Effect of the pore size on the adsorption of dimeric cationic surfactants from aqueous solution onto aluminosilicate adsorbents with a hexagonal pore arrangement

Abstract

The effect of the pore size of the adsorbent on the adsorption of dimeric alkanediyl-α,ω-bis (dode-cyldimethylammonium bromides) with alkanediyl spacer groups C₂H₄, C₆H₁₂, and C₁₂H₂₀ has been studied in aqueous solution at 298 K and free pH. Three mesoporous aluminosilicate materials of the MCM-41 type were used as solid supports with homogeneous pore size distributions. The analysis was based on the experimental adsorption isotherms, supplemented with measurements of the sodium and hydronium ion concentrations in the equilibrated supernatant liquid as well as electrophoretic curves. The adsorption and interfacial aggregation of the dimeric surfactants were found to occur both on the external surface and on the pore walls. The ultimate structure of the adsorbed phase appeared to depend not only on the pore size but also on the spacer group length and flexibility.

Presented at the 13th Conference of the European Colloid and Interface Society, Dublin 1999