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Need info on bromate/free bromine waste treatment

 

I am looking into a bromate based de-oxidizer for aluminum cleaning prior to anodizing and chem-filming. Is anyone familiar with treatment of bromate/free bromine in wastewater. The Tech Data Sheet mentions using sodium bisulfite for destruction, but I would like to know some specifics, like proper pH, ORP values (if applicable), alternate treatments.

Thanks,

Guy Lester
plating co. - Ontario, California, USA

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Bromine is a strong sanitizing agent that is difficult to break down by chemical reductants. It would be unlikely that any chemical processing solution would contain it, as it has a relatively low life in water. On the other hand, bromate is readily reduced by several methods.

I'm not certain about the use of MBS, but we could assume that it works. A non-additive method that would work is also granular activated carbon, UV light, and the use of ferrous sulfate ⇦this on eBay or Amazon [affil links] . I'm not certain why you would want to use a brominated solution for de-ox however, for the safety issues involved. Bromate (sodium and potassium) is a known carcinogen at extremely low levels, and the relative smallness of the ion itself allows for rapid skin absorption. I think I would look at the MSDS VERY carefully before I looked at putting it into play.

Tom Baker
wastewater treatment specialist - Warminster, Pennsylvania

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Hi Tom,

I was surprised to read about the carcinogenic properties of bromate, which MSDS had that information. One MSDS I found on the web must have old information.

Bromine is a strong oxidizer, wouldn't it, by definition, be reduced when the Bromine gains electrons?

The bromine atom is larger than the chlorine molecule, smaller than iodine. I know that iodine is absorbed through skin, although I am not sure exactly why this happens.

  
Tom Pullizzi
Falls Township, Pennsylvania

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Hi Tom - back!

This has been as recent as 2000 - 2001. The EPA identified bromates as a suspected carcinogen as early as 1990 from studies on potable water sterilization using ozone, which on water that contained bromides exhibited some carcinogenic characteristics. Quite a bit has been done in the last two years because of the increase in municipal water systems using ozone as a sterilization agent in lieu of the use of chloramines.

Mr. Lester, being in California, should be aware that the State of California Environmental Protection Agency, OEHHA has submitted bromate as a carcinogen to Proposition 65 in August 2000, which covers compounds that are identified as carcinogenic by one of 5 authoritative bodies and therefore recognized as such under CA Code 22CCR 12036 (1)(c)(d). Most of the studies show the bromate to be carcinogenic in water if ingested, however further tests have also shown that mutagenic effects do occur on a cellular level and that a route of exposure is through the skin. I don't think that most of the chemical manufacturers have yet been told they must identify the compounds as carcinogenic, but that does not mean that states don't regulate them as such.

I know there is quite a bit of brew ha ha in CA about OEHHA or O HEE HAW as they call it, and suspected carcinogens, like nickel and chrome. But I'm only suggesting that he evaluate the issue before he leaps.

Tom Baker
wastewater treatment specialist - Warminster, Pennsylvania

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I also find this surprising I thought that spa pool chemical suppliers use bromine for sanitising in pref to chlorine because of better stability at temperature. If what you say is true the lawyers should have a ball with the number of people who have been soaking themselves in it over the years.

Geoffrey Whitelaw
- Port Melbourne, Australia
 

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The difference is BROMINE vs. BROMATE. They are NOT interchangeable and they are NOT breakdown products of either. Please do not confuse the two.

Tom Baker
wastewater treatment specialist - Warminster, Pennsylvania
 

Hi Tom,

BrO3- (aq) + 5 Br- (aq) + 6 H+ (aq) => 3 Br2 (aq) + 3 H2O (l)

Langford and Parker, Analysis of Electroplating and Related Solutions [on on Amazon, ... on AbeBooks affil links] page 14, says that iodate and iodine are interchangeable for some titrations, because potassium iodide and iodate react, in the presence of mineral acids, to give free iodine, which the above equation does for bromate - bromide.

  
Tom Pullizzi
Falls Township, Pennsylvania

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"..in the presence of mineral acids..."

You have added a new condition - which unless you have warped sense of smell and feeling, spas do not usually have mineral acids in them.

Bromine and bromate ARE different - bromine can be as an element, BR or as a gas, Br2. Bromate is a stabilized compound that has reacted with a positively charged ion, such as potassium or sodium, and it scavenges oxygen atoms to balance it's outer shells.

Sublimation of the iodine via acidification doesn't count, and iodine, being the least stable of the halogens, is not the same as bromine, Tom. If you subject bromine to a strong mineral acid, you will actually make hydrogen bromide, and that's about all:

KBr(s) + H2SO4(l) ----> KHSO4(s) + HBr(g)

In your iodine reaction, there is actually a two step reaction, where the second step after you have made the hydrogen iodide, is such:

8HI(g) + H2SO4(l) ----> 2I2(s) + H2S(g) + 4H2O(l)

The reaction carries further because HI is a stronger reducing agent than HBr, and it reacts more completely with the oxidizing agent in sulfuric acid.

Your equation may balance, but that does not mean its works anywhere but on paper.

Tom Baker
wastewater treatment specialist - Warminster, Pennsylvania

Hi Tom,

That reaction does work; of course the pH is optimized to release all the bromine or iodine as the Br2 or I2, when you are using it to brominate a triple bond in an iodine flask. At higher pH, the reaction will proceed much more slowly, but I believe that some free Bromine, even if it is parts per million, could be released at neutral pH.

This question is about wastewater treatment, but a few ppm of bromine in a spa would have some sanitizing properties, being a strong oxidizer.

  
Tom Pullizzi
Falls Township, Pennsylvania

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April 28, 2009

Dear Mr Baker

It has come to my attention that a bromate pollution has taken place from a factory that was sited over a deep ground water course. The polluted water has travelled through the fissures of the ground and and is pumped up from the wells into a canal. This canal wends its way some 25 miles to water treatment plants. After treatment the water is fed into the public drinking water system. The deep ground water also surfaces via natural springs into marshes.
The density of pollution at the point where the water surfaces and the deep wells that the water is pumped out of, is stated as 50 ug/l. I have been informed that to meet current EU regulations for drinking water is 10 ug/l. I have also been informed that the company dilute the water from other sources. I have also been informed that the purification process creates bromate. My question. If the bromate level is already approximately 17 times regulation levels how can it be diluted with water that contains bromate from the purification process.

Bill Hammett
- ware hertfordshire U.K

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Q. Hi every one,
Can any one suggest me how to detect bromate in water using simple and low cost procedure???

Kogul
Quality controller

Kogul
- Ajman, Dubai
March 11, 2012

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