Wet chemical extraction of silicon from natural palygorskite for preparing a mesoporous molecular sieve of Al-SBA-16

Three-dimensional mesoporous molecular sieve, Al-SBA-16, was successfully prepared via a wet chemical route, which involved co-condensation of silicon source from natural palygorskite by alkali-melting extraction, and acidic mixture of templating agent F127 and aluminum sulfate. XRF and Raman spectra confirmed quantitative incorporation of aluminum into ordered cubic mesostructure. Pyridine-probed Fourier transformed infrared spectroscopy and 1H magic-angle spinning nuclear magnetic resonance showed a doubling of the Bronsted and Lewis acidity after aluminum activation. At neutral pH, the Al-SBA-16 was used as an adsorbent for the removal of aniline and basic fuchsin with the maximum adsorption capacities of 46.22 and 70.08 mg g−1, respectively. Adsorption kinetics and isotherm indicated that adsorption of aniline and basic fuchsin was occurred by their lone pair electrons on N atom interacting with the Bronsted and Lewis acid sites of Al-SBA-16. The adsorbed material could be easily regenerated by a simple process of acid washing. It was reused for five times with basic fuchsin removal rate still up to above 90%.