2、History of hypochlorous acid

1. History of hypochlorous acid

The strong sterilization effect of hypochlorous acid (HClO) was known to the elder generations.

Hypochlorous acid is a good bactericide with three characteristics as follows.

1. Strong and quick sterilization effect in low-concentration dosages
2. Little residue; hypochlorous acid liquids rinsed with water
3. No trihalomethane generated

Sodium hypochlorite (NaClO) stems from hypochlorous acid (HClO) which contains hypochlorous acid ions (ClO⁺) accounting for 90%. (As shown in the figure (top), the sterilization curve is drawn at the top.) Hypochlorous acid ions with little sterilization effect combine hydrogen ions (the molar ratio of hypochlorous acid ions to hydrogen ions=1:9) to become hypochlorous acid for sterilization. That is, sterilization is a slow process. Thus, hypochlorous acid ions are remained significantly.

Comparatively, weak-acid sodium hypochlorite contains hypochlorous acid ions (10% only) and hypochlorous acid for sterilization mostly. Thus, sodium hypochlorite features quick sterilization effect and little residues.

Moreover, trihalomethane which is a problem related to sodium hypochlorite is generated in alkaline environment rather than acidic environment.

 

There are two reasons which result in hypochlorous acid unpopular.

1. Difficulty in manufacturing (poor stability and diseconomy)
2. Difficulty in storage

That is, hypochlorous acid is produced difficultly and not stored for a long period.

 

2. Hypochlorous acid is produced in electrolysis first.

There are three methods shown as follows:

1. Electrolysis of saline solutions: By using salt water for producing strong acidic water but the HCLO is unstable.
2. Electrolysis of saline solutions in which HCl is mixed for production of hypochlorous acid (weak acid).
3. Electrolysis of water in which HCl is mixed for production of hypochlorous acid (weak acid).

Each of the methods has specific advantages but is uneconomic because of consumable platinum (titanium) electrode plates expensive.

 

3. Hypochlorous acid – the key element of sterilization!

Hypochlorous acid (HClO), which is similar to ozone or chlorine dioxide, is capable of resolving and killing bacteria (viruses) in oxidation. However, hypochlorous acid unlike alcohol does not induce antibiotic-resistant bacteria.

In addition, hypochlorous acid which has no toxicity of ozone or chlorine dioxide is a mild bactericide for human beings.

 

Hypochlorous acid (HClO) vs. sodium hypochlorite

 

The sterilization effects of hypochlorous acid (pH=5.2; chloride concentration=57ppm) and sodium hypochlorite (pH=9; chloride concentration=200ppm) are compared and shown in the table (below).

The sterilization effects of hypochlorous acid and sodium hypochlorite on Escherichia coli and Staphylococcus aureus are similar; however, the sterilization effects of hypochlorous acid and sodium hypochlorite on Bacillus subtilis (Bacillus) and mold are significantly different.

As shown in the table, hypochlorous acid has characteristics such as good sterilization effect and fast-acting property.

Tested strains	Microbial content	Hypochlorous acid			Sodium hypochlorite
		Chloride concentration=57ppm; pH5.2			Chloride concentration=200ppm; pH9
		After 1 minute	After 3 minutes	After 5 minutes	After 1 minute	After 3 minutes	After 5 minutes
Escherichia Coli	4.3x106	<10	<10	<10	<10	<10	<10
Staphylococcus aureus	4.5x106	<10	<10	<10	<10	<10	<10
Bacillus subtilis	4.6x106	3.7x105	<10	<10	4.4x106	4.5x106	4.5x106
Aspergillus niger	2.0x106	<10	<10	<10	2.0x105	50	<10

　　　<10: no microbe detected; test temperature=23°C (Japan Food Research Laboratories)

 

The sterilization effect of hypochlorous acid (pH=5.2; chloride concentration=80ppm) on bacteria is shown as follows.

There is no bacterium detected after one minute.

It can be seen that all bacteria and viruses are eliminated by hypochlorous acid.

※Note: These results are test data from experiments only because hypochlorous acid reacting with other organic matters is consumed. In practice, new hypochlorous acid should be added frequently for a constant concentration.

 

Tested strains	Testing liquid	Microbial content
		After 1 minute	After 3 minutes	After 5 minutes
Staphylococcus aureus	Object	1.0x105	1.0x105	1.0x105
	Hypochlorous acid	0	0	0
Escherichia coli	Object	1.0x105	1.0x105	1.0x105
	Hypochlorous acid	0	0	0
Bacillus subtilis	Object	1.0x105	1.0x105	1.0x105
	Hypochlorous acid	0	0	0
Salmonella	Object	1.1x105	1.1x105	1.1x105
	Hypochlorous acid	0	0	0
Bacillus cereus	Object	1.0x105	1.0x105	1.0x105
	Hypochlorous acid	0	0	0
Pseudomonas aeruginosa	Object	1.1x105	1.1x105	1.1x105
	Hypochlorous acid	0	0	0
MRSA	Object	1.1x105	1.1x105	1.1x105
	Hypochlorous acid	0	0	0
Legionella pneumophilia	Object	1.0x105	1.0x105	1.0x105
	Hypochlorous acid	0	0	0
Vibrio parahemolyticus	Object	1.1x105	1.1x105	1.1x105
	Hypochlorous acid	0	0	0
Clostridium perfringens	Object	1.1x105	1.1x105	1.1x105
	Hypochlorous acid	0	0	0
Campylobacter	Object	1.1x105	1.1x105	1.1x105
	Hypochlorous acid	0	0	0
Aspergillus niger	Object	1.0x105	1.0x105	1.0x105
	Hypochlorous acid	0	0	0
Test temperature=23°C

 

4. Spraying in space:

The airborne bacteria in space will be killed by sprayed hypochlorous acid.

The diagram below illustrates the counts of falling bacteria within one hour in a 6-bed ward in which hypochlorous acid (200ppm) was sprayed. The data was collected in the beginning and after 30 & 60 minutes with hypochlorous acid sprayed. During the test period, nurses moved in and out the ward as usual. The counts of falling bacteria were dropped dramatically in 30 minutes with hypochlorous acid sprayed and kept almost unchanged after the next 30 minutes. The status of MRSA, which was positive before spraying of hypochlorous acid, became negative after 30 minutes.

Counts of falling bacteria	Changes in counts of falling bacteria
	Before spraying　　　　　During spraying　　　　After spraying

 

5. Hypochlorous acid for deodorization:

As shown in the diagrams below, hypochlorous acid is particularly effective in deodorizing organic matters. Moreover, it is necessary to deodorize the source of odors which come from bacteria mostly.

CH3CHO	NH3	H2S
0　30 mins　60 mins	0　30 mins　60 mins	0　30 mins　60 mins
TMA	Methyl mercaptan	CH3COOH
0　30 mins　60 mins	0　30 mins　60 mins	0　30 mins　60 mins
Free effective chloride concentration in testing=80ppm

 

In the past, the ordinary deodorant discharges aroma to restrain foul smells. Comparatively, hypochlorous acid transforms reek to odorless air through chemical reactions.

Particularly, ammonia, which is one of four major sources of foul smells, disappears as shown in chemical reactions below.

Ammonia ＋ hypochlorous acid		Odorless ingredient (chloramine) ＋water no odor smelled

※ Note: The technique of sterilization based on chloramine had been adopted by some nations in Europe and Japan in the 1920’s because chloramine chemically reacts with organic matters slowly and the residual effect restrains foul smells.

 

Hypochlorous acid stored in ultrasonic sprayers can be sprayed in consulting rooms, operating rooms or doghouses by animal hospitals for odor control. Furthermore, hypochlorous acid is very effective in deodorization of pets’ feces.

 

6. Safety of hypochlorous acid

Hypochlorous acid can be created in blood of a person in whom the invading bacteria or viruses are killed. That is, our bodies are very familiar with hypochlorous acid.

Test results for animal safety with hypochlorous acid (50ppm):

Mistaken swallow	→	Normal
		Acute toxicity test by the single oral medicine
Skin (eye) contact		No irritation
		Single skin irritation test; eye irritation test
Allergy		No allergy
		Allergy test
Cancer		No cancer induced
		Mutation test in convalescence (mutagenicity test)

 

5、Application case:

 

1. Cleaning of chopped vegetables

Super Aqua sterilizing water can be used in cleaning chopped vegetables. In this regard, chopped vegetables should contact well-agitated sterilizing water (for expanded contact surfaces because of bubbles) despite hypochlorous acid effectively sterilizing microbes within one minute. Conversely, the sterilization effect is worst when chopped vegetables are dipped in water for a long period. (During the long soak of vegetables, the sterilization is effective in the intermediate stage but the sterilizing water is transformed to clean water finally.)

Please add new Super Aqua sterilizing water and keep it running to maintain the sterilization effect.

 

2. Seafood and processed meat

There is no bacterium inside seafood or meat in the beginning. However, the meat may be contaminated by bacteria when the outer skin or viscera is removed during meat processing. To prevent food or meat in food contaminated by microbes, an operator should spray Super Aqua sterilizing water to clean meat while removing outer skin or viscera.

 

3. Sterilization and cleaning of beverage bottles and caps

The hygiene index will be increased when both beverage bottles in which drinking water is to be filled and surrounding bacteria are cleaned and sterilized by sterilizing water. Moreover, the effective high-quality cleaning process is constructed in a beverage production line because the beverage bottles are easily cleaned with low-concentration sterilizing water in a small space. Additionally, the second pollution is prevented indirectly with airborne bacteria removed by sterilizing water sprayed indoors.

 

CIP (Clean in Place)sterlization

Beverage plant or food factories with well CIP ( Clean in Place) sterlization is very important. Traditionally use boiler for making high temperature steam with certain pressure and temperature working the CIP sterlization for tanks/pipes and equipment before manufacturing or after manufactured so that ensure to kill Bacillus bacteria ( Included preparation took some 50 minutes). Replace with Super Aqua hypochlorous acid liquid would just take 5-10 minutes. (Bacillus bacteria can be well killed within 3 minutes)。If increase some higher temperature the process might be sorter possible. 

Merits:

1. the sterilization time shorten significantly.

2. Reduce clients's fuel costs significantly  (energy saving)

3. Increase capability of production, etc.

4. Sprayer-based sterilization in space

The sterilization can be done with two-fluid spraying and ultrasonic spraying.

The two-fluid spraying which relies on compressed air to atomize sterilizing water is available to a factory or a spacious site for removal of airborne bacteria and no contamination of falling bacteria.

 

It is recommended to use the ultrasonic sprayer in tranquil indoor spaces.

The hypochlorous acid sprayer is designed for a small-size space with the floor area less than 13 × 36 square feet or a business premise with the floor area of 75 × 36 square feet.

 

5. Hand washing and cleaning of utensils

A user can spray sterilizing water to sterilize and clean fingers, work boots, kitchenware (e.g., cutting board and knife), and utensils on equipment or floors.

It is important to keep sanitation of users’ work boots, utensils and surroundings in addition to hands.

 

6. Location and purpose

Locations and purposes to use SUPER AQUA sterilizing water:

Location	Purpose
Food processing factory	Cleaning of food materials, utensils and workplaces
Seafood processing factory	Cleaning and defrosting of seafood; cleaning of utensils and workplaces
Beverage factory	Cleaning of bottles, utensils, machines, pipelines and indoor environment; indoor spraying
Kitchen	Cleaning of food materials, utensils and machines
Bakery	Cleaning of utensils and machines; indoor spraying
Stock farming	Spraying of environment
General manufacturer	Deodorization of wastes

 

【Types and purposes of hypochlorous acid】

Medical apparatus (topical bactericide)	Food additive (Sterilizing material)	Bleaching agent for sterilization and deodorization (grocery)
Sterilization of medical apparatus Sterilization of operating rooms and wards Sterilization of HB viruses Sterilization of pools for patients Sterilization of hands and skin Sterilization of skin at a surgical site and wound debridement	Sterilization of water Sterilization of vegetables and fruits	Bleaching, sterilization and deodorization of white clothes Bleaching, sterilization and deodorization of kitchenware, i.e., bowls and trays Sterilization and deodorization of bathtubs and bathrooms Cleaning and sterilization of medical apparatus Sterilization and deodorization of toilets, stools and urinals

 

For samples of hypochlorous-acid liquids, please contact us.

Except the applicant who had received samples several times, an ordinary applicant will receive Super Aqua hypochlorous acid liquid samples (200ppm; 25 liters) (freight collect).

Super Aqua will deliver samples to the applicant who completed the application accordingally. (NOTE: Some identified countries only )