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Youhong Nancy GUO, et al.
Hydrogel Airwell
Hydrogel Airwell
https://news.mit.edu/2023/salty-gel-could-harvest-water-desert-air-0615
This salty gel could harvest water from desert air
A new material developed by MIT engineers exhibits “record-breaking” vapor absorption.
Jennifer Chu -- MIT News Office --June 15, 2023
MIT engineers have synthesized a superabsorbent material that can soak up a record amount of moisture from the air, even in desert-like conditions.
As the material absorbs water vapor, it can swell to make room for more moisture. Even in very dry conditions, with 30 percent relative humidity, the material can pull vapor from the air and hold in the moisture without leaking. The water could then be heated and condensed, then collected as ultrapure water.
The transparent, rubbery material is made from hydrogel, a naturally absorbent material that is also used in disposable diapers. The team enhanced the hydrogel’s absorbency by infusing it with lithium chloride — a type of salt that is known to be a powerful dessicant.
As the material absorbs water vapor, it can swell to make room for more moisture. Even in very dry conditions, with 30 percent relative humidity, the material can pull vapor from the air and hold in the moisture without leaking. The water could then be heated and condensed, then collected as ultrapure water.
The researchers found they could infuse the hydrogel with more salt than was possible in previous studies. As a result, they observed that the salt-loaded gel absorbed and retained an unprecedented amount of moisture, across a range of humidity levels, including very dry conditions that have limited other material designs.
If it can be made quickly, and at large scale, the superabsorbent gel could be used as a passive water harvester, particularly in the desert and drought-prone regions, where the material could continuously absorb vapor, that could then be condensed into drinking water. The researchers also envision that the material could be fit onto air conditioning units as an energy-saving, dehumidifying element.
“We’ve been application-agnostic, in the sense that we mostly focus on the fundamental properties of the material,” says Carlos Díaz-Marin, a mechanical engineering graduate student and member of the Device Research Lab at MIT. “But now we are exploring widely different problems like how to make air conditioning more efficient and how you can harvest water. This material, because of its low cost and high performance, has so much potential.”
Díaz-Marin and his colleagues have published their results in a paper appearing today in Advanced Materials. The study’s MIT co-authors are Gustav Graeber, Leon Gaugler, Yang Zhong, Bachir El Fil, Xinyue Liu, and Evelyn Wang.
“Best of both worlds”
In MIT’s Device Research Lab, researchers are designing novel materials to solve the world’s energy and water challenges. In looking for materials that can help to harvest water from the air, the team zeroed in on hydrogels — slippery, stretchy gels that are mostly made from water and a bit of cross-linked polymer. Hydrogels have been used for years as absorbent material in diapers because they can swell and soak up a large amount of water when it comes in contact with the material.
“Our question was, how can we make this work just as well to absorb vapor from the air?” Díaz-Marin says.
He and his colleagues dug through the literature and found that others had experimented with mixing hydrogels with various salts. Certain salts, such as the rock salt used to melt ice, are very efficient at absorbing moisture, including water vapor. And the best among them is lithium chloride, a salt that is capable of absorbing over 10 times its own mass in moisture. Left in a pile on its own, lithium chloride could attract vapor from the air, though the moisture would only pool around the salt, with no means of retaining the absorbed water.
So, researchers have attempted to infuse the salt into hydrogel — producing a material that could both hold in moisture and swell to accommodate more water.
“It’s the best of both worlds,” says Graeber, who is now a principal investigator at Humboldt University in Berlin. “The hydrogel can store a lot of water, and the salt can capture a lot of vapor. So it’s intuitive that you’d want to combine the two.”
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But the MIT team found that others reached a limit to the amount of salt they could load into their gels. The best performing samples to date were hydrogels that were infused with 4 to 6 grams of salt per gram of polymer. These samples absorbed about 1.5 grams of vapor per gram of material in dry conditions of 30 percent relative humidity.
In most studies, researchers had previously synthesized samples by soaking hydrogels in salty water and waiting for the salt to infuse into the gels. Most experiments ended after 24 to 48 hours, as researchers found the process was too slow, and not very much salt ended up in the gels. When they tested the resulting material’s ability to absorb water vapor, the samples soaked up very little, as they contained little salt to absorb the moisture in the first place.
What would happen if the material synthesis was allowed to go on, say, for days, and even weeks? Could a hydrogel absorb even more salt, if given enough time? For an answer, the MIT team carried out experiments with polyacrylamide (a common hydrogel) and lithium chloride (a superabsorbent salt). After synthesizing tubes of hydrogel through standard mixing methods, the researchers sliced the tubes into thin disks and dropped each disk into a solution of lithium chloride with a different salt concentration. They took the disks out of solution each day to weigh them and determine the amount of salt that had infused into the gels, then returned them to their solutions.
In the end, they found that, indeed, given more time, hydrogels took up more salt. After soaking in salty solution for 30 days, hydrogels incorporated up to 24, versus the previous record of 6 grams of salt per gram of polymer.
The team then put various samples of the salt-laden gels through absorption tests across a range of humidity conditions. They found that the samples could swell and absorb more moisture at all humidity levels, without leaking. Most notably, the team reports that at very dry conditions of 30 percent relative humidity, the gels captured a “record-breaking” 1.79 grams of water per gram of material.
“Any desert during the night would have that low relative humidity, so conceivably, this material could generate water in the desert,” says Díaz-Marin, who is now looking for ways to speed up the material’s superabsorbent properties.
“The big, unexpected surprise was that, with such a simple approach, we were able to get the highest vapor uptake reported to date,” Graeber says. “Now, the main focus will be kinetics and how quickly we can get the material to uptake water. That will allow you to cycle this material very quickly, so that instead of recovering water once a day, you could harvest water maybe 24 times a day.”
https://onlinelibrary.wiley.com/doi/10.1002/adma.202211783
Extreme Water Uptake of Hygroscopic Hydrogels through Maximized Swelling-Induced Salt Loading
Gustav Graeber, Carlos D. Díaz-Marín, Leon C. Gaugler, Yang Zhong, Bachir El Fil, Xinyue Liu, Evelyn N. Wang
https://doi.org/10.1002/adma.202211783
https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202211783
https://www.youtube.com/watch?v=XFxVhcBIopI
Creating clean water from the air. Exploring super-absorbent hydrogels with Dr Youhong Nancy Guo
Dr Youhong Nancy Guo, a postdoctoral researcher at MIT discusses her team's research on super-absorbent hydrogels. These can absorb water directly from the surrounding air. These can help create clean, drinkable water in arid areas.
Dr Guo's team's research article was Nature Communications Top 25 Chemistry and Materials Sciences Articles of 2022
Dr Youhong Nancy Guo was chosen by Forbes for their 30 under 30: Science 2023 list.
https://www.youhongguo.com/
Youhong (Nancy) Guo
Polymers for a Sustainable Future -- Solar-to-Thermal Energy Conversion & Utilization
Youhong develops hydrogel-based solar-driven water purification systems for efficient clean water production. The unique water states in polymer materials enable fast water evaporation from hydrogels with much lower energy demand. By integrating solar-absorbing materials with spatial distribution into hydrogels, She demonstrated high light-to-thermal conversion efficiency and ultrafast water evaporation under natural sunlight. She further designed the device systems to achieve high water collection efficiency. Check her publications below for more details:
https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201907061
Adv. Mater. 2020, 32, 1907061
Biomass-Derived Hybrid Hydrogel Evaporators for Cost-Effective Solar Water Purification
Abstract -- Solar vapor generation has presented great potential for wastewater treatment and seawater desalination with high energy conversion and utilization efficiency. However, technology gaps still exist for achieving a fast evaporation rate and high quality of water combined with low-cost deployment to provide a sustainable solar-driven water purification system. In this study, a naturally abundant biomass, konjac glucomannan, together with simple-to-fabricate iron-based metal-organic framework-derived photothermal nanoparticles is introduced into the polyvinyl alcohol networks, building hybrid hydrogel evaporators in a cost-effective fashion ($14.9 m−2 of total materials cost). With advantageous features of adequate water transport, effective water activation, and anti-salt-fouling function, the hybrid hydrogel evaporators achieve a high evaporation rate under one sun (1 kW m−2) at 3.2 kg m−2 h−1 out of wastewater with wide degrees of acidity and alkalinity (pH 2–14) and high-salinity seawater (up to 330 g kg−1). More notably, heavy metal ions are removed effectively by forming hydrogen and chelating bonds with excess hydroxyl groups in the hydrogel. It is anticipated that this study offers new possibilities for a deployable, cost-effective solar water purification system with assured water quality, especially for economically stressed communities.
https://www.nature.com/articles/s41578-020-0182-4
Nat. Rev. Mater. 2020, 5, 388
https://pubs.acs.org/doi/10.1021/acsnano.9b02301
ACS Nano 2019, 13, 7913
Synergistic Energy Nanoconfinement and Water Activation in Hydrogels for Efficient Solar Water Desalination
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 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 1 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.
https://pubs.acs.org/doi/10.1021/acs.accounts.9b00455
Acc. Chem. Res. 2019, 52, 3244
Hydrogels as an Emerging Material Platform for Solar Water Purification
...In this Account, we review our recent progress on hydrogel-based evaporators for solar water purification in terms of material selection, molecular engineering, and structural design. First, we introduce the unique water state in hydrogels consisting of free, intermediate, and bound water, of which intermediate water has a reduced energy demand for water evaporation. Then, we describe the design principles of hydrogel-based solar evaporators, where the polymeric networks are tailored to regulate the water state. The water state in hydrogels defines the vaporization behavior of water. Thus, the polymer networks of hydrogels can be architected to tune the water state and, hence, to further reduce the evaporation enthalpy of water. Armed with fundamental gelation chemistry, we discuss synthetic strategies of hydrogels for efficient vapor generation. By incorporating solar absorbers with hydrophilic polymer networks, solar energy is harvested and converted to heat energy, which can be in situ utilized to power the vaporization of contained water in the molecular meshes, and the solar absorbers having strong interaction with hydrogels guide the formation of microstructure to reduce the energy loss and ensure adequate water transport of evaporative water. Regulating the vaporizing fronts, engineering the surface of hydrogels has been focused to favor the evaporationof water to further enhance the solar-to-vapor efficiency. By using hydrophilic polymers as building blocks, the hydrogel-based solar evaporators have also been endowed with multiple functionalities, such as antifouling, permselectivity, and thermal responsiveness, to improve water collection and purification abilities. Taking advantages of these merits, hydrogels have emerged as a promising materials platform to enable efficient solar water purification under natural sunlight. This Account serves to promote future efforts toward practical purification systems using hydrogel-based solar evaporators to mitigate water scarcity by improving their performance, scalability, stability, and sustainability.
https://pubs.rsc.org/en/content/articlelanding/2018/ee/c8ee00567b
Energy Environ. Sci. 2018, 11,1985
A hydrogel-based antifouling solar evaporator for highly efficient water desalination
Solar desalination is a promising method for large-scale water purification by utilizing sustainable energy. However, current high-rate solar evaporation often relies on optical concentration due to the diffusion of natural sunlight, which leads to inadequate energy supply. Here we demonstrate a hydrogel-based solar evaporator that is capable of generating vapor at a high rate of ∼2.5 kg m−2 h−1 under one sun irradiation (1 kW m−2), among the best values reported in the literature. Such highly efficient solar evaporation is achieved by a hybrid hydrogel composed of a hydrophilic polymer framework (polyvinyl alcohol, PVA) and solar absorber (reduced graphene oxide, rGO), which has internal capillary channels. The PVA can greatly facilitate the water evaporation owing to the reduced water evaporation enthalpy in the hydrogel network. The rGO penetrating into the polymeric network enables efficient energy utilization. The capillary channels sustain an adequate water supply for continuous solar vapor generation at a high rate. This hydrogel-based solar evaporator also exhibits promising antifouling properties, enabling long-term water desalination without recycling. The high-efficiency hydrogel-based solar vapor generators open significant opportunities to enhance solar water evaporation performance and reduce the cost of solar desalination systems.
Disclosed herein are water purifying networks. The networks efficiently absorb water and convert solar irradiation to heat, thereby evaporating absorbed water, which can be collected as purified water.
https://worldwide.espacenet.com/advancedSearch?locale=en_EP
Some Kojac Powder Preparation Patents :
Grinding device for konjac powder production -- CN219898482
Preparation method and application of konjac micro powder -- CN116918951
PREPARATION METHOD OF KONJAC GRANULE -- US2023309591
Method for preparing konjac glucomannan through efficient enzyme method -- CN116790691
METHOD FOR PREPARING KONJAC GLUCOMANNAN GUM -- US2023329279
Method for preparing konjac glucomannan through efficient enzyme method -- CN116790691
Extraction and purification method of konjac glucomannan and application of konjac glucomannan in gel food
CN116284489 (A)
&c...
https://hattongroup.mit.edu/youhong-nancy-guo/
Youhong (Nancy) Guo
https://scholar.google.ch/citations?user=2SLbtkUAAAAJ&hl=en&authuser=2
Publications:
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:qjMakFHDy7sC
Materials for solar-powered water evaporation
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:YsMSGLbcyi4C
Hydrogels and hydrogel-derived materials for energy and water sustainability
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:5nxA0vEk-isC
A hydrogel-based antifouling solar evaporator for highly efficient water desalination
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:UeHWp8X0CEIC
Architecting highly hydratable polymer networks to tune the water state for solar water purification
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:u5HHmVD_uO8C
Biomass‐derived hybrid hydrogel evaporators for cost‐effective solar water purification
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:0EnyYjriUFMC
Hydrogels as an emerging material platform for solar water purification
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:Se3iqnhoufwC
Synergistic energy nanoconfinement and water activation in hydrogels for efficient solar water desalination
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:d1gkVwhDpl0C
Tailoring nanoscale surface topography of hydrogel for efficient solar vapor generation
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:MXK_kJrjxJIC
Tailoring surface wetting states for ultrafast solar-driven water evaporation
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:IjCSPb-OGe4C
Topology‐controlled hydration of polymer network in hydrogels for solar‐driven wastewater treatment
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:zYLM7Y9cAGgC
Nanostructured functional hydrogels as an emerging platform for advanced energy technologies
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:eQOLeE2rZwMC
Carbon materials for solar water evaporation and desalination
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:ufrVoPGSRksC
Balancing the mechanical, electronic, and self-healing properties in conductive self-healing hydrogel for wearable sensor applications
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:roLk4NBRz8UC
Functional hydrogels for next-generation batteries and supercapacitors
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:3fE2CSJIrl8C
Scalable super hygroscopic polymer films for sustainable moisture harvesting in arid environments
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:2osOgNQ5qMEC
Materials engineering for atmospheric water harvesting: progress and perspectives
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:9yKSN-GCB0IC
Molecular engineering of hydrogels for rapid water disinfection and sustainable solar vapor generation
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:8k81kl-MbHgC
Polyzwitterionic hydrogels for efficient atmospheric water harvesting
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:_FxGoFyzp5QC
Highly elastic interconnected porous hydrogels through self‐assembled templating for solar water purification
https://scholar.google.ch/citations?view_op=view_citation&hl=en&user=2SLbtkUAAAAJ&citation_for_view=2SLbtkUAAAAJ:UebtZRa9Y70C
Engineering hydrogels for efficient solar desalination and water purification
Related: US11834351 -- Composite hydrogel sponge and its preparation method and application, solar desalination device