Iodide removal from brine using ion retardation resins
AssigneeChemetics Inc.
InventorsFelix Mok, Ganapathy Ramasubbu
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Abstract
Methods are disclosed for removing alkali metal iodide from concentrated aqueous alkali metal chloride solutions using ion retardation resins. The methods are suitable for solutions comprising substantially more than 1 ppm iodide and greater than 100 g/l alkali metal chloride and can remove the iodide to levels below 1 ppm. To effect removal, the pH of the solution is adjusted to be less than about 10 and is then flowed through a separation bed comprising the resin in a series of loading and elution cycles. The method is particularly useful for removing iodide impurity from the concentrated feed brine used in chloralkali electrolysis.
Claims20
A method for removing an alkali metal iodide from an amount of aqueous alkali metal chloride solution, the concentration of alkali metal chloride in the solution being greater than 100 g/l and the concentration of iodide in the solution being greater than 1 ppm, the method comprising:
- providing a separation bed comprising a housing, a fluid inlet, a fluid outlet, and an ion retardation resin within the housing wherein the separation bed has a bed volume for fluid;
- adjusting the pH of the amount of aqueous alkali metal chloride solution to be less than about 10;
- and
- flowing the amount of aqueous alkali metal chloride solution through the separation bed in a series of loading and elution cycles, wherein a loading and elution cycle comprises:
- supplying a loading amount of the aqueous alkali metal chloride solution to the bed inlet;
- flowing the loading amount through the ion retardation resin whereby iodide is preferentially adsorbed from the solution and alkali metal iodide depleted solution is obtained;
- collecting the alkali metal iodide depleted solution from the bed outlet;
- supplying an elution amount of water to the bed inlet;
- flowing the elution amount through the ion retardation resin whereby adsorbed iodide is eluted and eluent comprising alkali metal iodide is obtained;
- and
- removing the eluent from the bed outlet;
- and
- thereby removing alkali metal iodide from the amount of aqueous alkali metal chloride solution.
Dependencies are inferred from the claim text.