Synthesis and characterization of montmorillonite inorgano-intercalation compound assisted by microwave irradiation

Abstract

A montmorillonite inorgano-intercalation compound(MIIC) was synthesized by using a purified Na-exchanged bentonite (PNaB) as a matrix and Al-pillaring ion as an intercalating reagent under microwave irradiation. The synthesized products were characterized by X-ray diffraction (XRD), 27Al magic angle sample-spinning nuclear magnetic resonance (27Al MAS NMR), specific surface area (BET) measurement, and adsorption density determination. The results show that, at 5% solid (PNaB) concentration and 7 minutes irradiation in a 130 W microwave oven, the basal spacing d(001) of the synthesized MIIC increases to 1.740 nm from the original 1.218 nm of PNaB. The MIIC has much higher adsorptive densities to F− and Cr6+ from aqueous solution than the PNaB. The adsorption isotherm of F− on the MIIC follows the Freundlich equation, and the increased adsorption is mainly due to the porous structure of the MIIC which created larger adsorption surfaces. The adsorption isotherm of Cr6+ on MIIC follows the Langmuir equation and the adsorption is mainly monolayer as a result of chemisorptions.