Urea in low fume muriatic acid?

[mgtfp]

I was curious about what makes low fume MA low fume, apart from lower HCl concentrations, and looked up some data sheets to find out about the contents.

One example I found was "Green Envy Muriatic Acid". In their product use, swimming pools are explicitly included.

When looking into the data sheet, they list the following add-ons to HCl:

Ethoxylated Amines
Urea
Citric Acid

Urea and Citric Acid are certainly things I don't want to add to a pool, and "Ethoxylated Amines" also sounds like something that would create CC.

I can only assume that the concentrations of the above ingredients are miniscule, and therefore don't create practical problems, but I'm curious if anyone has looked into that.

 

[JoyfulNoise]

Urea is one of the simplest carbonyl amine in organic chemistry - CO(NH2)2. Chlorine will oxidize it into carbon dioxide gas, monochloramine and then finally nitrate or nitrogen gas.

Citric acid is a simple tricarboxylic acid. It tends to get oxidized into chloroform but does so rather slowly. Eventually it turns into carbon dioxide.

Ethoxylated amines are used as surfactants and surface tension modifiers. They are usually manufactured using fatty acids. Depending on exactly which one is used, it will sit on the surface of a fluid and act like barrier. This is why the “No Fume” doesn’t have much of an odor. However, if you shake it up and disturb the film layer, you should get some smell.

The citric acid and urea are likely used as scavengers in the mixture to protect the surfactant from chemical oxidation and acid hydrolysis. Muriatic acid often has trace metal impurities like iron and nickel in it from the manufacturing and storage processes. Those trace metals can catalyze polymerization reactions that would cause the surfactant to precipitate out and cause cloudiness.