Effects of carboxylic polyelectrolytes on the growth of calcium carbonate

International audienceIn this paper experimental results are reported on the effects of anionic polyelectrolytes (polyaspartate and polymaleic acid) on the formation of calcium carbonate on a metallic substrate. An experimental procedure which permits the in situ and real-time growth of particles in the micrometric range to be followed was used. By using image analysis, the determination of the morphometric parameters of crystals was done. Jointly, an adsorption study of the polyelectrolytes on calcite was conducted to complement the study of the interactions between polyelectrolytes and crystals.It has been shown that polyaspartate (PASP) and polymaleic acid (PMA) may influence the nucleation/growth process of calcium carbonate. At low concentrations (of about 1×10−5 mol dm−3), PMA and PASP reduce the surface coverage of deposits on the substrate by decreasing the number of micron size particles and/or the sizes of mineral. When the polyelectrolytes were added after 10 min of the experiment, they significantly decreased the growth rate of the crystals.Following the adsorption of the polyelectrolytes on the submicron size crystals of calcite complements this research. Langmuir isotherms show that PASP and PMA adsorb on calcite suggesting that the polyelectrolytes may block the active sites of growth of crystals