👶 👩🏽‍🎨 🏉 What's in my White for you or Sodium hypochlorite (bleach) Reference Guide 📘 ⚙️ 🙍🏿

Can’t convey how pleasant it is for me to write. This article is fully funded by subscribers to the LAB66 channel . Not a single manufacturer of the means described in the text showed their participation, so no hidden advertising, pure altruism and consumer interest :)

Today we read about the simplest, most accessible and most effective antiseptic - about sodium hypochlorite (aka “Whiteness”). Compatibility with various materials, safety measures, properties and effectiveness not only against coronavirus, but also against terrible mold and its mycotoxins. As a “cherry” - a control purchase of store bleaches and an assessment of their composition. To find out how in the era of a pandemic we are fooled by household chemical manufacturers and the other “managerial brother” - we go under the cat. And be sure to bookmark it. This information will come in handy more than once;)

Important ! The information proposed in this article, you will not find on any other Russian-language resource. Therefore I publish on a habr, on a portal of the highest user confidence. A request to all resources of dubious quality - give a link to the source. Do not rewrite without understanding - do not produce a useless informational noise, from which there is nowhere to get away lately. To a multi-colored "learned people" I also recommend not to be shy to write a link to the Habr in your "methodical instructions". I see where you are copying everything from, books from the 50-60s cannot always be covered up forever;) So I strongly recommend that you notify me of the use of materials, and you can write something like this in your list of literature:

Besarab, S.V. What is in my White for you or Reference manual on sodium hypochlorite (“bleach”) [Electronic resource] - Access mode: - habr.com/en/post/494512/- Access date: 04.04.2020.

Preface from the author . I look at the column "they are reading now" on the hub and with regret I see that the principle "until the thunder strikes - the man does not cross himself" even works here. One continuous coronavirus. And I recall right away my article published at the end of January ( Coronavirus 2019-nCoV. FAQ on respiratory protection and disinfection ) in which 30% of the minuses were marked "does not correspond to the subject of Habr." Apparently, it begins to comply only when the order from above arrives ...

Okay, what’s sad to say. If a couple of thousand readers even then, in January, without panic and haste, were able to buy PPE and the necessary antiseptics, then we can assume that my goal has been achieved. And now I’ll just join the trend and talk about the simplest, most affordable and very effective antiseptic. I do not think that he will ever be able to disappear in the same way that ethanol disappeared. There are enough raw materials, sodium hypochlorite can be produced as long as electricity exists ...

There is such an interesting (interesting not only for a chemist, but also for other specialists who speak English) book - 100 of the most important chemical compounds: Reference Guide ( The 100 Most Important Chemical Compounds: A Reference Guide) In this manual, in the section of sodium salts are located next to baking soda, sodium carbonate, sodium chloride, sodium hydroxide (means "Mole") and sodium hypochlorite. In principle, it is understandable how many of these salts have earned such a right. But on sodium hypochlorite I will dwell in more detail today. First of all, of course, the definition:

NaOCl NaClO, (Na₊) (OCl^- ClO^-). . -- , 18- , . , , - , «» .

Since its discovery in 1787 by the chemist Claude Louis Bertollet (for which we should be grateful for crackers, match heads, salutes and other inventions that use the so-called Bertolet salt ), sodium hypochlorite has acted purely as a whitening agent for a long time and only around the middle of the 19th century did his procession as a disinfectant begin. Therefore, I will walk a little on the chemical properties, preserving the "historical chronology."

Chlora as bleach

The whitening effect of hypochlorite is entirely due to the unstable hypochlorous acid. For this HClO is a very strong oxidizing agent (even stronger than gaseous Cl ₂ ) and can react and destroy many types of molecules, including dyes. In an aqueous medium, sodium hypochlorite NaOCl is reversibly hydrolyzed to produce hypochlorous acid and alkali:

NaOCl + H ₂ O → HOCl + NaOH

In turn, hypochlorous acid HOCl decomposes into atomic oxygen (O *) and hydrochloric acid:

HOCl → HCl + O *

Well, atomic oxygen is a very vigorous thing, one of the most powerful oxidizing agents on our planet. By the way, it is thanks to atomic oxygen that ozone exhibits its bactericidal properties. So, in a way, ozone and sodium hypochlorite are “oxygen brothers” :) The

bleaching ability of sodium hypochlorite (and similar chemicals) is due to their ability to destroy light-absorbing structures (the so-called chromophores ) in organic molecules. Moreover, it can be not only chromophores on the tissues. Hypochlorite does a good job of whitening mold stains on tiles, tooth stains caused by fluorosis and removes stains from tea tannins on mugs (the so-called “tea stone”).

if at school I knew chemistry by three - you can’t even open the spoiler

, . . . , , , . , , «» .

In fairness, it is worth noting that hypochlorous acid forms salts not only with sodium, but also, for example, with calcium. An example is the same bleach, widely used because of its low cost for the disinfection of warehouses, livestock farms, toilets, etc., etc. Sodium hypochlorite accounts for about 83% of world consumption (in the role of bleach / disinfectant), and bleach accounts for 17%. In 2005, about 1 million tons of sodium hypochlorite was used in the world, and about 53% of this amount was used in households to disinfect and bleach clothes (+ washing, because the alkaline environment of the hypochlorite solution saponifies fats well and makes them water-soluble).The remaining 47% was spent on wastewater treatment and drinking water treatment (as well as cleaning pools and cooling towers of hydroelectric power plants from biofouling / algae / mollusks, bleaching pulp / paper / fabrics, and using as a reagent for chemical syntheses). The water treatment effect, by the way, is not only disinfection. This includes the removal of odors (NaOCl neutralizes hydrogen sulfide and ammonia) and even the neutralization of cyanides in wastewater (for example, after gold mining or plating baths).

Chlora as a disinfectant

Any misfortune as an indicator shows the best and worst features of a person. So with the coronavirus pandemic. It is surprising to me that many sober-minded, excellent specialists, giving in to panic, began to lose their heads and give out something like “hypochlorite will not kill the coronavirus” (or even better, “coronavirus is a GMO bacterium”). I don’t care much about the opinions of numerous youtube bloggers and couch analysts, etc. with their amateurish "discussions about fishing" (in the LAB-66 channel, it is already necessary for particularly zealous clicks and "obsessed with a world conspiracy" to demand a diploma about having a specialized education). But I try to listen clearly to the information from WHO, CDC, EPA. It is expected that in the March newsletter issued by one of the mentioned organizations (EPA's Registered Antimicrobial Products for Use Against Novel Coronavirus SARS-CoV-2, the Cause of COVID-19 ) included quite a lot of hypochlorite in the list of effective “coronavirus” disinfectants. There is nothing to be surprised at, because NaOCl is one of the best disinfectants (due to a combination of a wide range of activity, availability and absence of long-term harm to the environment). Regarding the disinfecting effect, we look at the picture (clickable):

Just in case, I remind you that COVID-19 is a disease caused by the envelope virus SARS-CoV-2 , which contains single-stranded RNA inside its “envelope” .

In principle, any chlorine-based disinfectants, one way or another, act through the formation of HOCl (the very hypochlorous acid). But the strong bactericidal effect of hypochlorite is associated not only with the ability to produce atomic oxygen, but also with the action of hydroxyl ions. The alkaline environment disrupts the integrity of the cytoplasmic membrane and leads to irreversible enzymatic inhibition, a change in cell metabolism and degradation of phospholipids (as with lipid hyperoxidation). Sodium hypochlorite acts on the enzymatic apparatus of bacteria, contributing to irreversible inactivation caused by an alkaline environment and chlorination caused by chlorine. Those. we can say that when hypochlorite is treated with an infected object, lipid saponification, neutralization of amino acids and chloramination occur simultaneously.Thus, not only many microorganisms are deactivated, but also the degradation of lipids and fatty acids, with the formation of surfactants (= soap) and glycerol, i.e. already mentioned saponification reaction. Hypochlorite not only disinfects, but also washes :) It is logical that with such an action it is practically impossible to develop resistance (as to antibiotics).

When processing living tissues, another important thing is biocompatibility. This is the ability of a chemical reagent to not react at all with biological tissues for a certain period of time (and to have a moderate reactivity for a week, gradually decreasing to 0). High concentrations of hypochlorite are quite aggressive (see the section on safety), but at concentrations of 0.5-1% this is a very biocompatible drug. Therefore, high concentration sodium hypochlorite is used for chlorination of water at some (!) Water treatment plants - a 12% solution - some, because chlorine is most often used in cylinders. A 15% solution is used to disinfect wastewater at a sewage treatment plant. Solutions with a concentration of at least 10% are used to purify pool water and remove biofilms. By the waysodium hypochlorite can be an excellent way to kill pathogenslegionellosis . These microorganisms, by the way, very often live in those very biofilms.

Well, in disinfectant sprays and wipes used on hard surfaces, concentrations of up to 1.5% are most often used. By the way, about how to make home-made napkins with hypochlorite I wrote for a long time on Patreon in my article “ Reverse Engineering Wet Wipes or Hypochlorite in Your Tape ”. By the way, taking this opportunity I express gratitude to all my "patrons". You are few, but you support seriously!

It is traditionally believed that for the treatment of hospitals and rooms contaminated with body fluids (blood, etc.), it is necessary to use a 0.5% solution. Such a concentration is sufficient to deactivate the clostridium difficile in feces or to destroy any human papillomaviruses. For processing / washing hands, the most commonly used is a 0.05% solution of hypochlorite, which is prepared from granules (in the picture - an excerpt from the instructions for disinfection in an Ebola epidemic):

In the West, the so-called “ Dakin's solution ” ( ~~I’m almost sure that we don’t have anything like that, we have a panacea replacing many medicines and solutions -> it’ll probably carry it~~ ) it’s Karrel-Dakin’s solution, it’s also Karrel-Dakin’s liquid. This solution is a diluted solution of sodium hypochlorite (from 0.4% to 0.5%) with the addition of stabilizing ingredients (boric acid or baking soda), and is actively used as an antiseptic to clean wounds / treat burns, etc. ( method preparations for those interested). Such a solution shows the effectiveness of disinfection for some microorganisms even with a concentration of 0.025%.

Remark 1. About other “chlorine disinfectants”

In addition to the sodium hypochlorite and calcium hypochlorite that I have already mentioned, there are other substances that can actively produce chlorine (well, chlorine with water = “unstable hypochlorous acid HOCl” and then again see “Chlorine as a disinfectant”). Moreover, there may be substances of organic nature. On the Internet, I found information (most likely torn from some Soviet book on civil defense - because many names, and the drugs themselves, have long ceased to exist). This table gives an approximate idea of the spectrum of drugs and their comparative “chlorine disinfectancy”. I cleaned the copyright and offer it to your court. You can at least roughly estimate / compare the activity of different disinfectants (if you want something different from the good old NaOCl):

Perhaps the reader may come across such a disinfectant as chlorcin (this is NOT a Ukrainian ointment of the same name ). These are Na-DHCC (sodium salt of dichloroisocyanuric acid - chlorcin N) - 30.0% (or K-DHCC - 20.0% - chlorcin K), sodium tripolyphosphate - 6%, surfactant (sulfonol) -3%, sodium sulfate - up to 100%. Chlorcin contains 11-15% of active chlorine. Can meet and so-called. drug DP-2 . The encrypted name should not be scared, in fact - ordinary trichloroisocyanuric acid with surfactant additives.

I’ll introduce here a remark frometeh: "... electrolysis GPCN is possible and 5-7%. If you receive, respectively, not by flowing electrolysis, but by membrane from salt and water without adding additional reagents. Well, above, yes, there you only need to separately prepare a concentrated alkaline solution for saturation with chlorine" .

Remark 2. “bleach that heals”

All poison and all medicine. Hypochlorite, which can not only destroy all life, but also heal, for example, skin lesions, is no exception. I would like to recall baths with diluted hypochlorite, which in the West ( ~~we all treat with radon :)~~ ) have been used for decades to treat moderate and severe eczema ( link ). Moreover, the mechanism of action remained unclear for a long time. But in 2013, interesting information appeared in Stanford ( proof ) that very dilute (0.005%) sodium hypochlorite successfully treats inflammatory skin lesions in laboratory mice caused by radiation therapy, an excess of sun or aging (~~Kim Il Sung did not need to bathe in the blood of virgins, but in hypochlorite, purely according to the principle of Occam’s razor, and he would “expel the genies” and rejuvenated~~ ). Mice with radiation dermatitis swimming every day for 30 minutes in hypochlorite (= “swimming in domestic pools”) had better dynamics of skin healing and hair regrowth than mice bathed in ordinary water. In old mice, the skin after bathing generally became younger, thickened, and proliferation (reproduction by division) of cells increased . It would seem that it is a panacea for the elderly rulers, but no. The effect disappeared after the bathing stopped ...

In the "medical section" it is not a sin to mention the use of sodium hypochlorite in dentistry (because it was the dentists who most of all were interested in issues of concentration, dilution in, etc.). Sodium hypochlorite is the drug of choice in endodontics and root canal cleaning. Most often, dentists use concentrations from 0.5% to 5.25% (standard - 2%).

The rule works here - low concentrations of hypochlorite remove predominantly necrotic tissues and some types of bacteria, high concentrations - damage living tissues, but most completely destroy microbes. By the way, instead of increasing the concentration, you can warm up the solution (50-60 ° C), which will give comparable to a more concentrated solution effectiveness in removing soft tissues and disinfecting the root canal.

Remark 3. On field water treatment

The topic of water purification is quite extensive and quite worthy of a separate article. I will briefly mention the purification of water in the field. After all, there are situations when it is difficult to use or even boil water to use an ozonizer or a UV lamp. Therefore, chemical disinfectants, in my opinion , have no special alternative so far. Chlorine disinfection can be considered the oldest option for field disinfection of water. During the Second World War, the US military included Halazone tablets containing sodium salt of 4 - [(dichloramino) sulfonyl] benzoic acid as part of a dry ration.

Then gradually this substance was replaced by sodium dichloroisocyanurate (the same DHCC), it was he who was part of the Pantocid tablets widely known in narrow circles. The American version is DHCC compressed with adipic acid and soda, instant tablets. It is worth noting that for field disinfection tablets for pool disinfection can also be used (two-component tablets containing a mixture of chlorite + chlorate + sodium carbonate and sodium hydrogen sulfate) that produce chlorine dioxide. In general, this option is also suitable for disinfecting drinking water. Moreover, this option, for example, is effective against giardiamore than ordinary chlorine. All the options described are convenient in situ (tourists, military, emergency situations, etc.). For options like a natural disaster or some kind of technological disaster, tablets may not be available, or even too expensive. For this purpose, it is quite possible to use White (preferably without any surfactants and fragrances). It takes only a couple of drops of 5% sodium hypochlorite per liter of water with holding in a container with a closed lid for 30-60 minutes. Before direct use, it is advisable to open the lid and "let it ventilate." Do not immediately pour in yourself, no matter how thirsty you are.

CDC, as part of its Safe Water System (SWS) strategy for developing countries, recommends using a 0.5–1.5% sodium hypochlorite solution (two to three drops per liter and an exposure time of 30 minutes) to disinfect water. The EPA, by the way, advises using an 8.25% solution of sodium hypochlorite (two drops per liter and an exposure of 30 minutes), the important note is " double the amount of bleach if the water is cloudy, colored or very cold. After treatment, the water should have a faint smell of chlorine. If no, repeat the dosage and let stand for another 15 minutes before use . " It should be noted that in extreme cases, calcium hypochlorite (“bleach”) can also be used to disinfect water.

Remark 4. “Chlorine” vs mold, fungi and mycotoxins

And then they damaged his nervous system with a Russian military mycotoxin ...
William Gibson "Neuromancer"

There is in the small world of “chemists who are in the subject” such a “Grail” as mycotoxins.

The average person most often did not hear anything about it, or heard from the edge of his ear (such as "Johnny Mnemonic poisoned with such a substance ..."). In fact, this is the topic of a separate and very interesting article. In the meantime, I’ll just say that mycotoxins in the simplest application = mold, mold fungi of various varieties that can be found on vegetables, fruits, cereals, etc. etc. Mycotoxins - it is impossible to wash off with water or soap, it is impossible to remove by cutting off the rotten skin. Mycotoxins - can be evenly distributed throughout the volume of potatoes / apples, etc. etc. And, unfortunately, many mycotoxins in the human body cause multiple symptoms of organ damage (if they come in contact with the skin, lungs, or stomach). Due to the fact that their concentrations are quite small (I doubtthat someone constantly eats rotten fruits or moldy nuts) - the effect is time-consuming and seems to be familiar (= “got sick from a genetic predisposition / drunkenness / bad air”, and not because I was poisoned by mycotoxins from low-quality cereals). You can talk about this for a long time, but the hero of my article is hypochlorite, which means we should reduce the topic to it.

And it all boils down to the fact that sodium hypochlorite in certain concentrations can be used not only to destroy microbes and molds (see the table at the beginning of the section " Chlorachka, as a disinfectant "), but also to deactivate what is left after them, in t .h. mold, plant toxins and animal toxins .. For more details, see the table (30-minute exposure). Plus - the toxin is deactivated, minus - no.

So, looking at the table, you can see that sodium hypochlorite is able to deactivate T-2 mycotoxin, which is secreted by Fusarium molds .

T-2 toxin is a trichothecene mycotoxin, extremely toxic to eukaryotic organisms. Due to the use of moldy grain or flour, poisoning occurs in humans or farm animals. Acute toxic symptoms include vomiting, diarrhea, skin irritation, itching, rash, blisters, bleeding, and shortness of breath. If a person is exposed to T-2 for a longer period, gradual bone marrow degeneration is observed and foodborne toxic aleukia (ATA) develops.

And you’ll already habitually not wave it off, you won’t calm yourself with the phrase “where is that mycotoxin and Fusarium, and where am I” and vodka, as usual, you won’t heal ... Because they are many where. On strawberries for example:

Or even on pumpkins ...

So, quite an option to reduce the amount of mycotoxins in suspicious fruits and vegetables is to bathe them in alkaline sodium hypochlorite, followed by ordinary washing. With this treatment option, almost all possible “surface hares” are killed.

Stability and shelf life (= is there any point in purchasing for future use?)

If chemistry and medicine are not particularly interesting for an ordinary technician (it is enough to know whether it works or not), then the issues of storage stability are, on the contrary, paramount. Indeed, sodium hypochlorite is an unstable substance. At room temperature, approximately 0.75 g of active chlorine per day decomposes, i.e. a solution with a content of 250 g / l sodium hypochlorite loses about half of the active chlorine in 5 months, with a content of 100 g / l in 7 months, 50 g / l in 2 years, and 25 g / l in 5-6 years.

Its stability depends on a number of factors:

Hypochlorite concentration
Temperature
Alkalinity and pH
The concentration of impurities that catalyze the decomposition and / or formation of chlorates
Light exposure

In most cases, the decay proceeds according to these basic mechanisms:

2NaOCl → 2NaCl + O ₂ (A)
3NaOCl → 2NaCl + NaClO ₃ (B)

I’ll go through each item separately:

Concentration : the more concentrated the solution, the faster it decomposes, so the weakest solutions are the most stable. Literature data indicate that with a decrease in the concentration of sodium hypochlorite by half, the decomposition rate decreases by 5 times. This is due to a decrease in the total concentration of ions and a decrease in the ionic strength of the solution. Dilution reduces both the concentration of NaOCl and the concentration of other ions (equilibrium chlorides, chlorates, hydroxides, etc. - see the picture “pH equilibrium” below).

Temperature: decomposition of hypochlorite with increasing temperature in 90% of cases occurs according to equation (B). You can keep in mind the following rule - the decomposition rate increases 3-4 times, for every 10 ° C for solutions with concentrations of sodium hypochlorite from 5 to 16%. And if you strain and lower the storage temperature of chlorine to 5 ° C (provided that there are no metal impurities and other factors that accelerate decomposition), then you can store it in a dark bottle almost forever.

Alkalinity and pH of the solution: for stable storage, the hypochlorite solution should have a pH of 11.5 to 12.5. In the case of dilute NaOCl solutions at pH below 10.8, the decomposition rate begins to increase significantly, reaching a maximum value in the range of 5-9. But there is a nuance. When the pH of the solution decreases, the HOCl content increases and the redox potential increases (see the picture with the change in the forms of active chlorine in sodium hypochlorite solution depending on the pH of the solution, Cl ₂ - molecular chlorine, ClO ^- hypochlorite ion, HClO-hypochlorous acid )

Those. High-alkaline solutions are optimal for storage, and solutions for low pH are used for emergency disinfection. Although, frankly, raising the pH is also necessary to a reasonable limit. If the pH exceeds 13, the decomposition rate again increases stepwise. This is due to an increase in the ionic strength of the solution caused by the presence of a strong excess of alkali (NaOH). In general, it can be used as a rule - for chlorine-containing disinfectants we use only an alkaline environment. For peroxide disinfectants - the most effective acidic environment. HOURS are incompatible with acids and dramatically lose their disinfectant properties in their presence. Aldehydes (like formalin and glutaraldehyde) - work in both acidic and alkaline environments)

Impurities:aluminum, copper, nickel, iron, cobalt, manganese, etc. are catalysts for the decomposition of NaOCl. Metals primarily catalyze decomposition by reaction (A) to form gaseous oxygen. Solid suspensions, such as, for example, graphite particles in sodium hypochlorite obtained by the electrochemical method, also cause decomposition of NaOCl, in particular by reaction (B) to form sodium chlorate. By the way, as some manufacturers of disinfectants say, additives of magnesium sulfate, sodium silicate, boric acid - slow down the decomposition.

Light exposure: exposure to light accelerates the decomposition of NaOCl in solution. Modern packaging methods and the use of opaque plastic bottles virtually eliminate the effect of light on the stability of solutions. Amber or green glass bottles also have the same result. If specific numbers are important, it will look like this:

To prevent decomposition of hypochlorite, a container is required that cuts off light below 475 nm and transmits less than 2% at 500 nm.

To summarize, we can say the following. The longest-playing drug will be that:

Has a low concentration of hypochlorite
11.5 < pH in the range > 13
In which there are no impurities of metals / graphite (= filtered)
Stored at <30 ° C (= in the refrigerator)
Packed in absolutely lightproof containers

Material compatibility

The issue of compatibility of materials has something in common with what was said earlier (especially with regard to metals). In the table below you can even see at what speed what is corroding.

Here it is also clear that the issue of compatibility of materials is relevant mainly for the case of storage / transportation of high concentration hypochlorite and an ordinary "disinfector" should be of little concern. In the general piggy bank, I will mention a few more materials that are recommended for the role of gaskets / structural materials when working with concentrated sodium hypochlorite:

PVDF (fluorinated polyvinylidene)
Ethylene propylene rubber
Chlorobutyl rubber
CPVC (chlorinated polyvinyl chloride)
Tantalum
FRP (fiberglass with a suitable inert resin and curing system)
Polydicyclopentadiene

American Hypochlorite Resistance Label

, S = (satisfactory), U = (unsatisfactory). .

Hypochlorite Safety

In general, a typical (= diluted) household bleach such as whiteness is not more dangerous than water (if you respect him, sign a bottle there, hide from children, etc.). According to statistics, in 2002 in the UK there were about 3,300 accidents associated with sodium hypochlorite. And the vast majority of them - the use of a disinfectant inside ... I think the comments are superfluous.

As for sodium hypochlorite "industrial concentration", i.e. such which wastewater is treated with, it already belongs to the severe first hazard class (class 1B-skin lesion + class 1-eye damage).

If decrypted, it causes chemical burns if it comes into contact with skin and eyes. It will also cause irritation if it enters the mucous membranes of the upper respiratory tract (if inhaled). A stumbling block such as “bleach in pool water” deserves special mention. Usually, the concentration of sodium hypochlorite present in swimming pools is absolutely not harmful to people. But! But things change if there is a large amount of urea in the water (a mixture of urine and sweat), and then hypochlorous acid and urea react with the formation of vigorous chloramines (about the formation mechanism - below). It is chloramines that irritate the mucous membranes and give the so-called. "The smell of chlorine." In normal pools this should not be (normal = the one in which water is changed and ventilation works). If this does not happen, then the constant exposure to volatile chloramines can even lead to the development of atopic asthma (see article ).

Treatment for poisoning :

Given all of the above, I decided to attach a small "memo for the doctor", so that if something happens - everything was at hand. Description of actions in case of poisoning with sodium hypochlorite. By the way, it is about the same as in the case of alkali poisoning (a slippery sensation of bleach on the skin is associated with saponification of skin oils and tissue destruction). BUT! But this is only for pure sodium hypochlorite. If it is combined with various household chemicals, it may be necessary to treat poisoning from reaction products (see the next paragraph).

Note about the "smell of chlorine": you can often hear from readers the question "how to remove this unpleasant smell of chlorine from the hands / half mask / objects." In this case, sodium thiosulfate will help, and a solution with a concentration of about 5 mg / l (0.005%) is enough for active odor removal. Wash with this solution hands or __ (enter the desired), and then wash with soap and water. If thiosulfate could not be found, then only a proven method remains - “odor weathering with time”.

By the way, to neutralize spills of concentrated sodium hypochlorite (we assume that 5% and above), sodium sulfite can also be used, it works by the reaction:

NaOCl + Na ₂ SO ₃ → NaCl + Na ₂ SO ₄

or sodium hydrosulfite , which works by reaction:

NaOCl + NaHSO ₃ + NaOH → NaCl + Na ₂ SO ₄ + H ₂ O

And you can, in the case of a very small amount of hypochlorite, use hydrogen peroxide, but with caution (!) Because oxygen is released there.

Dangerous Neighborhood - Incompatible household chemicals

Sodium hypochlorite, being a very active component, easily enters into chemical reactions (including photochemical ones - that is, with sunlight and ultraviolet from currently popular bactericidal lamps). Often chlorine is released as a result of these reactions (= a serious irritant), for example, when our whiteness comes in contact with a rust cleaner. When hypochlorite comes into contact with ammonia compounds (including with the beloved people, HOURs that have now begun to be added to floor cleaners), and even in contact with urine (!) Which contains urea, toxic under normal conditions can form chloramines:

NH ₃ + NaOCl → NaOH + NH ₂ Cl
NH ₂ Cl + NaOCl → NaOH + NHCl ₂
NHCl ₂ + NaOCl → NaOH + NCl ₃

Upon contact of whiteness with some household detergents containing surfactants and various perfumes, volatile (!) Organochlorine compounds such as carbon tetrachloride (CCl ₄ ) and chloroform (CHCl ₃ ) can form . Everyone can see their hazard classes themselves. For example, in an articlethe researchers showed that when working with some “tricky” household chemicals, the concentrations of these solvents increase 8–52 times for chloroform and 1–1170 times for carbon tetrachloride, respectively higher. The lowest “exhaust” of a volatile organochlorine is provided by the simplest bleach (read “whiteness”), but the highest - by means in the form of a “thick liquid and gel” (such as all kinds of Domestos and their ilk that cannot be properly diluted). Therefore, for the future, a) it is worth avoiding in every possible way “super-effective means with a new formula” (= crap, which was developed by the manager, not the engineer) and adhere to the classical formula “better whiteness = hypochlorite and water”. And b) use respirators with a carbon filter when cleaning the apartment (= "to trap solvent vapor").

Sodium hypochlorite reacts quite violently with hydrogen peroxide, with the formation of sodium chloride ( ~~your favorite salt~~ ) and oxygen:

H ₂ O ₂ + NaOCl → NaCl (aq) + H ₂ O + O ₂

The heterogeneous reactions of hypochlorite with metals proceed rather slowly and result in a metal oxide (or hydroxide). For example, zinc:

NaOCl + Zn → ZnO + NaCl

With various metal complexes, whiteness reacts unmatched faster.

As already mentioned, sodium hypochlorite does not like high temperature (above 30 ° C), and when heated it decomposes into sodium chlorate and oxygen (for a 5% solution, the decomposition temperature is ~ 40 ° C), if it can be heated to 70 ° C, the decomposition can proceed with the explosion.

In general, high concentration hypochlorite is non-combustible and explosion proof. But in contact with organic combustible substances (sawdust, rags, etc.) during drying, it can cause a fire. In general, such a reactivity is at the same time a benefit, because the substance cannot remain in an unchanged state in the environment for a long time and is quickly deactivated (= you can simply rinse it in waste water).

As conclusions - everything written above is summarized in a single table of incompatible components (clickable).

Some of these compounds can be found in household, automotive and industrial chemicals and chemical mixtures = detergents for cleaning windows, toilets and surfaces, degreasing agents, antifreeze agents, water purifiers, chemicals for baths and pools. Therefore, more often look at the label. Demand that the composition be written on the label! Buy only the product where the label contains the maximum information about the composition. It's time to vote in rubles for an adequate attitude towards the buyer.

Workshop or All Whiteness of Minsk

Having fully understood the theory, now we come to the most interesting. To laboratory work. As promised to the readers, I drove around Minsk and collected all the available options for liquid bleach (namely liquid bleach, gels, etc. I did not even look). Now I want to tell how I compared them and “checked for lice” (= whether they are suitable for disinfection purposes).

By the way, I note that all the methods described in the article are quite functional in peacetime, to check the quality of water in pools or taps. If someone suddenly wants to say "the water is bad - it stinks of bleach," then after reading the article, I hope this can be done without problems. And now, now water with bleach is a blessing during a pandemic ...

In general, first of all, we select the necessary PPE (optional). As I mentioned above, gloves are enough for most tasks (and straight hands). Not knowing what the mixtures were in the bottles, I decided to play it safe and use a full protection kit (only from my 3M 7502 half mask did I replace the “coronavirus” aerosol anti-aerosol 6035 with coal cartridges of the “gases / vapors” class - like ABE1, as in my case, or better ABEK 1. Domestic gas masks and respirators for working with solvent vapors will also go.

the choice of filters for working with household chemicals (clickable)

We’ve sorted out the preliminary preparations, and now I bring to your attention the entire White of Minsk! Meet Belarusian beauties! This, by the way, is all that was found in the supermarkets of the hero city.

First of all, I appreciated the appearance, i.e. color and consistency of the proposed solutions. Although there is nothing extraordinary to be expected here (since, according to the conditions of the problem, there are no gels and other “chemo-stuffing”, maximum simplicity).

Then he measured their density (clickable) + pH, he is also a hydrogen indicator.

How to measure the density and pH of a house?

, — ( , «» ). - Hanna:

The result is such a pivot table with data (I had to rewrite some of the labels):

I’ll separately write the composition (i.e. the fact that there is EXCEPT Sodium hypochlorite there, this is important, especially considering all sorts of chloramines and volatile organochlorine, which I wrote about above). The writing style is preserved so that the reader understands who writes the instructions.

sample 1. Water, anionic surfactant - less than 5%, stabilizer, complexing agent
sample 2. Water
sample 3. Water, nonionic surfactant - less than 5 (%), flavoring (freshness)
- less than 5% sample 4. Water, anionic surfactant - less than 5% , stabilizer, complexing agent
sample 5. Water, alkali - less than 5%, water 30% or more
sample 6. <5% alkali, water, fragrance
sample 7. More than 30% drinking water, Trilon B, sodium hydroxide - less than 5%

Perhaps "as part of the elective" I will someday do an analysis of gels with active chlorine. But this form is very inconvenient for several reasons. Firstly, the composition may contain mutually exclusive components (see the incompatibility table) and when you open the bottle, you will immediately begin to receive a dose of chlorine / chloramine, etc. Secondly, because of the heap of additives that are not compatible with the human body, gels cannot be used for the same disinfection of water. And thirdly, the high viscosity of the solution will neither allow it to be diluted normally nor used in combination with a sprayer (for example, to irrigate door handles).

And finally, we’ve finished the preparatory phase, now the most important and interesting thing is the concentration of sodium hypochlorite. It is important because it is to this indicator that all recommendations for disinfection are attached. Well, the manufacturers themselves do not go towards the buyer and write the hell with those (see below). Although it is not so difficult to find out how much hypochlorite there is. A technique such as titration will help . We will simply add one component until it completely reacts with the second (the color of the solution will signal about this). To determine the active chlorine in hypochlorite, you can apply the domestic GOST method, or you can use the American ASTM.

The difference between analytical reactions

NaClO + 2KI + 2H₂SO₄ → NaCl + I₂ + K₂SO₄ + H₂O

NaOCl + 2KI + 2CH₃COOH → I₂ + NaCl + 2KC₂H₃O₂ + H₂O

, .

In principle, the differences by which I personally do not see work, the availability of reagents plays a role here, I used GOST, because sulfuric acid does not stink like acetic acid.

Method GOST R 57568-2017 (simplified):

For work, we need the following components:

1) Sulfuric acid 1n.

We measure out 28.6 ml of concentrated sulfuric acid (density = 1, 84 g / cm3) and bring to a liter with distilled water.

2) 10% solution of potassium iodide

Weigh 10 grams of potassium iodide and dissolve in 90 ml of distilled water. The solution is applied freshly prepared

3) A solution of sodium thiosulfate 0.1n

Weigh 25 g of sodium thiosulfate (pentahydrate) and bring distilled water to 1 liter. Store in a dark bottle.

4) Starch solution 1%

Weigh 1 g of starch (corn, potato, etc., at least rub the potatoes and brew, but! But do not forget to filter :)) and mix with 10 ml of distilled water. Then boil 90 ml of distilled water in a glass and when it boils, pour our 10 ml with starch. Cook, mixing for 2-3 minutes. We use freshly prepared.

The verification procedure itself is as follows. We take a sample of hypochlorite with a volume of 10 ml, and bring water to 250 ml. We take 10 ml from this volume and transfer it to a glass, add 10 ml of potassium iodide solution and 20 ml of sulfuric acid to the same glass. Mix well and put in the dark for 5 minutes. After 5 minutes, drip dropwise (from a calibrated dropper, and even better burette) sodium thiosulfate solution until the red solution (due to iodine released) becomes transparent.

tired of the factory burette and took out his travel option

When the liquid acquires a straw (light yellow) color - add 2-3 ml of starch to a glass, the solution turns blue.

that's how it turns blue

Now slowly add thiosulfate until the blue color disappears.

What are the nuances that affect the result of the determination? But the following (I advise you to keep them in mind).

Insufficient amount of potassium iodide (= you used the old semi-decomposed reagent when preparing the solution) added to the sample will cause not all hypochlorite to react and the active chlorine will be underestimated. Therefore, a small excess of iodide is better.
, . .
— . , .
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. , .
Adding starch too early will lead to an irreversible reaction of starch with iodine (the formation of a reddish color) and you simply will not be able to trace the end of the reaction. Add starch when the color of the solution is straw (light yellow), and not reddish .
Use of old sodium thiosulfate. This reagent in solution is prone to decomposition (therefore, it must be stored in a dark bottle, away from sunlight). Alternatively, either prepare a fresh solution each time, or check the existing one and make the appropriate amendments (the first is recommended).

During our titration, we calculate the number of drops that went into the neutralization of hypochlorite and calculate the mass concentration of active chlorine according to the formula:

X = (Volume of thiosulfate * 0.003545 * 250 * 1000) / 100.

for fans of everything american :)

, — - (.2-.4 ). (= .1) « » 500 500 .
: 25 , 250 / 0,01 . 250 . . / 10 / 250 . 50 , , 25 10% . - (. ). 10 . 3-5 . , 0,1 . . , . , - , 5 , (. ) . — . . :

% NaOCl = ( *N*3,723722)/0,04*

N — , 0,1

As a result of titration of my samples, the following was obtained (in parentheses, the concentration of hypochlorite, which is

calculated by the formula: hypochlorite concentration (NaOCl) = chlorine concentration * 1.05: sample 1. chlorine 19.32 g / l = (NaOCl 20, 29 g / l) = 2.029% solution of
sample 2. chlorine 5.67 g / l = (NaOCl 5, 96 g / l) = 0.596% solution of
sample 3. chlorine 32.26 g / l = (NaOCl 33, 87 g / l) = 3.387% solution of
sample 4. chlorine 21.27 g / l = (NaOCl 22, 33 g / l) = 2.233% solution
sample 5. chlorine 20.74 g / l = (NaOCl 21, 76 g / l) = 2.176% solution
sample 6. chlorine 18.97 g / l = (NaOCl 19, 91 g / l) = 1.991% solution
sample 7. chlorine 14.18 g / l = (NaOCl 14, 89 g / l) = 1.489% solution

Those. if we consider that the extreme "coronoparietal" concentration of sodium hypochlorite = 0.5%, it turns out that the solutions need to be diluted 4 times (means 1, means 6), 4.4 times (means 5) 4.5 times (means 4) , 7 times it is necessary to dilute the agent 3. We dilute the agent 7 3 times, and the agent 2 is generally not necessary to dilute (here you have a transparent container). Finally - a photo with a winner:

Gomel ODO BUDMASH! Habra hello to you and respect for your products :).

For a snack, I will show how the obtained experimental data correlate with the writing on the label:

sample 1. “sodium hypochlorite - 30% or more” = 2.029%
sample 2. “sodium hypochlorite (5% or more, but not less than 15%) = 0.596%
sample 3. “sodium hypochlorite 30 (%) and more” = 3.387%
sample 4. “sodium hypochlorite - 30% or more” = 2.233%
sample 5. “sodium hypochlorite - 5% or more, but less than 15%” = 2.176%
sample 6. "<30% sodium hypochlorite" = 1.991%
sample 7. "15% or more, but less than 30% sodium hypochlorite" = 1.489% The

answer is no. Full random. So here the advice is not even “Trust, but verify!”, But simply “Immediately verify, verify, verify!”

Well, do those who do not like titration (although IMHO is the simplest and most affordable option even in a distant village, know for yourself, just consider the drops). Such people can be helped by special test strips Desicont-GN-01 (indicator strips for express control of the concentration of working solutions of the disinfectant “Sodium Hypochlorite”). Which is probably much more difficult to find than ethanol in the era of the coronavirus pandemic :)

You can try to estimate the concentration by freezing temperature (the lower it is, the more concentrated hypochlorite).

You can measure the surface tension, viscosity or conductivity of the solution (TDS meter with aliexpress, yeah). For a 1% NaOCl solution, surface tension = 75 dyne / cm, viscosity = 0.968 centipoise, conductivity = 65.5 millisiemens. But correlations for a higher / lower concentration are very arbitrary and depend on many factors.

In the absence of titration reagents, a summary table of correlation of density / excess alkali with hypochlorite concentration may be of some help (true only if the concentration is> 4%, which in our area is only possible if you buy industrial hypochlorite used for the needs of water utilities, because whiteness - see for yourself what a whiteness):

By the way, let's say you have decided on the concentration necessary for disinfection, and on the concentration of the whiteness you purchased, but ... But suddenly you don’t know how to dilute your product (fantastic, IMHO, scenario, but you never know what, we were born to make a fairy tale come true). To solve this problem, you need to go to the link " solution dilution calculator " and enter the necessary numbers there. As an example, take our winner, 1 liter of whiteness with a concentration of sodium hypochlorite of 3.387% of Gomel Budmash and dilute to 0.5% to “wash floors from coronavirus”. The calculator writes to us - you need to add 5.774 liters of water (“solvent”).

As you can see, nothing complicated. Disinfect! :)

Brief conclusions

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(, ). — . , NaOCl — .
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Disclaimer : all information presented in the article is provided for informational purposes only and is not a direct call to action. All manipulations with chemical reagents and equipment you carry out at your own peril and risk. The author does not bear any responsibility for the careless handling of aggressive solutions, illiteracy, lack of basic school knowledge, etc. If you don’t feel confident in understanding what has been written, ask a relative / friend / acquaintance who has at least some technical education to control your actions (= “I studied well at school”). Try to use PPE and follow safety precautions to the maximum. And yes, be sure to clean your petsduring processing! And if you yourself do not wash your hands with 0.5% sodium hypochlorite, then do not do this for your dog's paws!

That's all! Traditionally, I propose to subscribe to my scientific and technical channel and join the discussion!

List of sources used

• Ronco, C. Mishkin, G.J. Disinfection By Sodium Hypochlorite Dialysis Applications/Nephrology, 2007, Vol. 154.
• Jeffrey M. Levine Dakin’s Solution: Past, Present, and Future /Advances in Skin & Wound Care: The Journal for Prevention and Healing, 2013,volume 26, issue 9, pages 410–414
• D. N. Herndon, and M. C. Robson Bactericidal and Wound-Healing Properties of Sodium Hypochlorite Solutions: The 1991 Lindberg Award/Journal of Burn Care & Rehabilitation, 1991, volume 12, issue 5, pages 420–424.
• L. Wang; et al. Hypochlorous Acid as a Potential Wound Care Agent/Journal of Burns and Wounds, 2007, 6: e5
• Sandin, Rasmus K. B. Karlsson, and Ann Cornell Catalyzed and Uncatalyzed Decomposition of Hypochlorite in Dilute Solutions/Industrial Engineering Chemical Research, 2015, volume 54, issue 15, pp. 3767–3774.
• Daniele S. Lantagne Sodium hypochlorite dosage for household and emergency water treatment/ e-Journal AWWA. 2008, 100 (8).
• Rutala, William A., Weber, David J. Guideline for Disinfection and Sterilization in Healthcare Facilities" (PDF). www.cdc.gov. [2008]
• J. P. Heggers, J. A. Sazy, B. D. Stenberg, L. L. Strock, R. L. McCauley, D. N. Herndon, and M. C. Robson Bactericidal and Wound-Healing Properties of Sodium Hypochlorite Solutions: The 1991 Lindberg Award"/Journal of Burn Care & Rehabilitation, 1991, volume 12, issue 5, pp. 420–424.
Root Canal Irrigants and Disinfectants. Endodontics: Colleagues for Excellence. Published for the Dental Professional Community by the American Association of Endodontists. 2011. —
• Hülsmann, M.; Hahn, W. Complications during root canal irrigation – literature review and case reports" (PDF). International Endodontic Journal. 2000, 33 (3): 186–193. —
• Odabasi, Mustafa Halogenated Volatile Organic Compounds from the Use of Chlorine-Bleach- Containing Household Products/Environmental Science & Technology. 42 (5): 1445–1451.
• Jones, F.-L. Chlorine poisoning from mixing household cleaners/J. Am. Med. Assoc. 1972, 222 (10)
• Minimizing Chlorate Ion Formation in Drinking Water when Hypochlorite is the Chlorinating Agent, American Water Works Association (AWWA) Research Foundation, G. Gordon and L. Adam, Miami University, Oxford, OH & B. Bubnis, Novatek, Oxford
• Emergency Response Plans for Chlor-Alkali, Sodium Hypochlorite, and Hydrogen Chloride Facilities, ed. 7; Pamphlet 64; The Chlorine Institute: Arlington, VA, 2014.

The author is grateful to his chief assistant - researcher Yustyna for help in testing Belarusian hypochlorites and my Ukrainian parteigenosse Sasha akainfiltree ____ ( , ?) :).

, ( ) , , , , , . — S Sh, , O! — steanlab. ! -Vivat LAB-66!

, ! !!! , .

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