AMINE ALGAE INTERACTIONS - CATION-EXCHANGE AND POSSIBLE HYDROGEN-BONDING

The sorption of amines on algae in acid media was found to be similar to that of metals, which occurs via an ion-exchange process. Protonated ethylenediamine and ethyl glycinate were found by C-14 labeling to displace Ca,Mg in equivalent amounts on sorption by Vaucheria sp. In turn, they were displaced by Sr2+, thus demonstrating the process to be one of cation exchange associated with anionic cell wall components. By use of Ca,Mg release as the measure of sorption, seven monoamines gave Langmuir adsorption equilibrium constants, a measure of bonding strengths, of 77 +/- 10 N-1 and maxima of 409 +/- 46-mu-equiv g-1, indicating little structure effect. On the other hand, equilibrium constants for the C2, C4 and C6 diamines were 317, 1361, and 1564 N-1, respectively. The low values for three amino acids (55 +/- 7 N-1) indicate a repulsive effect of carboxylate anions. Sorption of neutral ethylenediamine on algae occurs at pH 10, possibly due to hydrogen bonding to anions and hydroxyl groups.