Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (10): 20230214.doi: 10.7503/cjcu20230214

• Physical Chemistry • Previous Articles     Next Articles

Study on the Dielectric Relaxation Behavior of Fumed Silica Suspensions

LU Yuqiang, WU Xinjie, CHEN Zhen()   

  1. School of Natural Science,Anhui Agricultural University,Hefei 230036,China
  • Received:2023-04-27 Online:2023-10-10 Published:2023-07-07
  • Contact: CHEN Zhen E-mail:zchen@ahau.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21673002)

Abstract:

Colloidal suspensions of hydrophilic fumed silica in water and hydrophobic fumed silica in ethanol with different silica concentrations were prepared, and their dielectric spectra in the frequency range of 102 Hz to 107 Hz were measured by means of impedance analyzer. Two dielectric relaxation behaviors are observed locating in the vicinity of 104 Hz and 105 Hz in these spectra, they were then fit in line with Cole-Cole equation and characteristic parameters of these relaxations were accurately obtained. It is found that, the dielectric relaxation behaviors of both suspensions vary regularly with the concentration of silica. Based on the relaxation features and the regularity of the variation of the features with the silica concentration, it is confirmed that the low- and high-frequency relaxations are ascribed to counterion polarization and interfacial polarization of silica aggregate, respectively, furthermore, the surface behavior, the dispersing state, and their variation with the change of the concentration of silica of hydrophilic fumed silica in water and of hydrophobic fumed silica in ethanol were discussed in detail.

Key words: Fumed silica, Dielectric relaxation spectroscopy, Counterion polarization, Interfacial polarization, Colloidal suspension

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