Re-inventing the chlorine tablet?

woodyp

Mod Squad
TFP Expert
LifeTime Supporter
Apr 17, 2010
10,491
East Texas
Yes. The insurmountable financial loss to the pool industry from not being able to sell you everything under the sun.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
Yes. There are very significant problems from a chemistry point of view. Chlorine is very reactive and there are very few known ways to stabilize it enough to be safe for transport and handling. All of the know reasonably stable compounds containing chlorine have disadvantages and only one can be formed into tablets that dissolve slowly without becoming either explosive or ineffective.
 

JesseWV

LifeTime Supporter
Apr 26, 2011
526
North Central WV
If it's a component of air that reacts with un-stabilized chlorine, perhaps a gel based tablet would work?

JasonLion said:
Yes. There are very significant problems from a chemistry point of view. Chlorine is very reactive and there are very few known ways to stabilize it enough to be safe for transport and handling. All of the know reasonably stable compounds containing chlorine have disadvantages and only one can be formed into tablets that dissolve slowly without becoming either explosive or ineffective.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
The primary pure solid form of chlorine at reasonable temperatures, which is chlorine hydrate, can form from chlorine gas and very cold water and forms on the surface of ice, but it melts below room temperature and releases chlorine gas so is not suitable. A gel wouldn't help for that. It might work for something like lithium hypochlorite but that is very expensive. There are binders used to hold together Cal-Hypo, but they tend to leave a residue. The chemistry is tough. There might be some crystalline form of chlorine with something relatively innocuous, but it hasn't been discovered if it exists.
 

JesseWV

LifeTime Supporter
Apr 26, 2011
526
North Central WV
I am far from a chemist but stumbled upon an article that may or may not be relevant regarding stabilized chlorine. Would this Chlorinated Fullerene structure have acceptable solubility and oxidizing ability as current chlorinated cyanurates? It mentions that the substance is stable at STP for 30 days.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
Chlorine bound to carbon, as with these chlorinated fullerenes, isn't going to get released in water. Even if it did, it would leave carbon chain molecules behind. If one wants a carrier for the chlorine, then it should be something relatively innocuous that doesn't produce disinfection by-products. One can look for other chemical combinations such as magnesium hypochlorite, but that is like sodium hypochlorite in that it is only a diluted liquid. There is a solid dibasic magnesium hypochlorite, Mg(OCl)2•2Mg(OH)2 which adds magnesium hydroxide so would need substantial amounts of acid addition to maintain a stable pH.

It would probably be more fruitful to find a way to hydrolyze Cyanuric Acid into carbon dioxide, nitrogen gas and water without requiring chlorine to do so and to be able to do this in a controlled fashion. Either that or a way of physically removing Cyanuric Acid.
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,535
SW Indiana
brg88tx said:
yea, i can't believe no chemist in the world has been able to find a way to eliminate cya.
There is, and it used to be sold. It was excessively expensive though. Melamine, the reagent used for CYA testing, will form a relatively large crystal when combined with CYA, that can be filtered out of the water. There are health risks with the mixture though.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
The issue with using melamine is that it severely clouds the pool requiring a clarifier to clear it and, even worse, it is partly soluble at pool pH, roughly 20 ppm soluble, so it's always on the edge of looking cloudy and doesn't get completely removed. The CYA test uses a pH buffer to significantly lower the pH which causes the melmaine cyanurate to be effectively insoluble.

I've been thinking of ways where a melamine-like solid polymer with a lot of surface area might be able to capture CYA for physical removal. This would be similar to some products that exist that remove calcium from the water by entering into bags, precipitating/attaching there, and then the bag is removed. This will take a lot of money, research and time (and remember, this isn't my day job).