Takahashi Masayoshi
National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
J Phys Chem B. 2005 Nov 24;109(46):21858-64. doi: 10.1021/jp0445270.
Microbubbles are very fine bubbles and appropriate for the investigation of the gas-water interface electrical charge, because of their long stagnation, due to slow buoyancy, in the electrophoresis cell observation area. This study investigated the zeta potential of microbubbles in aqueous solutions and revealed that the bubbles were negatively charged under a wide range of pH conditions. The potential was positive under strong acidic conditions, and the inorganic electrolytes decrease the potential by increasing the amount of counterions within the slipping plane. OH(-) and H(+) are crucial factors for the charging mechanism of the gas-water interface, while other anions and cations have secondary effects on the zeta potential, because counterions are attracted by the interface charge. The addition of a small amount of propanol and butanol provided significant information for considering the mechanism of the gas-water interface charge. Even though these alcohols did not have any electrical charge, they had a strong effect on the gas-water interface charge and dispersed the zeta potential of the microbubbles in the aqueous solution. These alcohols tended to adsorb to the interface and affect the hydrogen-bonding network at the interface, so that it was concluded that the gas-water interface electrical charge must be related to the difference of the construction of the hydrogen-bonding network between the bulk water and the gas-water interface.
微泡是非常细小的气泡，由于其在电泳槽观察区域内由于浮力缓慢而具有较长的停滞时间，因此适合用于研究气-水界面电荷。本研究调查了水溶液中微泡的zeta电位，结果表明在广泛的pH条件下气泡带负电荷。在强酸性条件下电位为正，无机电解质通过增加滑动面内抗衡离子的数量来降低电位。OH(-)和H(+)是气-水界面充电机制的关键因素，而其他阴离子和阳离子对zeta电位有次要影响，因为抗衡离子被界面电荷吸引。添加少量的丙醇和丁醇为考虑气-水界面电荷机制提供了重要信息。尽管这些醇没有任何电荷，但它们对气-水界面电荷有很强的影响，并使水溶液中微泡的zeta电位分散。这些醇倾向于吸附到界面并影响界面处的氢键网络，因此得出结论，气-水界面电荷必须与本体水和气-水界面之间氢键网络结构的差异有关。
