Activated Carbons Impregnated with NaS and HSO: Texture, Surface Chemistry and Application to Mercury Removal from Aqueous Solutions

• Main Authors: Z. Abdelouahab-Reddam, A. Wahby, R. El Mail, J. Silvestre-Albero, F. Rodríguez-Reinoso, A. Sepúlveda-Escribano
• Format: Article
• Language: English
• Published: Hindawi - SAGE Publishing 2014-03-01
• Series: Adsorption Science & Technology
• Online Access: https://doi.org/10.1260/0263-6174.32.2-3.101

The effects of treatment of an activated carbon with sulphur precursors on its textural properties and on the ability of the complex synthesized for mercury removal in aqueous solutions are studied. To this end, a commercial activated carbon has been modified by treatments with aqueous solutions of Na 2 S and H 2 SO 4 at two temperatures (25 and 140 °C) to introduce sulphur species on its surface. The prepared adsorbents have been characterized by N 2 (–196 °C) and CO 2 (0 °C) adsorption, thermogravimetric analysis, temperature-programmed decomposition and X-ray photoelectron spectroscopy, and their adsorption capacities to remove Hg(II) ions in aqueous solutions have been determined. It has been shown that the impregnation treatments slightly modified the textural properties of the samples, with a small increase in the textural parameters (BET surface area and mesopore volumes). By contrast, surface oxygen content was increased when impregnation was carried out with Na 2 S, but it decreased when H 2 SO 4 was used. However, the main effect of the impregnation treatments was the formation of surface sulphur complexes of thiol type, which was only achieved when the impregnation treatments were carried out at low temperature (25 °C). The presence of surface sulphur enhances the adsorption behaviour of these samples in the removal of Hg(II) cations in aqueous solutions at pH 2. In fact, complete Hg(II) removal is only obtained with the sulphur-containing activated carbons.