Simulation of charge reversal in salty environments: Giant overcharging?

TL;DR

This study uses molecular dynamics simulations to investigate charge reversal in salty solutions, revealing that increased monovalent salt concentration decreases overcharging, contrary to some theories, and aligning with experimental results.

Contribution

The paper provides the first simulation-based evidence that challenges existing theories by showing decreased charge inversion with higher monovalent salt concentration.

Findings

Simulations agree with experimental observations of decreased overcharging.

Most theories overpredict charge reversal at higher salt concentrations.

The study highlights weaknesses in current theoretical models.

Abstract

We have performed MD simulations of a highly charged colloid in a solution of 3:1 and additional 1:1 salt. The dependency of the colloid's inverted charge on the concentration of the additional 1:1 salt has been studied. Most theories predict, that the inverted charge increases when the concentration of monovalent salt grows, up to what is called "giant overcharging", while experiments and simulational studies observe the opposite. Our simulations agree with the experimental findings and shed light onto the weaknesses of the theories.