  Recently reported colloidal aggregation data obtained for different
monovalent salts (NaCl, NaNO$_3$, and NaSCN) and at high electrolyte
concentrations are matched with the stochastic solutions of the master equation
to obtain bond average lifetimes and bond formation probabilities. This was
done for a cationic and an anionic system of similar particle size and absolute
charge. Following the series Cl$^-$, NO$_3^-$, SCN$^-$, the parameters obtained
from the fitting procedure to the kinetic data suggest: i) The existence of a
potential of mean force (PMF) barrier and an increasing trend for it for both
latices. ii) An increasing trend for the PMF at contact, for the cationic
system, and a practically constant value for the anionic system. iii) A
decreasing trend for the depth of the secondary minimum. This complex behavior
is in general supported by Monte Carlo simulations, which are implemented to
obtain the PMF of a pair of colloidal particles immersed in the corresponding
electrolyte solution. All these findings contrast the Derjaguin, Landau,
Verwey, and Overbeek theory predictions.
