Shujie You, Junchun Yu, Bertil Sundqvist, LA Belyaeva, Natalya V. Avramenko, Mikhail V. Korobov, an

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Almost all materials shrinks when cooled down but the graphite oxide expands surprisingly by cooling, in methanol or ethanol. Additionally absorbs graphite oxide selectively methanol from water-methanol mixtures.
Two recent studies by physicists at Umeå University published in the journals ACS Nano and the Journal of Physical Chemistry C presents new properties of oxidized graphite and graphene. Graphene is a thin film of carbon, just one atom thick. It is a unique adsorptive material vci because of its extremely large surface. One gram of the graph have a surface comparable to a football field. This space would be ideal for adsorption of gases and liquids in applications vci for gas storage, extraction of contaminants from water, and so on, unless the graph would be a hydrophobic, meaning that its surface repels water.
Oxidation of the graph results in notable changes of its properties. Graf oxide is hydrophilic and attracted to water, and is even highly soluble in water. Material consisting of many graphene oxide layer called graphite oxide. It has many unique features: it absorbs water and alcohols in large quantities and swelling clays such as when water is added.
A new study by Alexandr V. Talyzin and his team show that graphite oxide can absorb additional methanol and ethanol at low temperatures vci compared to room temperature. The structure expands as the material is cooled in a liquid solvent. At -130 degrees Celsius in graphene oxide layers separated by 20.4 Å by the incorporation of additional ethanol, compared with about 3.4 Å in graphite and about 6.5 Å in solvent-graphite oxide.
- The distance between vci the graphene oxide layers at low temperatures is so large that it becomes a composite material with graphene oxide sheets separated by at least four monolayers of methanol or ethanol molecules. What is also remarkable is that this phenomenon could only be observed in a particular type of graphite oxide. Many different types of graphite oxide is known and we are now beginning to understand the huge variations in their properties. It is not just a material, there is a whole family of materials, says Alexandr V. Talyzin, researchers at the Department of Physics.
In a separate study, published in Journal of Physical Chemistry C, shown to a particular type of graphite oxide can be used for selective absorption of methanol from mixtures of water and methanol. A very simple filtration experiments showed that when water-methanol vci mixture dripped through the graphite oxide powder was absorbed vci a portion of the methanol in the powder and it came out contained more pure water.
- In the future, we want to design specific membrane consisting of graphene oxide that can be used for separation of solvent vci or water. These first results help us understand the different ways to make such membranes, says Alexandr V. Talyzin.
The first example of successful separation of solvent were reported last year in a study by a research group at Manchester University, which is headed by I. Grigorieva, and A. Geim, Nobel laureate in physics for his discoveries in the graph area.
Original Publication Shujie You, Bertil Sundqvist, and Alexandr V. Talyzin: Enormous Lattice Expansion of Graphite Oxide Hummers in Alcohols at Low Temperatures. ACS Nano, Article ASAP. DOI: 10.1021/nn3051105
Shujie You, Junchun Yu, Bertil Sundqvist, LA Belyaeva, Natalya V. Avramenko, Mikhail V. Korobov, and Alexandr V. Talyzin: Selective intercalation vci of Graphite Oxide by Methanol in Water / Methanol Mixtures. J. Phys. Chem. C, Article ASAP. DOI: 10.1021/jp312756w
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