A salt-rejecting floating solar still for low-cost desalination

Ni, George; Zandavi, Seyed Hadi; Javid, Seyyed Morteza; Boriskina, Svetlana V.; Cooper, Thomas; Chen, Gang

doi:10.1039/c8ee00220g

Cited by 747 publications

(549 citation statements)

References 38 publications

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“…[21][22][23] Indeed, a small decline in one cycle (i.e., the consecutive operation of 12 h) especially after the eighth hour is observed (see Figure 3d,f), which might be caused by the salt deposition on the top surface of N-fGN/sGF. The salt residues often with white color will reduce the light absorption due to the light reflection from the salt crystals, and increase the interfacial thermal resistance between lightabsorbing materials and water, leading to deteriorated evaporation performances.…”

Section: Salt Deposition and Self-cleaningmentioning

confidence: 98%

“…[21] As such, more works are required to tackle these challenges and simultaneously achieve higher energy efficiency, long-term stability, anti-salt-fouling behavior, and improved clean water collection performance. The vapor mist and condensation will block (partially absorb or reflect) incident light, leading to significant declines of evaporation performance.…”

Section: Introductionmentioning

confidence: 99%

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Multifunctional Solar Waterways: Plasma‐Enabled Self‐Cleaning Nanoarchitectures for Energy‐Efficient Desalination

Xiong

Yang

et al. 2019

Advanced Energy Materials

125

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Evaporating seawater and separating salt from water is one of the most promising solutions for global water scarcity. State‐of‐the‐art water desalination devices combining solar harvesting and heat localization for evaporation using nanomaterials still suffer from several issues in energy efficiency, long‐term performance, salt fouling, light blocking, and clean water collection in real‐world applications. To address these issues, this work devises plasma‐enabled multifunctional all‐carbon nanoarchitectures with on‐surface waterways formed by nitrogen‐doped hydrophilic graphene nanopetals (N‐fGPs) seamlessly integrated onto the external surface of hydrophobic self‐assembled graphene foam (sGF). The N‐fGPs simultaneously transport water and salt ions, absorb sunlight, serve as evaporation surfaces, then capture the salts, followed by self‐cleaning. The sGF ensures effective thermal insulation and enhanced heat localization, contributing to high solar‐vapor efficiency of 88.6 ± 2.1%. Seamless connection between N‐fGPs and sGF and self‐cleaning of N‐fGP structures by redissolution of the captured salts in the waterways lead to long‐term stability over 240 h of continuous operation in real seawater without performance degradation, and a high daily evaporation yield of 15.76 kg m−2. By eliminating sunlight blocking and guiding condensed vapor, a high clean water collection ratio of 83.5% is achieved. The multiple functionalities make the current nanoarchitectures promising as multipurpose advanced energy materials.

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Section: Salt Deposition and Self-cleaningmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Multifunctional Solar Waterways: Plasma‐Enabled Self‐Cleaning Nanoarchitectures for Energy‐Efficient Desalination

Xiong

Yang

et al. 2019

Advanced Energy Materials

125

View full text Add to dashboard Cite

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“…[65] Similarly, a cotton rod was designed as the stem of umbrella-like solar evaporator to act as 1D water supply channel. Until now, numerous 3D porous materials have been applied to efficiently pump up water into solar absorber, including cellulose fabric, [3] lotus seedpods, [89] hydrophilic poly(tetra-fluoroethylene) (PTFE) membrane, [130] cotton, [66] aerogels, [131] sponge, [132] and hydrogel. Besides, a confined 2D water pathway was designed for water supplies of solar absorber (laminated GO film) through a thin cellulose layer wrapped over the surface of a thermal insulator in 2016.…”

Section: Strategies For Enhancing Water Evaporation Efficiencymentioning

confidence: 99%

“…[3] The according salt-rejection mechanism is probably ascribed to advection and diffusion of concentrated salt down back into the body of water, and the driving force is resulted from the increased osmotic pressure within the evaporation structure where the salt concentration exceeds the ambient ocean concentration. The typical example presented by Chen and co-workers, an evaporator with simultaneous salt rejection and heat localization ability mainly contained a black fabric for solar absorption, a white fabric wick and polystyrene foam insulation.…”

Section: Device Configuration Designmentioning

confidence: 99%

Harnessing Solar‐Driven Photothermal Effect toward the Water–Energy Nexus

et al. 2019

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Producing affordable freshwater has been considered as a great societal challenge, and most conventional desalination technologies are usually accompanied with large energy consumption and thus struggle with the trade‐off between water and energy, i.e., the water–energy nexus. In recent decades, the fast development of state‐of‐the‐art photothermal materials has injected new vitality into the field of freshwater production, which can effectively harness abundant and clean solar energy via the photothermal effect to fulfill the blue dream of low‐energy water purification/harvesting, so as to reconcile the water–energy nexus. Driven by the opportunities offered by photothermal materials, tremendous effort has been made to exploit diverse photothermal‐assisted water purification/harvesting technologies. At this stage, it is imperative and important to review the recent progress and shed light on the future trend in this multidisciplinary field. Here, a brief introduction of the fundamental mechanism and design principle of photothermal materials is presented, and the emerging photothermal applications such as photothermal‐assisted water evaporation, photothermal‐assisted membrane distillation, photothermal‐assisted crude oil cleanup, photothermal‐enhanced photocatalysis, and photothermal‐assisted water harvesting from air are summarized. Finally, the unsolved challenges and future perspectives in this field are emphasized. It is envisioned that this work will help arouse future research efforts to boost the development of solar‐driven low‐energy water purification/harvesting.

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“…On the contrary, the dark performance degraded linearly as RH rose up, implying the dark evaporation was dominantly governed by the ambient RH. [38][39][40] However, in-depth understanding of evaporator-seawater interaction is not yet revealed systematically. The ambient RH is therefore found to subtly affect solar evaporation because a low-RH zone is built up near the hot surface region and imposes more influential impact on water evaporation than the surrounding ambient RH (Figure 4f).…”

Section: Wwwadvsustainsyscommentioning

confidence: 99%

Systematic Study of the Effects of System Geometry and Ambient Conditions on Solar Steam Generation for Evaporation Optimization

Zhang

Ravi

Tan

2019

Advanced Sustainable Systems

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growing use of solar energy in steam generation techniques. [8][9][10] Steam generation is a crucial energy-intensive step in seawater desalination, which is typically followed by water vapor condensation to collect the desalinated water. By wielding interfacial evaporator to localize solar heat and boil sea water, steam (clean water) can be produced at a significantly higher rate than naturally ubiquitous evaporation process without the support of solar absorbers. [1,11,12] Of late, with a wide variety of new solar-absorber materials mushrooming, the solar desalination approach has begun to bear fruit. [13][14][15][16][17][18] To maximize the evaporation rate (ER) which is a key performance metric of solar steam generators, enormous efforts are underway, primarily focused on enhancing the light absorption, heat management, and water transport. [1,19] However, current studies often overlook the impacts from environment and the system itself. The understanding of the system-ambience interplay is still lacking in this area. Those neglectful factors, such as humidity that broadly changes with place and time, may be capable of manipulating the solar evaporation process. However, quite opposite to the common notion that the relative humidity (RH) affects ER, recent reports have confirmed that the solar evaporation is still able to maintain a high rate even when the RH greatly increases, [20,21] but understanding of how the evaporation can be sustained under such high humidity is still inadequate. [22] It is therefore more pressing to systematically study how the various system/ambient factors influence the evaporation process than to engineer a new solar absorber material, which sums up the motive of this work.This work shines light on the roles of relative humidity level of the ambience/system, waterlogged surface level, specific weight, carbonization thickness, and water salinity in influencing the water evaporation in a solar steam generation system, where microchanneled balsa wood was employed as an ideal research model for quantitative comparisons. Focusing on the system geometry and ambient conditions, the study aims to uncover the insights of the interplay between solar steam generation and practical operating environment, and provide constructive strategies for performance optimization of solar steam generators without any further sophisticated modifications on materials or system design. Solar steam generation as an emerging solar desalination technology has drawn tremendous research attention owing to its enticing prospects in tackling the rising water crisis across the globe. Despite the numerous reports on materials with high evaporation rates, little is known about how the system geometry and ambient conditions impact the evaporation rate. The ambient relative humidity (RH), which can potentially impact on the evaporation process in the system is one such element that is not well studied. In this work, microchanneled balsa wood is employed as the research model in the quantitative investigations of these ...

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A salt-rejecting floating solar still for low-cost desalination

Abstract: A floating, low-cost solar desalination system was constructed, capable of simultaneous salt rejection and heat localization for continuous operation.

Cited by 747 publications

References 38 publications

Multifunctional Solar Waterways: Plasma‐Enabled Self‐Cleaning Nanoarchitectures for Energy‐Efficient Desalination

Multifunctional Solar Waterways: Plasma‐Enabled Self‐Cleaning Nanoarchitectures for Energy‐Efficient Desalination

Harnessing Solar‐Driven Photothermal Effect toward the Water–Energy Nexus

Systematic Study of the Effects of System Geometry and Ambient Conditions on Solar Steam Generation for Evaporation Optimization

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