• Journal of Soil and Groundwater Environment
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• v.27 no.2
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• pp.41-49
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• 2022

To abate the environmental burdens arising from CO₂ emissions, biochar offers a strategic means to sequester carbons due to its recalcitrant nature. Also, biochar has a great potential for the use as carbon-based adsorbent because it is a porous material. As such, developing the surface properties of biochar increases a chance to produce biochar with great adsorption performance. Given that biochar is a byproduct in biomass pyrolysis, characteristics of biochar are contingent on pyrolysis operating parameters. In this respect, this work focused on the investigation of surface properties of biochar by controlling temperature and reaction medium in pyrolysis of pine sawdust as case study. In particular, CO₂ was used as reaction medium in pyrolysis process. According to pyrolytic temperature, the surface properties of biochar were indeed developed by CO₂. The biochar engineered by CO₂ showed the improved capability on CO₂ sorption. In addition, CO₂ has an effect on energy recovery by enhancing syngas production. Thus, this study offers the functionality of CO₂ for converting biomass into engineered biochar as carbon-based adsorbent for CO₂ sorption while recovering energy as syngas.

• Environmental Engineering Research
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• v.24 no.4
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• pp.608-617
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• 2019

The adsorption of sulfamethoxazole (SMX) onto a NaOH-activated pine wood-derived biochar was investigated via batch experiments and models. Surprisingly, the maximum adsorption capacity of activated biochar for SMX (397.29 mg/g) was superior than those of pristine biochars from various feedstock, but comparable to those of commercially available activated carbons. Elovich kinetic and Freundlich isotherm models revealed the best fitted ones for the adsorption of SMX onto the activated biochar indicating chemisorptive interaction occurred on surface of the activated biochar. In addition, the intraparticle diffusion limitation was thought to be the major barrier for the adsorption of SMX on the activated biochar. The main mechanisms for the activated biochar would include hydrophobic, π-π interactions and hydrogen bonding. This was consistent with the changes in physicochemical properties of the activated biochar (e.g., increase in sp² and surface area, but decrease in the ratios of O/C and H/C).

• Journal of Soil and Groundwater Environment
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• v.27 no.1
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• pp.17-24
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• 2022

This work examined the effect of mixing transition metal-based additives [FeCl₃, Fe-containing paper mill sludge (PMS), CoCl₂·H₂O, ZrO₂, and α-Fe₂O₃] on the thermochemical conversion of coffee waste (CW) in carbon dioxide-assisted pyrolysis process. Compared to the generation amounts of syngas (0.7 mole% H₂ & 3.0 mole% CO) at 700℃ from single pyrolysis of CW, co-pyrolysis in the presence of Fe- or Zr-based additives resulted in the enhanced production of syngas, with the measured concentrations of H₂ and CO ranging 1.1-3.4 mole% and 4.6-13.2 mole% at the same temperature, respectively. In addition, α-Fe₂O₃ biochar possessed the adsorption capacity of As(V) (19.3 mg g^-1) comparable to that of ZrO₂-biochar (21.2 mg g^-1). In conclusion, solid-type Fe-based additive can be highly considered as an efficient catalyst to simultaneously produce syngas (H₂ & CO) as fuel energy resource and metal-biochar as sorbent.