Formation of a carbon film by the molten salt electrochemical process and its applications

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CARBON 49 (2011) 4953– 4955

Carbon fiber from micro to nano Eiichi Yasuda Tokyo Institute of Technology, Japan Fifty years ago, research on traditional carbon fiber was started for rayon-based carbon fiber in the USA. Dr. A. Shindo invented a method for producing high performance carbon fiber by oxidizing PAN fiber in 1960. In 1963 Prof. S. Otani invented high performance pitch-based carbon fiber by aligning the mesophase molecules in the fiber direction by applying a shear stress at the spinneret. In addition to their excellent inventions, other key persons such as Dr. K. Morita of Toray and Dr. K. Gomi of Kureha Corporation were behind the success of carbon fiber development

To understand the hygroscopic properties of recent activated carbon products for industrial and occupational hygiene, we measured their pore and chemical properties, and water vapor isotherms at around room temperature (at 283, 293 and 298 K). The activated carbon specimens examined were used in 11 types of gas filter for Japanese respirators. The N-BET specific surface areas of the specimens are in the region of approximately 1200– 1600 m2/g. The water vapor isotherms show that keeping relative humidity below 40% in storage is efficient to eliminate moisture adsorption of the activated carbon products around room temperature. [TANSO 2011 (No. 248) 127–32.] doi:10.1016/j.carbon.2011.06.055

and the cultivation of new fields of application. Recently new technologies have been developed for carbon nanofiber production, such as CCVD, electro-spinning, super growth and spinning of a polymer blend. In this paper the history

Modeling of gaseous adsorption of activated carbon bed by

of carbon fibers will be reviewed to learn lessons from past efforts

Wheeler–Jonas equation and estimation of breakthrough time

and, making use of the results, to develop an excellent carbon

using the extended equation

nano-fiber.

Hironobu Abiko

[TANSO 2011 (No. 248) 112–21.] doi:10.1016/j.carbon.2011.06.053

Work Environment Research Group, National Institute of Occupational Safety and Health, Japan (JNIOSH), Japan The Wheeler–Jonas equation is an effective function for understanding gaseous adsorption in a compact activated carbon

Influence of surface charge and textural properties of carbon electrodes on nitrate ion removal by electroadsorption Mitsuhiro

Hamada, Takaya Nakamura, Kiyoharu Nakagawa,

Hirokazu Oda

bed. This report presents a summary of the derivation process described by Wheeler et al. and the modification of the equation by Yoon et al. The mathematical properties of the equation are also discussed from the viewpoints of adsorption capacity, breakthrough concentration and time for 50% breakthrough (stoichi-

Department of Chemical Engineering and High Technology Research

ometric time). The equation is also useful for estimating the

Center (HRC), Kansai University, Japan

breakthrough time of the carbon bed in gas filters for respirators, and it has been used in many previous studies of breakthrough

It is shown how to remove nitrate ions from aqueous solution

time simulation. Particularly, the estimation model reported by

by electrosorption in a way that has a low environmental impact

Wood et al.., which makes use of the Wheeler–Jonas equation,

and is energy saving. In order to elucidate adsorption/desorption

the Dubinin–Radushkevich equation and several empirical for-

mechanism of nitrate ions, ion removal using flow through

mulas for constants in the above mentioned equations, can also

capacitor and cyclic voltammetry measurements were investi-

take into consideration the effects of temperature and relative

gated. Characterization of suitable electrodes for electroadsorp-

humidity. We also summarized the components of Wood’s esti-

tion was determined. The static attraction by surface charges of

mation model, and investigated the points of relevance in appli-

carbon electrodes had a profound effect on adsorption of nitrate

cation of the model for actual measurement.

ions. It is difficult for nitrate ion to desorb from the electrode,

[TANSO 2011 (No. 248) 133–43.]

therefore an electrode with pHPZC (point zero of charge) of a weak acid is appropriate. Due to the overlapping effect of diffusion lay-

doi:10.1016/j.carbon.2011.06.056

ers in pores, it is thought that large mesopores (>20 nm) and the voids between particles are effective in dilute solution for nitrate ion removal. [TANSO 2011 (No. 248) 122–6.] doi:10.1016/j.carbon.2011.06.054

Formation of a carbon film by the molten salt electrochemical process and its applications Yasuhiko Ito Energy Conversion Research Center, Doshisha University, Japan

Water vapor adsorption and desorption isotherms of activated carbon products used in Japanese gas respirators Hironobu Abiko

Electrochemical formation of a carbon film can be achieved by either anodic oxidation of C2 2 ions or cathodic reduction of CO3 2 ions dissolved in a molten salt. A dense and adherent carbon film coating can be achieved by the anodic oxidation reaction. The

Work Environment Research Group, National Institute of Occupational

obtained carbon-coated metal shows advantageous features for

Safety and Health, Japan (JNIOSH), Japan

a fuel cell separator as well as a current collector for a Li-ion

CARBON 49 (2011) 4953– 4955

4955

secondary battery. On the other hand, the carbon film obtained by

attractive also from the aspects of fixation and effective use of

the cathodic reduction of CO3 2 ions has a micro-porous struc-

CO2.

ture, which is advantageous for an electrochemical capacitor. It

[TANSO 2011 (No. 248) 144–51.]

is also possible to electrochemically form a porous carbon film on a very thin, dense and adherent carbon film that is electrochemically formed on the metal surface beforehand. The layered carbon film thus obtained shows a high operating voltage span in an electrochemical capacitor. The cathodic reduction process is

doi:10.1016/j.carbon.2011.06.057