A Janus evaporator with low tortuosity for long-term solar desalination

Hu, Rong; Zhang, Junqi; Kuang, Yudi; Wang, Kebing; Cai, Xiaoying; Fang, Zhiqiang; Huang, Wenqi; Chen, Gang; Wang, Zhongxing

doi:10.1039/c9ta01576k

Cited by 177 publications

(98 citation statements)

References 48 publications

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Section: Salt Rejection Strategies For Long‐term Solar Desalinationmentioning

confidence: 99%

“…Hu et al demonstrated a Janus evaporator with conversion efficiency of 80% achieved by combining hydrophilic backbone and hydroscopic coating. [ 142 ] The backbone structure ensures rapid water supply for evaporation, and also thermally insulates heat from downward conduction. Effect of hydrophilic structure with different tortuosity of the water pumping structure on salt rejection was further studied.…”

Section: Salt Rejection Strategies For Long‐term Solar Desalinationmentioning

confidence: 99%

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Structure Architecting for Salt‐Rejecting Solar Interfacial Desalination to Achieve High‐Performance Evaporation With In Situ Energy Generation

et al. 2020

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requirement has given rise to research thrusts being focused on the development of solar-driven evaporation based desalination technologies. [4][5][6][7] The research on using solar energy in the desalination process has a long history. [3,8,9] In a traditional singleslope basin-like solar still (Figure 1a), saline water is heated and subsequently evaporated by directly exposing to solar radiation. Solar energy is absorbed and converted into thermal energy by a black light-absorbing liner that is situated at the bottom of the solar basin. [10] Due to this design, the solar absorber is immersed in bulk seawater and it hardly receives a fraction of the incoming solar radiation owing to poor light penetration through the thick water layer. Furthermore, the produced heat is easily dissipated into the bulk water, and further lost to the surroundings through water surface radiation, convection and conduction. Due to the above reasons, the resulting solar-tosteam conversion efficiency is inevitably low. Nanoparticle dispersed fluid was then demonstrated to harness solar energy and found to be a great boon to direct water vapor generation. [11,12] A solar conversion efficiency of up to ≈70% can be possibly achieved because heat loss to bulk water is mitigated ( Figure 1b). [13,14] However, research on this advancement didn't last because of the development of solar interfacial heating strategy, which is shown in Figure 1c. The concept of interfacial evaporation was first put forth in 2014 by two reports simultaneously, [15,16] and received a surge of attention and interest immediately in the following years. The most prominent feature of solar interfacial evaporation lies in the position of the solar absorber, which is at the interface between saline liquid and the above air. This special configuration not only minimizes heat loss from the solar absorber to bulk water, but also provides significantly more surface area for prompt vapor release. Also, solar radiation is photothermally localized at the surface of solar absorber, giving rise to high surface temperature, which enables fast heat transfer to water. With it, water transported from reservoir can be heated and evaporated immediately to achieve a higher rate of steam generation. In addition to the differences in heating strategies, it should be noted that all the solar stills follow the same evaporation-condensation route for desalination and clean water collection, and to this end, a similar device structure (e.g., solar still with sloping cover) is usually employed.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 e...

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Section: Salt Rejection Strategies For Long‐term Solar Desalinationmentioning

confidence: 99%

Section: Salt Rejection Strategies For Long‐term Solar Desalinationmentioning

confidence: 99%

Structure Architecting for Salt‐Rejecting Solar Interfacial Desalination to Achieve High‐Performance Evaporation With In Situ Energy Generation

et al. 2020

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“…They are realized with the hydrophobic layer and the hydrophilic layer of Janus membranes, respectively. [ 33,42,43,47,111,112 ] The hydrophobic layer loaded with light‐absorbing materials aims to absorb solar energy as much as possible for heating water on the surface. It is also conducive to reduce the interactions of water molecules with the membrane pores, leading to a rapid steam escape from the membrane.…”

Section: Asymmetric Surface Engineering Of Janus Membranes For Targetmentioning

confidence: 99%

Asymmetric Surface Engineering for Janus Membranes

Yang

2020

Adv Materials Inter

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Emerging Janus membranes, named after the ancient Roman god with two faces to better survey both the past and the future, are appealing materials to tackle this challenge. They possess opposing chemicophysical properties on two sides for achieving a breakthrough in their performances. [12] The opposite surface properties usually include asymmetric wettability and charge but not limited to them. [13] Janus membranes with asymmetric wettable surfaces have received most of the attention in diverse research fields for a wide variety of applications because of their distinctive mass (e.g., liquid or gas) transport behaviors in two-phase or multiphase systems. Such unique fluid transportation relies on the cooperative effect arisen from the asymmetric wettability in the direction of membrane thickness. [14] Therefore, how to create and regulate asymmetry is a core task in the preparation of Janus membranes.Surface engineering, a process for modifying the surface of a material, provides a powerful toolbox to enhance and optimize the performance of the material, especially for porous membranes with large internal surface area. A myriad of modification methods including surface coating, grafting, and self-assembling have been developed to regulate membrane surface properties which are usually uniform in the spatial distribution. As distinguished from ordinary surface treatments, asymmetric surface engineering aims to accurately control the uneven distribution of surface properties or functionalities in the direction of membrane thickness, being an effective means for the preparation of Janus membranes.Benefiting from the asymmetric surface engineering, the researches on Janus membranes have mushroomed in recent years. Hundreds of literatures have explored the possibilities for Janus membranes to substitute traditional ones for achieving enhanced performances in the mass transfer between two phases, including water−oil, water−gas, and oil−gas systems. Some researchers have reviewed the research progresses on Janus membranes from different perspectives. Our previous review has discussed the definition and fabrication of Janus membranes and summarized their applications in the field of environmental science. [13] Another two reviews, presented by Zhao et al. [14] and Zhou et al., [15] have described the distinctive unidirectional fluid transport phenomenon of Janus membranes and their functional applications. Besides, a recent review has detailed the potential of Janus configuration in terms of enhancing energy efficiency in membrane processes. [12] However, the vital role of asymmetric surface engineering in the construction of asymmetric configurations, the modulation of surface properties, and the implementation of ultimate applications has not been addressed. Herein, Janus membranes show great promise toward various applications and are undergoing a fast-paced development in materials science. The asymmetric surface engineering on surface wettability, layer thickness, and pore structure enables Janus membranes with super...

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“…When the illumination is absorbed by solid particles, temperature difference is produced between the nanoparticles and the surrounding medium, and the local temperature rise is sufficient to directly convert the liquid into steam. Due to the plasmonic resonance effect of the nanoparticles, the liquid forms isolated bubbles on the surface of the particles, the thermal conductivity of the particle-liquid interface is reduced, and the particles are encased in steam with low thermal conductivity during the non-equilibrium process [70].…”

Section: Solar-thermal Conversion Mechanisms and Evaluation Standardsmentioning

confidence: 99%

“…Fig. 8 shows several typical combinations between water transportation and thermal insulation based on solar steam generation [43,70,74,76]. Cellulosic foam, polyurethane and polystyrene foam, AAO, graphene oxide aerogels, carbon nanotube arrays, natural wood, cotton and other substrates have been developed.…”

Section: Structure For Thermal Insulation and Water Transportmentioning

confidence: 99%

Solar-thermal conversion and steam generation: a review

Shi

Wang

et al. 2020

Applied Thermal Engineering

100

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Highlights  Solar absorbed materials and their photo-thermal conversion mechanism are reviewed.  The evaluation principle of photo-thermal conversion process are investigated.  Different solar absorbed evaporation methods and system are summarized.  The prospects and challenges of photo-thermal conversion and steam generation are discussed Abstract: Recently, steam generation systems based on solar-thermal conversion have received much interest, and this may be due to the widespread use of solar energy and water sources such as oceans and lakes. The photo-thermal desalination system becomes attractive as it can convert absorbed solar light energy into thermal energy and realise the desalination and water purification of saline water through the evaporation process. In this paper, the research status of solar-thermal conversion materials such as metal-based materials, semiconductor materials, carbon-base materials, organic polymer materials, composite photo-thermal materials and their solar-thermal conversion mechanism in recent years are reviewed. The physical process and evaluation principle of solar-thermal conversion are both carefully introduced. The methods of optimising thermal management and increasing the evaporation rate of a hybrid system are also introduced in detail. Four main applications of solar-thermal conversion technologies (seawater desalination, wastewater purification, sterilisation and power generation) are discussed. Finally, based on the above analysis, the prospects and challenges for future research in the field of desalination are discussed from an engineering and scientific viewpoint to promote the direction of research, in order to stimulate future development and accelerate commercial application.

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A Janus evaporator with low tortuosity for long-term solar desalination

Cited by 177 publications

References 48 publications

Structure Architecting for Salt‐Rejecting Solar Interfacial Desalination to Achieve High‐Performance Evaporation With In Situ Energy Generation

Structure Architecting for Salt‐Rejecting Solar Interfacial Desalination to Achieve High‐Performance Evaporation With In Situ Energy Generation

Asymmetric Surface Engineering for Janus Membranes

Solar-thermal conversion and steam generation: a review

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