Protonation stabilized high As/F mobility red mud for Pb/As polluted soil remediation

Area of Science:

• Environmental Science
• Materials Science
• Green Chemistry

Background:

• Red mud (RM) poses environmental risks due to mobile arsenic (As) and fluoride (F).
• Heavy metal-polluted soils present significant ecological and health challenges.
• Effective waste valorization and soil remediation strategies are urgently needed.

Purpose of the Study:

• To develop a cost-effective method for stabilizing hazardous red mud (RM).
• To recycle stabilized RM as an eco-material for remediating lead (Pb) and arsenic (As) contaminated soils.
• To assess the immobilization of As/F and the reduction of heavy metals in plants.

Main Methods:

• A protonation approach was employed to treat red mud, immobilizing As and F.
• Stabilized RM was applied to Pb/As-polluted soil in oilseed rape pot experiments.
• Plant uptake of Pb and As was measured to evaluate remediation efficiency.

Main Results:

• Protonation effectively immobilized As and F in RM, meeting World Health Organization leaching standards.
• Application of stabilized RM reduced plant Pb concentrations by 40.9–49.7% and As by 40.8–54.8%.
• The process demonstrated no secondary pollution or soil degradation.

Conclusions:

• The protonation method offers a green chemical strategy for red mud recycling and soil remediation.
• Stabilized RM acts as an effective heavy metal passivator, reducing metal uptake in plants.
• This approach presents high economic feasibility and significant ecological benefits.