Properties of modified crude clay by iron and copper nanoparticles as potential hydrogen sulfide adsorption

The present work aimed at modifying original kaolin with iron and copper chlorides in order to introduce active centers for hydrogen sulfide (H2S) adsorption. In the first modification, interlayer sodium cations were exchanged with two metals. In the second one, iron oxide (FeOx) was introduced to the clay surface. Kaolin and modified kaolin were analyzed using ICP, X-ray diffraction (XRD), Infrared Ray, Fluorescence-X, BET surface area analysis and SEM. The modified clay samples were tested as hydrogen sulfide adsorbents. Iron-doped and copper-doped samples showed a significant improvement in the capacity for H2S removal, despite a noticeable decrease in microporosity compared to the initial pillared clay. The smallest capacity was obtained for the clay modified with FeOx. Variations in adsorption capacity are likely due to differences in the chemistry of metals species, degree of their dispersion on the surface, and accessibility of small pores for H2S molecule. Results suggest that on the surface of metal-modified clay, hydrogen sulfide reacts with Cu2+ and Fe+3 ions to form sulfides or can be catalytically oxidized to SO2 on iron (hydro) oxides. Subsequent oxidation may lead to sulfate formation. (C) 2016 Elsevier B.V. All rights reserved.