Adsorption of peptides produced by cyanobacterium Microcystis aeruginosa onto granular activated carbon

The aim of this study was to investigate adsorption of peptides included in the cellular matter of cyanobacterium Microcystis aeruginosa, as they are difficult to remove during the coagulation/flocculation processes. In order to elucidate the effect of solution properties on peptide uptake, there were carried out equilibrium and kinetic experiments at different pH values and ionic strengths, using 2 types of activated carbon with different textural and charge characteristics - Picabiol 12x40 and Filtrasorb TL830. The results showed that the peptide adsorption on both carbons increases with decreasing pH value. The highest adsorption capacity was reached at pH 5 for Picabio112x40 due to a high portion of mesopores in its structure and the electrostatic attraction between functionalities of the carbon and the peptides. It wae demonstrated that increasing ionic strength can enhance adsorption of the peptides by screening the repulsive forces, or by strengthening the attractive ones in the adsorption system, all of that depending on the type of carbon used and pH applied. Among peptides, those with low molecular weight of 1.0-4.5 kDa were adsorbed preferentially. Formation of H-bonds and electrostatic interactions were confirmed to play an essential role during the adsorption of peptides onto activated carbon. (C) 2013 Elsevier Ltd. All rights reserved.