Sugarcane bagasse-derived granular activated carbon hybridized with ash in bio-based alginate/gelatin polymer matrix for methylene blue adsorption.

Sugarcane bagasse (SCB) and sugarcane bagasse ash (SCB-ash) are major agricultural residues from sugar processing industries in Thailand. In this study, SCB-derived activated carbon (SCBAC) with the optimum surface area of 489 m2/g was prepared by steam activation at 900 °C for 1 h. Hybrid granular activated carbons (GACs) were successfully developed by mixing SCBAC with bio-based polymers, alginate and gelatin, at the weight ratio of 3:1 for methylene blue (MB) adsorption. SCB-ash, which was additionally mixed in the GACs, could significantly increase compressive strength of the GACs, but decrease their surface areas and MB adsorption efficiencies. An existence of gelatin up to 30 wt% in the polymer matrix of the GACs showed a slight increase in swelling degree and iodine number, but could not enhance bead strength and MB adsorption efficiency due to its relatively lower bulk density and specific surface area. Maximum MB adsorption capacities of the GACs were found at 290-403 mg/g under this study's experimental condition. MB adsorption efficiencies at above 90 % with no deformation of all of the selected SCB hybrid GACs were finally confirmed after seven consecutive adsorption-desorption cycles using a simple regeneration with ethanol.

Torrefaction under mechanical pressure of 10-70 MPa at 250 °C and its effect on pyrolysis behaviours of leucaena wood.

In this study, torrefaction under mechanical pressure of 10-70 MPa at 250 °C was proposed as a pretreatment method and its effect on pyrolysis behaviours of Leucaena (LC) was examined at 900 °C. It was found that the mechanical pressure applied during torrefaction could significantly increase the char yield at 900 °C. The char yield increased from 18.7% for Raw to 26.4% and 27.5% for MP40 and MP70, respectively. The %C of biochar prepared from MP40 (MP40-900) was 86.5%, whereas the %C of biochar prepared from raw (Raw-900) was 82.6%. From TG-MS analyses during the pyrolysis of MP, a large amount of oxygen was removed as H2O and CO2. The analyses of tars produced from MP showed higher fraction of acids and furans compared with tar produced from Raw. Furthermore, the mechanism of the pyrolysis of LC torrefied under mechanical pressure was discussed.

Gas-pressurized torrefaction of biomass wastes: Co-gasification of gas-pressurized torrefied biomass with coal.

Co-gasification of coal and biomass offers a relatively cleaner utilization way of fossil fuel. The fuel property improvement of biomass can not only improve the property of syngas but also enhance the synergistic effect during the co-gasification. In our previous work, a novel gas-pressurized (abbreviated as GP) torrefaction was proposed to effectively upgrade the biomass under mild condition. In this work, the co-gasification of GP torrefied biomass and coal were conducted to explore the synergistic effect and kinetics. Significant synergistic effect during the co-gasification was proved. The CO yield of co-gasification increased to as high as 70.70 mol/kg, resulting from the promotion of carbon in coal converting into CO by GPRS. Furthermore, the kinetic model of RPM was most fitting for the co-gasification, and the activation energy of co-gasification was reduced. Thus, the coal gasification was promoted significantly by GP torrefied biomass through obvious synergistic effect during the co-gasification.

Gas-pressurized torrefaction of biomass wastes: The optimization of pressurization condition and the pyrolysis of torrefied biomass.

A novel gas-pressurized (GP) torrefaction with high oxygen removal efficiency at mild temperature was proposed in our previous work. However, the optimal condition of the GP torrefaction and subsequent pyrolysis of the torrefied biomass were not clear. In this work, the effect of pressure on the GP torrefaction and pyrolysis product properties of the torrefied biomass were studied in detail. The results show that the pressure increasing from 1.7 MPa to 5.0 MPa just slightly contributed to further oxygen removal, and 1.7 MPa was thus selected as the optimum pressure. The GP torrefaction significantly improved the product property of biomass pyrolysis compared to the conventional torrefaction (AP torrefaction). The acids content in bio-oil was reduced from 15-20% to less than 5%, and the calorific value of biogas increased to as high as 16.57-19.31 MJ/Nm3. Furthermore, an overall conversion mechanism of combined GP torrefaction and subsequent pyrolysis of biomass was proposed.

Torrefaction behavior of hot-pressed pellets prepared from leucaena wood.

In this study, torrefaction behavior of hot-pressed wood pellet prepared at 250 °C and compression pressure of 70 MPa was examined at temperature 260-300 °C. It was found that the torrefaction behavior of hot-pressed pellet (HP) was significantly different from that of Raw and cold-pressed pellet (CP). The mass yield and energy yield for torrefaction at 300 °C and 30 min holding time for HP were 54.5% and 84.4%, respectively. Whereas the mass yield and energy yield for torrefaction at 300 °C and 30 min for Raw were 41.5% and 58.1%, respectively. From the gas formation analysis, it was found that the dehydration and deoxygenation reactions were accelerated to produce a large amount of H2O and CO2 during the torrefaction of HP. It was judged that torrefaction of hot-pressed pellet was very effective to prepare high quality black pellet.

Gas-pressurized torrefaction of biomass wastes: Roles of pressure and secondary reactions.

A gas-pressurized (GP) torrefaction method, proposed in our resent work, can significantly promote the upgrading and oxygen removal of biomass wastes, compared to the traditional torrefaction (AP). However, the mechanism of the GP torrefaction process is not clear. In present work, semi-closed (SC) torrefaction, GP torrefaction, and AP torrefaction were conducted to reveal the roles of pressure and secondary reactions during GP torrefaction quantitatively. The results showed that the pressure significantly promoted the upgrading of biomass during GP torrefaction at 200 °C. The contribution of pressure on the oxygen removal of GP torrefaction at 200 °C was 63.87%. At relatively high temperature of around 250 °C, the promotions were caused by the synergistic effect of pressure and secondary reactions. The contribution of secondary reactions on the oxygen removal was 53.99%. Thus, the process of the GP torrefaction of biomass wastes was preliminarily understood.

Degradative solvent extraction of biomass using petroleum based solvents.

The aim of this study was to examine the possibility to use two petroleum based solvents, kerosene and a distillate rich in benzene (A150), as practical solvents for the degradative solvent extraction at 350 °C in reference to 1-MN. It was found that the thermal degradation behavior of two biomass samples, a rice straw and Leucaena, in the three solvents was rather similar and that only the distribution of Soluble, Deposit, and Residue was affected by the difference of solubility of the solvents. Preparation of solvent treated biomass (STB) using the three solvents gave the yields close to the sum of the yields of Soluble, Deposit, and Residue. It was judged that A150 may be used to preparing Soluble and that Kerosene can well be used to prepare STB.