Radeva T
Institute of Physical Chemistry, Bulgarian Academy of Sciences, Sofia, 1113, Bulgaria
J Colloid Interface Sci. 1999 Dec 1;220(1):118-122. doi: 10.1006/jcis.1999.6484.
Counterion polarization of sodium and magnesium polystyrenesulfonate (NaPSS and MgPSS), adsorbed in an excess onto ellipsoidal beta-ferric hydrous oxide particles (beta-FeOOH), is studied in both the absence and the presence of added simple electrolytes, NaCl and MgCl(2). The amplitude of the low-frequency (10(2)-10(4) Hz) and the high-frequency (10(4)-10(6) Hz) electro-optical effects of NaPSS is found to decrease with increasing NaCl concentration, while the critical frequency of relaxation of both effects remains unchanged. Addition of MgCl(2) to the suspension containing MgPSS also reduces the amplitude of the low-frequency electro-optical effect, but the amplitude of the high-frequency effect increases. The increased number of mobile (not bound) divalent ions, which produce larger charge fluctuation, could explain the high-frequency effect increase in the presence of a small excess of MgCl(2). Substitution of Na(+) counterions of PSS by Mg(2+) is found to increase the critical frequency of relaxation and to reduce the amplitude of the low-frequency effect, probably due to the strong repulsion between bound divalent counterions. The polyion length remains nearly unchanged during this substitution, as evidenced by the constant relaxation time of the polyelectrolyte-coated particles. The increase of counterion valence is not found to affect the amplitude of the high-frequency electro-optical effect in the absence of added salt. Copyright 1999 Academic Press.
研究了过量吸附在椭球形β-氢氧化铁颗粒（β-FeOOH）上的聚苯乙烯磺酸钠和聚苯乙烯磺酸镁（NaPSS和MgPSS）在添加简单电解质NaCl和MgCl₂存在和不存在的情况下的抗衡离子极化。发现NaPSS的低频（10² - 10⁴Hz）和高频（10⁴ - 10⁶Hz）电光效应的幅度随NaCl浓度的增加而降低，而两种效应的临界弛豫频率保持不变。向含有MgPSS的悬浮液中添加MgCl₂也会降低低频电光效应的幅度，但高频效应的幅度会增加。产生较大电荷波动的可移动（未结合）二价离子数量的增加可以解释在存在少量过量MgCl₂的情况下高频效应的增加。发现用Mg²⁺取代PSS的Na⁺抗衡离子会增加临界弛豫频率并降低低频效应的幅度，这可能是由于结合的二价抗衡离子之间的强排斥作用。在这种取代过程中，聚离子长度几乎保持不变，这由聚电解质包覆颗粒恒定的弛豫时间证明。在没有添加盐的情况下，发现抗衡离子价数的增加不会影响高频电光效应的幅度。版权所有1999年学术出版社。
