Properties of carbonaceous materials from sewage sludge to remove organic matter. Phenol as a particular case

Abstract

Carbonaceous material obtained from the pyrolysis of sewage sludge, activated carbon (AC), a composite CM(Fe-Cu) (carbonaceous material/nanoparticles of Fe-Cu) and nanoparticles N(Fe-Cu) were used to evaluate and compare their abilities to remove phenol from aqueous solutions by adsorption followed by oxidation. The adsorbents were characterized by scanning electron microscopy, transmittance electron microscopy, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction and Infrared (IR) spectroscopy. The presence of Fe-Cu nanoparticles was confirmed by the TEM technique. Sorption kinetics and isotherms were determined in the presence and absence of hydrogen peroxide. The experimental kinetic data of the activated carbon and the carbonaceous material were treated with Lagergren, Elovich and Ho models. The results show that both materials are best fit to the second order model indicating a chemisorption mechanism. The adsorption equilibrium of phenol by the different adsorption materials was observed in 24 h. The adsorption capacity of CM(Fe-Cu) for phenol was not affected by the pH, and the adsorption capacities for CM and AC decreased as the pH increased. The isotherms were lineal in all cases. N(Fe-Cu) was the most efficient material for the removal of phenol from aqueous solutions. The adsorption capacities decreased as the doses increased and the adsorption capacities of the materials were not affected by the temperature when it was between 30 and 50°C; only the composite CM(Fe-Cu)in the presence of hydrogen peroxide showed an endothermic behavior. The highest adsorption capacities were for N(Fe-Cu) in the presence and absence of hydrogen peroxide.