Issue 15, 2025

Immobilization of lead and zinc in contaminated soil using taro stem-derived biochar and apatite amendments: a comparative study of application ratios and pyrolysis temperatures

Abstract

Soil contamination by heavy metals presents a substantial environmental challenge. Remediation strategies employing biochar and apatite offer promise for restoring compromised sites. However, the efficacy of apatite and biochar derived from various biomass sources remains an under-investigated area. Taro stem-derived biochar produced at 300 and 500 °C (TSB300 and TSB500) and apatite amendments were incubated in contaminated soil for one month at various ratios (biochar 3%, 6%, 10%, mixture of biochar/apatite 3 : 3%, and 6 : 6% w/w) to investigate their potential to immobilize Pb and Zn. The initial concentrations of Pb and Zn in the contaminated soil were 4165.1 ± 19.6 mg kg−1 and 3424.9 ± 20.4 mg kg−1, respectively. Soil samples were subjected to Tessier's sequential extraction for analysis of Pb and Zn in five chemical fractions (F1: exchangeable fraction; F2: carbonate fraction; F3: Fe/Mn oxide fraction; F4: organic carbon fraction and F5: residual fraction). The results indicated that one-month biochar and/or apatite amendment significantly increased soil pH, organic carbon (OC), and electrical conductivity (EC) compared to the control (p < 0.05). Amendments also notably reduced exchangeable fractions of Pb and Zn (F1) up to 71.8% and 61.5%, respectively, while enhancing their presence in more stable fractions (F4 and F5). This immobilization effect peaked at the 10% biochar application and 6 : 6% biochar–apatite combination. These findings suggest that TSB300, TSB500, and their blends with apatite hold promise for immobilizing Pb and Zn in heavily contaminated soil, potentially mitigating environmental risks.

Graphical abstract: Immobilization of lead and zinc in contaminated soil using taro stem-derived biochar and apatite amendments: a comparative study of application ratios and pyrolysis temperatures

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Article information

Article type
Paper
Submitted
07 Feb 2025
Accepted
07 Apr 2025
First published
16 Apr 2025
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2025,15, 11975-12000

Immobilization of lead and zinc in contaminated soil using taro stem-derived biochar and apatite amendments: a comparative study of application ratios and pyrolysis temperatures

T. X. Vuong, D. P. Nguyen, V. H. Ngoc Nguyen, T. T. Ha Pham and T. T. Thuy Nguyen, RSC Adv., 2025, 15, 11975 DOI: 10.1039/D5RA00912J

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