Preparation and characterization of purified Na-activated bentonite from Karak (Pakistan) for pharmaceutical use

The purpose of this paper was to prepare purified Na- bentonite with improved properties for use in the pharmaceutical industry. Calcium bentonite from the Shagia region of Karak district, Pakistan, was activated with various proportions of sodium carbonate (2, 3, 5 and 8 wt.%) and purified by sedimentation to remove impurities, especially quartz. X-ray diffraction (XRD), and swelling volume confirmed the conversion of raw bentonite to sodium bentonite by using 5% Na 2 CO 3 . The sodium bentonite (K5) obtained by activation met the chemical and microbiological requirements set by the pharmacopeias regarding the toxic trace elemental content (Pb and As), absence of E. coli , total aerobic microbial contents and physicochemical properties such as swelling volume, pH and sedimentation volume. Therefore K5 bentonite could be designated as potentially suitable for pharmaceutical applications. The CEC, surface area, porosity, pH, gel formation and swelling volume indicated that K5 bentonite could be used in the formulation of oral suspension and in topical application.