Effects of Ageing on Surface Properties of Biochar and Bioavailability of Heavy Metals in Soil

Zhengwu Cui, Yang Wang (), Nan Wang, Fangfang Ma and Yuyu Yuan
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Zhengwu Cui: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
Yang Wang: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
Nan Wang: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
Fangfang Ma: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
Yuyu Yuan: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China

Agriculture, 2024, vol. 14, issue 9, 1-15

Abstract: This study aims to explore the effects of biochar ageing on its surface properties and the bioavailability of heavy metals in soil. The biochar was subjected to chemical oxidation/dry–wet cycles (CDWs), chemical oxidation/freeze–thaw cycles (CFTs), and natural ageing (NT) to analyze changes in the elemental composition, pH, specific surface area, pore volume, and surface functional groups. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were applied to characterize the functional groups and microstructure, and the BCR sequential extraction method was employed to demonstrate the fractionation distribution of Cu, Cd, and Pb. The results showed that the CDWs and CFTs treatments significantly reduced the carbon content of the biochar (with a maximum reduction to 47.70%), increased the oxygen content (up to 49.17%), and notably increased the specific surface area and pore volume. The pH decreased significantly from 9.91 to 4.92 and 4.99 for the CDWs and the CFTs, respectively. The FTIR analysis indicated notable changes in hydroxyl and carboxyl functional groups, and the SEM revealed severe microstructural damage in biochar after the CDWs and CFTs treatments. The heavy metal fractionation analysis indicated that exchangeable Cu, Cd, and Pb significantly increased after the CDWs treatment, reaching 31.40%, 5.25%, and 6.79%, respectively. In conclusion, biochar ageing significantly affects its physicochemical properties and increases the bioavailability of heavy metals, raising concerns about its long-term remediation effectiveness.

Keywords: biochar; ageing; surface properties; heavy metals; bioavailability (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2024
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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