Pilot scale application of ²²⁶Ra-contaminated soil leaching remediation

Juncheng Han ¹, Guangming Xu ¹, Kexin Shao ¹

⁰College of Water Sciences, Beijing Normal University, Beijing, 100875, China; Engineering Research Center for Groundwater Pollution Control and Remediation Ministry of Education, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.

Chemosphere +

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November 27, 2024

View abstract on PubMed

Summary

This study developed effective chemical leaching methods using organic acids and carbonates to remove radium from contaminated soil. These safe and reliable techniques achieved high removal rates, restoring soil functionality.

Area Of Science

Environmental Science
Geochemistry
Soil Remediation

Background

Soil contamination by radioactive elements, particularly radium (<sup>226</sup>Ra), is a significant environmental issue stemming from radioactive mineral extraction and processing.
Effective remediation strategies are crucial to mitigate the risks associated with radium-contaminated soils and restore their usability.

Purpose Of The Study

To investigate the efficacy of organic acid- and carbonate-based chemical leaching methods for remediating radium-contaminated soil.
To determine optimal operational conditions for large-scale soil slurry reactors in field experiments.
To assess the safety, reliability, and impact of these remediation techniques on soil structure and nutrient content.

Main Methods

Employed two distinct chemical leaching systems: one utilizing organic acids, salts, and solubilizers (e.g., FeCl<sub>3</sub>, oxalic acid, NaClO<sub>2</sub>, HEDP), and another using carbonates and oxidizers (e.g., Na<sub>2</sub>CO<sub>3</sub>, NaHCO<sub>3</sub>, H<sub>2</sub>O<sub>2</sub>, deep eutectic solvent [DES]).
Conducted large-scale field experiments using soil slurry reactors to evaluate acidic and alkaline leaching agents.
Utilized characterization techniques including X-ray diffraction (XRD), Fourier Transform Infrared Spectrometry (FT-IR), and Scanning Electron Microscopy (SEM) to analyze soil post-treatment.

Main Results

Both organic acid and carbonate leaching systems demonstrated high radium removal rates, achieving 93.02% and 90.66% efficiency, respectively, under optimal conditions.
Laboratory-scale tests indicated high radionuclide removal rates with combined organic acids, salts, and solubilizers.
Characterization analyses confirmed the safety and reliability of the methods, showing minimal impact on the soil's original structure.

Conclusions

Chemical leaching using organic acids or carbonates is a highly effective and safe method for remediating radium-contaminated soil.
The studied methods successfully removed radium, preserved soil structure, and showed potential for replenishing soil nutrients.
These remediation techniques offer a viable solution for restoring the functional use of radium-contaminated land.

Keywords:

(226)Ra-contaminated soil Leaching Pilot-scale trial Restoration

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