ENHANCING THE DISSOLUTION OF LIZARDITE WITH OXALATE

The dissolution of lizardite is an important process for scientific study on carbon sequestration, and field weathering rates, yet the kinetics of this reaction has received little interest in the scientific community. The use of oxalic acid in increasing dissolution rates of various minerals has been evaluated in an attempt to increase carbon sequestration potential. This research follows suit by carrying out laboratory based dissolution experiments in order to prove the idea that oxalate increases the dissolution rate of lizardite. To establish a rate law for lizardite dissolution and determine the effect of total oxalate, batch reactors systematically varying pH and oxalate concentration were constructed and run for 48 hours. Samples were extracted at set time intervals and analyzed for magnesium, silicon, iron, aluminum, nickel, chromium, copper, cobalt and titanium. Magnesium and silicon release rates were used to calculate dissolution rates of lizardite with and without oxalate. From this study we were able to draw conclusions about the effect of oxalate on the dissolution of the mineral lizardite in a batch reactor in regard to both major (Mg, Si) and trace (Fe, Al, Ni, Cr, Cu, Co, Ti) metals. First, all analyzed metals dissolve from the lizardite substrate, and the oxalate present in solution increase the amount of metals that can be dissolved in the 48 hour time period studied. Second, the rate of magnesium and silica release from the lizardite, and accordingly lizardite dissolution rate, is greater when oxalate is added to batch reactor solutions. Third, while larger quantities of oxalate increase lizardite dissolution more, smaller amounts of oxalate are more efficient at increasing lizardite dissolution per unit added due to the changing oxalate: solid ratio. Lastly, trace metal behavior in batch reactor solutions is highly correlated to iron behavior. The conclusions drawn from these experiments are expected to contribute to numerous areas of research including field weathering rates, remediation, and carbon sequestration.