Effect of pH in an Aqueous Medium on the Surface Area, Pore Size Distribution, Density, and Porosity of Montmorillonite

✍ Scribed by Orhan Altin; H.Önder Özbelge; Timur Dogu

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 130 KB
• Volume: 217
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1999.6271

✦ Synopsis

Surface area, pore volume distribution, and porosity of montmorillonite are determined after being exposed to aqueous solutions with various pH values. For measurement, after each pH treatment the clay samples were freeze-dried in order to keep the structure of the clay same as that in the aqueous solution. Surface area and pore size distribution measurements were performed on an unmodified and four pH (2.5, 4.0, 5.5, 9.0)-adjusted clay samples using N 2 and CO 2 as adsorbates. The surface area measurements at lower pH are lower than those measured at higher pH due to the replacement of Na ؉ ions from interlayers at lower pH which may be followed by the reduction of repulsive forces. As the pH of the montmorillonite increases to 9.0, the surface area increases almost seven times compared to that at pH 2.5.