Phosphate-modified attapulgite for efficient Pb(II) and Cd(II) removal: surface functionalization and adsorption
Xinyao Zhang1, Rong Yang2, Wenxia Zhu1
1School of Minerals Processing and Bioengineering, Central South University, Changshaa, 410083, China.
Environmental Research
|January 13, 2026
Summary
Phosphate-functionalized attapulgite (C-ATP) effectively removes lead (Pb(II)) and cadmium (Cd(II)) from water and soil. This novel material shows superior adsorption and immobilization, offering a cost-effective solution for heavy metal remediation.
Area of Science:
- Environmental Science
- Materials Science
- Geochemistry
Background:
- Heavy metal ions like lead (Pb(II)) and cadmium (Cd(II)) contaminate aquatic environments and soils, posing significant risks to ecosystems and human health.
- Effective removal and immobilization strategies are crucial for mitigating these environmental hazards.
Purpose of the Study:
- To synthesize a phosphate-functionalized attapulgite material (C-ATP) for enhanced heavy metal removal.
- To investigate the adsorption performance and immobilization efficiency of C-ATP for Pb(II) and Cd(II).
- To elucidate the molecular mechanism behind the improved adsorption capabilities of C-ATP.
Main Methods:
- Synthesis of C-ATP via a calcination-assisted modification strategy.
- Adsorption experiments to determine maximum adsorption capacities for Pb(II) and Cd(II).
- Soil remediation experiments to assess immobilization efficiencies.
- X-ray photoelectron spectroscopy (XPS) and Atomic Force Microscopy (AFM) for mechanistic studies.
Main Results:
- C-ATP demonstrated significantly enhanced adsorption capacities for Pb(II) (80.89% increase) and Cd(II) (21.44% increase) compared to unmodified attapulgite (ATP).
- C-ATP exhibited excellent adsorption stability across a wide range of pH and temperature, and tolerance to competing Ca(II) ions.
- In soil remediation, C-ATP achieved higher immobilization efficiencies for Pb(II) (77.9%) and Cd(II) (35.59%) than ATP, maintaining stability over 56 days.
- XPS and AFM analyses confirmed that phosphate groups actively bind heavy metals via inner-sphere coordination, with stronger affinity for Pb(II) than hydroxyl groups.
Conclusions:
- The calcination-assisted synthesis provides a cost-effective method for producing C-ATP with superior heavy metal adsorption and immobilization properties.
- Phosphate functionalization enhances attapulgite's capacity for heavy metal remediation by improving binding affinity and stability.
- C-ATP offers a promising solution for the effective removal of Pb(II) and Cd(II) from contaminated water and soils.
