engleski

Interfacial Equilibria at Goethite Aqueous Interface in Presence of Amino Acids

Adsorption of ortho-, meta- and para-aminobenzoic acid on goethite was investigated by means of adsorption and electrokinetic measurements, and interpreted on the basis of the Surface Complexation Model (SCM). All three examined acids showed similar behavior with adsorption maximum at pH = 4.5, while the adsorption affinity decreased in order para-, ortho- meta-aminobenzoic acid. Electrokinetic measurements indicated that isoelectric points of goethite with adsorbed amino acids were shifted to lower pH values with respect to the pure goethite suggesting adsorption of negatively charged species (-1). This conclusion was confirmed by the calculations based on SCM. The equilibrium constant for exchange of Cl&#61485 ; ions with amino acid ions (-1) were determined as logKA/L =2.62 ą 0.13 for ortho-aminobenzoic acid, logKA/L = 2.37 ą 0.11 for meta-aminobenzoic acid and logKA/L = 2.85 ą 0.14 for para-aminobenzoic acid.

Adsorption; Electrokinetics; Goethite; Aminobenzoic acid

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