Monoliths: Synthesis and Characterization using lignocellulosic precursor

D. P. VARGAS, L. GIRALDO, J.C. MORENO-PIRAJÁN, Y. LADINO, K. SAPAG.

Edimburgo

Simposio; Characterization of Porous Solids; 2008

Royal Society of Chemistry

In recent years, rapid industrial growth has generated serious environmental problems that are a threat to the sustainability of the planet. As an alternative solulion, porous materials are now widely used in the field of adsorption in both gas and liquid phase; one of these materials is activated carbon, which has excellent properties for the adsorption of different pollutant substances. 1 The monolith type refers to compact structures; lhe most common are the disc and honeycomb-type monoliths. The lalter are structural units crossed by parallellengthwise2canals. Honeycombs allow the passage of gases with a very small of load; they have a great geometric surface per weight or volume unit; they are easy to handle and have a series of properties to be improved, which make them effective adsorbents and catalytic supports to be used in environment decontamination. One of the main objectives in adsorption studies is to maximize the adsorbent density, minimizing the spaces that are not useful in the storage of certain gases and pollutants (meso·and macroporosíty and inter particle spaces), while maintaining a high volume of micropores. In order to reduce these spaces, proper compaction is essential. This can be carried out by using mixtures of grains of various sizes or uniaxially compressing powders (with or without additives), or by preparin§ compact monoliths using a binder. As has been highlighted in several studies 3-l·S-6·7· .9, the last option, which involves preparing activated carbon monoliths (MCA), is a way to reduce the space between particles, maximizing the material density. The aim of this work was to prepare and sludy MCA monoliths through the chemical activation of coconut shell with zinc chloride, without the use of any binder. The structures Vere characterizcd by nitrogen adsorption at 77K, scanning electron microscopy and benzene immersion calorimetry. Finally, the monoliths were tested by adsorption ofphenol in an aqueous solution.