Juping You, Lei Ye, Shihan Zhang et al.

Biotechnology advances • 2024

Bioelectrochemical systems (BES) as environmental remediation biotechnologies have boomed in the last two decades. Although BESs combined technologies with electro-chemistry, -biology, and -physics, microorganisms and biofilms remain at their core. In this review, various functional microorganisms in BESs for CO2 reduction, dehalogenation, nitrate, phosphate, and sulfate reduction, metal removal, and volatile organic compound oxidation are summarized and compared in detail. Moreover, interrelationship regulation approaches for functional microorganisms and methods for electroactive biofilm development, such as targeted electrode surface modification, chemical treatment, physical revealing, biological optimization, and genetic programming are pointed out. This review provides promising guidance and suggestions for the selection of microbial inoculants and provides an analysis of the role of individual microorganisms in mixed microbial communities and its metabolisms.

Ellen Wohl

Environmental Science • 2014

River networks, and even individual river segments, are complex ecosystems that can be studied from many perspectives. Arguably the most common differentiation is between studies that focus on various aspects of rivers, such as contemporary physical processes (river engineering, hydrology, or geomorphology); physical processes over longer time spans (geomorphology); chemical processes (geology or aqueous chemistry); individual species or groups of organisms (fish biology); and biological communities (aquatic and riparian ecology). Each of these approaches to understanding rivers has an extensive technical literature. The works cited in this bibliographic entry draw from these sometimes disparate bodies of literature and focus on rivers in an environmental context rather than treating a specific river as an isolated feature or focusing solely on one component of rivers. River segments and river networks provide a wealth of information about past and contemporary environmental conditions, for rivers inherently integrate fluxes of matter and energy within a landscape through the entity of a drainage basin. The entire land surface that drains to a specified point makes up the drainage basin for that point. In addition to water, sediment, solutes, and organic matter enter the river network via atmospheric, surface, and subsurface pathways. Matter and energy move upstream, laterally, and vertically within a river network, as well as downstream. A well-studied example comes from the upstream migration of spawning salmon that then die and transfer ocean-derived nutrients to the river network and adjacent riparian zone. Because a river so effectively integrates diverse inputs and reflects conditions across the entire drainage basin, investigators have used physical, chemical, and biological characteristics of rivers as metrics for the environmental state of the river itself, and of the larger drainage basin. Three of the sections within this bibliographic entry include works that provide examples of these metrics for prehistoric, historic, and contemporary environmental conditions. Rivers also provide numerous ecosystem or environmental services, such as clean water and recreational fisheries, and another section provides examples of studies focusing on this aspect of rivers. Attempts to manage rivers and preserve desired attributes such as clean water, flood control, or fisheries constitute an important subset of environmental management, and are addressed in the final section of this entry.

Edward J. Anthony

Environmental Science • 2016

River deltas are subaqueous and subaerial coastal accumulations of river-derived sediments adjacent to, or close to, the source river. The word “delta,” however, is used in a more general sense to describe any feature resulting from this type of marginal accumulation, including in lakes, lagoons, ponds, mining tails, and reservoirs. Most river deltas are formed on the margins of marine basins. River deltas vary considerably in size, and some are the largest coastal landforms in the world. In addition to fluvial sediments, delta deposits sometimes include marine or along-shore derived sediments transported by waves and currents. Deltas form where the hydrodynamic conditions in the receiving basin are not energetic enough to disperse all or the bulk of the sediment brought in by rivers. Sediment transported through deltas contributes to deposition on adjacent coasts, continental shelves, and marine basins. Much of the early research on modern deltas focused on their oil- and gas-bearing potential and how they are analogs for ancient deltas in the rock record. There has been a shift, however, toward increasingly more diverse and cross-disciplinary research on deltas. Deltas are complex landforms. Recent research has shown that deltas also act as filters, sinks, and reactors for continental materials, including carbon, in transit to the ocean. Deltas are home to nearly six hundred million people. They commonly have highly productive soils, rich and biodiverse ecosystems, and offer a wide range of ecosystem services such as coastal defense, drinking water supply, recreation, green tourism, and nature conservation. Many deltas support intense agriculture and fisheries and are food baskets for many nations. Industry and transport in some deltas are also very important, leading to the development of major urban centers, ports, and harbors. Deltas are characterized by low topography and thus particularly vulnerable to catastrophic river floods, tsunami, cyclones, subsidence, and global sea-level rise. This vulnerability is increasing as a result of reduced sediment flux from rivers and various other modifications caused by human interventions. Although deltas may develop resilience and adapt to changes in sediment supply and sea level, commonly by reorganizing their channels and their patterns of sedimentation, human impacts coupled with the effects of climate change are rendering many deltas economic and environmental hotspots. A better understanding of delta dynamics and vulnerability, and a lot of political goodwill, are needed to implement adaptive delta management, and delta restoration and rehabilitation strategies.

Jennifer Hubbard

Oxford Research Encyclopedia of Environmental Science • 2017

Fisheries science emerged in the mid-19th century, when scientists volunteered to conduct conservation-related investigations of commercially important aquatic species for the governments of North Atlantic nations. Scientists also promoted oyster culture and fish hatcheries to sustain the aquatic harvests. Fisheries science fully professionalized with specialized graduate training in the 1920s. The earliest stage, involving inventory science, trawling surveys, and natural history studies continued to dominate into the 1930s within the European colonial diaspora. Meanwhile, scientists in Scandinavian countries, Britain, Germany, the United States, and Japan began developing quantitative fisheries science after 1900, incorporating hydrography, age-determination studies, and population dynamics. Norwegian biologist Johan Hjort’s 1914 finding, that the size of a large “year class” of juvenile fish is unrelated to the size of the spawning population, created the central foundation and conundrum of later fisheries science. By the 1920s, fisheries scientists in Europe and America were striving to develop a theory of fishing. They attempted to develop predictive models that incorporated statistical and quantitative analysis of past fishing success, as well as quantitative values reflecting a species’ population demographics, as a basis for predicting future catches and managing fisheries for sustainability. This research was supported by international scientific organizations such as the International Council for the Exploration of the Sea (ICES), the International Pacific Halibut Commission (IPHC), and the United Nations’ Food and Agriculture Organization (FAO). Both nationally and internationally, political entanglement was an inevitable feature of fisheries science. Beyond substituting their science for fishers’ traditional and practical knowledge, many postwar fisheries scientists also brought progressive ideals into fisheries management, advocating fishing for a maximum sustainable yield. This in turn made it possible for governments, economists, and even scientists, to use this nebulous target to project preferred social, political, and economic outcomes, while altogether discarding any practical conservation measures to rein in globalized postwar industrialized fishing. These ideals were also exported to nascent postwar fisheries science programs in developing Pacific and Indian Ocean nations and in Eastern Europe and Turkey. The vision of mid-century triumphalist science, that industrial fisheries could be scientifically managed like any other industrial enterprise, was thwarted by commercial fish stock collapses, beginning slowly in the 1950s and accelerating after 1970, including the massive northern cod crisis of the early 1990s. In the 1980s scientists, aided by more powerful computers, attempted multi-species models to understand the different impacts of a fishery on various species. Daniel Pauly led the way with multi-species models for tropical fisheries, where the need for such was most urgent, and pioneered the global database FishBase, using fishing data collected by the FAO and national bodies. In Canada the cod crisis inspired Ransom Myers to use large databases for fisheries analysis to show the role of overfishing in causing that crisis. After 1980 population ecologists also demonstrated the importance of life history data for understanding fish species’ responses to fishery-induced population and environmental change. With fishing continuing to shrink many global commercial stocks, scientists have demonstrated how different measures can manage fisheries for species with different life-history profiles. Aside from the need for effective scientific monitoring, the biggest ongoing challenges remain having politicians, governments, fisheries industry members, and other stakeholders commit to scientifically recommended long-term conservation measures.

Karam Ahmad, Melinda Laituri

Environmental Science • 2017

The use of geographic information systems (GIS) in environmental science is a complex, multifaceted, and amorphous topic. Environmental science is a multidisciplinary field that integrates the biological, social, and physical sciences to address the seemingly intractable environmental problems humans face. Increasingly, GIS is the tool used to organize, analyze, manage, and visualize geospatial data that links models to derive outputs from environmental analysis and modeling. Coupled, the fields of GIS and environmental science cover a multitude of topics and approaches scattered across a broad bibliographic landscape. The environmental movement of the 1960s and 1970s fueled the development of environmental science as a disciplinary field closely related to ecology, geography, and hydrology. In the 1980s, GIS became a more accessible tool for researchers through such programs as GRASS, Intergraph, and ESRI’s ArcInfo to characterize and analyze complex environmental problems. During the 1990s, approaches to environmental science focused on risk management, pollution, and monitoring. The coincidence of Internet development, data accessibility, visualization, and software modeling tools have created a perfect storm for the adoption of an integrated approach—environmental science with an integrated technology (GIS)—to address environmental issues. There has been a virtual explosion of applications and research utilizing GIS that cover a broad range of issues: water resources, climate change, urban planning, environmental justice, vulnerability studies, etc. This bibliography provides an entrée to the complex landscape of GIS applications for environmental science. It is not an exhaustive bibliography, but one that highlights some of the main avenues of GIS applications. Utilizing the Web of Science, Academic Search Premier, and Google Scholar, key articles on GIS and environmental science were accessed and organized around various thematic areas, including Disasters, Ecology, Pollution, Public Health and Epidemiology, and Water Resources Analysis. There are numerous other areas of this topic, but selecting these areas presents the reader with an overview of the field. Many of the articles in this bibliography provide a jumping off point to explore other topic areas that are not included in this bibliography.

Sven Wunder

Environmental Science • 2023

Payments for environmental services (PES), also sometimes called payments for ecosystem services, emerged from the perceived need of conservation practitioners around the world for more cost-effective and equitable ways of using scarce funds. Also sometimes referred to as ecocompensation, rewards, or cash transfers, PES consist of direct conditional payments from the users of environmental services (or their collective representatives) to landowners or stewards who provide them by adopting environmentally friendlier practices of protection or restoration. Environmental service (ES) users effectively rent out certain partial land rights from landholders (e.g., limiting their rights to deforest). This only works when ES provision can be well-monitored and enforced and when landholders can flexibly and legitimately change their preferred modes of production. Otherwise, ES users might prefer to buy out environmentally sensitive lands entirely (e.g., creating municipal reserves for spring protection in a watershed), although becoming responsible for land stewardship may over time be costly. While some PES started as long-term public environmental subsidy programs (e.g., the US Conservation Reserve Program), the big push for PES in this millennium came from economists arguing for more direct, performance-based incentives. The PES approach has become more popular among both scholars and conservation practitioners over the last few decades, with the majority of PES programs focused on forest conservation. Geographically, PES have been most popular in the Americas (North, South, Central) and in China. PES can predominantly be seen as a private lands counterpart to public protected areas, although in most countries PES are far less extensive. Increasingly, PES are applied alongside a mix of policy approaches, as a tool in a toolbox of conservation mechanisms, with the aim of incentivizing landholders to engage in sustainable practices, and promising potential long-term provenance of ES while also supporting livelihoods. PES contracts can range from short term to the indefinite duration of perpetual conservation easements. With more application of PES globally, and a font of new experiences to study, a growing body of research has emerged, seeking to evaluate the environmental and poverty reduction impacts of PES. These studies assess the successes and limitations of PES schemes, and promote best practices in preconditions, design, and implementation, as well as contextual backdrops that can affect the effectiveness and efficiency of PES schemes. Some obstacles and conditions may not be designed away, such as land-tenure insecurity and organizational capacity to pay for ES: these jeopardize the emergence and expansion of PES schemes, especially in tropical forest frontiers. However, despite the worrying record of government-led PES schemes in terms of design and implementation errors, their ability to organize collective payments at scale and to intelligently bundle them into complex policy mixes may be important future arguments in their favor.

Christopher A. Scott, Bhuwan Thapa

Environmental Science • 2015

Environmental security, as a subset of broader concerns over human security, is addressed from the disciplinary perspectives of international relations, political science, geography, development studies, and environmental studies. The concept of environmental security views ecological processes and natural resources as sources or catalysts of conflict, barriers or limits to human well-being, or conversely, as the means to mitigate or resolve insecurity. Security over natural resources—particularly energy and increasingly water—seen in terms of territorial control, treaty arrangements, and trade agreements (including the application of economic instruments) over production and conveyance of resources to demand locations, has tended to frame the analysis in international relations and political science. While spatial and transboundary concerns over resources continue to occupy geographers, attention in the field of geography is drawn increasingly to social equity and environmental justice dimensions of resource use and outcomes. Development studies focused on emerging economies and societies in rapid transition addresses environmental security in terms of differential national or regional access to resources and impacts, e.g., associated with pollution, deprivation, etc. And among other points of concern, environmental studies addresses environmental security in terms of local, intra-household, and gender-differentiated access to water, energy, and food as well as outcomes such as public health, nutrition, and quality of life. While the term environmental security has existed since at least the 1980s, its prominence in academic and political circles rose significantly after the 1994 Human Development Report of the United Nations Development Programme, which formulated the broadly accepted concept of human security. This report identified environmental security together with economic, food, health, personal, community, and political security as core components of human security. Since the 1990s, the definition and scope of environmental security have broadened to include multiple subsets, including food security, energy security, and water security, as well as emerging notions of adaptation and resilience to hazards, e.g., climate security, and all of these are referred to in this article. No attempt is made to treat the broad and ever-widening field of environmental security exhaustively. The principal aims are to trace the evolution of security discourses, consider securitization of the environment and natural resources, and assess new conceptions of environmental security in the context of global change. This work is funded by the Lloyd’s Register Foundation, a charitable foundation helping to protect life and property by supporting engineering-related education, public engagement, and the application of research.

Roger Perman

Environmental Science • 2015

Environmental economics uses the tools of economic analysis to address issues relating to the impacts of human activity on the natural environment, the ways in which those impacts affect human well-being, and the appropriate policy and regulatory responses to environmental problems. Such policy responses include targets (how much pollution is acceptable) and instruments (what means are available to achieve particular targets and their relative merits). Environmental economics emerged as a well-defined subdiscipline in the 1960s; in the 1970s and 1980s, most research considered local air and water pollution problems, with a key theme emerging that the use of economic incentive-based policy instruments had large potential efficiency gains compared with traditional (command-and-control) regulatory instruments. As the subject became more actively researched, other strands have become interwoven into environmental economics. First, recognition that sustainability of activity is as important as economic efficiency and that these two objectives may not always be mutually consistent. Second, system-level thinking showed that researchers cannot properly address environmental concerns without being aware of the material basis of economic activity and without considering the ecosystems within which particular configurations of resources are found—hence, the emergence of ecological economics and the linkage of natural resource economics with mainstream environmental economics. Early work in environmental economics was national or subnational in focus and heavily dominated by papers that addressed issues of particular concern to the more affluent Organisation for Economic Co-operation and Development (OECD) countries. This emphasis changed for several reasons. Global poverty reduction became more central to the international agenda, and governments became aware that dealing with poverty was a necessary condition for achieving sustainability goals. Globalization and greater economic interdependence of nations pointed to the need to bring international trade into the analysis of environmental problems. In addition, perhaps of most importance in terms of its effect on studies by environmental economists, it became evident that many of the most serious and least tractable environmental problems were international, with impacts spilling over national boundaries and thus requiring international policy coordination. In this vein, research has begun on solving acid rain pollution, ozone layer–depleting substances (both of which have been dealt with relative success), and global environmental problems such as biodiversity loss and climate change (the track record for both is far less impressive). One unifying feature throughout the whole discipline of environmental economics is the issue of valuation of non-marketed goods and services, including environmental amenities. A central precept within the discipline is that environmental problems arise because of the presence of externalities, particularly “public good” externalities. By definition, externalities are not priced. However, designing appropriate policy responses requires that shadow prices be imputed, and the huge literature on non-market valuation considers how these shadow prices can be estimated.

, Behnam Mortazavi, Najaf Allahyari Fard et al.

Research in Molecular Medicine • 2020

Background: Contraceptive vaccines (CVs) can be used as a valuable and alternative method for the prevention of gestation in humans and animals. These vaccines can have several targets, such as superficial sperm proteins. Vaccines based on sperm antigens are quite efficacious to create a contraceptive effect. However, multi-epitope vaccines are more effective in stimulating the immune system and producing more antibodies to reduce the infertility rate. Materials and Methods: This study aimed to design and evaluate a chimeric fusion protein containing IZUMO, SACA3, and PH-20 epitopes. IZUMO1, SACA3, and PH-20 were assessed, and appropriate regions were selected using various bioinformatics tools, including IEDB, I-TASSER, ProtParam, Asa-View, and Chimera software. Protein epitopes were selected based on various characters, including specificity, solvent accessibility, their weight and length, antigenic intensity, and topology. Epitopes with high antigenic potential were selected and joined together by linkers. The designed fusion protein was simulated using Molecular Dynamic, GROMACS 5, and Chimera 1.14 software. Results: The results demonstrated that all antigenic plots and availability of epitopes in the new construct remained constant. The spermatic antigens were combined using rigid linkers as a new construct and showed a stable formation with proper solvent accessibility validated by ProSA-web and PROCHECK. Also, comparing the new structure with its original one did not show any structural change. Conclusion: Based on bioinformatics results, the fusion protein that consists of three spermatic antigens has productive potential to stimulate the immune system and capable of producing more antibodies in circulation and reliable infertility.

Ihsanullah Ihsanullah

Nano-Micro Letters • 2020

A broad overview of MXenes and MXene-based nanomaterials in desalination is presented. Recent advancement in the synthesis of MXenes for applications in desalination is critically evaluated. Salt removal mechanisms and regeneration capability of MXenes are appraised. Current challenges and future prospect of MXenes in desalination are highlighted. Research directions are provided to safeguard the applications of MXenes in future desalination. MXenes, novel 2D transition metal carbides, have emerged as wonderful nanomaterials and a superlative contestant for a host of applications. The tremendous characteristics of MXenes, i.e., high surface area, high metallic conductivity, ease of functionalization, biocompatibility, activated metallic hydroxide sites, and hydrophilicity, make them the best aspirant for applications in energy storage, catalysis, sensors, electronics, and environmental remediation. Due to their exceptional physicochemical properties and multifarious chemical compositions, MXenes have gained considerable attention for applications in water treatment and desalination in recent times. It is vital to understand the current status of MXene applications in desalination in order to define the roadmap for the development of MXene-based materials and endorse their practical applications in the future. This paper critically reviews the recent advancement in the synthesis of MXenes and MXene-based composites for applications in desalination. The desalination potential of MXenes is portrayed in detail with a focus on ion-sieving membranes, capacitive deionization, and solar desalination. The ion removal mechanism and regeneration ability of MXenes are also summarized to get insight into the process. The key challenges and issues associated with the synthesis and applications of MXenes and MXene-based composites in desalination are highlighted. Lastly, research directions are provided to guarantee the synthesis and applications of MXenes in a more effective way. This review may provide an insight into the applications of MXenes for water desalination in the future.

Lenan Zhang, Zhenyuan Xu, Lin Zhao et al.

Energy & Environmental Science • 2021

Solar desalination holds significant promise for the water-energy nexus. Recent advances in passive solar desalination using thermal localization show great potential for high-efficiency freshwater production, which is particularly beneficial for areas without well-established water and energy infrastructure. However, there is a significant knowledge gap between laboratory scale innovation and commercial adoption. In this review, we discuss two critical factors – water production and reliability – which, if addressed systematically, could enable high-performance thermally-localized solar desalination systems. We show that optimizing heat and mass transfer of the entire device and recycling the latent heat of condensation are important to enhance total water production. Meanwhile, we discuss the potential of novel system architectures and fluid flow engineering to enable anti-fouling and robust desalination devices. In addition, we present techno-economic analysis that highlights the balance between water production, reliability, and cost. A criterion for economic feasibility is provided by comparing the price of desalinated water with commercially available bottle and tap water, which provides a roadmap for future development of solar desalination technologies.

Wenhui Shi, Xiaoyue Liu, Tianqi Deng et al.

Advanced Materials • 2020

The application of electrochemical energy storage materials to capacitive deionization (CDI), a low‐cost and energy‐efficient technology for brackish water desalination, has recently been proven effective in solving problems of traditional CDI electrodes, i.e., low desalination capacity and incompatibility in high salinity water. However, Faradaic electrode materials suffer from slow salt removal rate and short lifetime, which restrict their practical usage. Herein, a simple strategy is demonstrated for a novel tubular‐structured electrode, i.e., polyaniline (PANI)‐tube‐decorated with Prussian blue (PB) nanocrystals (PB/PANI composite). This composite successfully combines characteristics of two traditional Faradaic materials, and achieves high performance for CDI. Benefiting from unique structure and rationally designed composition, the obtained PB/PANI exhibits superior performance with a large desalination capacity (133.3 mg g−1 at 100 mA g−1), and ultrahigh salt‐removal rate (0.49 mg g−1 s−1 at 2 A g−1). The synergistic effect, interfacial enhancement, and desalination mechanism of PB/PANI are also revealed through in situ characterization and theoretical calculations. Particularly, a concept for recovery of the energy applied to CDI process is demonstrated. This work provides a facile strategy for design of PB‐based composites, which motivates the development of advanced materials toward high‐performance CDI applications.

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 &amp; 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 &amp; 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 &amp; 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.