Positive Electrokinetic Charge of Silica in the Presence of Chlorides

✍ Scribed by Marek Kosmulski

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 67 KB
• Volume: 208
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1998.5859

✦ Synopsis

The presence of chlorides promotes a positive electrokinetic charge of silica. Silica shows an isoelectric point (iep) at pH 2 in the presence of HCl but at pH < 1.5, if any, in the presence of HClO 4 and HNO 3 . The iep of silica in the presence of different 1:1 salts depends on the nature and concentration of the salt. The highest value of pH, 5.5, was observed for 0.1 mol dm ؊3 cesium chloride and nitrate. A larger increase in cesium salt concentration shifts the iep back to low pH values and at >0.5 mol dm ؊3 there is no iep (only negative potentials).