[ka7niq]

Hello everyone, we use a mixture of Sodium Hypochlorite and water to remove mildew and algea with on shingle and tile roofs.
I was told that I can add Sodium Bromide to my mixture to make it clean better.

The sodium hypochlorite can kill plants, and I was told that Calcium Hypochlorite would be better to use.
Problem is, it is not as good a cleaner.
Could the Calcium Hypochlorite have sodium bromide added to it to equal the cleaning effectiveness of Sodium Hypochlorite ?
I think the sodium in the Hypochlorite is killing the plants.
 

[ARGOS++]

Dear Ka7niq,

I’m not able to tell you which of all Mixtures may be the best cleaner at all, but you are definitely wrong with “your” these about sodium should kill the plants.

It is the contrary; the “Hypochlorite” will be the real killer with its quite strong oxidative power that kills “nearly all life” (Chlorine in “stati nascendi”).
In History the “Hypochlorite” was the ‘first known’ disinfection agent.

Good Luck!
                    ARGOS⁺⁺

[ka7niq]

Dear Ka7niq,

I’m not able to tell you which of all Mixtures may be the best cleaner at all, but you are definitely wrong with “your” these about sodium should kill the plants.

It is the contrary; the “Hypochlorite” will be the real killer with its quite strong oxidative power that kills “nearly all life” (Chlorine in “stati nascendi”).
In History the “Hypochlorite” was the ‘first known’ disinfection agent.

Good Luck!
                    ARGOS⁺⁺

Thanks for reply.
Posted a similar question about killing plants in a Botany forum.
Was told by a Botanist that Sodium Hypochlorite kills two ways.
1 - By cellular degeneration when the oxidizer contacts the cells of the plant
2 - By Sodium Posioning of the soil.

Now, we have covered plants to protect them, but left the cleaning solution on the roof.
When it rains, the plants suffer.
I was told that the Chlorine in the Sodium Hypochlorite evaporates, and salt remains.
And it is the Salt doing damage.
That is why the Botanist advised we use Calcium Hypochlorite instead.

Your thoughts ??

[Borek]

It is a dose that makes poison.

Once sodium hypochlorite is decomposed what is left is NaCl. Depending on the amount of hypochlorite used, amout of NaCl can be killing or not (note that NaCl is the main salt present in the sea water; you never use salt water to water your plants - we are talking about the same problem here). Calcium hypochlorite will left CaCl₂ in soil - and for sure its presence is not neutral to the plants. To make things more complicated CaCl₂ will probably react with sulfates from the soil and with the carbon dioxide present in the air, creating solids - that'll remove calcium, but how fast, and at what cost to the soil (lowering pH perhaps) - I have no idea.

How much hypochlorite do you use on one site?

[ARGOS++]

Dear Ka7niq,

When I answered you, I did not know, that in your case the “Hypochlorite” would attack the roof for such a long period.

But in this case I agree absolutely with Mr. Borek, that the Concentration of all kinds of salts are causing the ground plants to suffer.

You can minimise that your plants suffer, if you strongly water your plants as soon as the rain will wash all the salt from the roof.
(As Mr. Borek told already several times:  The Concentration is making the poison!)

Good Luck!
                    ARGOS⁺⁺

[ka7niq]

The problems come when it rains.
If it is a really good rain, no problems.
But a slight rain can cause problems.
IS there a way to increase the cleaning power of the Hypochlorite so less Sodium will be left behind ?
How about the addition of Sodium Bromide, what will this do mixed with Sodium Hypochlorite ?
How about acidifying the sodium hypochlorite, bring the ph down, clean with less ?

[ARGOS++]

Dear Ka7niq,

A little simple spoken: That’s all counterproductive!

You are right! that a slight rain will cause much more problems then a “good” rain.
But what is left behind is not Sodium, - it is Sodium Chloride what has not a significant increase on pH.

Additional Sodium Bromide may very slightly increase the cleaning effect, but the corresponding very significant increase of the Salt Concentration can’t be compensated in any way.

To lower the pH is also very bad work, because nearly all Grounds are tooo low in pH because the air pollution we have.
That’s also why everybody spends so much lime to all his lawn at spring time.

So there is only one recipe left:
As soon as rain brings the salt to the ground dilute the water from the roof as much as you can by additionally watering your plants. 
And - It is the smallest influence you are able to do.
You know how much water you can spend for that.
(Or collect the water from the roof and let it dry!)

Good Luck!
                    ARGOS⁺⁺

[ka7niq]

Sodium Hyopchlorite cleanes I am told by releasing hyperchlorous acid.
I was told this reaction was more favorable at lower PH ?
So, is it possible/practical to lower the PH of the Hypochlorite/water solution ?
What shall I use to minimise the release of chlorien Gas ?
Is there any way to tell if sodium bromide will make the hypochlorite stronger, and if so, how much ?

[ARGOS++]

Dear Ka7niq,

Sorry! – It seems you have misunderstood quite a Lot of things!

From its production process “Sodium Hypochlorite” contains only Water, Sodium Chloride, and Sodium Hypochlorite (and maybe some minor impurities).

The Solution is also NOT very stabile above pH 8 and get absolutely instable below pH 7! (The Chlorine Gas you can smell!).
So lowering the pH significantly (with HCl for Example) will immediately release ALL Chlorine of the “Sodium Hypochlorite” and it would lose in the same moment all its cleaning power at once. I don’t believe it’s what you want.
Quintessence: 
Not the “Hypochlorite Acid” is the cleaning agent, but the over time generated Chlorine in “stati nascendi” is doing the real job.
From this it follows too, that to avoid the release of the Chlorine gas is absolutely useless and  counterproductive too.

Nearly “all” chemical rules will tell you, that any addition of Sodium Bromide (SB) will have no effect, because it will not do any reaction with any part of the “Sodium Hypochlorite”.
(SB is a very close relative to Sodium Chloride, your “Table Salt”.)
The only effect it has is that it increases the total strength of Ions, and that has a positive effect for cleaning your Laundry in the Clothes Washer.

I hope now I have made a few things come more clear.

Good Luck!
                    ARGOS⁺⁺

[ka7niq]

Here is where I got the Bromide idea to make the hypochlorite stronger http://www.freepatentsonline.com/4755354.html

[ARGOS++]

Dear Ka7niq,

Thank you very much for the reference to the patent.
(It’s a quite interesting fact!)

But the presented information is not in any contrast to what I have told you till jet.
Recognising the Info and also the Language in the Patent it is telling that it's quite sure NOT a chemical Effect, because in my knowledge Bromine in “stati nascendi” is a less strong oxidising agent then the Chlorine in “stati nascendi”.

The possible “Activation” (the word of the Patent) and the Explanation gives me the imagination (Sorry! - they hide some information) that it is a similar physical Effect as the Ion strength, only with the Effect/Result that it may stabilise the  “stati nascendi” for a longer period what results in a better/longer “bio-availability” of the Chlorine in this particular state.
But it is still in all cases the Chlorine in “stati nascendi” that acts as the cleaner.

If you would try to have a similar Effect you have to keep in mind that you “surely” will work in a quite different (higher) Concentration-Range!
The Patent uses 20 – 100 ppm Chlorine (= 40 – 200 mg “Hypochlorite” per Liter Water), and that is in my opinion less by some factors as your application.
I don’t know if the “Activation” effect will still remain, and if how strong (There is no information about in the Patent.).

If the Effect remains you would at least be able, because you need only catalytic amounts of Sodium Bromide, to lower the concentration of the required “Hypochlorite”, what would be a good “present/work” for your plants, because it reduces the total amount of “generated Salts” (I hope.).

Thank you once again for the interesting reference.

Good Luck!
                    ARGOS⁺⁺


P.S.: REMEMBER! that you take care NOT to lower the pH of the  undiluted “Hypochlorite”, as already Explosions and Fires as result were told!!
.

[ka7niq]

I found this on Google.

Sodium hypochlorite (NaOCl) is a chemical compound consisting of sodium, oxygen, and chlorine that has been used for centuries for bleaching and disinfecting. Today, sodium hypochlorite (commonly called chorine bleach) is mass produced by the chlorination of soda ash and is employed in many household products, including laundry bleaches, hard surface cleaners, mold and mildew removers, and drain cleaners.

Sodium hypochlorite is the salt formed by a negatively charged hypochlorite ion (OCl-) and a positively charged sodium ion (Na+). Pure hypochlorite is highly reactive and unstable; therefore, it is usually supplied as a dilute aqueous solution. In solution, hypochlorite eventually decomposes to yield a variety of byproducts including oxygen, chlorine gas, and salt. One of these byproducts, hypochlorous acid, is a powerful oxidizing agent (meaning it can accept electrons from other materials) that lends hypochlorite excellent bleaching and disinfecting abilities. The term "available chlorine" is often used to describe the concentration of hypochlorous acid in solution (which provides a measure of the solution's oxidative ability).

Due to its reactive nature, hypochlorite is particularly sensitive to the presence of trace metals such as copper, nickel, iron, chromium, cobalt and manganese that catalyze its decomposition. In fact, it is so reactive that it will aggressively attack many materials, including rubber, most types of fabrics, and certain plastics. Therefore, care must be taken in handling and storing hypochlorite solutions; all vessels should be glass, PVC plastic, porcelain, or glazed earthenware.

[ARGOS++]

Dear Ka7niq,

Sorry Ka7niq! – But your cited Article contains noting new, not even the mistakes they have written therein!

As nearly every Chemist knows, that at pH >> 8 the concentration of H₃O⁺ is “less” then Zero so the following Reaction:  H₃O⁺ + OCl^-  <====> H2O + HOCl  is impossible. But this would be an indispensable precondition that the solution can contain Hypochloric Acid (= HOCl).
Such is only possible below pH 7, where the instability increases dramatically, especially in such concentrations.
Quintessence:  The term "available chlorine" is often used to describe ONLY the THEORETICAL concentration of hypochlorous acid in solution.

Also the sometimes published Disproportion Reactions is not absolutely to believe, because the absolutely enormous oxidising power is still working above pH 10, what is also an argument against that postulate.

But believing the Hypochloric Acid hypotheses has at least one good thing in that you know, that you have to be very carefully in handling it, and that lower pH can be of very danger depending on Concentration.

I hope this may help anyway.

Good Luck!
                    ARGOS⁺⁺

[ka7niq]

Would it be safe to say Argos that Hyperchlorous acid is what does the cleaning, and that it's formation is better at lower Ph's ?
I realize that dropping the PH can be dangerous if dropped below PH of 8.
But is there a safe way to drop it a few points ?
Would Borax work for this ?

[ARGOS++]

Dear Ka7niq,

I realise that we may nearly never agree about the reacting “particle” in the “Sodium Hypochlorite”, and that lowering the pH will not surly make it stronger.

Apropos: THEORETICAL concentration of hypochlorous acid:   This term is only meaning how much "available chlorine" you would get, if you could be able to generate from every “Hypochlorite Ion” the corresponding “reactive chlorine".
But remember it’s only theoretically!

There is a save way to lower the pH not only a little bit, - NO you can lower it very much, if you like, BUT I’m not sure you are able to realise it !!!!!

To do it safely, – lower the pH a Lot – you have to do it on the “diluted Side” and NOT on the “concentrated Side”. Do you understand how it MUST work!

At least the recipe:

• a.)   In the first mixing chamber you dilute the “Hypochlorite” to the final application concentration as you did it till jet.
• b.)   Now the whole mixture passes a second mixing chamber wherein you now adjust the pH to the value you would like.
• c.)   The pH adjusted mixture you can now release through the “Jet” to your roof. Keep the way very short between second mixing chamber and the “Jet”.

Is now all clear?  – But I’m not sure you will got the effect you like or if you only destroy a lot of your “Hypochlorite” content.

On the “concentrated Side”: Please take very much care with EVERY chemical you add!
Read first several “Safety Data Sheets” (Not Wikipedia) about “Hypochlorite” on the Internet!

Good Luck!
                    ARGOS⁺⁺