucidate scale-inducing mechanisms, observe actual crystal growth, and analyze the outcome of scaling behaviors of desalination membranes. We conclude with an outlook on research needs and future research directions to provide guidelines for scale mitigation in water treatment and desalination.
Chuxin Lei, Weixin Guan, Youhong Guo et al.
Angewandte Chemie International Edition · 2022
Interfacial solar vapor generation (SVG) is regarded as a promising and sustainable strategy for clean water production. While many materials have demonstrated excellent evaporation rates under one sun, it remains challenging to design solar evaporators without compromising SVG performance in high-salinity brines (≥ 10 wt%). Herein, polyzwitterionic hydrogels (PZHs) are proposed as a novel platform for high-salinity solar desalination. Taking advantage of the unique anti-polyelectrolyte effects, PZHs can trap salt ions from the brine water to form a more hydrated polymer network, leading to enhanced SVG performance. PZHs exhibit an exceptional solar evaporation rate of 4.14 kg m -2 h -1 in 10 wt% brine, which is ~20% higher than that in pure water. It is anticipated that salt-responsive PZHs may provide insights for the design of next-generation solar desalination systems.
Hongqi Zou, Xiangtong Meng, X. Zhao et al.
Advanced Materials · 2022
Solar‐driven water evaporation technology holds great potential for mitigating the global water scarcity due to its high energy conversion efficiency. Lowering the vaporization enthalpy of water is key to boost the performance of solar‐driven desalination. Herein, a highly hydratable hydrogel (PMH) network, consisting of modified needle coke as photothermal material and polyvinyl alcohol (PVA) as hydratable matrix, is crafted via simple physical cross‐linking method. When capitalizing on the PMH as evaporator for 3.5 wt% NaCl solution, a high evaporation rate of 3.18 kg m−2 h−1 under one sun illumination is deliver ed, unexpectedly outperforming that in pure water (2.53 kg m−2 h−1). More importantly, the PMH shows a robust desalination durability, thus enabling a self‐cleaning system. Further investigations reveal that the outstanding evaporation performance of PMH in brine roots in its hydrability tuned by chaotropic Cl−, wherein the Cl− can mediate the hydration chemistry of PVA in PMH and suppress related crystallinity, thus contributing to the increased content of intermediate water and the lowered vaporization enthalpy of brine. This work first scrutinizes the Hofmeister effect on the evaporation behavior of PMH evaporator in brine and provides insights for high‐efficiency solar‐driven interfacial desalination.
Weixin Guan, Youhong Guo, Guihua Yu
Small · 2021
Seawater desalination is viewed as a promising solution to world freshwater scarcity. Solar assisted desalination is proposed to overcome the high energy consumption in current desalination technologies, as it uses abundant and sustainable solar energy as the only energy input. Interfacial solar vapor generation (SVG) has attracted considerable research interest due to its high energy conversion efficiency, simple implementation, and cost-effectiveness. Among all the candidate materials for solar evaporators, carbon-based materials stand out due to their intrinsic high solar absorption, highly tunable structure, easy preparation, low cost, and earth-abundancy. In this review, the recent progress on carbon-based materials for the development of interfacial SVG is summarized. First, a brief introduction to the basic design principles of the interfacial SVG system is presented. Then, recent efforts in carbon-based solar evaporators, from artificial structures to bioinspired configurations, focusing on their structure-function relationship are highlighted. Strategies for designing antisalt-fouling desalination systems are also summarized. Last, the challenges and opportunities of carbon-based materials for solar evaporation technology are elaborated.
Pankaj P. Gohil, H. Desai, Ajay Kumar et al.
Water · 2023
Emerging hybrid technologies have better potential than conventional technology for diversifying the desalination industry, which is presently being dominated by thermal and membrane-based desalination. Notwithstanding the technological maturity of the desalination processes, they remain highly energy-intensive processes and have certain disadvantages. Therefore, the hybridization of thermal and membrane desalination processes holds great attention to mitigate limitations of individual processes in terms of energy consumption, quality and quantity of potable water, overall efficiency and productivity. This paper provides an oversight of conventional and developing desalination technologies, emphasizing their existing state and subsequent potential to reduce water scarcity. Conventional hybrid desalination systems (NF-RO-MSF, MED-AD, FO-MED, MSF-MED, RO-MED, RO-MSF and RO-MD) are briefly discussed. This study reveals that the integration of solar thermal energy with desalination has a great potential to substantially reduce greenhouse emissions besides providing the quality and/or quantity of potable water in cost-effective ways. Due to its abundant availability with minimal/no carbon footprint and the ability to generate both thermal and electrical energy, solar energy is considered better than other renewable energy technologies. The findings further suggest that hybrid desalination systems are technically sound and environmentally suitable; however, a significant study of the research process and development is still required to make this technology efficient and economically viable.
M. K. Shahid, Bandita Mainali, P. Rout et al.
Water · 2023
The rising demand for clean water and the environmental challenges associated with fossil fuels have encouraged the application of renewable and greener energy systems in desalination. Moreover, the small footprint and high productivity favored the membrane-based process in the water industry. In the past few decades, noticeable work has been performed on the development and applicability of membrane-based desalination processes powered by renewable energy sources such as solar, wind, tidal, and geothermal. Several integrated membrane desalination processes for producing clean water with sustainable and clean energy are introduced. This review details the source and performance efficiencies of existing renewable energy technologies and their application in membrane-based desalination processes, with a special focus on current advancements and challenges. This study reviews the interconnections between water, energy, and the environment and explores future energy-efficient desalination options for energy savings and environmental protection.
Tyler E. Culp, Biswajit Khara, Kaitlyn P. Brickey et al.
Science · 2021
Finding the path to better desalination Polyamide membranes have been used in large-scale desalination for decades. However, because of the thinness of the membranes and their internal variability, it has been hard to determine which aspects of the membranes most affect their performance. Culp et al. combined electron tomography, nanoscale three-dimensional (3D) polyamide density mapping, and modeling of bulk water permeability with zero adjustable parameters to quantify the effect of 3D nanoscale variations in polymer mass on water transport within the polyamide membrane (see the Perspective by Geise). They found that variability in local density most affects the performance of the membranes. Better synthesis methods could thus improve performance without affecting selectivity. Science, this issue p. 72; see also p. 31 Electron tomography reveals how inhomogeneities in pore distributions affect performance of water filtration membranes. Biological membranes can achieve remarkably high permeabilities, while maintaining ideal selectivities, by relying on well-defined internal nanoscale structures in the form of membrane proteins. Here, we apply such design strategies to desalination membranes. A series of polyamide desalination membranes—which were synthesized in an industrial-scale manufacturing line and varied in processing conditions but retained similar chemical compositions—show increasing water permeability and active layer thickness with constant sodium chloride selectivity. Transmission electron microscopy measurements enabled us to determine nanoscale three-dimensional polyamide density maps and predict water permeability with zero adjustable parameters. Density fluctuations are detrimental to water transport, which makes systematic control over nanoscale polyamide inhomogeneity a key route to maximizing water permeability without sacrificing salt selectivity in desalination membranes.
Tiezheng Tong, Xitong Liu, Tianshu Li et al.
Environmental Science & Technology · 2023
Membrane desalination that enables the harvesting of purified water from unconventional sources such as seawater, brackish groundwater, and wastewater has become indispensable to ensure sustainable freshwater supply in the context of a changing climate. However, the efficiency of membrane desalination is greatly constrained by organic fouling and mineral scaling. Although extensive studies have focused on understanding membrane fouling or scaling separately, organic foulants commonly coexist with inorganic scalants in the feedwaters of membrane desalination. Compared to individual fouling or scaling, combined fouling and scaling often exhibits different behaviors and is governed by foulant-scalant interactions, resembling more complex but practical scenarios than using feedwaters containing only organic foulants or inorganic scalants. In this critical review, we first summarize the performance of membrane desalination under combined fouling and scaling, involving mineral scales formed via both crystallization and polymerization. We then provide the state-of-the-art knowledge and characterization techniques pertaining to the molecular interactions between organic foulants and inorganic scalants, which alter the kinetics and thermodynamics of mineral nucleation as well as the deposition of mineral scales onto membrane surfaces. We further review the current efforts of mitigating combined fouling and scaling via membrane materials development and pretreatment. Finally, we provide prospects for future research needs that guide the design of more effective control strategies for combined fouling and scaling to improve the efficiency and resilience of membrane desalination for the treatment of feedwaters with complex compositions.
Zewei Hao, Xiaoqi Sun, Jiabin Chen et al.
Small · 2023
Due to substantial consumption and widespread contamination of the available freshwater resources, green, economical, and sustainable water recycling technologies are urgently needed. Recently, Faradic capacitive deionization (CDI), an emerging desalination technology, has shown great desalination potential due to its high salt removal ability, low consumption, and hardly any co-ion exclusion effect. However, the ion removal mechanisms and structure-property relationships of Faradic CDI are still unclear. Therefore, it is necessary to summarize the current research progress and challenges of Faradic CDI. In this review, the recent progress of Faradic CDI from five aspects is systematically reviewed: cell architectures, desalination mechanisms, evaluation indicators, operation modes, and electrode materials. The working mechanisms of Faradic CDI are classified as insertion reaction, conversion reaction, ion-redox species interaction, and ion-redox couple interaction in the electrolytes. The intrinsic and desalination properties of a series of Na+ and Cl- capturing materials are described in detail in terms of design concepts, structural analysis, and synthesis modulation. In addition, the effects of different cell architectures, operation modes, and electrode materials on the desalination performance of Faradic CDI are also investigated. Finally, the work summarizes the challenges remaining in Faradic CDI and provides the prospects and directions for future development.
D. Curto, V. Franzitta, A. Guercio
Applied Sciences · 2021
Desalination is commonly adopted nowadays to overcome the freshwater scarcity in some areas of the world if brackish water or salt water is available. Different kinds of technologies have been proposed in the last century. In this paper, the state of the mainstream solutions is reported, showing the current commercial technologies like reverse osmosis (RO), Multi-Stages Flash desalination (MSF) and Multi-Effect Distillation (MED), and the new frontiers of the research with the aim of exploiting renewable sources such as wind, solar and biomass energy. In these cases, seawater treatment plants are the same as traditional ones, with the only difference being that they use a renewable energy source. Thus, classifications are firstly introduced, considering the working principles, the main energy input required for the treatment, and the potential for coupling with renewable energy sources. Each technology is described in detail, showing how the process works and reporting some data on the state of development. Finally, a statistical analysis is given concerning the spread of the various technologies across the world and which of them are most exploited. In this section, an important energy and exergy analysis is also addressed to quantify energy losses.
S. Dutta, R. F. de Luis, J. Gościanska et al.
Advanced Functional Materials · 2023
Rapid industrialization and ever‐increasing global population culminate in continuous upsurge in freshwater crisis worldwide. The most reliable and promising solution to this crisis is utilizing sea‐water as the freshwater source, and desalination technologies pave the way for efficient production of freshwater from sea‐water. In this regard, membrane‐based desalination method comes forth owing to its' efficient separation, operational ease, and low‐energy consumption. Metal–organic frameworks (MOFs), the most explored crystalline porous materials, show tremendous promise as membrane‐materials for desalination owing to their structural diversity, tunability, and porous voids which provide secondary water channels. Given significant advances are made in MOF‐materials for desalination in the past few years, it is crucial to systematically summarize the recent progress and development of this field. In this review, a brief overview of various saline water systems and prerequisites for desalination are first presented. Then, advanced fabrication strategies MOF‐membranes followed by the recent progress in MOF‐materials for various desalination processes such as reverse osmosis and forward osmosis are systematically summarized. Finally, the authors’ perspectives on the unsolved scientific and technical challenges and opportunities for MOF‐integrated membranes toward real‐world implementation are proposed. With further systematic development, MOF‐materials promise to provide an ideal platform for next‐generation desalination technology.
Marufa Khondoker, Sujata Mandal, Ranjit G Gurav et al.
Earth · 2023
Climate-change-induced freshwater shortage and saline intrusion have been posing significant risks to agricultural sectors in arid and semi-arid regions, negatively impacting irrigation, crop yield, and food production. Climate-smart sustainable solutions are the requirement to combat these major concerns. To overcome freshwater scarcity, pressure-driven desalination techniques are used that require advanced operational systems and electricity, which creates an additional economic burden when applied in the agriculture sector. Therefore, more sustainable methods for soil and water desalination using plant-, microbial-, algal-, biomass-, and carbon-based systems are needed. This scoping review addresses the effects of climate change on freshwater shortage and global food production, the influence of salinity and sodicity on agriculture, and sustainable desalination technologies.
Sushil Kumar, Najat Maher Aldaqqa, E. Alhseinat et al.
Angewandte Chemie International Edition · 2023
Recent years have seen the emergence of capacitive deionization (CDI) as a promising desalination technique for converting sea and wastewater into potable water, due to its energy efficiency and eco-friendly nature. However, its low salt removal capacity and parasitic reactions have limited its effectiveness. As a result, the development of porous carbon nanomaterials as electrode materials have been explored, while taking into account of material characteristics such as morphology, wettability, high conductivity, chemical robustness, cyclic stability, specific surface area, and ease of production. To tackle the parasitic reaction issue, membrane capacitive deionization (mCDI) was proposed which utilizes ion-exchange membranes coupled to the electrode. Fabrication techniques along with the experimental parameters used to evaluate the desalination performance of different materials are discussed in this review to provide an overview of improvements made for CDI and mCDI desalination purposes.
Demin Zhao, Meichun Ding, Tianhao Lin et al.
Advanced Science · 2024
Solar desalination is a promising strategy to utilize solar energy to purify saline water. However, the accumulation of salt on the solar evaporator surface severely reduces light absorption and evaporation performance. Herein, a simple and eco‐friendly method to fabricate a 3D gradient graphene spiral sponge (GGS sponge) is presented that enables high‐rate solar evaporation and zero liquid discharge (ZLD) desalination of high‐salinity brine. The spiral structure of the GGS sponge enhances energy recovery, while the gradient network structures facilitate radial brine transport and directional salt crystallization, which cooperate to endow the sponge with superior solar evaporation (6.5 kg m−2 h−1 for 20 wt.% brine), efficient salt collection (1.5 kg m−2 h−1 for 20 wt.% brine), ZLD desalination, and long‐term durability (continuous 144 h in 20 wt.% brine). Moreover, the GGS sponge shows an ultrahigh freshwater production rate of 3.1 kg m−2 h−1 during the outdoor desalination tests. A continuous desalination–irrigation system based on the GGS sponge for crop growth, which has the potential for self‐sustainable agriculture in remote areas is demonstrated. This work introduces a novel evaporator design and also provides insight into the structural principles for designing next‐generation solar desalination devices that are salt‐tolerant and highly efficient.
Jie Li, Xing Dai, Lin Zhu et al.
Nature Communications · 2018
Direct removal of 99TcO4− from the highly acidic solution of used nuclear fuel is highly beneficial for the recovery of uranium and plutonium and more importantly aids in the elimination of 99Tc discharge into the environment. However, this task represents a huge challenge given the combined extreme conditions of super acidity, high ionic strength, and strong radiation field. Here we overcome this challenge using a cationic polymeric network with significant TcO4− uptake capabilities in four aspects: the fastest sorption kinetics, the highest sorption capacity, the most promising uptake performance from highly acidic solutions, and excellent radiation-resistance and hydrolytic stability among all anion sorbent materials reported. In addition, this material is fully recyclable for multiple sorption/desorption trials, making it extremely attractive for waste partitioning and emergency remediation. The excellent TcO4− uptake capability is elucidated by X-ray absorption spectroscopy, solid-state NMR measurement, and density functional theory analysis on anion coordination and bonding. Direct removal of 99TcO4− from highly radioactive and acidic nuclear waste solutions is beneficial for uranium and plutonium recovery and radioactive pollution control but this represents a huge challenge. Here the authors show a cationic polymeric network with high 99TcO4− sorption capability and stability.
M. Alazaiza, A. Albahnasawi, G. Ali et al.
Water · 2021
Nanotechnology has been widely used in many fields including in soil and groundwater remediation. Nanoremediation has emerged as an effective, rapid, and efficient technology for soil and groundwater contaminated with petroleum pollutants and heavy metals. This review provides an overview of the application of nanomaterials for environmental cleanup, such as soil and groundwater remediation. Four types of nanomaterials, namely nanoscale zero-valent iron (nZVI), carbon nanotubes (CNTs), and metallic and magnetic nanoparticles (MNPs), are presented and discussed. In addition, the potential environmental risks of the nanomaterial application in soil remediation are highlighted. Moreover, this review provides insight into the combination of nanoremediation with other remediation technologies. The study demonstrates that nZVI had been widely studied for high-efficiency environmental remediation due to its high reactivity and excellent contaminant immobilization capability. CNTs have received more attention for remediation of organic and inorganic contaminants because of their unique adsorption characteristics. Environmental remediations using metal and MNPs are also favorable due to their facile magnetic separation and unique metal-ion adsorption. The modified nZVI showed less toxicity towards soil bacteria than bare nZVI; thus, modifying or coating nZVI could reduce its ecotoxicity. The combination of nanoremediation with other remediation technology is shown to be a valuable soil remediation technique as the synergetic effects may increase the sustainability of the applied process towards green technology for soil remediation.
H. Abdelhamid, A. Mathew
Frontiers in Chemical Engineering · 2021
Cellulose-based materials have been advanced technologies that used in water remediation. They exhibit several advantages being the most abundant biopolymer in nature, high biocompatibility, and contain several functional groups. Cellulose can be prepared in several derivatives including nanomaterials such as cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidized cellulose nanofibrils (TOCNF). The presence of functional groups such as carboxylic and hydroxyls groups can be modified or grafted with organic moieties offering extra functional groups customizing for specific applications. These functional groups ensure the capability of cellulose biopolymers to be modified with nanoparticles such as metal-organic frameworks (MOFs), graphene oxide (GO), silver (Ag) nanoparticles, and zinc oxide (ZnO) nanoparticles. Thus, they can be applied for water remediation via removing water pollutants including heavy metal ions, organic dyes, drugs, and microbial species. Cellulose-based materials can be also used for removing microorganisms being active as membranes or antibacterial agents. They can proceed into various forms such as membranes, sheets, papers, foams, aerogels, and filters. This review summarized the applications of cellulose-based materials for water remediation via methods such as adsorption, catalysis, and antifouling. The high performance of cellulose-based materials as well as their simple processing methods ensure the high potential for water remediation.
J. G. Ibanez, M. Rincón, S. Gutiérrez-Granados et al.
Chemical Reviews · 2018
Conducting polymers (CPs), thanks to their unique properties, structures made on-demand, new composite mixtures, and possibility of deposit on a surface by chemical, physical, or electrochemical methodologies, have shown in the last years a renaissance and have been widely used in important fields of chemistry and materials science. Due to the extent of the literature on CPs, this review, after a concise introduction about the interrelationship between electrochemistry and conducting polymers, is focused exclusively on the following applications: energy (energy storage devices and solar cells), use in environmental remediation (anion and cation trapping, electrocatalytic reduction/oxidation of pollutants on CP based electrodes, and adsorption of pollutants) and finally electroanalysis as chemical sensors in solution, gas phase, and chiral molecules. This review is expected to be comprehensive, authoritative, and useful to the chemical community interested in CPs and their applications.
Sheng Cheng, Tao Chen, Wenbin Xu et al.
Molecules · 2020
Soil contamination by heavy metals threatens the quality of agricultural products and human health, so it is necessary to choose certain economic and effective remediation techniques to control the continuous deterioration of land quality. This paper is intended to present an overview on the application of biochar as an addition to the remediation of heavy-metal-contaminated soil, in terms of its preparation technologies and performance characteristics, remediation mechanisms and effects, and impacts on heavy metal bioavailability. Biochar is a carbon-neutral or carbon-negative product produced by the thermochemical transformation of plant- and animal-based biomass. Biochar shows numerous advantages in increasing soil pH value and organic carbon content, improving soil water-holding capacity, reducing the available fraction of heavy metals, increasing agricultural crop yield and inhibiting the uptake and accumulation of heavy metals. Different conditions, such as biomass type, pyrolysis temperature, heating rate and residence time are the pivotal factors governing the performance characteristics of biochar. Affected by the pH value and dissolved organic carbon and ash content of biochar, the interaction mechanisms between biochar and heavy metals mainly includes complexation, reduction, cation exchange, electrostatic attraction and precipitation. Finally, the potential risks of in-situ remediation strategy of biochar are expounded upon, which provides the directions for future research to ensure the safe production and sustainable utilization of biochar.
Rabia Baby, Bullo Saifullah, M. Hussein
Nanoscale Research Letters · 2019
Nanotechnology is an advanced field of science having the ability to solve the variety of environmental challenges by controlling the size and shape of the materials at a nanoscale. Carbon nanomaterials are unique because of their nontoxic nature, high surface area, easier biodegradation, and particularly useful environmental remediation. Heavy metal contamination in water is a major problem and poses a great risk to human health. Carbon nanomaterials are getting more and more attention due to their superior physicochemical properties that can be exploited for advanced treatment of heavy metal-contaminated water. Carbon nanomaterials namely carbon nanotubes, fullerenes, graphene, graphene oxide, and activated carbon have great potential for removal of heavy metals from water because of their large surface area, nanoscale size, and availability of different functionalities and they are easier to be chemically modified and recycled. In this article, we have reviewed the recent advancements in the applications of these carbon nanomaterials in the treatment of heavy metal-contaminated water and have also highlighted their application in environmental remediation. Toxicological aspects of carbon-based nanomaterials have also been discussed.
Xue Yang, Shiqiu Zhang, M. Ju et al.
Applied Sciences · 2019
As a new functional material, biochar was usually prepared from biomass and solid wastes such as agricultural and forestry waste, sludge, livestock, and poultry manure. The wide application of biochar is due to its abilities to remove pollutants, remediate contaminated soil, and reduce greenhouse gas emissions. In this paper, the influence of preparation methods, process parameters, and modification methods on the physicochemical properties of biochar were discussed, as well as the mechanisms of biochar in the remediation of soil pollution. The biochar applications in soil remediation in the past years were summarized, such as the removal of heavy metals and persistent organic pollutants (POPs), and the improvement of soil quality. Finally, the potential risks of biochar application and the future research directions were analyzed.
Osamah Al-Hashimi, Khalid S. Hashim, E. Loffill et al.
Molecules · 2021
The provision of safe water for people is a human right; historically, a major number of people depend on groundwater as a source of water for their needs, such as agricultural, industrial or human activities. Water resources have recently been affected by organic and/or inorganic contaminants as a result of population growth and increased anthropogenic activity, soil leaching and pollution. Water resource remediation has become a serious environmental concern, since it has a direct impact on many aspects of people’s lives. For decades, the pump-and-treat method has been considered the predominant treatment process for the remediation of contaminated groundwater with organic and inorganic contaminants. On the other side, this technique missed sustainability and the new concept of using renewable energy. Permeable reactive barriers (PRBs) have been implemented as an alternative to conventional pump-and-treat systems for remediating polluted groundwater because of their effectiveness and ease of implementation. In this paper, a review of the importance of groundwater, contamination and biological, physical as well as chemical remediation techniques have been discussed. In this review, the principles of the permeable reactive barrier’s use as a remediation technique have been introduced along with commonly used reactive materials and the recent applications of the permeable reactive barrier in the remediation of different contaminants, such as heavy metals, chlorinated solvents and pesticides. This paper also discusses the characteristics of reactive media and contaminants’ uptake mechanisms. Finally, remediation isotherms, the breakthrough curves and kinetic sorption models are also being presented. It has been found that groundwater could be contaminated by different pollutants and must be remediated to fit human, agricultural and industrial needs. The PRB technique is an efficient treatment process that is an inexpensive alternative for the pump-and-treat procedure and represents a promising technique to treat groundwater pollution.