Ma Xiaodong, Pawlik Marek
Norman B. Keevil Institute of Mining Engineering, The University of British Columbia, 517-6350 Stores Road, V6T 1Z4, Vancouver, BC, Canada.
J Colloid Interface Sci. 2007 Sep 15;313(2):440-8. doi: 10.1016/j.jcis.2007.04.075. Epub 2007 Jun 15.
Adsorption of guar gum onto alumina, titania (rutile), hematite, quartz, and kaolinite was investigated as a function of pH, ionic strength (from distilled water to saturated NaCl and KCl), and the type of background electrolyte (0.01 mol/L LiCl, NaCl, KCl, and CsCl). It was demonstrated that the adsorption density of the polymer does not depend on pH for any of the tested minerals, so only hydrogen bonding was identified as the dominant adsorption mechanism. The minerals could, however, be divided into two groups depending on the effect of the salt type on polymer adsorption. Guar gum adsorption onto quartz and kaolinite significantly increased in the presence of even a small amount of KCl, while NaCl equally enhanced guar gum adsorption on these two minerals only at concentrations approaching saturation. In contrast, no significant differences between the effects of KCl and NaCl on polysaccharide adsorption were observed on titania, alumina, and hematite. The results were correlated with the chaotropic (KCl) and kosmotropic (NaCl) properties of the background salts, and-based on a review of the available literature data-with the presence (quartz) or absence (titania, alumina, hematite) of an extensive hydration layer on the oxide surfaces. It was concluded that the main role of background ions in the studied systems was to control the stability of the interfacial water layer on oxide particles whose presence serves as a barrier to guar gum adsorption.
研究了瓜尔胶在氧化铝、二氧化钛（金红石型）、赤铁矿、石英和高岭石上的吸附情况，考察了pH值、离子强度（从蒸馏水到饱和氯化钠和氯化钾）以及背景电解质类型（0.01 mol/L氯化锂、氯化钠、氯化钾和氯化铯）对吸附的影响。结果表明，对于任何一种测试矿物，聚合物的吸附密度均不依赖于pH值，因此仅氢键被确定为主要的吸附机制。然而，根据盐类型对聚合物吸附的影响，这些矿物可分为两组。即使存在少量氯化钾，瓜尔胶在石英和高岭石上的吸附也会显著增加，而氯化钠只有在接近饱和浓度时才会同等程度地增强瓜尔胶在这两种矿物上的吸附。相比之下，氯化钾和氯化钠对二氧化钛、氧化铝和赤铁矿上多糖吸附的影响没有显著差异。这些结果与背景盐的离液序列性质（氯化钾）和促水序列性质（氯化钠）相关，并根据现有文献数据，与氧化物表面是否存在广泛的水化层（石英）或不存在（二氧化钛、氧化铝、赤铁矿）相关。得出的结论是，在研究的体系中，背景离子的主要作用是控制氧化物颗粒界面水层的稳定性，而界面水层的存在对瓜尔胶的吸附起到了阻碍作用。
