ABSTRACT
This work had the aim of evaluate the efficiency of the activated carbon with CO2 (CA) produced from peanut shell as adsorbent which was applied to remove phenol from aqueous water (100-300 mg.L-1). The characterization of the CA was performed by BET, DRX, TGA, FT-IR e pHpcz methods and was performed the characterization of the peanut shell (CS) for comparison. The influence of initial pH of the solution and the dosage of the adsorbent (D.A.) was studied. Working conditions were defined with the help of a 23 factorial design (FD) evaluating the variables influence: DA, particle size (P.S) and stirring speed (S.S.) on the adsorption process, it is found as response the adsorption capacity, q (mg g-1). Based on the FD results kinetic studies and adsorption equilibrium were performed. The coal was classified as mesoporous and is predominantly amorphous. In the TGA greater stability of the material was observed after the activation. By FT-IR spectra bands were identified hydroxyl, carboxylic and ester groups. The pHpcz was 10.4 allowing the use of phenolic solutions in the natural pH of the solution. In FD the highest q was obtained for the level 4 g.L-1, G.<0.090 mm and 300 rpm, adopted condition for executing the kinetic and equilibrium studies. The kinetic evolution was fast up to 120 minutes, reaching equilibrium around 480 minutes. The pseudo-order n model was the best fit for experimental data and it was found that the process is controlled by more than one step, including intraparticle diffusion. For the equilibrium study the models that best fit the experimental data were Fritz-Schlunder and Redlich-Peterson with a qmax of 29.01 ± 0.96 mg.g-1. The results demonstrate the technical potential of the coal under study for the removal of phenol in aqueous solutions.
Key words:
agroindustrial residue; industrial effluent; physical activation
