Interactions of Metals and Protons with Algae

Abstract

Proton uptake by intact algal cells was found to consist of two processes: (1) a fast (<4 s) surface reaction and (2) a slow (2 h) diffusion of protons into cells. A pH titration technique measured only the rapid surface reaction that forms negative sites at higher pH. Adsorption of alkali, alkaline earth, and transition metal ions on algae was quantitatively represented by the Langmuir adsorption isotherm with its two parameters ym, the maximum amount of metal adsorbed, and K, the equilibrium constant taken as a measure of bond strength. Variations of these parameters with pH and type of metal indicate that metals adsorb to algal surfaces by electrostatic attraction to negative sites, such as carboxylate anions of poly(galaturonic acid) (pectin), as previously suggested. © 1988, American Chemical Society. All rights reserved.