EEWS
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Adsorbent That Can Selectively Remove Water Contaminants
Professor Cafer T. Yavuz and his team at the Graduate School of Energy, Environment, Water, and Sustainability (EEWS) have developed an adsorbent that can selectively capture soluble organic contaminants in water.
This water treatment adsorbent is a fluorine-based nanoporous polymer that can selectively remove water-soluble micromolecules. It has the added advantage of being cheap and easily synthesized, while also being renewable.
The results of this research have been published online in Nature Communication on November 10, 2016. The research paper is titled “Charge-specific Size-dependent Separation of Water-soluble Organic Molecules by Fluorinated Nanoporous Networks.” (DOI: 10.1038/ncomms13377)
Water pollution is accelerating as a result of global industrial development and warming. As new materials are produced and applied in the agricultural and industrial sectors, the types of contaminants expelled as sewage and waste water are also becoming diverse.
Chemicals such as dyes and pesticides can be especially harmful because they are made up of small and highly soluble organic particles that cannot be completely removed during the water treatment process, ultimately ending up in our drinking water.
The current conventional water treatment systems utilize processes such as activated carbon, ozonolysis, and reverse osmosis membrane. These processes, however, are designed to remove larger organic molecules with lower solubility, thus removal of very small molecules with high solubility is difficult. In addition, these micromolecules tend to be charged, therefore are less easily separated in aqueous form.
The research team aimed to remove these small molecules using a new adsorbent technology.
In order to remove aqueous organic molecular contaminants, the team needed an adsorbent that can adsorb micro-sized molecules. It also needed to introduce a chemical function that would allow it to selectively adsorb molecules, and lastly, the adsorbent needed to be structurally stable as it would be used underwater.
The team subsequently developed an adsorbent of fluorine-based porous organic polymer that met all the conditions listed above. By controlling the size of the pores, this adsorbent is able to selectively adsorb aqueous micromolecules of less than 1-2 nm in size.
In addition, in order to separate specific contaminants, there should be a chemical functionality, such as the ability to strongly interact with the target material. Fluorine, the most electronegative atom, interacts strongly with charged soluble organic molecules.
The research team incorporated fluorine into an adsorbent, enabling it to separate charged organic molecules up to 8 times faster than neutral molecules.
The adsorbent developed by Professor Yavuz’s team has wide industrial applications. It can be used in batch-adsorption tests, as well as in column separation for size- and charge-specific adsorption.
Professor Yavuz stated that “the charge-selective properties displayed by fluorine has the potential to be applied in desalination or water treatment processes using membranes."
This paper was first-authored by Dr. Jeehye Byun, and the research was funded by KAIST’s High Risk High Return Program and the Ministry of Science, ICT and Future Planning of Korea’s Mid-Career Researcher Program, as well as its Technology Development Program to Solve Climate Change.
Figure 1. Diagram conceptualizing the process of charge- and size-specific separation by the fluorine-based porous polymer adsorbent
Figure 2. Difference in absorbance before and after using a porous fluorine polymer column to separate organic molecules
Figure 3. Adsorption properties of a fluorine polymer according to the charge and size of organic molecules
2017.01.17 View 9376 -
Direct Utilization of Elemental Sulfur for Microporous Polymer Synthesis
Using elemental sulfur as an alternative chemical feedstock, KAIST researchers have produced novel microporous polymers to sift CO2 from methane in natural-gas processing.
Methane, a primary component of natural gas, has emerged recently as an important energy source, largely owing to its abundance and relatively clean nature compared with other fossil fuels. In order to use natural gas as a fuel, however, it must undergo a procedure called “hydrodesulfurization” or “natural gas sweetening” to reduce sulfur-dioxide emissions from combustion of fossil fuels. This process leads to excessive and involuntary production of elemental sulfur. Although sulfur is one of the world’s most versatile and common elements, it has relatively few large-scale applications, mostly for gunpowder and sulfuric acid production.
Thus, the development of synthetic and processing methods to convert sulfur into useful chemicals remains a challenge. A research team led by Professor Ali Coskun from the Graduate School of EEWS (Energy, Environment, Water and Sustainability) at Korea Advanced Institute of Science and Technology (KAIST) has recently introduced a new approach to resolving this problem by employing elemental sulfur directly in the synthesis of microporous polymers for the process of natural-gas sweetening.
Natural gas, containing varying amounts of carbon dioxide (CO2) and hydrogen sulfide (H2S), is generally treated with amine solutions, followed by the regeneration of these solutions at increased temperatures to release captured CO2 and H2S. A two-step separation is involved in removing these gases. The amine solutions first remove H2S, and then CO2 is separated from methane (CH4) with either amine solutions or porous sorbents such as microporous polymers.
Using elemental sulfur and organic linkers, the research team developed a solvent and catalyst-free strategy for the synthesis of ultramicroporous benzothiazole polymers (BTAPs) in quantitative yields. BTAPs were found to be highly porous and showed exceptional physiochemical stability. In-situ chemical impregnation of sulfur within the micropores increased CO2 affinity of the sorbent, while limiting diffusion of CH4. BTAPs, as low-cost, scalable solid-sorbents, showed outstanding CO2 separation ability for flue gas, as well as for natural and landfill gas conditions.
The team noted that: “Each year, millions of tons of elemental sulfur are generated as a by-product of petroleum refining and natural-gas processing, but industries and businesses lacked good ideas for using it. Our research provides a solution: the direct utilization of elemental sulfur into the synthesis of ultramicroporous polymers that can be recycled back into an efficient and sustainable process for CO2 separation. Our novel polymeric materials offer new possibilities for the application of a little-used natural resource, sulfur, to provide a sustainable solution to challenging environmental issues.”
This work was published online in Chem on September 8, 2016 and also highlighted in C&EN (Chemical & Engineering News) by the American Chemical Society (ACS) on September 19, 2016. The research paper was entitled “Direct Utilization of Elemental Sulfur in the Synthesis of Microporous Polymers for Natural Gas Sweetening.” (DOI: 10.1016/j.chempr.2016.08.003)
Figure 1. A Schematic Image of Direct Utilization of Elemental Sulfur
This image shows direct utilization of elemental sulfur in the synthesis of microporous polymers and its gas separation performance.
Figure 2. BTAP’s Breakthrough Experiment under Pre-mixed Gas Conditions
This data presents the breakthrough measurements for CO2-containing binary gas-mixture streams with different feed-gas compositions to investigate the CO2 capture capacity of ultramicroporous benzothiazole polymers (BTAPs) for large-scale applications under simulated conditions of natural and landfill gases.
2016.10.05 View 8364 -
A New Way to Look at MOFs
An international research team composed of researchers from KAIST (led by Professors Osamu Terasaki and Jeung Ku Kang at the Graduate School of Energy, Environment, Water and Sustainability) and other universities, including UC Berkeley, has recently published research results on the adsorption process of metal-organic frameworks (MOFs) in Nature (November 9, 2015).
MOFs are porous three-dimensional crystals with a high internal surface area, which have a wide range of applications involving adsorption such as hydrogen, methane, or carbon dioxide storage. In the paper entitled “Extra Adsorption and Adsorbate Superlattice Formation in Metal-organic Frameworks,” the research team described their observation of a very specific interpore interaction process in MOFs.
For additional information, please see:
A New Way to Look at MOFs
International study challenges prevailing view on how metal organic frameworks store gases
EurekAlert, November 9, 2015
http://www.eurekalert.org/pub_releases/2015-11/dbnl-anw110915.php
(Courtesy of the US Department of Energy and Lawrence Berkeley National Laboratory news release)
2015.11.13 View 7798 -
KAIST Develops a Credit-Card-Thick Flexible Lithium Ion Battery
Since the battery can be charged wirelessly, useful applications are expected including medical patches and smart cards.
Professor Jang Wook Choi at KAIST’s Graduate School of Energy, Environment, Water, and Sustainability (EEWS) and Dr. Jae Yong Song at the Korea Research Institute of Standards and Science jointly led research to invent a flexible lithium ion battery that is thinner than a credit card and can be charged wirelessly.
Their research findings were published online in Nano Letters on March 6, 2015. Lithium ion batteries are widely used today in various electronics including mobile devices and electronic cars. Researchers said that their work could help accelerate the development of flexible and wearable electronics.
Conventional lithium ion batteries are manufactured based on a layering technology, stacking up anodes, separating films, and cathodes like a sandwich, which makes it difficult to reduce their thickness. In addition, friction arises between layers, making the batteries impossible to bend. The coating films of electrodes easily come off, which contributes to the batteries’ poor performance.
The research team abandoned the existing production technology. Instead, they removed the separating films, layered the cathodes and anodes collinearly on a plane, and created a partition between electrodes to eliminate potential problems, such as short circuits and voltage dips, commonly present in lithium ion batteries.
After more than five thousand consecutive flexing experiments, the research team confirmed the possibility of a more flexible electrode structure while maintaining the battery performance comparable to the level of current lithium ion batteries.
Flexible batteries can be applied to integrated smart cards, cosmetic and medical patches, and skin adhesive sensors that can control a computer with voice commands or gesture as seen in the movie “Iron Man.”
Moreover, the team has successfully developed wireless-charging technology using electromagnetic induction and solar batteries.
They are currently developing a mass production process to combine this planar battery technology and printing, to ultimately create a new paradigm to print semiconductors and batteries using 3D printers.
Professor Choi said, “This new technology will contribute to diversifying patch functions as it is applicable to power various adhesive medical patches.”
Picture 1: Medical patch (left) and flexible secondary battery (right)
Picture 2: Diagram of flexible battery
Picture 3: Smart card embedding flexible battery
2015.03.24 View 10736 -
Materials Developed for Sodium Rechargeable Battery by EEWS
The research group of Professor William Goddard III, You-Sung Jung, and Jang-Wook Choi from the Graduate School of Energy, Environment, Water, and Sustainability (EEWS) at KAIST has developed a new sodium-ion rechargeable battery which operates at a high voltage, can be charged, and stably discharges over 10,000 cycles. The research results were published in the online version of the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on December 30, 2013.
Since the material costs of sodium rechargeable batteries is 30 to 40 times lower than lithium batteries, it has received attention as an energy saving tool for smart grids and as the next generation of lithium rechargeable batteries. Until now, sodium-ion rechargeable batteries have had issues with stability when charging and discharging. The research group developed a vanadium-based electrode to solve these problems.
The group said follow-up research will be continued to develop advanced technology on sodium rechargeable batteries as it is still currently in the beginning stages.
The research team: From left to right is Professors William Goddard, You-Sung Jung, and Jang-Wook Choi
2014.01.13 View 9922 -
2013 EEWS Forum on National Energy Plan and Smart Grid Strategy
The Graduate School of Energy, Environment, Water, and Sustainability (EEWS) at KAIST hosted a forum on national energy planning and smart grid strategies on December 2 in the Jong-Hyun Choi Hall on KAIST’s Seoul campus. EEWS is a research and education program operated by KAIST to deal with the issues of energy, global warming, water, and sustainable growth.About 20 specialists including Jae-Kyu Lee, President of the Graduate School of Green Growth at KAIST; Kwang-Sik Choi, President of the EEWS Forum; Seong-Hoon Lee, Chairman of the Presidential Committee on Green Growth; Yang-Hoon Sohn, President of the Energy Economics Institute; and Jun-Dong Kim, Deputy Minister in the Ministry of Trade, Industry, and Energy, participated in the forum. Presentations and discussions were made in the fields of national energy plans, smart grid strategies, energy policy, as well as gas, electricity and sustainable energy.
2013.12.11 View 7492 -
Secondary, High Capacity Battery developed from Rice Husks
Rice husks, a waste product from rice polishing, has been successfully utilized as the silicon anode for use in high capacity lithium ion secondary batteries. The new silicon anode derived from rice husks exhibit superior output and lifespan.
Professor Choi Jang Wook (The Graduate School of Energy, Environment, Water and Sustainability (EEWS)) and Professor Park Seung Min (Department of Biochemistry) and their respective research teams separated naturally occurring, highly porous silica material within the rice husks and developed a 3-dimensional, highly porous silicon anode material.
The result of the research effort was published in the online edition of the Proceedings of the National Academy of Sciences (PNAS) journal, a world renowned journal in the field of natural sciences.
Silicon has attracted much attention as anode material for next generation lithium ion secondary batteries because it exhibits 3~5 times higher capacity than conventional graphene. The high capacity will pave the way to lithium secondary batteries with higher energy densities than conventional batteries. It is anticipated that the application of silicon batteries will yield electronic devices with a longer duration for use in addition to electronic vehicles boasting longer mileage.
The silicon anode is based on the 3-dimensional, highly porous structure of rice husks which remedies the problematic extreme volume expansion of conventional silicon anodes.
Utilization of inexpensive rice husks to create high value silicon anodes will cause a ripple effect on the industry and academia.
2013.08.23 View 9724 -
Ultra-High Strength Metamaterial Developed Using Graphene
New metamaterial has been developed, exhibiting hundreds of times greater strength than pure metals.
Professor Seung Min, Han and Yoo Sung, Jeong (Graduate School of Energy, Environment, Water, and Sustainability (EEWS)) and Professor Seok Woo, Jeon (Department of Material Science and Engineering) have developed a composite nanomaterial. The nanomaterial consists of graphene inserted in copper and nickel and exhibits strengths 500 times and 180 times, respectively, greater than that of pure metals. The result of the research was published on the July 2nd online edition in Nature Communications journal.
Graphene displays strengths 200 times greater than that of steel, is stretchable, and is flexible. The U.S. Army Armaments Research, Development and Engineering Center developed a graphene-metal nanomaterial but failed to drastically improve the strength of the material.
To maximize the strength increased by the addition of graphene, the KAIST research team created a layered structure of metal and graphene. Using CVD (Chemical Vapor Deposition), the team grew a single layer of graphene on a metal deposited substrate and then deposited another metal layer. They repeated this process to produce a metal-graphene multilayer composite material, utilizing a single layer of graphene. Micro-compression tests within Transmission Electronic Microscope and Molecular Dynamics simulations effectively showed the strength enhancing effect and the dislocation movement in grain boundaries of graphene on an atomic level.
The mechanical characteristics of the graphene layer within the metal-graphene composite material successfully blocked the dislocations and cracks from external damage from traveling inwards. Therefore the composite material displayed strength beyond conventional metal-metal multilayer materials. The copper-graphene multilayer material with an interplanar distance of 70nm exhibited 500 times greater (1.5GPa) strength than pure copper. Nickel-graphene multilayer material with an interplanar distance of 100nm showed 180 times greater (4.0GPa) strength than pure nickel.
It was found that there is a clear relationship between the interplanar distance and the strength of the multilayer material. A smaller interplanar distance made the dislocation movement more difficult and therefore increased the strength of the material. Professor Han, who led the research, commented, “the result is astounding as 0.00004% in weight of graphene increased the strength of the materials by hundreds of times” and “improvements based on this success, especially mass production with roll-to-roll process or metal sintering process in the production of ultra-high strength, lightweight parts for automobile and spacecraft, may become possible.” In addition, Professor Han mentioned that “the new material can be applied to coating materials for nuclear reactor construction or other structural materials requiring high reliability.”
The research project received support from National Research Foundation, Global Frontier Program, KAIST EEWS-KINC Program and KISTI Supercomputer and was a collaborative effort with KISTI (Korea Institute of Science and Technology Information), KBSI (Korea Basic Science Institute), Stanford University, and Columbia University.
A schematic diagram shows the structure of metal-graphene multi-layers. The metal-graphene multi-layered composite materials, containing a single-layered graphene, block the dislocation movement of graphene layers, resulting in a greater strength in the materials.
2013.08.23 View 14271 -
Joint Research Center on EEWS with Hyundai Heavy Industries Plans to Open
The research center will conduct collaborative R&D projects on energy, environment, water, and sustainability for the next five years.Hyundai Heavy Industries (HHI), the world’s largest shipbuilding company, signed an MOU with KAIST for future business development and joint research collaboration.
KAIST and HHI signed an MOU as an agreement to establish the “HHI-KAIST EEWS Research Center (HK Research Center) on June 21st.”
The major mission of the HK Research Center is to build a strong base for creating future businesses through developing fundamental, core technology in the field of EEWS and designing business models based on the new technology.
Toward this goal, HHI will sponsor the R&D budget and operation expenses of the research center for the next five years.
Prior to the signing of the MOU, a delegation from HHI, led by the Vice President, Mr. Si-Young Hwang, visited the Office of EEWS Initiative at KAIST and held a workshop. During the workshop, HHI and KAIST agreed to collaborate in fields such as LNG-propelled ships, solar power generation, energy storage, fuel cells, and CO2 capture.
KAIST has run a EEWS graduate program that receives government grants over the last five years, with a research emphasis on energy, environment, water, and sustainability, which are crucial issues to humankind in the 21st century. The EEWS program achieved 24 core technological developments and educates more than 200 masters- and PhD-degree students annually.
The EEWS program also emphasizes commercializing its research outcomes. Through the annual Business Planning Competition and Investment Drive, there have been eight new companies founded by alumni and professors over the last five years of the program. The HK Research Center will be an excellent foundation for future education and research in EEWS.
Professor Jae-Kyu Lee, the head of the HK Research Center and the director of the EEWS Initiative, said, “This event is a benchmarking example of Industry-KAIST collaboration. We hope that the HK Research Center will be a place for disruptive innovations to translate into creative business opportunities.”
MOU signed for Hyundai Heavy Industries-KAIST EEWS Research Center
2013.07.15 View 7878 -
Synthesis of a New Organic Supermolecule Succeeded
From left to right: Prof.Stoddart, Prof.Goddard and Prof.Jang Wook Choi
KAIST EEWS graduate school’s research team led by Prof. Stoddart, Prof. Goddard and Prof. Jang Wook Choi has succeeded the synthesis of a new organic supermolecule that is stable in a radical condition under room temperature.
Prof. Stoddart, who mainly led this research, is the world’s great scholar on orgaic molecular structure especially on catenane with an interconnection of several ring structures. Catenane is originated from Latin “catenane” referring to “chain”. The brief structure of the synthesized catenane is as following:
Usually radicals are known to be unstable since they are electronically neutral and have very high reactivity. However, the radicals from this research showed air- and water- stability. It also showed a reversible change in oxidation number from o to +8 through chemical/electrochemical oxidation-reduction reaction. The phenomenon where paramagnetic and diamagnetic characteristics change according to the oxidation number has also been observed.
Thus, the research like this - on the molecules showing various characteristics with stable radical - is expected to give a new direction to the next-generation electromemory system, semiconductor and energy storage system research.
Meanwhile, this research, led by Prof.Stoddart team with Prof.Goddard and Prof. Jang Wook Choi’s team, is conducted under the support of Science and Technology’s World Class University project by Ministry of Education and published in ‘Science’ on 25th of Jan.
2013.02.24 View 9975
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A Substance with Amazingly Improved Efficiency of Capturing Carbon Dioxides Developed
From left to right: Prof.Ali Coskun, Prof. Cafer T. Yavuz and Prof. Yousung Jung
- Selectivity of CO2 increased by 300 times in comparison to nitrogen, published in Nature Communications-
KAIST EEWS graduate school’s joint research team led by Prof. Cafer T. Yavuz, Prof. Ali Coskun, and Prof. Yousung Jung has developed the world"s most efficient CO2 absorbent that has 300 times higher carbon dioxide selectivity in comparison to nitrogen.
Recently, the importance of CCS* technology, which is about capturing, storing and treating carbon dioxides, has begun to emerge world-widely as a practical alternative for the response to climate change.
* CCS : Carbon Capture and sequestration
Current carbon dioxide capturing technologies are wet capturing using liquid absorbent, dry capturing using solid absorbent and separation-membrane capturing using a thin membrane like a film.
For the places like power plant and forge, where the emission of carbon dioxides is huge, the main task is to maintain the capturing efficiency under extremely hot and humid conditions.
The previously studied dry absorbents, such as MOF or zeolite, had the disadvantages of instability in moist conditions and expensive cost for synthesis.
On the other hand, the research team"s newly discovered dry absorbent, named ‘Azo-COP’, can be synthesized without any expensive catalysts so the production cost is very low. It is also stable under hot and humid conditions.
COP is a structure consisting of simple organic molecules combined into porous polymer and is the first dry carbon dioxide capturing material developed by this research team.
The research team introduced an additional functional group called "Azo" to the substance, so that it can selectively capture carbon dioxides among the mixture of gas.
Azo-COP, which includes ‘Azo’ functional group, is manufactured easily by using common synthesis methods, and impurities are removed simply by using cheap solvents like water and acetone instead of expensive catalysts. As a result, the manufacturing cost has lowered drastically.
Especially, Azo-COP is combined with carbon dioxides by weak attraction force rather than chemical attraction so the recycling energy cost for the absorbent can be reduced innovatively, and it is expected to be used for capturing substances other than carbon dioxides in various areas as it is stable under extreme conditions even under 350 degrees Celsius.
This research is supported by Korea Carbon Capture&Sequestration R&D Center(Head: Sangdo Park) and KAIST EEWS planning group.
Prof. Cafer T. Yavuz and Prof. Ali Coskun said that “when Azo-COP is used for separation of CO2 and N2, the capturing efficiency has increased by hundred times.” He continued “This substance does not need any catalysts and has great chemical characteristics like water stability and structure stability so is expected to be used in various fields including carbon dioxides capturing”
Meanwhile, this research is published in ‘Nature’s stablemate ‘Nature Communications’ on 15th of Jan.
2013.02.24 View 11494
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Prof. Jang-Uk Choi develops Strong, Long-lasting Lithium-ion Battery
Lithium-ion secondary battery with high power, as well asmuch longer life span, has been developed using nanotechnology. Professor Jang-Uk Choi and his colleagues at KAIST University EEWS graduate school has succeeded in developing a new lithium-ion secondary battery that has more than five times the output and three times the life span of the conventional batteries.
The industry expects the new battery to significantly improve the acceleration performance and solve the drawbacks of slow electric cars, which occurred due to failure of battery performance to keep up with the output of the motors during acceleration.
It is also expected that the new battery could be utilized in various fields that require high power batteries such as Smart Grid, which is the next generation intelligent electrical grid, as well as electric tools and many others.
Currently, the most widely used commercial lithium ion batteries’ lithium-cobalt-based cathode material has the disadvantage of expensive cost, high toxicity, short life expectancy and long-charge/discharge time. Also, it has been difficult to apply in electric cars that require a large current density and are vulnerable to heat generated during charging/discharging.
On the other hand, Professor Choi and his colleagues’ lithium-manganese based cathode material is gaining popularity for having the advantages such as abundant raw materials, cheap prices, eco-friendliness and especially excellent high-temperature stability and high output, which are suitable for use as electrode material in electric cars.
The pure lithium manganese based cathode material has a critical drawback of a very short life expectancy, only lasting about average of 1-2 years, which is due to the elution when the melted manganese flows out into the electrolyte. There have been various studies to solve this problem; however, the unique crystal structure of the material remained as a challenge for many scientists.
Professor Choi’s team analyzed the structure of the crystal at the time shortly before manganese oxides were formed, while controlling the reaction temperature at the step of synthesizing nanomaterial. It has been found that, at 220℃, there are simultaneously existing two crystal faces, one that inhibits the dissolution of manganese ions and the other that enables lithium ions to move smoothly.
Each of these crystal faces improves both the life span and output, increasing the output more than five times and life expectancy over three times. In addition, the existing high temperature life span, that was known to be especially vulnerable, has improved ten-fold.
“By controlling the crystal face of lithium manganese anode material, which has previously existed in the battery as chunks of about 10 micro-meter particles, both output and life span has significantly improved,” said Professor Choi, “Domestic and international patent application for the regarding technology has been finished and we have plans to work with companies in the future for commercialization within 2-3 years.”
Professor Yi Cui of Stanford University, the world’s leading scholar on the secondary battery, has evaluated that “This research exemplifies how nanotechnology can innovatively develop the field of secondary battery.”
Meanwhile, the research led by Professor Jang-Uk Choi and participated by researcher Ju-Seong Kim has been published on the online edition (dated Nov 27th) of Nanoletters, the world’s leading authority on Nanoscience.
2012.12.21 View 8769