KINETIC-STUDY OF SO2 REACTION WITH DOLOMITE

In today's industrialized environments, sulfur dioxide, to the exclusion of other pollutant gases, is the main cause of chemical deterioration of building materials such as marble, limestone, and dolomite. This paper gives the results of an experimental study of the reaction of laurel dolomite, a coarsely crystalline variety of dolomite, with sulfur dioxide. With the progress of reaction it was found that a gypsum-epsomite crust grows outward due to a continuous supply of Ca and Mg ions from an increasingly greater depth inside the stone. Therefore, the rate data were analyzed by following a shrinking unreacted core model using first- and fractional-order (0.5) kinetic rate constants. These two reaction orders fit the experimental data equally well for the initial phase of the reaction, but the fractional rate constant, 0.19 mmol0.5 cm-0.5 h-1, gives the best fit to the overall experimental data.