Ion Correlations Decrease Particle Aggregation Rate by Increasing Hydration Forces at Interfaces

Area of Science:

• Colloid and surface science
• Materials science
• Physical chemistry

Background:

• Understanding solid-liquid interfaces is crucial for predicting particle aggregation.
• Interfacial solution structure, particle forces, and aggregation phenomena are not fully understood.

Purpose of the Study:

• To establish a connection between interfacial solution structure, hydration forces, and boehmite particle aggregation.
• To investigate the effect of electrolyte concentration on aggregation kinetics and forces.

Main Methods:

• Experimental studies on boehmite aggregation in varying electrolyte concentrations.
• Molecular dynamics (MD) simulations to analyze interfacial structure and forces.

Main Results:

• Aggregation rate showed a nonmonotonic dependence on electrolyte concentration, decreasing significantly at high molality.
• Repulsive hydration forces and interfacial oscillations increased with electrolyte concentration.
• MD simulations revealed enhanced ion correlations and loosely bound aggregates retaining electrolyte.

Conclusions:

• Interfacial solution structure and hydration forces play a critical role in particle aggregation, deviating from continuum theories.
• Findings enable prediction of particle aggregation, attachment, and assembly at interfaces.
• Results have broad implications for interfacial phenomena and materials design.