Stability and Dynamic Aggregation of Bare and Stabilized Zero-Valent Iron Nanoparticles under Variable Solution...

Area of Science:

• Environmental Science
• Materials Science
• Nanotechnology

Background:

• Nanoscale zero-valent iron (nZVI) is crucial for environmental remediation.
• nZVI aggregation limits its stability and transport in aqueous systems.
• Polymer stabilizers like sodium carboxymethyl cellulose (CMC) are used to mitigate nZVI aggregation.

Purpose of the Study:

• To investigate the stability and aggregation of bare and CMC-stabilized nZVI.
• To evaluate the effects of pH, ionic strength (IS), and particle concentration on nZVI behavior.
• To understand the role of CMC in enhancing nZVI colloidal properties.

Main Methods:

• Characterization of bare and CMC-nZVI hydrodynamic size and zeta potential.
• Assessment of nZVI stability under varying pH, IS, and concentration.
• Application of Derjaguin, Landau, Verwey and Overbeek (DLVO) theory for interaction energy calculations.

Main Results:

• CMC coating significantly reduced hydrodynamic size and increased zeta potential of nZVI.
• Bare nZVI exhibited maximum aggregation at high IS, near neutral pH, and high particle concentration.
• CMC-nZVI demonstrated substantially increased stability across a range of IS.
• DLVO calculations supported experimental findings, showing energy barriers at low IS.

Conclusions:

• CMC effectively enhances the stability and transport of nZVI.
• High IS and particle concentration promote nZVI aggregation, but CMC mitigates this effect.
• CMC-nZVI offers improved performance for in-situ environmental applications.