Removal of H2S from biogas by adsorption with commercial activated carbon and granular iron oxide

Remoção de H2S de biogas por adsorção em carvão ativado comercial e oxido de ferro granular

ABSTRACT

Among the impurities that are harmful to the energy conversion of biogas generated in landfills is hydrogen sulfide (H₂S). The present study compared the efficiency of H₂S removal with the use of granular activated carbon (GAC) of two commercial brands, Norit GAC and Pelegrini GAC, and with the use of granular iron oxide from mineral residues. The tests were conducted on a laboratory scale, in a glass column, filled with filtering material, applying an inlet flow of gas and monitoring the outlet concentration. The best removal efficiencies occurred with the use of Norit GAC, which presented longer rupture times. Wet gas tests were also carried out, in which rupture and equilibrium times increased with the use of Norit GAC, while with the use of Pelegrini GAC the same adsorptive behavior was not observed. Tests with iron oxide showed low potential for H₂S removal due to reduced specific surface values, although it provided removal of the contaminant. Knowledge of the saturation time and adsorption equilibrium data is essential for a better understanding and planning of adsorption systems, in addition to the conduction of studies on the influence of external factors and variations in initial concentration.

Keywords
biogas; treatment; landfill; removal of hydrogen sulfide; activated carbon; iron oxide