Smectite Interactions with Riboflavin

M. M. Mortland1 and J. G. Lawless
NASA Ames Research Center, Moffett Field, California 94035
1 Senior NRC Associate on leave from Michigan State University, East Lansing, Michigan 48824.

Abstract: Smectite with polyvalent cations on the exchange complex readily absorbed riboflavin from aqueous solution to a limit of about 0.5 mmole/g. The shape of the adsorption isotherms was of the Langmuir type. An exception was Na+-smectite which provided an S-shaped isotherm and smaller amounts of adsorption. Ca2+-vermiculite had no interlamellar adsorption of riboflavin, suggesting that this mineral does not swell sufficiently to permit such adsorption. Adsorption isotherms, X-ray powder diffraction data, and UV-visible spectroscopic data suggest that the mechanisms of interaction between smectite and riboflavin may involve a combination of ion-dipole, charge transfer, hydrogen bonding, and physical effects.

Key Words: Adsorption • Charge-transfer complex • Riboflavin • Smectite • UV-visible spectra • Vermiculite

Clays and Clay Minerals; December 1983 v. 31; no. 6; p. 435-439; DOI: 10.1346/CCMN.1983.0310604
© 1983, The Clay Minerals Society
Clay Minerals Society (www.clays.org)