Biochar is a carbon-rich product prepared by pyrolysizing biomass or agricultural waste under oxygen-limited atmosphere. It has great potential in carbon fixation, energy production, waste management, and soil quality improvement. Due to the high surface area and strong sorption ability, biochars is increasingly considered as an environmental-friendly agent in soil remediation. Many studies have found that the sorption ability of biochars are highly affected by biochars’ structures. However, various precursors and different preparation procedures generated multiple structures of biochars, leading to a heterogeneous structure which hinders the development of the structure-sorption relationships. Therefore, we proposed a quaternary structure model of biochar, including heterogeneous phases, graphene-like aggregates, nanosized aromatic clusters, and atomic arrangements. Via FT-IR and elemental analysis, the constituents of biochar phases can be identified, and by applying high-solution TEM, we were able to directly observe the aromatic cluster structures of biochars. Both macroscopic and microscopic levels structures of biochars contribute the biochar’s sorption ability. For example, the sorption mechanism transited from partition-domain to adsorption-domain with increasing pyrolysis temperature. Quantitative relationships were developed between biochars aromatic cluster structures and sorption ability after collecting data of various biochars. We believe that the summarization on the relationships between multiple-level structures and soil remediation will benefit the understanding of biochar structures and will guide the biochar design and selective application.

Multiple-level structures of biochars and soil remediation applications

256th National Meeting (2018)

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