ZnFe2O4/activated carbon as a regenerable adsorbent for catalytic removal of H2S from air at room temperature

A series of ZnFe2O4/activated carbon adsorbents with various ZnFe2O4 loadings was synthesized and used for removing H2S from moist air at a room temperature. The materials were characterized using adsorption of nitrogen, SEM-EDS, ICP-OES, XPS, XRD, FT-IR, TGA, Raman spectroscopy and potentiometric titration. The experimental results showed that the adsorbent with 10 wt% ZnFe2O4 had the highest H2S breakthrough capacity of 122.5 mg/g, ~ twice larger than the capacity calculated assuming the stoichiometric chemical reactivity of the inorganic phase. Moreover, the capacity remained more or less constant after three thermal regeneration cycles. The characterization results indicated that the desulfurization process involved reactive adsorption and catalytic oxidation of H2S. Besides the chemical nature of the active phase, the H2S removal performance was found to be dependent on the textural properties (surface area and pore volume) and surface pH. FeOOH formed as an intermediate during the desulfurization process played also a catalytic role.