Impact of sodium poly(4-styrene sulfonate) coating on the dissolution kinetics of fluorite nanoparticles

Abstract

The adsorption of poly(4-styrene sulfonate) (PSS) polyanions onto the positively charged surface of fluorite nanoparticles, along with the dissolution of fluorite, was investigated using UV–Vis spectrophotometry, dynamic light scattering, and electrophoresis. Optimal conditions for adsorption were established, and the dissolution kinetics of fluorite nanoparticles in water at different pH values were analysed both before and after coating with PSS, using fluoride (F-ISE) and calcium ion-selective electrodes (Ca-ISE). Dynamic light scattering and electrophoretic measurements were employed to assess particle size and electrokinetic potential during dissolution. During the study of dissolution kinetics Ca-ISE data show a decreasing dissolution rate with increasing pH. Dissolution of coated particles was generally slower, with Ca-ISE data indicating the release of calcium ions from the fluorite surface and the substitution of sodium ions bound to the polyelectrolyte coatings. This initial stimulation of fluorite dissolution diminishes over time due to the slower diffusion of dissolved ions through the polyelectrolyte coating.