Electrolytic cell for the production of hypochlorous acid

Abstract

An electrolytic cell for the production of hypochlorous acid and sodium hydroxide from brine as separate product streams is described. The electrolytic cell includes an electrolysis chamber containing an anode and a cathode; electrical connections to each of the anode and cathode; a brine inlet into the electrolysis chamber for the supply of a brine solution into the electrolysis chamber; a first liquid outlet from the electrolysis chamber proximal the anode; a second liquid outlet from the electrolysis chamber proximal the cathode; at least one pump arranged to draw liquid from the electrolysis chamber through the first liquid outlet at a first flow rate and through the second liquid outlet at a second flow rate. The cell generates hypochlorous acid for use in situ, for example as a cleaning product in the home or at commercial or industrial premises.

1 . An electrolytic cell for the production of hypochlorous acid and sodium hydroxide from brine as separate product streams, the electrolytic cell comprising:
 an electrolysis chamber comprising an anode and a cathode;   electrical connections to each of the anode and cathode;   a brine inlet into the electrolysis chamber for supplying a brine solution into the electrolysis chamber;   a first liquid outlet from the electrolysis chamber proximal the anode;   a second liquid outlet from the electrolysis chamber proximal the cathode; and   at least one pump arranged to draw liquid from the electrolysis chamber through the first liquid outlet at a first flow rate and through the second liquid outlet at a second flow rate;   wherein either:   (a) the first flow rate and second flow rate are variable relative to one another; or   (b) the first flow rate and second flow rate are fixed relative to one another at a predetermined difference in flow rate.   
     
     
         2 . An electrolytic cell according to  claim 1  wherein the at least one pump comprises:
 a first pump arranged to draw liquid from the electrolysis chamber through the first liquid outlet at the first flow rate; and 
 a second pump arranged to draw liquid from the electrolysis chamber through the second liquid outlet at the second flow rate. 
 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . An electrolytic cell according to  claim 1 , wherein;
 (i) the anode and the first liquid outlet are arranged such that at least a portion of the liquid passing from the brine inlet to the first liquid outlet must pass through the anode; and/or the cathode and the second liquid outlet are arranged such that at least a portion of the liquid passing from the brine inlet to the second liquid outlet must pass through the cathode; or   (ii) the anode divides the electrolysis chamber into an inlet chamber on a first side of the anode, adjacent the cathode, and an anode collection chamber on a second side of the anode, wherein the first liquid outlet is located in the anode collection chamber; such that, in use, liquid passes from the brine inlet into the inlet chamber, then through the anode into the anode collection chamber before passing out of the first liquid outlet; or   (iii) the cathode divides the electrolysis chamber into an inlet chamber on a first side of the cathode, adjacent the anode, and a cathode collection chamber on a second side of the cathode, wherein the second liquid outlet is located in the cathode collection chamber; such that, in use, liquid passes from the brine inlet into the inlet chamber, then through the cathode into the cathode collection chamber before passing out of the second liquid outlet; or   (iv) each of the anode and cathode are liquid-impermeable and the electrolytic cell comprises means for the passage of liquid past or around the electrode; or   (v) one or both of the anode and cathode comprise a metal substrate and a noble metal oxide catalyst supported on the substrate; or   (vi) each of the anode and cathode are liquid-permeable.   
     
     
         6 . An electrolytic cell according to  claim 1 , further comprising a housing defining the electrolysis chamber and containing the anode and cathode, the housing comprising an opening in fluid communication with the brine inlet and the electrolysis chamber, such that when the housing is at least partially submerged in a brine reservoir, brine from the reservoir enters the housing through the opening and is drawn through the electrolytic cell by operation of the at least one pump to draw liquid from the electrolysis chamber. 
     
     
         7 . An electrolytic cell according to  claim 1 , comprising a porous diaphragm arranged between the anode and the cathode. 
     
     
         8 . An electrolytic cell according to  claim 7 , wherein the porous diaphragm is a lint free cloth. 
     
     
         9 . An electrolytic cell according to  claim 1 , wherein the electrolytic cell does not contain any diaphragm structure between the anode and the cathode. 
     
     
         10 . An electrolytic cell according to  claim 1 , wherein the electrolytic cell is configured to provide a higher liquid flow rate from the second liquid outlet than the first liquid outlet. 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . A hypochlorous acid generator comprising an electrolytic cell according to  claim 1 , further comprising:
 one or more of a brine reservoir and a brine feed conduit;   a hypochlorous acid storage unit;   a sodium hydroxide storage unit;   a power source; and   a product dispensing device.   
     
     
         15 . A method of producing hypochlorous acid using an electrolytic cell according to  claim 1 , the method comprising:
 passing brine through the brine inlet and into the electrolysis chamber;   applying a voltage across the electrical connections of the anode and cathode to electrolyse the brine;   drawing a first product stream from the first liquid outlet at a first flow rate, the first product stream comprising hypochlorous acid; and   drawing a second product stream from the second liquid outlet at a second flow rate, the second product stream comprising sodium hydroxide;   wherein the concentration of hypochlorous acid in the first product stream is higher than the concentration of hypochlorous acid in the second product stream.   
     
     
         16 . A method according to  claim 15 , wherein the second flow rate is higher than the first flow rate. 
     
     
         17 . A method according to  claim 15 , wherein before passing through the liquid inlet the brine has an NaCl concentration of from 0.5 to 20 g/L. 
     
     
         18 . A method according to  claim 15 , further comprising reversing the polarity of the anode and the cathode after a predetermined electrolysis time period. 
     
     
         19 . A method according to  claim 15 , wherein the electrolytic cell is operated under galvanostatic conditions. 
     
     
         20 . A method according to  claim 15 , wherein the flowrate of the brine into the liquid inlet is from 2 to 50 mL/min. 
     
     
         21 . A method according to  claim 15 , wherein the first product stream and the second product stream are combined together in predetermined proportions to provide a third product stream. 
     
     
         22 . A method according to  claim 15 , further comprising diluting one or more of the first product stream and the second product stream with water to provide a diluted product stream, wherein the diluted product stream has an NaCl concentration of less than 1 g/L. 
     
     
         23 . A method according to  claim 15 , wherein:
 (i) the electrolytic cell is at least partially submerged in a brine reservoir which contains the brine, and the method comprises drawing brine into the electrolytic cell through the brine inlet from the brine reservoir; or   (ii) the electrolytic cell is operated at a current within the range 0.4 to 0.8 A and at a voltage within the range 5 to 20 V.   
     
     
         24 . (canceled) 
     
     
         25 . A method according to  claim 15 , wherein the pH within the electrolytic cell during electrolysis is maintained within the range 4.5 to 9.5. 
     
     
         26 . A household cleaning product dispenser comprising the electrolytic cell according to  claim 1 .