Storage-Stable Hypochlorous Acid via pH and NaCl Control
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Solution Overview
Problem
Existing methods for producing aqueous solutions of hypochlorous acid and/or hypochlorite result in solutions with low storage stability, leading to a significant decrease in concentration over time, which compromises their effectiveness.
Innovation Solution
A method involving electrolysis of an NaCl solution with a concentration of more than 100 ppm NaCl in an electrolytic cell with separated compartments, adjusting the pH value of the resulting solution to 5 to 6, and optionally mixing cathode or anode solutions to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolysis methods are used to produce hypochlorous acid solutions, then the antimicrobial effectiveness is achieved, but the storage stability is low and concentration decreases significantly over time
Solution Approach 1:
The patent applies parameter changes by optimizing the pH value to a specific range (5.0-6.5) and controlling the NaCl concentration (100-500 ppm) to achieve storage stability. By adjusting these chemical parameters during and after electrolysis, the solution maintains its hypochlorous acid concentration without significant degradation over time, resolving the contradiction between reliability and quantity preservation.
Solution Approach 2:
The patent employs preliminary action by adjusting the pH value and NaCl concentration before the degradation process begins. The pH is adjusted to the optimal range (5.0-6.5) and NaCl is supplemented to 100-500 ppm after electrolysis but before storage, creating pre-conditions that prevent concentration loss during storage, thus maintaining both stability and concentration.
2Reliability
If the pH value is adjusted to 5 to 6 to improve storage stability, then the solution becomes storage-stable, but additional processing steps are required
Solution Approach 1:
The pH adjustment is performed as a preliminary action immediately after electrolysis and before storage. By establishing the correct pH range (5.0-6.5) at this stage, the solution is pre-conditioned for long-term stability, eliminating the need for complex continuous monitoring or adjustment systems during storage.
Solution Approach 2:
The solution exhibits self-service characteristics where the adjusted pH (5.0-6.5) and supplemented NaCl (100-500 ppm) create a self-stabilizing system. The buffer capacity at this pH range and the presence of sufficient NaCl automatically prevent degradation without requiring external intervention or complex control mechanisms during storage.
3Reliability
If NaCl concentration is increased to more than 100 ppm to improve solution stability, then the storage stability increases, but the initial solution composition becomes more concentrated
Solution Approach 1:
The patent applies parameter changes by setting the NaCl concentration to a specific optimal range (100-500 ppm) after electrolysis. This parameter optimization ensures that there is sufficient NaCl to maintain stability and buffer capacity during storage, while avoiding excessive concentration that would be wasteful or harmful. The pH is simultaneously adjusted to work synergistically with this NaCl level.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces a storage-stable aqueous solution with hypochlorous acid and/or hypochlorite, maintaining concentration stability for several months, thereby extending the solution's effective lifespan and logistical usability.
Implementation Method 1
applying a direct current to a cathode in the cathode compartment (2) and to an anode in the anode compartment (3) to produce a cathode solution in the cathode compartment (2) and an anode solution in the anode compartment (3)
Implementation Method 2
a membrane or diaphragm, which separates the cell into an anode compartment and a cathode compartment, is located in the electrolytic cell. The membranes or, respectively, diaphragms used for this can be traversed only by small ions such as sodium and hydroxide ions so that there will be no mixing of the solutions emerging at the anode or, respectively, the cathode
Data Source
AI summary
The present patent application relates to a method of producing a storage-stable aqueous solution comprising hypochlorous acid and/or hypochlorite, comprising the steps of:a. introducing an aqueous NaCl solution into an electrolytic cell (1) which comprises a cathode compartment (2) and an anode compartment (3), which are separated from each other by a separator (4), wherein the aqueous NaCl solution is introduced into the cathode compartment (2) via a first feed line (5) and into the anode compartment (3) via a second feed line (6), and wherein the aqueous NaCl solution comprises more than 100 ppm NaCl,b. applying a direct current to a cathode in the cathode compartment (2) and to an anode in the anode compartment (3) to produce a cathode solution in the cathode compartment (2) and an anode solution in the anode compartment (3), andc. mixing a portion of the cathode solution with the aqueous NaCl solution before introducing it into the anode compartment (3) and/or with the anode solution in the anode compartment (3) and/or with the anode solution in a discharge line (7) associated with the anode compartment (3), or adding an NaOH solution into the anode compartment (3) and/or into a discharge line (7) associated with the anode compartment (3),in order to produce a storage-stable aqueous solution comprising hypochlorous acid and/or hypochlorite that has a pH value of 5 to 6 and can be discharged via the discharge line (7).