Zhivkov Alexandar M, Hristov Rosen P
"Rostislaw Kaishew" Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 11, Sofia 1113, Bulgaria.
"Rostislaw Kaishew" Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 11, Sofia 1113, Bulgaria.
J Colloid Interface Sci. 2015 Jun 1;447:159-66. doi: 10.1016/j.jcis.2014.11.051. Epub 2014 Nov 25.
The polyelectrolyte adsorption on colloid particles is often used for stabilization or flocculation of water suspensions. The aim of this work is to study the adsorption of carboxymethyl cellulose (CMC) on alumina (γ-Al2O3) colloid particles. The particles and polymer are chosen because of the capability of the metal-oxide ampholyte surface and the weak polyelectrolytes to alter their charge by pH. The measurements are done at pH 6.0 where the CMC carboxylic gropes are almost fully dissociated and the alumina surface is positively charged. The high linear charge density of the polyelectrolyte chain provides Na(+) counterions condensation on the COO(-) groups. The main employed method is the electric light scattering based on particle orientation in sinusoidal electric field. The electric polarizability and the relaxation time after field switching off (both depending on the particle charge and size) are used as criteria for polymer adsorption and particle aggregation. Micro-electrophoresis is applied as additional techniques indicating the sign and density of the surface charge. The results obtained give the conditions (time dependence, particle and polymer concentrations) where the CMC adsorption is complete and the suspension is stable.
聚电解质在胶体颗粒上的吸附常用于水悬浮液的稳定或絮凝。本工作的目的是研究羧甲基纤维素（CMC）在氧化铝（γ-Al₂O₃）胶体颗粒上的吸附。选择颗粒和聚合物是因为金属氧化物两性电解质表面和弱聚电解质具有随pH改变其电荷的能力。测量在pH 6.0下进行，此时CMC的羧基几乎完全解离，氧化铝表面带正电。聚电解质链的高线性电荷密度使得Na⁺抗衡离子在-COO⁻基团上凝聚。主要采用的方法是基于正弦电场中颗粒取向的电光散射。电场关闭后的电极化率和弛豫时间（两者均取决于颗粒电荷和尺寸）用作聚合物吸附和颗粒聚集的标准。微电泳作为指示表面电荷符号和密度的附加技术被应用。所得结果给出了CMC吸附完全且悬浮液稳定的条件（时间依赖性、颗粒和聚合物浓度）。
