Characterization of hydrochar obtained from hydrothermal carbonization of wheat straw digestate

Abstract

Hydrothermal carbonization (HTC) of wheat straw digestate was performed at 180–260 °C for 2–8 h. The resulted hydrochars were analyzed by ultimate analyzer. Elemental carbon and oxygen concentration of hydrochars were fitted with power law correlation. Moreover, chemical structures of feedstocks and hydrochars were investigated by 13C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy. In particular, a procedure including CP dynamics analysis was applied to obtain semi-quantitative information on the composition of the analyzed materials from 13C CP/MAS spectra. Up to a process temperature of 220 °C, digestate-derived hydrochar contained primarily crystalline cellulose and lignin. At 260 °C, crystalline cellulose was degraded and more aliphatic carbon and lignin-rich hydrochars were produced. Ester bands corresponding to hemicellulose disappeared at mild HTC conditions at 180 °C and 2 h

Chemical, structural and energy properties of hydrochars from microwave-assisted hydrothermal carbonization of glucose

“…It is a green and efficient approach for treating organic materials because of its comparatively low emission, and generation of nontoxic waste [4]. Due to its simple operation, mild reaction conditions, and ability to exploit renewable biomass with minimal pre-treatment, it is of a particular environmental advantage when compared to other techniques of carbonization [5][6][7]. Among potential precursors used in the preparation of carbonaceous materials, glucose is very promising and its hydrothermal carbonization process has been studied several times using the conventional method of oven heating [6,[8][9][10].…”

A novel method of sewage sludge pre-treatment - HTC

“…The HTC method has usually been used for a wide range of biomass feedstocks [4][5][6][7][8][9][10][11], where the effect of temperature, residence (carbonization) time, and carbonization yields have been studied. In the case of sewage sludge, the hydrothermal carbonization process was not so widely investigated, but studies were largely focused on the properties of solid product, energy recovery rate, hydrochar yields and its combustion characteristic, and improved dewaterability of sludge.…”

Optimization of Nutrient and Carbon Recovery from Anaerobic Digestate via Hydrothermal Carbonization and Investigation of the Influence of the Process Parameters

“…However, Reza et al carbonized digestate from wheat straw without changing the pH and they report a reduction of cellulose in the hydrochar due to a relative increase of aromatic and aliphatic carbon atoms with higher temperature. They also state that no considerable degradation of cellulose happened at 180 °C, while degradation seems to start at 220 °C and aromatization is increased at this temperature with longer carbonization time [32]. It can be seen that higher acidic conditions combined with high temperature increased the hydrolysis rate of cellulose to smaller chains and finally glucose units which are better carbonized via furanoid intermediates as described by Coronella et al [11].…”