Mineral Coating Enhances the Carbon Sequestration Capacity of Biochar Derived from <i>Paulownia</i> Biowaste
Liang Xiao,
Jinghua Wu,
Wenhan Li,
Guodong Yuan,
Qing Xu,
Jing Wei,
Fengxiang Han
Affiliations
Liang Xiao
Guangdong Provincial Key Laboratory of Environmental Health and Land Resource, Guangdong Technology and Equipment Research Center for Soil and Water Pollution Control, Zhaoqing University, Zhaoqing 526061, China
Jinghua Wu
Guangdong Provincial Key Laboratory of Environmental Health and Land Resource, Guangdong Technology and Equipment Research Center for Soil and Water Pollution Control, Zhaoqing University, Zhaoqing 526061, China
Wenhan Li
Guangdong Provincial Key Laboratory of Environmental Health and Land Resource, Guangdong Technology and Equipment Research Center for Soil and Water Pollution Control, Zhaoqing University, Zhaoqing 526061, China
Guodong Yuan
Guangdong Provincial Key Laboratory of Environmental Health and Land Resource, Guangdong Technology and Equipment Research Center for Soil and Water Pollution Control, Zhaoqing University, Zhaoqing 526061, China
Qing Xu
Guangdong Provincial Key Laboratory of Environmental Health and Land Resource, Guangdong Technology and Equipment Research Center for Soil and Water Pollution Control, Zhaoqing University, Zhaoqing 526061, China
Jing Wei
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
Fengxiang Han
Department of Chemistry, Physics and Atmospheric Sciences, Jackson State University, Jackson, MS 39217, USA
Biochar holds great promise for carbon sequestration but is restricted by high costs. Here, we introduced the water–fire coupled method and developed a mineral coating technique for biochar production from paulownia waste (Paulownia fortune). Exposure time and mineral (lime) coating were assessed for their impacts on biochar properties. The former had a dominant adverse effect on carbon content, specific surface area, and carbon capture capacity of the biochar. In contrast, the latter alleviated the adverse impact on carbon capture capacity and specific surface area, the highest being 67.07% and 176.0 m2 g−1, respectively. Without a mineral coating (B), biochar functional groups reduced at the exposure time of 0–4 min (-COOH from 0.50 to 0.19 mol/kg, phenolic-OH from 0.43 to 0.14 mol/kg). In contrast, a mineral coating (B-Ca) increased -COOH from 0.25 to 0.83 mol/kg and phenolic-OH from 0.19 to 0.72 mol/kg. The pyrolysis process with a mineral coating is conceptualized as (1) wrapping the paulownia branch with the mineral, (2) enabling oxygen-limited pyrolysis inside the branch, and (3) ending the pyrolysis with water to form biochar. Ca2+ played multiple functions of ion bridging, complexation, and reduction of COx gas formation, thus enhancing the carbon capture capacity (the ratio of C in biomass converted to biochar) to 67%. This research would improve the feasibility of biochar use for carbon sequestration and climate change mitigation.
