ADSORPTION OF ANIONIC AND CATIONIC POLYMERS ON POROUS AND NONPOROUS CALCIUM-CARBONATE SURFACES

The adsorption of anionic and cationic polymers onto calcium carbonate surfaces was studied by ellipsometry. Sodium polyacrylate was observe d to both adsorb on and promote dissolution of polished limestone surf aces in 5 mM CaSO4, solution at pH 10.3. It was not possible to differ entiate between the two processes when they occurred simultaneously. C ationic starch adsorbed on the limestone surfaces at low concentration s and caused mineral dissolution at higher concentrations. The adsorbe d amount of starch was higher on surfaces which were first made porous by partial dissolution than on freshly polished surfaces. Surfaces cr eated by cleavage of Iceland spar calcite were quite stable against di ssolution and the amount of starch adsorbed determined by ellipsometry agreed well with the adsorbed mass determined from batch adsorption e xperiments on ground calcite.