ROLE OF POLYELECTROLYTE CHARGE-DENSITY AND MOLECULAR-WEIGHT ON ADSORPTION AND FLOCCULATION OF COLLOIDAL SILICA WITH POLYETHYLENIMINE
ROLE OF POLYELECTROLYTE CHARGE-DENSITY AND MOLECULAR-WEIGHT ON ADSORPTION AND FLOCCULATION OF COLLOIDAL SILICA WITH POLYETHYLENIMINE
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DOI：
10.1016/0021-9797(76)90007-2
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发表时间：
1976-01-01
影响因子：
9.9
通讯作者：
STRATTON, RA
中科院分区：
文献类型：
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作者：
LINDQUIST, GM;STRATTON, RA
以聚乙烯亚胺（PEI）-水-Ludox AM胶体二氧化硅体系为模型体系，研究了聚电解质的电荷密度和分子量对带相反电荷的胶体颗粒的吸附和随后的絮凝的关系。制备并表征了范围为1760至18，400的窄分子量级分的PEI。采用聚合物分子量、盐浓度和pH的差异来改变每个PEI分子的阳离子电荷数。在引发Ludox AM絮凝所需的PEI浓度下，无论分子量、pH或离子强度如何，PEI都发生完全吸附。然而，在较高的浓度，吸附增加分子量，pH值，和离子强度。絮凝结果表明，聚合物桥接和静电因素之间的相对重要性是pH值依赖性。在pH 9及更高时，由于PEI分子的阳离子电荷较低，聚合物桥接是不稳定的主要机制。然而，在pH小于9时，PEI和胶体二氧化硅之间的电荷相互作用是主要考虑因素。发现引发絮凝所需的PEI的摩尔浓度的对数与PEI分子上的阳离子电荷的对数之间存在反比线性关系。
The polyethylenimine (PEI)-water-Ludox AM colloidal silica system was used as a model system to investigate the relationship of charge density and molecular weight of the polyelectrolyte on the adsorption and subsequent flocculation of oppositely charged colloidal particles. Narrow molecular weight fractions of PEI ranging from 1760 to 18,400 were prepared and characterized. Differences in polymer molecular weight, salt concentration, and pH were employed to vary the number of cationic charges per PEI molecule. At the concentrations of PEI required to initiate flocculation of Ludox AM, complete adsorption of PEI occurred regardless of molecular weight, pH, or ionic strength. However, at higher concentrations, adsorption increased with molecular weight, pH, and ionic strength. The flocculation results indicated that the relative importance between polymer bridging and electrostatic considerations is pH dependent. At pH 9 and greater, polymer bridging is the dominant mechanism of destabilization due to the low cationic charge of the PEI molecule. Howevei, at pH less than 9, charge interaction between PEI and colloidal silica is the dominant consideration. An inverse linear relationship was found between the logarithm of the molar concentration of PEI required to initiate flocculation and the logarithm of the cationic charge on the PEI molecule.