Effects of pH on water-solubilization of carbon nanotube using microplasma in aqueous solution

Kiminobu Imasaka, Yuki Kato, Usama Khaled, Junya Suehiro

Research output: Contribution to journalArticle

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Abstract

The authors have previously proposed a novel technique for the preparation of water-soluble carbon nanotubes (CNTs) using microplasma generated by a pulsed streamer discharge in water. This paper describes effects of pH values on water-solubility of single-walled CNT (SWCNT) treated by the microplasma. The SWCNT treated under basic conditions showed two times higher solubility compared to that treated under neutral condition, whereas the SWCNT solubility considerably decreased under acidic conditions. Based on optical emission measurements of microplasma showed that radical formation was not pH sensitive. Fourier transform infrared (FTIR) spectroscopy and Xray photoelectron spectroscopy (XPS) analysis showed that the microplasma treated SWCNT was functionalized with -COO- groups with little pH dependence. In contrary, clear pH dependence was observed for zeta potential of the microplasma-treated SWCNT. The lowest zeta potential was-46 mV, which was obtained with basic solution adjusted by NH3 (pH≈9). The SWCNT treated under basic conditions was more negatively charged due to suppressed protonation of -COO- groups. As a result, the electrostatic repulsion force between SWCNTs could overcome van der Waals force improving their solubility and dispersibility in water.

Original languageEnglish
Article number065004
JournalJapanese Journal of Applied Physics
Volume48
Issue number6
DOIs
Publication statusPublished - Jun 1 2009

Fingerprint

microplasmas
Carbon nanotubes
Solubility
carbon nanotubes
aqueous solutions
Zeta potential
water
solubility
Water
Van der Waals forces
Protonation
Single-walled carbon nanotubes (SWCN)
Photoelectron spectroscopy
Fourier transform infrared spectroscopy
Electrostatics
light emission
infrared spectroscopy
photoelectron spectroscopy
electrostatics
preparation

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Effects of pH on water-solubilization of carbon nanotube using microplasma in aqueous solution. / Imasaka, Kiminobu; Kato, Yuki; Khaled, Usama; Suehiro, Junya.

In: Japanese Journal of Applied Physics, Vol. 48, No. 6, 065004, 01.06.2009.

Research output: Contribution to journalArticle

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