Effect of oxidant treatment of date pit activated carbons application to the treatment of waters

Three activated carbons have been prepared from dates stones, by carbonization without adjuvant and by chemical activation with ZnCl2 and KOH. According to the nature of the adjuvant, the activated carbons present different porosities. Chemical activation of the date stones with KOH produces an activated carbon having mesoporosity as well developed as in the ZnCl2 activation. This last process led also to develop the microporosity more than KOH activation. The surface area, pore texture, and dosage of Boehm, of the activated carbons have been studied. Adsorption at 298 K of phenol, p-cresol and o-chlorophenol from aqueous solutions on activated carbons has been studied. The adsorption capacity of the activated carbons depended on the surface area and porosity of the carbon, the solubility of the phenolic compounds, and the hydrophobicity of the substituent. The modification of the porous texture and the chemical nature of the surface of activated carbons have been realized by oxidization with nitric acid. This oxidization lead to a considerable decrease of the surface area S-N2 and of the microporeux volume W-0, fixing a large amount of oxygen surface groups who influences negatively to the properties of adsorption of the activated carbons. A heat treatment of these activated carbons leads to a reduction of the concentration of the oxygen groups and therefore an amelioration of the adsorption capacity.