Enhancing the Dissolution of Lizardite with Oxalate

The dissolution of lizardite (Mg3Si2O5(OH)4) 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 (OxT), batch reactors systematically varying pH and oxalate concentration were constructed. Samples were extracted 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. The rate expressions for lizardite dissolution, as obtained from silicon release were: rLiz = 10-10.79[H+]0.15 rLiz = 10-10.53[OxT]0.20 Calculated rate laws show that oxalate increases the dissolution rate of lizardite.Concentration vs. time data of trace metals show the response of trace metals depends on both pH and oxalate concentration