Efficiency of biochar and activated carbon in the remediation of Cd, Pb and Zn in soil in laboratory conditions

Abstract

The immobilization of contaminants using Biochars (BC) in soil is seen as an attractive alternative of remediation. However, the production of activated carbon (AC) from agricultural by-products has received a special attention because, since the activation of the residue is performed in the presence of water vapors, increases the network of micropores, increases the surface area of the porous structure, resulting in a higher adsorption of metals compared to BC, thus having an important role in the control of contaminants in the environment. Therefore, this project aims to (a) evaluate the effectiveness of BC and CA samples, obtained by a compost of sewage sludge and bagasse cane sugar, in the retention of Zn, Cd and Pb after the saturation of sites exchange with contaminated solution, (b) Assess the efficacy of BC and CA samples previously selected in the remediation of a very clayey soil from the mining region of Vazante-MG, under laboratory conditions. The first experiment will be performed to calculate the adsorption and desorption isotherms of Zn, Pb and Cd in contaminated solution, treated with samples of BC and CA, thus obtaining materials with greater potential for application in contaminated soil. The second experiment will be conducted to investigate the leaching of these metals by the application of acetate-buffered columns with soil contaminated by mining activity and treated with doses of BC and CA. Equally to the second experiment, a study of the chemical fractionation will done and as a complementary analysis, the fractions of the soil solid phase by standard techniques of X-ray diffraction (XRD) and infrared (FTIR) as well as techniques based on light synchrotron such as micro x-ray fluorescence (XRF-¼), micro spectroscopy extended X-ray absorption fine structure (EXAFS-¼) and micro X-ray absorption near edge structure (XANES-¼ ). (AU)