BACKGROUND

[0001] Chlorine and alkaline solutions are used as cleaning solutions, particularly by washing machines (e.g., commercial washing machines). Stocking chlorine and alkaline solutions for use by washing machine is possible. However, shipping chlorine and alkaline solutions and maintaining an inventory of chlorine and alkaline solutions can be expensive, use valuable resources (e.g., inventory space), and dangerous. It would be advantageous to make and use chlorine and alkaline solutions on-site and on-demand to address the issues with shipping and stocking chlorine and alkaline solutions. However, making and using chlorine and alkaline solutions on-site presents a number of difficulties, including raising the pH level of chlorine solution produced during electro-chemical activation.

SUMMARY

[0002] Provided are compositions and methods for neutralizing an output stream of an electrochemical activation system, including a dual stream electrochemical activation system.

[0003] In one aspect, methods for neutralizing an output stream of an electrochemical activation system are provided. In an embodiment, such a method comprises passing a current through an anolyte within an anode chamber of an electrochemical activation system to generate an output stream comprising active chlorine, the anolyte comprising a chlorine source and an alkaline source, wherein the alkaline source is present in the anolyte in an amount to provide the output stream with a pH value sufficient to suppress the formation of chlorine gas in the output stream.

[0004] In another aspect, related compositions are provided. In one such embodiment, a tablet for use in an electrochemical activation system is provided, the tablet comprising an alkaline source and a chlorine source, wherein the alkaline source is present at an amount to provide an output stream of an electrochemical activation system with a pH value sufficient to suppress the formation of chlorine gas in the output stream.

[0005] In another such embodiment, a tablet for use in an electrochemical activation system is provided, the tablet consisting essentially of an alkaline source selected from NaOH, Na2C03,Na2CCb, and combinations thereof, and a chlorine source ofNaCl. [0006] Other principal features and advantages of the present disclosure will become apparent to those skilled in the art upon review of the following drawings, the detailed description, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Illustrative embodiments of the present disclosure will hereafter be described with reference to the accompanying drawings.

[0008] FIG. 1 is a schematic illustration of a dual stream electrochemical activation system according to an illustrative embodiment.

[0009] FIG. 2 is a schematic illustration of a tablet for use in an electrochemical activation system according to an illustrative embodiment.

DETAILED DESCRIPTION

[0010] Provided are compositions and methods for neutralizing an output stream of an electrochemical activation system, including a dual stream activation system.

[0011] In one aspect, a method for neutralizing an output stream of an electrochemical activation system is provided. In an embodiment, such a method comprises passing a current through an anolyte within an anode chamber of an electrochemical activation system to generate an output stream comprising active chlorine, the anolyte comprising a chlorine source and an alkaline source. The alkaline source is present in the anolyte in an amount to provide the output stream with a pH value sufficient to suppress the formation of chlorine gas (Ch). In embodiments, the pH value is at least 4, at least 4.5, at least 5, at least 5.5, at least 6, at least 6.5, at least 7, at least 7.5, or at least 8. The upper end of the pH value is not particularly limited.

[0012] The present methods obviate the need for a post-electrolysis process, such as combining an otherwise acidic anolyte stream with a portion of a catholyte steam or passing the otherwise acidic anolyte stream through a neutralization chamber. As such, the present methods are less complex and more cost-effective than conventional methods. In addition, the catholyte stream produced using the present methods, including the entire catholyte stream, can be preserved for other, more desirable uses, e.g., cleaning.

[0013] FIG. 1 shows a schematic illustration of a dual stream electrochemical activation system 100 which may be used to carry out the present methods. The system 100 comprises an electrochemical cell 102 comprising an anode chamber 104 and a cathode chamber 106. The anode chamber 104 is separated from the cathode chamber 106 by a membrane 108. The anode chamber 104 comprises an anode 110 and the cathode chamber 106 comprises a cathode 112 in electrical communication with the anode 110. Various materials may be used for the membrane 108, the anode 110 and the cathode 112, but the materials are generally those which are appropriate for the electrolysis of aqueous solutions comprising Cl . By way of illustration, the membrane 108 may be configured to hinder migration of Cl across the membrane 108. The anode 110 may be made from titanium with a titanium oxide coating or an iridium(oxide) coating or a dimensionally stable anodes-Cl (DSA-C1) type coating. In other embodiments, the anode 110 may be made from graphite. The cathode 112 may be made from titanium or graphite. Otherwise, the form (e.g., solid, porous (e.g., particles or mesh)) of the anode 110 and the cathode 112 are not particularly limited. Similarly, the relative positions of the anode 110, the membrane 108, and the cathode 112 within the electrochemical cell 102 are not particularly limited.

[0014] As shown in FIG. 1 the system 100 may comprise one or more supply tanks in fluid communication with the electrochemical cell 102 via one or more supply lines to deliver one or more input streams of desired reactants to the electrochemical cell 102. In the embodiment of FIG. 1 a water supply tank 114 delivers water (e.g., reverse osmosis water) to the cathode chamber 106 via a first water supply line 1 l6a. A brine supply tank 118 delivers a chlorine source to the anode chamber 104 via a brine supply line 1 l6b. The water supply tank 114 may also be in fluid communication with the brine supply tank 118 via second water supply line 1 l6c and with the anode chamber 104 via a third water supply line 1 l6d. In the present disclosure, the term“chlorine source” means a material which provides a source of chlorine anions (Cl ). By way of illustration, the chlorine source may be a chloride salt such as an alkali metal chloride (e.g., NaCl, LiCl, KC1) or an alkaline earth metal chloride (e.g., CaCh. MgCh). In embodiments, the chlorine source is NaCl. The term“chlorine source” encompasses both the solid form of the chlorine source and the dissociated form of the chlorine source (e.g., dissolved Na ⁺ cations and Cl anions). Combinations of different chlorine sources may be used. As shown in FIG. 1, the system 100 may include a hopper configured to deliver the chlorine source in its solid form to the brine supply tank 118. A saturated aqueous solution may be formed by combining water via from second water supply line 1 l6c with the solid chlorine source. [0015] The system 100 may also comprise one or more output lines to carry one or more output streams from the electrochemical cell 102. The specific embodiment of FIG. 1 (dual stream electrochemical activation system) shows two output streams. Specifically, a first output line l20a carries a catholyte stream to an external destination (e.g., a washing machine/tap). A second output line l20b carries an anolyte stream to the external destination or another external destination. Variations of the configuration shown FIG. 1 may be used. For example, the system 100 may be configured to recirculate the anolyte stream and/or the catholyte stream through the electrochemical cell 102 in order to increase the concentration of certain species in the anolyte and/or catholyte prior to use of the anolyte/catholyte streams at the external destination(s). Similarly, the system 100 may include one or more flow controllers to regulate fluid flow through the electrochemical cell 102. Regardless of the configuration, fluids entering the anode and cathode chambers 104, 106 may be referred to as input streams (whether from a supply tank or recirculated anolyte/catholyte streams), and fluids exiting the anode and cathode chambers 104, 106 may be referred to as output streams.

[0016] An electrolysis process occurs by applying an electric potential across the anode 110 and the cathode 112, thereby passing a current through electrolyte solution present within the anode chamber 104 (the anolyte) and through solution present within the cathode chamber 106 (the catholyte). In the anode chamber 104, the current induces the following anode half-cell reaction:

Cl ^~ + H ₂ 0 ® HOCI + H ⁺ + 2e ^~ (1)

As noted above, the anolyte may be recirculated (e.g., from about 2 times to about 10,000 times) through the anode chamber 104 in order to increase the concentration of active chlorine in the anolyte, e.g., until the concentration of active chlorine is in a range of from about 0.02% to about 14% (i.e., from about 200 ppm to about 140,000 ppm). Although recirculating the anolyte creates a concentrated chlorine solution, the reaction represented by equation (1) also forms protons. These protons increase acidity of the anolyte, resulting in a pH drop. Chlorine gas (Ch) can form at low pH values, typically in a range below about pH 4. The formation of chlorine gas creates a safety issue as chlorine gas is harmful to users. Chlorine gas is also highly corrosive towards stainless steel and a variety of other common construction materials.

[0017] By providing an alkaline source in the anolyte, the present methods enable neutralization of the protons and an increase in the pH value of the anolyte. The term “alkaline source” means a material capable of reacting with dissolved protons and capable of increasing the pH of an aqueous solution. By way of illustration, the alkaline source may be a hydroxide salt such as an alkali metal hydroxide (e.g., NaOH, LiOH, KOH) or an alkaline earth metal hydroxide. In embodiments, the alkaline earth metal hydroxide is, e.g., Ca(OH) ₂ or Mg(OH)2. In embodiments, the alkaline source is NaOH. The term“alkaline source” encompasses both the solid form of the alkaline source and the dissociated form of the alkaline source, analogous to the chlorine source described above. Combinations of different alkaline sources may be used.

[0018] Other alkaline sources may be used. In embodiments, the alkaline source may be a carbonate or a bicarbonate salt, e.g., an alkali metal carbonate/bicarbonate or an alkaline earth metal carbonate/bicarbonate. In embodiments, the alkaline source is Na ₂ C03 or NaHC03.

[0019] Combinations of different alkaline sources may be used.

[0020] In some embodiments, however, certain alkaline sources are not utilized. For example, although some embodiments may make use of Ca(OH) ₂ , in other embodiments, the alkaline source is not a calcium salt, e.g., calcium hydroxide, calcium carbonate, or calcium bicarbonate. Thus, the anolyte may be free of such a calcium salt. By“free” it is meant substantially free such that the amount of material is zero or sufficiently close to zero so as to have no material effect on the present methods. As another example, although some embodiments may make use of a carbonate or a bicarbonate salt, in other embodiments, the alkaline source is not a carbonate or a bicarbonate salt and the anolyte is free of such a salt. Finally, generally, alkaline sources which would interfere with the electrolysis process (e.g., equations (1) and (2)) during normal operation of the system 100 are not utilized and the anolyte is fee of such alkaline sources. In embodiments, the alkaline source is not a silicate salt or an amine salt and the anolyte is free of such salts.

[0021] As noted above, in the present methods, the alkaline source is present in the anolyte in an amount to provide an output stream of the electrochemical system (in this embodiment, the output stream is the anolyte stream) with a pH value sufficient to suppress the formation of chlorine gas (Cl ₂ ). This may be an amount sufficient to provide the anolyte stream with a pH value of at least 4, at least 4.5, at least 5, at least 5.5, at least 6, at least 6.5, at least 7, at least 7.5, or at least 8. The upper end of the pH value of the anolyte stream is not particularly limited. [0022] With reference back to FIG. 1, the alkaline source may be provided in the anolyte by delivering the alkaline source to the anode chamber 104. This may be accomplished in a variety of ways. By way of illustration, a separate, additional supply tank may be included in the system 100 to deliver the alkaline source, e.g., in the form of a concentrated aqueous solution, to the anode chamber 104 via a separate, additional supply line in fluid

communication with the anode chamber 104. Alternatively, the alkaline source may be delivered along with the chlorine source. In other words, the alkaline source and the chlorine source may be delivered to the anode chamber 104 together, as a single input stream. This may be accomplished by combining the brine supply line 116b delivering the chlorine source with the separate, additional supply line delivering the alkaline source prior to delivery to the anode chamber 104. This may also be accomplished via a single feedstock comprising the chlorine source and the alkaline source, e.g., the brine supply tank 118 may comprise both the chlorine source and the alkaline source for delivery to the anode chamber 104 as a single input stream via the brine supply line 1 l6b.

[0023] With reference to the cathode chamber 106 of the system 100, the passage of the current induces the following cathode half-cell reaction:

2H ₂ 0 + 2e ^~ ® H ₂ (g) + 20H ^~ (2)

Similar to the anolyte, the catholyte may be recirculated (e.g., from about 2 times to about 10,000 times) in order to increase the alkalinity of the catholyte, e.g., until the concentration is in a range of from about 0.02% Na ₂ 0 to about 50% Na ₂ 0 (i.e., from about 200 ppm Na ₂ 0 to about 500,000 ppm Na ₂ 0). In the present methods, the catholyte stream may be used for a variety of purposes, e.g., cleaning. Since the anolyte stream has already been neutralized in the anode chamber 104, the entire portion of the catholyte stream may be used for the desired purpose.

[0024] The circulation of the anolyte and the catholyte may be performed at least partially simultaneously. During operation of the system 100, the pH level of the anolyte stream may be monitored. As the pH level drops to a predetermined level (e.g., below pH 4, below 4.5, below 5, etc.), the circulation of the anolyte and/or the catholyte may be reduced or stopped so that an additional amount of the alkaline source may be added so as to raise the pH level of the anolyte to a desired level.

[0025] In addition to those already described, variations of the configuration of the system 100 shown in FIG. 1 may be used, while preserving the functions described herein. By way of illustration, delivery of the chlorine source and the alkaline source may be further accomplished by including an additional chamber between the anode chamber 104 and the cathode chamber 106 as illustrated in FIGs. 5, 9A and 9B of International Patent Publication No. W02017200772, the contents of which are hereby incorporated by reference in their entirety. In addition, although the present methods obviate the need for use of a neutralization chamber to treat an anolyte stream, electrochemical activation systems including such neutralization chambers may be used to carry out the present methods. Thus, any of the electrochemical activation systems described in International Patent Publication No.

W02017200772 and International Patent Application No. PCT/US2018/015144 may be used. The contents of International Patent Publication No. W02017200772 and International Patent Application No. PCT/US2018/015144 are both hereby incorporated by reference in their entireties. The present methods may also be used in single stream electrochemical activation systems. Finally, electrochemical activation systems for use with the present method may comprise a variety of other components typically used with such systems, e.g., pumps for generating a flow of the various fluids, flow rate controllers, filters, holding tanks to collect output streams until their solutions are needed, etc.

[0026] In another aspect, compositions for use in any of the present methods are also provided. In an embodiment, a tablet comprising a chlorine source and an alkaline source is provided. Any of the chlorine sources and the alkaline sources described above may be used (or combinations of chlorine sources and/or combinations of alkaline sources). The term “tablet” is used to connote a compressed, solid composition. However, the shape and dimensions of the tablet are not particularly limited. Thus, the terms pellet, chunk, block, and the like may also be used interchangeably with the term“tablet.”

[0027] In embodiments, the tablet comprises a first portion comprising the chlorine source and a second portion comprising the alkaline source, the first and second portions separated from one another. Such embodiments are distinguished from compositions based on a blend or mixture of a chlorine source and an alkaline source. However, like the tablet itself, the first and second portions may assume a variety of shapes/dimensions. In embodiments, the tablet comprises a core comprising the alkaline source and a shell (i.e., coating) comprising the chlorine source. The shell/coating may encapsulate the core.

Encapsulation shields a user from coming into contact with the alkaline source within the tablet or with an alkaline solution made from the tablet. Thus, use of such tablets in an electrochemical activation system as described herein achieves more efficient cleaning/sanitizing (e.g., use of the entire catholyte stream as described above) while still eliminating the need to ship, store or handle alkaline solutions. In embodiments, the tablet consists of the core and the shell, i.e., there are no interlayers or sublayers between the core and the shell and there are no additional outer layers on the shell.

[0028] In other embodiments of the tablet, the chlorine source and the alkaline source may be blended or mixed together to provide a uniform composition throughout the tablet.

[0029] A variety of amounts of the chlorine source and the alkaline source in the tablet may be used, although the alkaline source is present in an amount sufficient to suppress the formation of chlorine gas (Ch) and/or to achieve any of the pH values described above. The selected amount may take into account use of a plurality of tablets (i.e., as opposed to a single tablet); i.e., the selected amount may be that which allows a predetermined number of tablets to suppress the formation of chlorine gas (Ch) and/or to achieve any of the pH values described above. That predetermined number of tablets may be the number of tablets needed to provide a saturated aqueous solution, e.g., in the brine supply tank 118. The specific amount depends, at least in part, on the conversion efficiency of the electrochemical activation system used. In embodiments, the alkaline source is present in an amount of at least about 10% by weight of the tablet, at least about 15% by weight of the tablet, or at least about 20% by weight of the tablet. This includes embodiments in which the alkaline source is present in an amount of about 18.5% by weight of the tablet. In embodiments, the chlorine source is present in an amount of at least about 80% by weight of the tablet, at least about 85% by weight of the tablet, or at least about 90% by weight of the tablet. This includes embodiments in which the chlorine source is present in an amount of 81.5%. Generally, the tablet contains more of the chlorine source than the alkaline source.

[0030] In embodiments, the tablet consists or consists essentially of one or more types of the chlorine source and one or more types of the alkaline source. In such embodiments, the amount of the alkaline source (or combined alkaline sources) may be any of the values described above, with the balance provided by the chlorine source (or combined chlorine sources). Such embodiments encompass tablets which include impurities typically associated with the manufacture of the selected alkaline source(s), chlorine source(s) and solid tablets. That is, such embodiments may still be considered to“consist” or“consist essentially of’ the alkaline source(s) and the chlorine source(s). In embodiments, the tablet consists or consists essentially of an alkali metal hydroxide (e.g., NaOH, LiOH, KOH) and an alkali metal chloride (e.g., NaCl, LiCl, KC1). In such embodiments, the tablet may have a core/shell structure as described above. An embodiment of a tablet 200 composed of a core 202 of NaOH and a shell 204 of NaCl encapsulating the core 202 is shown in FIG. 2. However, in other embodiments, the chlorine source and the alkaline source are blended or mixed together to provide a uniform composition as described above. By way of illustration, such an embodiment may include a tablet consisting of, or consisting essentially of, a mixture of NaCl and NaHCCb or a mixture of NaCl and Na2CCb. Use of tablets according to this paragraph in the present methods can provide an anolyte which consists or consists essentially of water, one or more types of the chorine source and one or more types of the alkaline source.

[0031] In embodiments, the tablet is free of one or more or all of the excluded compounds described above (e.g., a calcium salt, a carbonate salt, a bicarbonate salt, a silicate salt, an amine salt). The term“free” has the same meaning as described above with respect to these excluded compounds. In embodiments, the tablet is free of one or more of the following species: an anion of a carboxylic acid, an anion of a carbonic acid, an anion of an oxo acid, a sugar acid, a zinc/zinc salt, a polyacrylate, sodium hypochlorite, a nitrate, a gelling agent, a delayed release acid breaker. Thus, in such embodiments, the anolyte is also free of such species.

[0032] Although in some embodiments, the present tablets and/or input streams may comprise other functional materials, generally, desired functional materials may be added to the output streams instead. This is done to avoid competing half-cell reactions which would reduce the efficiency of either the chloride ion oxidation or the water reduction.

[0033] To make use of any of the tablets (or a plurality of tablets) with the system 100 (or other electrochemical activation systems), a user may feed the tablet(s) into the brine supply tank 118, e.g., via the hopper 119, to provide a saturated aqueous solution of dissolved tablet(s)). This saturated aqueous solution may be delivered to the anode chamber 104 as a single, input stream via the brine supply line 1 l6b.

[0034] Electrochemical activation systems for carrying out the present methods are also encompassed by the present disclosure. In an embodiment, such a system comprises an electrochemical cell comprising an anode chamber, a cathode chamber separated from the anode chamber by a membrane, a water supply tank in fluid communication with the electrochemical cell, and a brine supply tank in fluid communication with the anode chamber. The brine supply tank may be configured to deliver a chlorine solution and an alkaline solution to the anode chamber as a single input stream. In embodiments, the system does not comprise a neutralization chamber to treat an anolyte stream provided by the system. In embodiments, the system does not comprise fluid handling components for combining a catholyte stream provided by the system with the anolyte stream.

[0035] The word "illustrative" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "illustrative" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Further, for the purposes of this disclosure and unless otherwise specified, "a" or "an" means "one or more.”

[0036] The foregoing description of illustrative embodiments of the present disclosure has been presented for purposes of illustration and of description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosure. The embodiments were chosen and described in order to explain the principles of the disclosure and as practical applications of the invention to enable one skilled in the art to utilize the disclosure in various embodiments and with various modifications as suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the claims appended hereto and their equivalents.