Résumé:
This study was devoted to the valorization of a plant waste (olive stones): that is widely available in Mediterranean countries in order to remove
mercury from natural gas. The raw material from olive stones was prepared by pyrolysis, chemical activation with phosphoric acid, and physical
activation under steam. Two olive stone-based granular activated carbons were prepared: one with the virgin stones, while the other was
impregnated with sulphur. After treatment, the adsorbents obtained were characterized by determining the iodine number, the methylene blue
index, and by estimating the porous properties by N2 adsorption at 77 K. Thermogravimetric analysis and infrared spectroscopy analysis were
carried out to determine the functional groups before and after mercury adsorption. An experimental study of vapour-phase mercury adsorption by
the activated carbons (virgin and sulphur-impregnated) and a comparison with a commercial material (HGR) were performed. The comparison,
made by analyzing the adsorption in a continuous mode, showed that the proportion of sulphur and the porosity were important for the removal of
mercury. In the conditions used, the mercury adsorption on the ACs studied follows a physisorption mechanism. The results showed that granular
activated carbon-based olive stones (sulphur-impregnated) are very efficient to remove mercury (with 2864 mg/g) and also less expensive than
commercial activated carbon due to their local availability.
