Water chlorinator having dual functioning electrodes

#The present disclosure generally relates to dual functioning electrodes adapted for anodic and cathodic use for a reverse current electrolytic chlorination apparatus such as may be desired for treating pool water, spas, and the like.

#Electrolytic pool chlorinators have evolved to overcome the problems associated with chemical dosing of swimming pools, spas, and the like to prevent the accumulation growth of algae and bacteria therein. The electrolytic chlorinator generally includes two spaced apart electrodes including an anode for oxidation of chloride ions from, normally, sodium based chloride salts to chlorine, which subsequently hydrolyzes in solution to form hypochlorite; and a cathode for reduction of water to hydrogen. Water to be treated is dosed with the chloride salts and flows between the electrodes. The electrolytically generated chlorine and hypochlorite act as the active ingredients to oxidatively destroy bacteria and other harmful agents in the water.

#One of the disadvantages associated with electrolytic disinfection is the cost of the electrolytic cell, as well as the cost of replacement electrodes, which can corrode, become fouled with scale and the like or otherwise become inactivated over time. These costs are primarily driven by the size of the electrodes, which are typically constructed from titanium coated with platinum or ruthenium. Electrodes having a surface area sufficient to generate adequate chlorine levels represent a significant portion of the cost of installing and maintaining an electrolytic disinfection system. In addition, electrolytic cell life is limited due to the current density through the cell over time.

#Referring now to the FIGURES wherein the like elements are numbered alike:

#The FIGURE illustrates a partial sectional view of a water chlorinator.

#Disclosed herein are dual functioning electrodes for water chlorinators. The dual function electrodes are formed of the same material and are configured to function as both anodically and cathodically depending on current polarization. In one embodiment, the dual function electrode includes a coating containing a mixed metal oxide consisting essentially of 5 to 25 mol % RuO2 with the remainder TiO2 deposited onto a conductive substrate, and in other embodiments, about 15 to 20 mol % RuO2 with the remainder TiO2 and in still other embodiments, about 15 mol % RuO2. The total amount of ruthenium (Ru) in the coating is about 10 to 15 g/m2, which is about 50% less than that previously used, thereby providing a significant commercial advantage. By way of example, in one embodiment, the molar ratio of ruthenium to titanium is 5:95 to 25:75 respectively; in other embodiments, 15:85 to 20:80, respectively, and in still other embodiments, the molar ratio is 15:85, respectively. As will be described in greater detail herein, it has unexpectedly been found that current efficiency and accelerated lifetime analysis for the relatively low ruthenium coating as noted above, when exposing the electrodes in a reverse current, was about the same as continuous anode formed of titanium having a coating at a 30:70 ratio of RuO2 relative to TiO2 (i.e., without reverse current). As noted above, previous studies had shown that anodes having lower RuO2 content (i.e., less than 20%) exhibited poor durability relative to coatings with higher RuO2 content, i.e., greater than or equal to 30 to about 40 mole %. Thus, these results were surprising and unexpected.

#Suitable conductive substrates include, without limitation, titanium, lead, tantalum, tungsten, molybdenum, vanadium, zirconium, niobium, and the like.

#A portion of the electrode may have a coating either applied to it or an additional strip of coated titanium may be spot welded to the electrode. The coating on the titanium is composed of ruthenium and titanium. The use of the same material makes it possible to use a reversal of polarity of the power source to have a self-cleaning effect and increase the lifetime of the cell before any maintenance is needed. In all applications, the conductive metal base is cleaned and free of oxide or other scale. This cleaning can be done in any way, by mechanical or chemical cleaning, such as, by sand blasting, etching, pickling or the like.