Reaction of OH-Al Polymers with Smectites and Vermiculites1

Pa Ho Hsu
Department of Environmental Sciences Rutgers, The State University of New Jersey New Brunswick, New Jersey 08903
1 New Jersey Agricultural Experiment Station Publication No. D-07425-1-91.

Abstract: Five montmorillonites, one hectorite, and two vermiculites were treated with OH-Al solutions containing rapid- and slow-reacting polymers of similar concentrations. With all smectites, both rapid- and slow-reacting OH-Al polymers were much more preferentially adsorbed than monomeric species. Relatively slow-reacting OH-Al polymers were more preferentially adsorbed than rapid-reacting ones. The average basicity of the adsorbed Al was 2.46, which was close to that of the OH-Al polymers in the original solution. The OH-Al polymers that enter the interlayer resemble those in original solutions.

With vermiculites, the solution concentration of rapid-reacting OH-Al polymers was much reduced after reaction. The average basicity of the adsorbed Al was 1.99, which was considerably lower than that in the original solution. It is postulated that OH-Al polymers break to monomeric Al ions and then enter the clay. The monomeric Al species that enter the clay interlayers hydrolyze and polymerize in situ and become fixed. The H+ ions released from hydrolysis convert the rapid-reacting OH-Al polymers to monomeric Al in solution. Limited amounts of slow-reacting polymers were adsorbed because of their resistance to acid depolymerization.

Key Words: Smectite • Vermiculite • OH-Al • Pillared clay

Clays and Clay Minerals; June 1992 v. 40; no. 3; p. 300-305; DOI: 10.1346/CCMN.1992.0400308
© 1992, The Clay Minerals Society
Clay Minerals Society (www.clays.org)