Dissolution of the carbonate minerals of phosphate ores: catalysis by carbonic anhydrase II, from bovine erythrocytes, in acid solutions.

In this manuscript we report detailed experimental and theoretical evidence of the effect of carbonic anhydrase II, from bovine erythrocytes, on the dissolution process of carbonate minerals of phosphate ores (Epirus area, Greece) in dilute acetic acid, by recording the pH value of the acid solution as a function of time in the pH range from 2.37 to 6.40. We found that mass transfer makes a significant contribution to the determining step of the overall enzymatic reaction, while we distinguished five separate pH regions within the pH range from 2.37 to 6.40. Two different reaction systems and two model equations fitted perfectly the corresponding experimental data, and were used to evaluate all rate constants and parameters. Subsequently, we proposed the possible mechanisms of action for this enzyme from pH 2.37 to 6.40, within which carbonic anhydrase II was found active.