Sustainable removal of soil arsenic by naturally-formed iron oxides on plastic tubes

Zhao Feng Yuan, Tong Yao Pu, Chen Yu Jin, Wei Jia Feng, Jia Yue Wang, Williamson Gustave, Jonathan Bridge, Yi Li Cheng, Xian Jin Tang, Yong Guan Zhu, Zheng Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Arsenic (As) pollution in paddy fields is a major threat to rice safety. Existing As remediation techniques are costly, require external chemical addition and degrade soil properties. Here, we report the use of plastic tubes as a recyclable tool to precisely extract As from contaminated soils. Following insertion into flooded paddy soils, polyethylene tube walls were covered by thin but massive Fe coatings of 76.9–367 mg Fe m−2 in 2 weeks, which adsorbed significant amounts of As. The formation of tube-wall Fe oxides was driven by local Fe-oxidizing bacteria with oxygen produced by oxygenic phototrophs (e.g., Cyanobacteria) or diffused from air through the tube wall. The tubes with As-bound Fe oxides can be easily separated from soil and then washed and reused. We tested the As removal efficiency in a pot experiment to remove As from ~ 20 cm depth/40 kg soils in a 2-year experiment and achieved an overall removal efficiency of 152 mg As m−2 soil year−1, comparable to phytoremediation with the As hyperaccumulator Pteris vittata. The cost of Fe hooks was estimated at 8325 RMB ha−1 year−1, and the profit of growing rice (around 16080 RMB ha−1 year−1 can be still maintained. The As accumulated in rice tissues was markedly decreased in the treatment (>11.1 %). This work provides a low-cost and sustainable soil remediation method for the targeted removal of As from soils and a useful tool for the study and management of the biogeochemical Fe cycle in paddy soils.

Original languageEnglish
Article number129626
JournalJournal of Hazardous Materials
Volume439
DOIs
Publication statusPublished - 5 Oct 2022

Keywords

  • Adsorption
  • Arsenic remediation
  • Iron oxides
  • Paddy soil
  • Rice

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