Pyrolysis self-activation: An environmentally friendly method to transform biowaste into activated carbon for arsenic removal.

A green method for production of activated carbon and combustible gas was introduced. Without any external reagents and gases, the H2O and CO2 produced by the pyrolysis of bamboo shoot shells were used as activators. The prepared activated carbon had good arsenic adsorption properties with the maximum adsorption capacities of 10.9 mg/g for As(III) and 16.0 mg/g for As(V). The gaseous products were mostly CO and H2, with higher heating value of 11.7 MJ/Nm3. Thermogravimetric experiments were performed in N2, H2O and CO2 atmospheres to simulate the self-activation process and investigate the self-activation mechanism. This work will help to improve the competitiveness of self-activation technology and reduce the production cost of activated carbon.

Thermal Characteristics of Ash from Bamboo and Masson Pine Blends: Influence of Mixing Ratio and Heating Rate.

Thermal characteristics and kinetic parameters of ash from bamboo and masson pine blends with different mixing ratios were investigated using a thermogravimetric analyzer at different heating rates. The results showed that bamboo ash had lower fusion temperatures than the ash of masson pine. Mixing ratios and heating rates had a significant impact on the thermal characteristics and activation energy of ash samples. There was a synergistic interaction of chemical compositions in the bamboo and masson pine ashes. The mass loss of ash samples increased with the increase in the bamboo content of the blends. All ash samples had the maximum activation energy at the heating rate of 20 °C/min. The activation energy had a good linear correlation with mixing ratios at high conversion and heating rates. The optimum blend was suggested as 20% bamboo/80% masson pine due to its high activation energy. The results of this study are helpful to design a combustion system of bamboo and masson pine blends.

Fuel Characteristics of Briquettes Manufactured by Natural Stacking Bamboo/Chinese Fir Mixtures.

Bamboo wastes were naturally stacked for 1 month and were uniformly mixed with Chinese fir. Briquettes were manufactured by a briquette extruder at different process temperatures and mixing ratios. The physical, mechanical, pyrolysis, and combustion characteristics of briquettes were determined. The results showed that the mixing ratios and process temperature had a significant impact on the fuel properties of briquettes. The optimum briquettes were manufactured by 70% bamboo/30% Chinese fir blends at a process temperature of 520 °C. The fuel properties of optimum briquettes met the standard requirement of LY/T 2552-2015 and GB/T 28669-2012. The lower heating rate at the primary pyrolysis stage increased the yield of charcoal during the carbonization process of briquettes. The combustion process of briquettes added a char combustion stage, compared with the pyrolysis process. There were no synergistic interactions of bamboo and Chinese fir during pyrolysis and combustion process. The results of this research are helpful to develop large-scale production of bamboo briquettes or charcoal.

Investigating the co-firing characteristics of bamboo wastes and coal through cone calorimetry and thermogravimetric analysis coupled with Fourier transform infrared spectroscopy.

To evaluate the combustion characteristics of raw or torrefied bamboo wastes and coal blends, the co-firing process determined by cone and pollutant emission was investigated by thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The results showed that torrefaction improved the fuel properties of bamboo wastes. Torrefied bamboo had a lower volatile fuel ratio, H/C and O/C ratios, pollutant emission and a higher heating value. They further affected the co-firing process of raw or torrefied bamboo and coal. All blends had a lower ignition temperature and a more stable flame than coal. Torrefied bamboo and coal blends had a lower percentage of quality loss, a higher heat release rate (HRR), total heat release (THR) and total smoke release (TSR). With an increase in the proportion of torrefied bamboo in the blends, the HRR, THR, TSR and percentage of quality loss increased. The main pollutant emissions included CO2, CO, SO2 and NOx. All blends of torrefied bamboo and coal had a lower pollutant emission. The optimum blend suggested was 20% torrefied bamboo/80% coal.

Investigation of the Cofiring Process of Raw or Torrefied Bamboo and Masson Pine by Using a Cone Calorimeter.

Cofiring characteristics of raw or torrefied bamboo and masson pine blends with different blend ratios were investigated by cone calorimetry, and its ash performance from cofiring was also determined by a YX-HRD testing instrument, X-ray fluorescence, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Results showed that bamboo and masson pine had the different physicochemical properties. Torrefaction improved fuel performances, resulting in a more stable cofiring process. It also decreased the heat release rate, total heat release, and total suspended particulates of fuels, especially CO2 and CO release. Masson pine ash mainly included CaO, SiO2, Fe2O3, K2O, and Al2O3. Bamboo ash was mainly composed of K2O, SiO2, MgO, and SO3. There were different melting temperatures and trends between different samples. The synergistic reaction of ash components was found during the cofiring process. The surface morphology of blend ash changed with the variation of bamboo or masson pine content.

Nitrogen Self-Doped Activated Carbons Derived from Bamboo Shoots as Adsorbent for Methylene Blue Adsorption.

Bamboo shoots, a promising renewable biomass, mainly consist of carbohydrates and other nitrogen-related compounds, such as proteins, amino acids and nucleotides. In this work, nitrogen self-doped activated carbons derived from bamboo shoots were prepared via a simultaneous carbonization and activation process. The adsorption properties of the prepared samples were evaluated by removing methylene blue from waste water. The factors that affect the adsorption process were examined, including initial concentration, contact time and pH of methylene blue solution. The resulting that BSNC-800-4 performed better in methylene blue removal from waste water, due to its high specific surface area (2270.9 m2 g-1), proper pore size (2.19 nm) and relatively high nitrogen content (1.06%). Its equilibrium data were well fitted to Langmuir isotherm model with a maximum monolayer adsorption capacity of 458 mg g-1 and a removal efficiency of 91.7% at methylene blue concentration of 500 mg L-1. The pseudo-second-order kinetic model could be used to accurately estimate the carbon material's (BSNC-800-4) adsorption process. The adsorption mechanism between methylene blue solution and BSNC-800-4 was controlled by film diffusion. This study provides an alternative way to develop nitrogen self-doped activated carbons to better meet the needs of the adsorption applications.