Study of the Textural Changes in the Nowshera (Pakistan) Ca-Bentonite Caused by the Physical Purification Before and After NaCl Treatment

• Published in: Mining, metallurgy & exploration Vol. 38; no. 2; pp. 875 - 884
• Main Authors: Shah, Liaqat Ali, Farooq, Muhammad, Shah, Zait Ullah, Valenzuela-Díaz, Francisco Rolando
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-04-2021
• Subjects: Engineering; Materials Engineering; Metallic Materials; Mineral Resources; Clay; Specific surface area; Porosity; Montmorillonite; Sedimentation
• ISSN: 2524-3462; 2524-3470
• DOI: 10.1007/s42461-020-00367-7

Bentonite collected from Nowshera (Pakistan) was treated with NaCl, and the < 2-μm clay fractions were separated by sedimentation process. The textural changes in NaCl treated purified bentonite were compared with raw and physically purified sample. It was detected that the NaCl-treated purified bentonite and the sample purified by simple sedimentation, respectively, consist of sodium-montmorillonite and calcium-montmorillonite as a major clay mineral. The honeycombed-type morphology was observed for both the purified samples; however, the particles of NaCl treated purified bentonite were relatively in a compact form. The particle sizes of both the purified samples were found considerably smaller. The high volume percent of the fine particles was noticed in the NaCl-treated purified bentonite. This attributed that the sodium exchange has a valuable impact on the bentonite dispersion in aqueous media during particle size measurement. The relatively high mesopore area/volume and micropore area/volume and specific surface area (SSA) were detected in purified samples. The NaCl-treated purified sample showed relatively high mesopores area/volume than the sample obtained by simple sedimentation. These changes seem to be originated from either high montmorillonite contents and/or the smaller particle size, which might be produced after the layer re-arrangement during the interlayer cation replacement by Na
+
ions. The large SSA and high porosity of purified samples particularly the NaCl-treated bentonite suggest their potential use as adsorbents, catalysts, pharmaceuticals, and cosmetics.