Electrochemical growth of calcium hydroxide crystals from electrolyte solutions

Abstract

An electrochemical crystal growth method wherein nutrient material (e.g., Ca(OH).sub.2) is continuously supplied to one electrode of a cell, is dissolved by electrolytic action, forming a concentration gradient, and concurrently is deposited (e.g., as Ca(OH).sub.2) near the other electrode in a predetermined amount dependent on the current through the cell. An electrolyte may be utilized which is selected from an aqueous mixture of an alkali metal salt and a soluble salt containing a metal ion in the product compound, crystals of which are to be grown. Alkaline earth hydroxides are preferred products and for growth of Ca(OH).sub.2 a preferred electrolyte is a mixture of calcium chloride and potassium chloride wherein the Ca.sup.2+ ion is regulated between 0.05-0.5 molar. A highly preferred electrolyte mixture is 0.5 molar KCl and 0.5 molar CaCl.sub.2 utilizing 1 mA current. The electrodes on the anode side may be constructed of any metal with low overvoltage for the oxidation of hydrogen (e.g., platinum or palladium of the platinum group metals) and the cathode is preferably copper or other metal with low overvoltage for the reduction of H.sub.2 O. The current density utilized is 0.1-3.0 mA and the EMF is at least 1.5 volts.

Dependencies are inferred from the claim text.