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Hydrothermal carbonization (HTC) at 200 and 250 °C was combined with acetic acid and NaOH (changing feedwater pH from 2 to 12) to treat woody biomass for enhancing its pelletization and fuel properties. The treated biomass (hydrochar) was characterized by composition analysis and Fourier transform infrared spectroscopy, after which the energy consumption of pelletization; tensile strength; fuel properties, including proximate, elemental analysis, and mass density; and combustion characteristics of corresponding pellets were analyzed. The results showed that both the acetic acid and NaOH-aided HTC processes decreased the energy consumption of hydrochar compression. Weakly basic or acidic feedwater decreased the tensile strength of hydrochar pellets, but it increased at pH 2 and 12. The changes in treatment pH from 4 to 9 had little effect on the O/C and H/C content of the hydrochar pellets, while the addition of acetic acid enhanced oxygen and hydrogen loss more than NaOH. The heating values of hydrochar pellets produced at pH 2 from 200 and 250 °C were 20.7 and 22.8 MJ/kg, respectively. Hydrochar pellets produced from HTC at 250 °C and pH 2 had higher mass density and lower equilibrium water content than those produced under other conditions. The combustion process was promoted with reduced ignition temperature, maximum weight loss rate, and burnout temperature. These findings demonstrate that acetic acid-aided HTC of woody biomass was more suitable than NaOH for producing hydrochar pellets for use as a biofuel.

A low-cost material with high adsorption and oxidation ability for Hg0capture is needed, whereas it is hard to prepare by present methods. Here, halide ions (I–) and metal oxides (MnOxand ZrO2) were both loaded on peanut shells carbon to synthesize 6Mn-6Zr/PSC-I3. Various characterizations and experiments were used to investigate the physiochemical properties and Hg0removal performances. The sample exhibited an abundant pore structure and the active components dispersed well on its surface. The excellent total Hg0removal efficiency (more than 90%) was obtained in a wide reaction temperature range (150–300 °C) under a N2+ 6% O2atmosphere. Moreover, the Hg0adsorption capacity in 1440 min was 5587.0 μg·g–1and the Hg0oxidation efficiency after reaching adsorption equilibrium was more than 30%. Further, the reaction mechanism at 150 °C was proposed. The main chemical adsorption sites of carbon-iodine groups dominate Hg0removal at the initial reaction stage. As reaction progresses, chemical adsorption is weakened due to the gradual saturation of adsorption sites, whereas catalytic oxidation caused by lattice oxygen and hydroxyl oxygen substitutes chemical adsorption and dominates Hg0removal at the final reaction stage. Thus, the 6Mn-6Zr/PSC-I3 with economic and environmental benefits has a promising prospect in industrial applications.