Characterization of biochars produced from peanut hulls and pine wood with different pyrolysis conditions

Abstract

Background: Application of modern biomass pyrolysis methods for production of biofuels and biochar is potentially a significant approach to enable global carbon capture and sequestration. To realize this potential, it is essential to develop methods that produce biochar with the characteristics needed for effective soil amendment.Methods: Biochar materials were produced from peanut hulls and pine wood with different pyrolysis conditions, then characterized by cation exchange (CEC) capacity assays, nitrogen adsorption-desorption isotherm measurements, micro/nanostructural imaging, infrared spectra and elemental analyses.Results: Under a standard assay condition of pH 8.5, the CEC values of the peanut hull-derived biochar materials, ranging from 6.22 to 66.56 cmol kg −1 , are significantly higher than those of the southern yellow pine-derived biochar, which are near zero or negative. The biochar produced from peanut hulls with a steam activation process yielded the highest CEC value of 66.56 cmol kg −1 , which is about 5 times higher than the cation exchange capacity (12.51 cmol kg −1 ) of a reference soil sample. Notably, biochar produced from peanut hulls with batch barrel retort pyrolysis also has a much higher CEC value (60.12 cmol kg ) from Eprida's H 2 -producing continuous steam injection process. The CEC values were shown to correlate well with the ratios of oxygen atoms to carbon atoms (O:C ratios) in the biochar materials. The higher O:C ratio in a biochar material may indicate the presence of more hydroxyl, carboxylate, and carbonyl groups that contribute to a higher CEC value for the biochar product. In addition, the increase in surface area can also play a role in increasing the CEC value of biochar, as in the case of the steam activation char. Conclusion:Comparison of characterization results indicated that CEC value is determined not only by the type of the source biomass materials but also by the pyrolysis conditions. Biochar with the desirable characteristics of extremely high surface area (700 m 2 /g) and cation exchange capacity (> 60 cmol kg) was created through steam activation.

Immobilizing Laccase on Different Species Wood Biochar to Remove the Chlorinated Biphenyl in Wastewater

“…These results demonstrated that the surface area and pore volume of Mba are more superior than those of Sba. Compared to those reported elsewhere, 168 m 2 /g for wood chip biochar produced at 600 °C 19 and 186 m 2 /g for yellow pine biochar 20 , the surface area of Mba is higher. A larger surface area means more porous structures within biochar 21 .…”

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“…It has been estimated the char carries metals like magnesium, calcium, potassium and iron at a significant level but however other heavy metals like zinc (Zn), chromium (Cr), nickel (Ni), molybdenum (Mo), manganese (Mn) and aluminum (Al) also present in negligible amounts. Certain sequential solvent extraction process helps in the significant removal of magnesium, calcium and potassium ( Lee et al, 2012 ).…”

Risk assessment of low-temperature biochar used as soil amendment on soil mesofauna

“…Our study is presumably the first attempt to study the interactions between biochar and soil-dwelling mesofauna (springtails and mites), simultaneously in field and laboratory conditions. The low-temperature pine/wood chip biochar used in the experiment had a high carbon content but low surface area and ability for nutrient storage, which was in agreement with the findings of other authors (Lee et al 2016 ; Jiang et al 2017 ). The analysis of metal concentration did not report any chemical interference by biochar amendment in the agro-ecosystem.…”