Modelling adsorption equilibrium of STX and dc-STX onto GAC samples with different pore size distribution

Abstract

AbstractMany different species of cyanobacteria have been identified worldwide as a threat to drinking water safety since they are capable of producing saxitoxins (STX), one of the most toxic non-protein substances known in nature. Although removal of these components can be accomplished by adsorption on granular activated carbon (GAC), a method to accurately model how effectively they can be removed in GAC filters has not yet been published. This research investigated adsorption equilibrium of dc-STX and STX on four coconut shell GAC samples, with positive surface charge but different pore size distribution, and experimental data were mathematically modelled providing elements for future GAC filter simulations. Adsorption of STX and dc-STX could be fitted to either Langmuir or Freundlich isotherms and the GAC sample with greater amount of mesopores, presented the largest adsorption capacity for both dc-STX and STX, although its BET area and pore volume were similar to the other GAC tested.