Utilisation de charbon actif en poudre dans un procédé d'adsorption du phénol en milieu aqueux

Abstract

The aim objective of this work is to study the elimination of Phenol by powder activated carbon (PAC) from aqueous solution. The PAC was characterized by measurement of pHPZC, Boehm titration, Fourier Transmission Infrared (FTIR), iodine index and methylene blue index. The results obtained show that the pHPZC is 7.5, the PAC surface is rich by acid surface function consisting mainly of hydroxyl group and phenol (GIII) and strong carboxylic acid (GI) groups, and finally the nature of PAC is microporous. The effect of the operating parameters on the kinetic adsorption of Phenol by PAC shows that the increase in adsorbent mass from 0.1 to 0.4 g causes a decrease in adsorbed quantity, the optimal mass found is 0 15 g. The increase in the initial Phenol concentration is accompanied by the increase in motive power, which favors the increase of the amount of adsorbate fixed on the PAC. The stirring speed and the ionic strength have not a remarkable effect on the elimination of Phenol. Raising the temperature above the optimum value estimated at 20°C, resulted in a decrease in the amount adsorbed. The basic pH is unfavorable for adsorption. Phenol adsorption isotherms on PAC at temperatures of 20, 30 and 40 ° C presented an H-type pattern, indicating a high affinity between the adsorbent and the adsorbate. The modeling of adsorption isotherms equilibria by several isothermal models informs us that the two isotherms of Freundlich and Langmuir (II) can describe the equilibrium adsorption data of Phenol by PAC, Temkin informs us that the Elemental adsorption process is exothermic. The average adsorption energy (E = 0.59 KJ.mol-1) calculated by Dubinin-Radushkerich shows that the adsorption process is physical. The Fowler-Guggenheim and Kiselev isotherms are not applicable to equilibrium data, and they inform us that the interaction between the adsorbed molecules is attractive and that there is no complex formation between the adsorbed molecules. Phenol adsorption kinetics by PAC follows very well the kinetic model of pseudo second order. While the adsorption mechanism was found to be controlled by intraparticular diffusion model. The thermodynamic study shows that the adsorption is exothermic and spontaneous.