Structural similarity of the humic substances from hydrochar obtained from vinasse and sugarcane bagasse with the Black Earth (TPI)

Abstract

The agro-industry is responsible for producing large amounts of waste in the world, and the Brazilian sugarcane industries are responsible for the generation of 149 million tons of sugarcane bagasse and 10 billion liters of vinasse. The "Terra Preta de Indio" (TPI) or Amazonian Dark Earth are soils known for their high fertility, this soil has a large amount of organic matter formed by a binary mixture of pyrogenic carbon and polycondensed and functionalized structures, formed by the burning of animal and plants wastes the indigenous population. Studies have shown that hydrothermal carbonization (HTC) of biomass produces a recalcitrant carbon rich material, called hydrochar. The process employs temperatures around 300 oC, humid biomass and self-generated pressures. The objective this study will be to characterize structurally the humic substances (HS) extracted from the hydrochars produced from HTC with wastes from the sugarcane industry in different conditions with the HS of the TPI soils. The HS will be extracted from four hydrochars produced from the HTC, TPI soil profile and adjacent area profile, a total of 14 samples. HS will be characterized using UV-VIS, Molecular Fluorescence, NMR, FTIR, TGA and CHNS techniques. Soil and hydrochars samples will be characterized by 13C NMR, FTIR, TGA, DRX and CHNS. Calcium, magnesium, iron and potassium will be quantified by Atomic Absorption Spectrophotometry with Flame Atomization and also total phosphorus by UV-VIS. A granulometric analysis and pH measurement will be performed. The recalcitrance of hydrochar and TPI soils in terms of pyrogenic carbon will be evaluated. It is expected with the structural characterization of SH from TPI and hydrochars to infer whats the condition of hydrochar production that provides structural characteristics similar to TPI soils. (AU)