Cadmium immobilization and phosphorus supply using wastewater-derived ferric phosphate
Xinjing Yuan1, Weiquan Li1, Ying Pu1
1State Key Laboratory of Soil Pollution Control and Safety, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Journal of Hazardous Materials
|June 19, 2026
Summary
Recovered amorphous ferric phosphate from wastewater effectively supplies phosphorus for crops and immobilizes heavy metals like cadmium. This dual-action soil amendment shows significant promise for agricultural applications.
Area of Science:
- Environmental Chemistry
- Soil Science
- Materials Science
Background:
- Agricultural phosphorus loss and heavy metal contamination pose significant environmental challenges.
- Innovative soil amendments are needed for simultaneous phosphorus supply and heavy metal immobilization.
- Electrochemically recovered ferric phosphate (FePO4·xH2O) is a potential dual-functional amendment.
Purpose of the Study:
- To recover amorphous and crystalline ferric phosphate from wastewater using an electrochemical method.
- To evaluate the potential of recovered ferric phosphate for phosphate release and cadmium (Cd2+) immobilization.
- To elucidate the mechanisms of heavy metal stabilization by ferric phosphate.
Main Methods:
- Electrochemical recovery of ferric phosphate from real wastewater.
- Batch experiments to assess phosphate release and Cd2+ immobilization.
- Solid characterization (e.g., surface area, structure) and sequential extraction analyses.
Main Results:
- Amorphous ferric phosphate (amo-FePO4) released significantly more phosphate (1.2 mg·L-1 P) beneficial for crops compared to crystalline ferric phosphate (cry-FePO4).
- Amo-FePO4 achieved nearly 90% Cd2+ fixation in aqueous solutions.
- Cd2+ immobilization was attributed to inner-sphere binding and a Fe(III)(hydr)oxide-rich shell, resulting in highly stable sequestration.
Conclusions:
- Wastewater-derived amorphous ferric phosphate is a promising material for simultaneous phosphorus supply and heavy metal immobilization in agriculture.
- The amorphous structure and surface properties of FePO4 are key to its efficacy in heavy metal stabilization.
- This electrochemical recovery method offers a sustainable approach to producing dual-functional soil amendments.
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