Remoção de benzeno e tolueno em solução aquosa por adsorção utilizando carvão ativado produzido a partir do lodo doméstico

Abstract

Monoaromatic compounds (BTEX) are toxic and carcinogenic substances that even in small dimensions harm the environment and human health. These compounds are used as solvents and found in fuels such as petroleum and gasoline and it is continuously released into the environment. Therefore, the methods of removal of these contaminants are being studied a way to reduce high concentrations present on soils and groundwater. Thus, the adsorption process is based on a solid, denominated adsorbent, to adsorb on surface the contaminants present in the aqueous solutions analyzed. Sludge, a subproduct generated during the sewage treatment process, is a recent problem of worldwide concern. Activated carbon (AC) production for any adsorption process is relatively high, can be used as a potentially economic alternative, and feedstock value and residue reduction can be added. The aim of the present work is to prepare and characterize the activated carbon from the sewage sludge and to apply on monoaromatic compounds (benzene and toluene) in aqueous solutions. In the process of activated carbon synthesis, a chemical activation with potassium hydroxide (KOH) was studied, submitted to the thermal treatment of pyrolysis in a nitrogen flow at 100 mL.min-1, at a temperature of 550ºC. X-ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM) and the study of the surface area using the BET method. The adsorption studies were performed by evaluating the effects of the adsorbent mass (m = 0.08 g), concentrations (50-200 ppm) and the contact time between the adsorbent and the adsorbate (0.0333 at 30 min.). The most suitable kinetic parameters for the pseudosecond model for the two adsorbates. In addition, it was possible to observe that the benzene data, Freundlich model are more adequate for the results, as for toluene the Langmuir model it was able to predict the experimental data for an adsorption. The results obtained in the present work presented results obtained with a reduction of approximately 75% for benzene and 83% for the total of studies in the studies and studies in fixed bed column showed a removal of approximately 87% for benzene and 91% For the method of proving the efficiency of the applied adsorption technique and favoring the application costs, it can be a classic alternative for the treatment of effluents.