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Patent Issued for Microwave-Assisted Synthesis of Carbon Nanotubes from Tannin, Lignin, and Derivatives

July 2, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- Board of Trustees of the University of Arkansas (Little Rock, AR) has been issued patent number 8753603, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventor is Viswanathan, Tito (Little Rock, AR).

This patent was filed on March 22, 2011 and was published online on June 17, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "Carbon nanostructures in the form of carbon black, graphite, fullerene, single walled, double walled, multi-walled carbon nanotubes as well as nanodiamonds play a significant role in present and future technology. The applications of these nanostructures range from reinforcement in rubber tires, electrodes in batteries and fuel cells, electrostatic dissipation, electromagnetic interference shielding, and photo-voltaic cells, to radar-evading stealth coatings. Specific exemplary applications of carbon nanotubes are their use in nanocomposites and in faster and more efficient electronic devices. Other potential applications include biocomposites and delivery of drugs. They may also serve as semi-transparent optical material. The high surface area of nanotubes also renders them useful as a catalyst support material. They could also be used in field effect transistors.

"Thus, nanotube form of carbon is poised to become one of the most important carbon forms in terms of use and applications. The synthesis carbon nanotubes, however, involves substantial investment in terms of safety, cost, time, and apparatus, besides requiring expertise in instrument operation. For example, one of the synthetic techniques involves chemical vapor deposition (CVD) on selected catalysts placed on special supports. The reaction takes place in a reducing or inert atmosphere and requires significant investment in time, energy, expertise and cost. The technique is also not easily scalable.

"Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventor's summary information for this patent: "In one aspect, the present invention provides a method of synthesizing carbon nanotubes, comprising the steps of:

"dissolving a first amount of a first transition-metal salt and a second amount of a second transition-metal salt in water to form a solution;

"adding a third amount of tannin to the solution to form a mixture;

"heating the mixture to a first temperature for a first duration of time to form a sample; and

"subjecting the sample to a microwave radiation for a second duration of time effective to produce a plurality of carbon nanotubes.

"In one embodiment, the first transition metal salt is iron chloride (FeCl.sub.3), and the second transition metal salt is nickel chloride (NiCl.sub.2).

"In one embodiment, the molar ratio of FeCl.sub.3 and NiCl.sub.2 is about 3:1.

"In one embodiment, the first temperature is about 250.degree. C. or about 300.degree. C., respectively.

"In one embodiment, the heating step comprises the step of heating the mixture in a furnace with or without air flow to dry the sample, respectively.

"In one embodiment, prior to the subjecting step, further comprising the steps of:

"placing the sample in a first container; and

"placing the first container with the sample in a second container that contains graphite or carbon black.

"In one embodiment, the step of subjecting comprises the step of subjecting the dry sample placed in the first container to the microwave radiation, wherein the first container is placed in the second container, which is positioned such that at least part of the graphite or carbon black contained in the second container is also subjected to the microwave radiation.

"In another embodiment, the frequency of the microwave radiation is about 2.45 GHz.

"In yet another embodiment, the tannin is Quebracho tannin.

"In a further embodiment, the tannin is unmodified and hot water-soluble.

"In another aspect, the present invention provides an article of manufacture made by the method set forth immediately above.

"In yet another aspect, the present invention provides a method of synthesizing carbon nanotubes, comprising the steps of:

"dissolving a first amount of a first transition-metal salt and a second amount of a second transition-metal salt in water to form a solution;

"adding a third amount of lignin to the solution to form a mixture;

"heating the mixture to a first temperature for a first duration of time to form a sample; and

"subjecting the sample to a microwave radiation for a second duration of time effective to produce a plurality of carbon nanotubes.

"In one embodiment, the first transition metal salt is iron chloride (FeCl.sub.3), and the second transition metal salt is nickel chloride (NiCl.sub.2).

"In one embodiment, the molar ratio of FeCl.sub.3 and NiCl.sub.2 is about 3:1.

"In one embodiment, the first temperature is about 300.degree. C.

"In one embodiment, the heating step comprises the step of heating the mixture in a furnace with air flow to dry the sample.

"In one embodiment, prior to the subjecting step, further comprising the steps of:

"placing the sample in a first container; and

"placing the first container with the sample in a second container that contains graphite or carbon black.

"In another embodiment, the step of subjecting comprises the step of subjecting the dry sample placed in the first container to the microwave radiation, wherein the first container is placed in the second container, which is positioned such that at least part of the graphite or carbon black contained in the second container is also subjected to the microwave radiation.

"In yet another embodiment, the frequency of the microwave radiation is about 2.45 GHz.

"In a further embodiment, wherein the lignin comprises a sodium salt of lignin.

"In a further aspect, the present invention provides an article of manufacture made by the method set forth immediately above.

"These and other aspects of the present invention will become apparent from the following description of the preferred embodiment taken in conjunction with the following drawings and their captions, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure."

For the URL and additional information on this patent, see: Viswanathan, Tito. Microwave-Assisted Synthesis of Carbon Nanotubes from Tannin, Lignin, and Derivatives. U.S. Patent Number 8753603, filed March 22, 2011, and published online on June 17, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8753603.PN.&OS=PN/8753603RS=PN/8753603

Keywords for this news article include: Anions, Graphite, Minerals, Chlorides, Fullerenes, Nanostructural, Nanostructures, Nanotechnology, Carbon Nanotubes, Hydrochloric Acid, Emerging Technologies, Board of Trustees of the University of Arkansas.

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Source: Journal of Engineering


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