Hydrothermal carbonization (HTC) is a thermochemical process, wherein biomass is subjected to high-pressure, high-temperature subcritical water to improve the combustion characteristics of biomass as a solid fuel. Australian saltbush was subjected to HTC at three temperatures (200, 230, and 260 °C) and four holding times (0, 15, 30, and 60 min) using a custombuilt batch reactor. The resultant hydrochars demonstrated improved higher heating values (HHVs), with temperature more influential than time. At the most severe condition of 60 min and 260 °C, the hydrochar possessed numerous key similarities to fossil coal, such as a HHV of 27.5 MJ/kg, similar ratios of carbon/oxygen and hydrogen/oxygen, and equivalent levels of volatile matter, fixed carbon, and ash. The HTC process also proved effective in reducing the high levels of inorganic elements naturally present within saltbush, with 60 min at 260 °C again shown to be the most effective condition, removing almost 95% of sodium, chloride, and potassium.

No abstract

Hydrothermal Carbonization (HTC) is the thermochemical conversion of biomass in subcritical water to form an energy-enriched "hydrochar" as a renewable replacement for coal. Lignocellulosic biomass contains a variety of complex, interconnected biopolymers with very different physical and chemical structures, including hemicellulose, cellulose, lignin, and protein. These differing structures lead to different rates of decomposition during the HTC reaction. Where previous studies have attempted to elucidate these various rates through the use of individual, purified model compounds, the complexity of whole biomass makes understanding these reactions in their natural state difficult. This present study offers a first step toward gaining a more thorough knowledge of the HTC reaction by accurately quantifying the degradation of hemicellulose, cellulose, and lignin within whole biomass, and producing a simple kinetic and mechanistic model to describe this degradation. Australian saltbush was subjected to HTC at three temperatures (200, 230, 260 °C), and four residence times (0, 15, 30, 60 min). The resultant hydrochars were assayed for hemicellulose, cellulose, and lignin content, via HPLC, Updegraff assay, and acetyl bromide assay, respectively. The degradation of each component was measured, and the reaction order n and key Arrhenius parameters reaction rate constant k, activation energy E a , and the pre-exponential factor A 0 were calculated. It was found that hemicellulose degraded fastest (n = 1, E a = 61 kJmol −1 ), cellulose the slowest (n = 0.5, E a = 127 kJmol −1 ), and only a portion of lignin reacted (n = 1, E a = 66 kJmol −1 ), the remaining 22% being stable under HTC conditions.

Chymotrypsin is a protease that is commonly used as a standard for protein crystallization and as a model system for studying serine proteases. Unliganded bovine α-chymotrypsin was crystallized at neutral pH using ammonium sulphate as the precipitant, resulting in crystals that conform to P65 symmetry with unit cell parameters that have not been reported previously. Inspection of crystallographic interfaces revealed that the major interface between any two molecules in the crystal lattice represents the interface of the biological dimer, as previously observed for crystals of unliganded α-chymotrypsin grown at low pH in space group P21.

No abstract