ADSORPTION OF SHORT-CHAIN TETRAALKYLAMMONIUM BROMIDE ON SILICA

The adsorption of tetraalkylammonium (TAA) ions on silica shifts the i soelectric point to higher pH values. The IEP shift increases with inc reasing alkyl chain length. Also, tetraethylammonium (TEA) and tetrapr opylammonium (TPA) ions can be adsorbed in larger amounts than tetrame thylammonium (TMA) ions. The chemisorption of TAA ions can be explaine d by assuming an attraction between hydrophobically hydrated regions a round surface siloxane bridges and around the TAA ions. The adsorption data of TMA ions are compatible with the stimulated adsorption model.