Elucidating the redox-driven dynamic interactions between arsenic and iron-impregnated biochar in a paddy soil using geochemical and spectroscopic techniques

Xing Yang, Sabry M. Shaheen, Jianxu Wang, Deyi Hou, Yong Sik Ok, Shan Li Wang, Hailong Wang, Jörg Rinklebe

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Iron (Fe)-modified biochar, a renewable amendment that synthetizes the functions of biochar and Fe materials, demonstrates a potential to remediate arsenic (As)-contaminated soils. However, the effectiveness of Fe-based biochar to immobilize As in paddy soils under varying redox conditions (Eh) has not been quantified. We tested the capability of the raw (RBC) and Fe-impregnated (FeBC) biochars to immobilize As in a paddy soil under various Eh conditions (from -400 to +300 mV) using a biogeochemical microcosm system. In the control, As was mobilized (686.2–1535.8 μg L-1) under reducing conditions and immobilized (61.6–71.1 μg L-1) under oxidizing conditions. Application of FeBC immobilized As at Eh < 0 mV by 32.6%–81.1%, compared to the control, because of the transformation of As-bound Fe (hydro)oxides (e.g., ferrihydrite) and the formation of complexes (e.g., ternary As-Fe-DOC). Application of RBC immobilized As at Eh < -100 mV by 16.0%–41.3%, compared to the control, due to its porous structure and oxygen-containing functional groups. Mobilized As at Eh > +200 mV was caused by the increase of pH after RBC application. Amendment of the Fe-modified biochar can be a suitable approach for alleviating the environmental risk of As under reducing conditions in paddy soils.

Original languageEnglish
Article number126808
JournalJournal of hazardous materials
Volume422
DOIs
Publication statusPublished - 2022 Jan 15

Keywords

  • Fe-based biochar
  • Immobilization mechanisms
  • Redox conditions
  • Soil remediation
  • Toxic metal(loid)s

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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