Synthesis and characterization of Al-pillared and cationic surfactant modified Al-pillared Algerian bentonite

Abstract

Al-pillared and a cationic surfactant modified Al-pillared montmorillonite were prepared by reacting a purified bentonite from deposits in Maghnia and Mostaghanem (in the West of Algeria), with a solution of aluminum chlorohydrate alone or with both Al-chlorohydrate and cetyl trimethyl ammonium bromide (CTAB) solutions. The most favorable conditions for producing the Al-pillared and the CTAB-modified Al-pillared montmorillonite were established as follows: an OH/Al molar ratio of 1.8; an Al/bentonite ratio of 4 mmol/g; a CTAB/bentonite ratio of 2 (w/w). The Al-pillared clays have a basal spacing of about 1.8 nm and a surface area between 250 and 300 m 2/g. A good thermal stability was found at 500°C. The CTAB modified Al-montmorillonite showed a greater basal spacing of about 2.1 nm, but it was reduced down to 1.4 nm upon heating to 500°C when the CTAB was adsorbed on the Al-hydroxy-montmorillonite prior the calcination and to 1.8 nm when it was adsorbed on the calcined pillared solid. The BET surface area of CTAB modified Al-montmorillonite was much lower than that of Al-pillared clays.