Surface charge of silica determined using X-ray photoelectron spectroscopy

The approach is demonstrated using results for dispersions consisted of SiO2 colloids in 20 mM NaCl and 100 mM KCl electrolyte solutions with a pH between ∼9 and ∼2. The work has shown that the surface charge density determined by XPS is in good agreement with potentiometric titration experiments in the pH interval investigated, where the former technique may provide constraints for determining unambiguously the absolute surface charge density.