Biochar is the material produced from incomplete burning of carbon-rich biomass, under conditions of minimal oxygen. The application of biochar in soils is mainly used to improve fertility and carbon sequestration. Most recently, because of their retention properties, biochar has been studied for immobilization of inorganic contaminants in contaminated areas. Mining activities generate residues rich in potentially toxic elements (PTE's), i.e. Cd and Zn. Such elements may cause ecotoxicological and human health risk when present in concentrations above the permissible limits in soils. This project has the following objectives: I) evaluate the effect of biochar produced from sugar cane bagasse on the adsorption and desorption of Cd and Zn in soils with different physicochemical properties; II) evaluating the effectiveness of biochar in retaining PTE's cationic in soils contaminated by mine waste, as well as the individual retention mechanisms of these metals. Bagasse of sugar cane will be ground and burned under controlled conditions of O2 at 550 °C for one hour to produce biochar. An experiment will be performed to calculate the isotherms of adsorption and desorption of Cd and Zn in a clayey and in a sandy soil treated with doses of biochar. A second experiment will evaluate the effect of doses of biochar in the retention of metals (Cd and Zn) in soils contaminated by mining activities. Soil solution will be collected to study the speciation. In addition, we will evaluate the retention of metals to soils treated with biochar, using techniques of X-ray diffraction (XRD) and Fourier transform infrared (FTIR), and advanced techniques based on synchrotron radiation (µ-XRF/XAFS).
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