Influence of the iron content on the arsenic adsorption capacity of Fe/GAC adsorbents

Abstract

Adsorbents of granular activated carbon doped with iron (Fe/GAC) were synthesized in the laboratory and their capacity for removal of arsenic species was measured by means of techniques of equilibrium adsorption and breakthrough curves. These data were obtained at room temperature and normal pH conditions. The materials were further characterized to determine their chemical composition and texture (specific surface, pore volume distribution). It was found that the adsorbents with 10%, 20% and 30% Fe had a great capacity for arsenic adsorption, showing uptake values of 2000-3500 μg of As per gram of Fe/GAC filter material. Doping with Fe increases the As adsorption capacity of granular activated carbon and the maximum capacity of adsorption is obtained with 10% Fe loading. Higher Fe contents decrease the capacity for arsenic removal. This was related to the decreased pore volume and pore size of the adsorbents with high Fe content. A decrease of surface accessibility due to pore plugging and a higher intraparticle diffusion resistance in the high loaded adsorbents would shift the point of bed breakthrough to lower values of eluted volume.