Increasing Dissolution Speed of Bromine in Water

[iori8sun]

I have mixed ammonia with BCDMH granules and resulted with 9% Br solution however for reasons i wont go into i am looking for alternative easier methods of production Br solution using BCDMH granules or powder.

I have also tried mixing with caustic soda but find it to dangerous, do any of you experts here provide me with advice to mixing ratios etc.. I m loooking into using Cal Chloride as another means of production do you think it would be possible.?

And how can i stabilize the bromine as im looking as a source to replace sodium hypo for pool sanitation.

 

[JohnT]

And how can i stabilize the bromine as im looking as a source to replace sodium hypo for pool sanitation.

You can't. That's why bromine is primarily used in indoor pools.

 

[Guest]

I have mixed ammonia with BCDMH granules and resulted with 9% Br solution however for reasons i wont go into i am looking for alternative easier methods of production Br solution using BCDMH granules or powder.

A 9% solution of exactly what chemical and how did you arrive at the 9%?

I have also tried mixing with caustic soda but find it to dangerous, do any of you experts here provide me with advice to mixing ratios etc.. I m loooking into using Cal Chloride as another means of production do you think it would be possible.?

What exactly are you trying to acheive here since this is NOT the way bromine is used to sanitize a pool or spa?


And how can i stabilize the bromine as im looking as a source to replace sodium hypo for pool sanitation.

Bromine cannot be stabilzied againt UV loss, that is one of it's downsides. Are you trying to use bromine in a liquid feeder? Won't work because bromine needs both the bromide ions added to the water AND an oxidizer to conver them to hypobromous acid, your active bromine sanitizer.

I am net really sure what you are tying to accomplish here and I am fairly well versed in bromine sanitation chemistry (and chemistry in general).

When you say you are trying to produce a Br solution what is the actual chemical you want in solution? (I hope you are NOT trying to produce liquid elemental bromine! )

 

[chem geek]

First off, welcome to TFP!

A related question was put to me in a PM as follows:

... can you give me any advice in increasing the dissolution of BCDMH into Br solution? Likewise is there anything i can do to stabilize the solution for use as a liquid like sod. hypo.

I respond to that here as follows:

Normally BCDMH or DBDMH tablets/pucks are put in a floating feeder so you increase their rate of dissolving by opening up the feeder slots so that there is more water flow. They are also designed to work in hot water so the water should remain warm by keeping a cover on the tub when not in use.

If you just want to increase the bromine level, you simply shock with chlorine (such as unscented bleach) or with non-chlorine shock (MPS) assuming you have a sufficient bromide bank (if not, you can add sodium bromide). The BCDMH or DBDMH are only necessary if the bromide bank is low -- they are mostly a convenient way of adding bromine and chlorine (for BCDMH; for DBDMH this only adds bromine) since they are slow-dissolving tablets. See this article in the Pool School for more info on bromine.


Additional comments:

I'm also not sure what is trying to be accomplished here. Is this for some experiment or for actual pool or spa use? From the first post it sounds like this will be for a pool, but why is bromine going to be used in a pool replacing sodium hypochlorite? You can't stabilize bromine to protect it from breakdown from sunlight -- it will last longer than chlorine in a pool with no CYA, but not as long as chlorine in a pool with CYA. I suppose that having CYA in a bromine pool might help shield lower depths from the UV in sunlight, but no one has tried that and it wouldn't protect water near the surface. CYA does not combine with bromine so the protection effect would certainly be far less than with chlorine.

Also, mixing ammonia with a bromine solution (from BCDMH) doesn't make bromine, but rather bromamine -- that is bromine combined with ammonia. Also, calcium chloride has nothing to do with production of bromine so I'm unclear as to why that is being considered.

It sounds like maybe you are trying to make a "concentrated bromine solution" analogous to chlorinating liquid. That's not how you normally add bromine to your pool. You could add sodium bromide to the pool and then add chlorinating liquid to activate it to bromine. Chlorine added to a pool with bromide in it will convert the bromide to bromine (and the chlorine gets converted to chloride). However, that doesn't eliminate the regular required addition of chlorinating liquid to the pool, if that's what you were trying to avoid (and I'm not sure why, since adding a bromine solution would be just as much effort). If you didn't want to have to regularly add a solution to the pool, then you would use BCDMH in a floating feeder if there is such a thing for pools (the water is colder so it dissolves more slowly). I don't understand why you want to use bromine in your pool -- perhaps you could start by answering that question.

Richard

 

[iori8sun]

Im trying to use Br as a replacement to Cl for a poorly ventilated indoor pool.


Adding an erosion feeder is out of the question since equipment would have to come by plane, floating feeders wont work for us since the pool size we are talking about is around 500m3.
As such im trying to stay with the equipment i have to feed bromine.

As CG has been saying im trying to make a concentrated Br solution. The use of calcium chloride is really to increase the thermal decomposition of BCDMH granules in the feed tank so would this be possible.?

As with the process of making 9% Br here goes as follows:
1.Mixing of 28% BCDMH to 72% Carbamide
2. Then adding BCDMH & Carbamide mixture into double its weight of water in 40 - 45 Celcius
End Result - Approx 9% Br Solution.

Havent been using my eng. that much these days so pls do bare with me.

Can any of you experts provide me with a solution?

Nonetheless does anyone of you have experience with DCDMH? or DCEMH? What are its properties and benefits?

Thanks

 

[iori8sun]

As with the use of sodium bromide and sod. hypo mixture will it cause cyrstalization of salt around the pool premises?

Can i just chuck sodium bromide into a 12% Sodium Hypo solution instead? Will mixing Cal Hypo and Sodium Bromide in feed tank work?


thanks again

 

[Guest]

Bromine chemistry is different than chlorine chemistry so you cannot use a 'bromine solution' like you would sodium hypo. Switching to bromine will not necessitate improve air quality if the air handler is not sufficient for the pool. The easiest way to convert the pool to a bromine pool would be to add sodium bromide to the water to create a bromide reserve and then use sodium hypochlorite to convert the bromide ions in the water to hypobromous acid. Usually 3 lbs sodium bromide are added per 1000 gallon of water in the pool to create the bromide reserve.
The only reason to use brominated/clorinated hydantoins is because they are slow dissolving and are used in an erosion feeder. If you are not using a feeder then the sodium bromide (aka 2 step bromine system) directly in the pool and then oxidizing with chlorine or MPS (and possibly ozone) is what you want to do.

 

[Guest]

As with the use of sodium bromide and sod. hypo mixture will it cause cyrstalization of salt around the pool premises?
The amount of sodium bromide needed to create the bromide reserve is small. Much smaller than the salt levels used in SWGs for example and thee should be no crystalization of salt (which normally is not noticed with SWGs either.)

Can i just chuck sodium bromide into a 12% Sodium Hypo solution instead? Will mixing Cal Hypo and Sodium Bromide in feed tank work?


thanks again

No, you are not understanding bromine chemistry. It is not the same as chlorine chemistry. The bromide reserve has to be established in the water. This is done by adding sodium bromide. The bromide ions are then oxidized to hypobromous acid (active bromine santizer) by the addition of an oxidizer such as clorine (in any of it's forms), MPS, or ozone. Hypobromous acid, per se, is not added directly to the pool.
Once the bromine sanitzer is 'used up' by oxidizing contaminants in the water it reforms bromine ions that can, again, be regenerated into hypobromous acid by the addition of more oxidizer (chlorine, MPS, or ozone). The bromine in the water is a 'renewable resource' so to speak.

 

[iori8sun]

Only problem i have in question regarding use of Sodium Bromide is wether it will
- How it would effect the copper and iron fittings within the system (corrosion)?

Is it possible that i add add a solution of sodium bromide and further downstream in the piping dose sodium hypo? I notice this is recommedned practice with cooling towers sodium bromide application, can you explain the needs in the differences of the dosing techniques for pools?

 

[Guest]

As such im trying to stay with the equipment i have to feed bromine.
Posting your equipment would be helpful!

As CG has been saying im trying to make a concentrated Br solution. The use of calcium chloride is really to increase the thermal decomposition of BCDMH granules in the feed tank so would this be possible.?
BCDMH contains both bromine and chlorine. It is also slow dissolving so it is ideal for erosion feeders (as opposed to sodium bromide which is very fast dissolving and just dumped into the pool all at once to create the bromide reserve). The bromine builds up the bromide reserve in the water and the chlorine then oxidizes the bromide into bromine sanitizer as the BCDMH dissolves...often called a 1 step bromine system. However, until enough bromide ions build up in the water the only sanitizer that is present is the chlorine! This is why sodium bromide is added to start the bromide reserve, even with the brominated hydantions.

As with the process of making 9% Br here goes as follows:
1.Mixing of 28% BCDMH to 72% Carbamide
2. Then adding BCDMH & Carbamide mixture into double its weight of water in 40 - 45 Celcius
End Result - Approx 9% Br Solution.
Carbamide (urea peroxide) is an oxidizing agent that will effectively convert the bromide ions from the dissolved BCDMH into hypobromous acid. However, realize that this is not stable and will quickly decompose. That is why bromine sanitizer is created in situ instead of added directly like chlorine.

Carbamide is not one of the oxidizers normally used in bromine systems so I really cannot comment on whether it would be effective or safe to use in a pool. Personally, I would not recommend it.

Havent been using my eng. that much these days so pls do bare with me.

Can any of you experts provide me with a solution?

Assuming you have some sort of feeder for liquid chlorine (sodium hypochlorite), I would just add the sodium bromide to the water and continue to use your current chlorine feed system and adjust it to maintain your total bromine levels at about 4 ppm. Bromine still has the problem of volatile oxidation byproduct formation, much like chlorine, so I really don't know how much it will help with your air quality if you do not have a suitable air handler on the pool.

Nonetheless does anyone of you have experience with DCDMH? or DCEMH? What are its properties and benefits?

Thanks

Both DCDMH and DCEMH are chlorine sources that are not commonly used in pools in the US so I cannot comment on them. They are not used in bromine sanitation of pool water since they contain no bromine.