Calcium carbonate dissolution and channel electrodes

Initial experiments on the dissolution of calcium carbonate were made with suspensions of the powdered material [213-224], In this way, it was shown that the dissolution rate is increased by the presence of both H+ and dissolved C02. In particular, Plummer et al. [223] were able to write the following equation for the net dissolution rate of calcite, based on their work with crushed Iceland spar crystals 

Attempts to separate surface chemical kinetic phenomena from mass transport effects have frequently employed no more experimental sophistication 

Tne results of Daly and co-workers allowed the rate equation for the flux of dissolving Caz+, yCa2+, in the absence of dissolved C02 to be given by 

An additional merit of the channel electrode set-up is that the exposed calcite surface can be viewed in situ, by light microscopy, allowing the crystallographic nature of the dissolution process to be linked directly to kinetic measurements. Furthermore, it should be noted that ex-situ studies on the morphology of crystal surfaces subjected to dissolution in the channel set-up are likely to provide greater information, by nature of the non-uniform accessibility of the crystal surface to protons, than might be anticipated from the same measurements on a crystal surface exposed to a uniform flux of electrolyte (vide infra). 

we describe crystal-detector electrode shielding experiments for both the dissolution process alone and in the presence of polymaleic acid. Homo- and co-polymers of maleic acid are well-documented precipitation inhibitors [249-251]. Firstly, however, we consider the theoretical relationship between the shielding current and the heterogeneous rate constant for the reaction of H+ with the crystal surface. 

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