The regulation of the pyrolysis process is a key step in increasing the carbon sequestration capacity of biochar.The effect of K_(3)PO_(4)addition on the yield,chemical composition,characteristic functional groups,mac...The regulation of the pyrolysis process is a key step in increasing the carbon sequestration capacity of biochar.The effect of K_(3)PO_(4)addition on the yield,chemical composition,characteristic functional groups,macromolecular skeleton,graphite crystallites,and stability of biochar was studied in this paper using two-dimensional infrared correlation spectroscopy(2D-PCIS),X-ray photoelectron spectroscopy,Raman spectrum,and other characterization methods combined with thermal/chemical oxidation analysis.It is discovered that adding K_(3)PO_(4)may effectively minimize the graphitization temperature range and increase biochar’s yield,aromaticity,H/C ratio,and proportion of refractory/recalcitrant organic carbon.The 2D-PCIS and Raman analysis revealed that K_(3)PO_(4)mostly promoted the dehydrogenation and polycondensation process of the aromatic rings in the char precursor,transforming the amorphous carbon structure of biochar into an ordered turbostratic microcrystalline structure.K_(3)PO_(4)enhanced biochar stability mostly at medium-high temperatures(350~750℃)by stimulating the transformation of unstable structures of biochar to stable carbon-containing structures or by inhibiting the interaction of its active sites with oxidants through the mineralization process.A 20%phosphorus addition increased biochar’s refractory index(R_(50))by roughly 11%,and it also boosted biochar’s oxidation resistance(H_(2)O_(2)or K_(2)CrO_(4))efficiency,reducing carbon oxidation loss by up to 7.31%.However,at higher temperatures(>750℃),the doping of phosphorus atoms into the carbon skeleton degraded the biochar structure’s stability.The results of this study suggest that using exogenous phosphorus-containing additives is an efficient way to improve the stability of biochar.展开更多
基金funded by the National Natural Science Foundation of China(52306243,52125601)the China Postdoctoral Science Foundation(2023M731182).
文摘The regulation of the pyrolysis process is a key step in increasing the carbon sequestration capacity of biochar.The effect of K_(3)PO_(4)addition on the yield,chemical composition,characteristic functional groups,macromolecular skeleton,graphite crystallites,and stability of biochar was studied in this paper using two-dimensional infrared correlation spectroscopy(2D-PCIS),X-ray photoelectron spectroscopy,Raman spectrum,and other characterization methods combined with thermal/chemical oxidation analysis.It is discovered that adding K_(3)PO_(4)may effectively minimize the graphitization temperature range and increase biochar’s yield,aromaticity,H/C ratio,and proportion of refractory/recalcitrant organic carbon.The 2D-PCIS and Raman analysis revealed that K_(3)PO_(4)mostly promoted the dehydrogenation and polycondensation process of the aromatic rings in the char precursor,transforming the amorphous carbon structure of biochar into an ordered turbostratic microcrystalline structure.K_(3)PO_(4)enhanced biochar stability mostly at medium-high temperatures(350~750℃)by stimulating the transformation of unstable structures of biochar to stable carbon-containing structures or by inhibiting the interaction of its active sites with oxidants through the mineralization process.A 20%phosphorus addition increased biochar’s refractory index(R_(50))by roughly 11%,and it also boosted biochar’s oxidation resistance(H_(2)O_(2)or K_(2)CrO_(4))efficiency,reducing carbon oxidation loss by up to 7.31%.However,at higher temperatures(>750℃),the doping of phosphorus atoms into the carbon skeleton degraded the biochar structure’s stability.The results of this study suggest that using exogenous phosphorus-containing additives is an efficient way to improve the stability of biochar.
