Highly selective and efficient Pb²⁺ capture using PO₄-loaded 3D-NiFe layer double hydroxides derived from MIL-88A

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Lead (Pb) contamination in water necessitates advanced remediation technologies.
• Phosphate precipitation is a common but limited method for lead removal.
• Layered double hydroxides (LDHs) offer potential for water treatment applications.

Purpose of the Study:

• To develop novel 3D mesoporous layered double hydroxide (LDH) sorbents functionalized with phosphate anions for efficient Pb2+ removal.
• To utilize a sacrificial template metal-organic framework (MOF) for synthesizing stable LDH structures.
• To investigate the adsorption performance, kinetics, and selectivity of the developed LDH materials for lead ions.

Main Methods:

• Conversion of MIL-88A(Fe) MOF into NiₓFe LDH via a template strategy.
• Anion exchange reaction to functionalize LDH with phosphate anions.
• Characterization of synthesized materials using techniques like surface area analysis and adsorption isotherm/kinetic studies.

Main Results:

• Synthesized stable 3D microrod crystals of NiₓFe-PO₄ LDH with a high surface area (>110 m²/g).
• Achieved a high Pb²⁺ adsorption capacity of 538 mg/g, following the Langmuir isotherm model.
• Demonstrated fast adsorption kinetics (pseudo-second order model) and high selectivity for Pb²⁺ over Ni²⁺ and Cd²⁺.

Conclusions:

• The novel phosphate-functionalized LDH material is a highly effective adsorbent for Pb²⁺ removal from contaminated water.
• The MOF-templated synthesis preserves structural integrity and prevents aggregation, leading to superior performance.
• The material's high capacity, selectivity, and fast kinetics make it a promising candidate for water decontamination.