Sunday, April 19, 2015

Distilling pure anhydrous ammonia

I have a few upcoming projects that require anhydrous ammonia. In this video, I show how to distill it from "ammonia water" similar to common glass cleaner.
http://en.wikipedia.org/wiki/Birch_reduction
http://www.engineeringtoolbox.com/ammonia-pressure-temperature-d_361.html



9 comments:

  1. Saw youtube comments, this stuff is really nasty, but please don't mess with something ├╝ber bad like HF

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    1. I have %49 HF in my shop, and have used it regularly to make etch solutions. I wouldn't take a shower with the stuff, but it really doesn't deserve the reputation that is has gained for being some kind of spooky dangerous stuff.

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  2. I have to disagree with you on this one Ben,

    I was a chemist before medicine and would argue that HF has earned every bit of it's bad reputation. If you work with HF and don't follow the basic rules for that particular substance, you are asking for serious trouble. One thing in particular is Calcium Gluconate Gel. You need this on hand anywhere HF is stored or used. The Fluoride ion is both cardio and nephrotoxic. A surface burn penetrates very deeply, often without obvious or apparently significant injury. The chronic end game is renal. The acute endgame is sudden cardiac death. Really :)

    Please respect HF. We can't afford to have you on the disabled list :)

    Doug

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    1. Doug, I agree that the chemical is dangerous, and it requires special handling. The reason that I believe it to be less dangerous than explosive, pyrophoric, corrosive, and rapidly fuming chemicals is because there are lots of incident reports regarding those types of hazard, but I cannot find many documented cases of HF exposure and consequences. I found a report of a worker who was drenched from an overhead pipeline of HF. Yeah, that was bad. I also read about a worker at a car wash who used HF wheel cleaner without gloves. Her fingers were quite damaged indeed, but she survived apparently without threat to her life. I spent hours looking for more detailed accounts of HF accidents. Have you seen any reports of death or systemic injury resulting from exposure to HF in lab quantities (ie a liter or less)?

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    2. The short answer is: Yes,
      Here is a little from the National Library of Medicine.

      /SIGNS AND SYMPTOMS/ INGESTION OF EST 1.5 G OF ... ACID PRODUCED SUDDEN DEATH WITHOUT GROSS PATHOLOGIC DAMAGE. ON OTHER HAND REPEATED INGESTION OF SMALL AMT OF HYDROFLUORIC ACID ... RESULTED IN MODERATELY ADVANCED ... OSTEOSCLEROSIS ... THUS HYDROFLUORIC ACID ... CAPABLE OF INDUCING SYSTEMIC MANIFESTATIONS OF BOTH ACUTE & CHRONIC ... POISONING. ... ADDITIONAL HAZARD ... CORROSIVE ...
      [Gosselin, R.E., R.P. Smith, H.C. Hodge. Clinical Toxicology of Commercial Products. 5th ed. Baltimore: Williams and Wilkins, 1984., p. III-190] **PEER REVIEWED**

      /SIGNS AND SYMPTOMS/ Hydrofluoric acid is an irritant to the mucosa of the upper and lower portions of the respiratory tract. As in ocular tissues, concentrations as low as 5 mg/L (5 ppm) may produce irritation to the nasal mucosa. When hydrofluoric acid is present in concentrations greater than 48%, the solution fumes, adding to the volatile airborne fraction. Mucosal edema, bronchospasm, bronchorrhea, wheezing, atelectasis, and airways obstruction may result. A chemical tracheobronchitis or pneumonitis, either of which may be hemorrhagic, and pulmonary edema may follow. Onset of signs and symptoms may be immediate, with death reported in as little as 30 minutes after exposure, or they may not appear for several days. Symptoms in survivors may be sustained for greater than 1 year.
      [Haddad, L.M. (Ed). Clinical Management of Poisoning and Drug Overdose 3rd Edition. Saunders, Philadelphia, PA. 1998., p. 814] **PEER REVIEWED**


      /CASE REPORTS/ Two accidental deaths from hydrofluoric acid (HF) overexposure /are described/. The two workers were splashed with hydrofluoric acid when a bottle containing the acid exploded. They were immediately showered and transferred to a distant hospital. On examination, one worker showed no respiratory distress or pain. Burns of various size and degree covered 15% of the body surface. Except for a moist cough and a few wheezes in the chest, he was doing well until sudden respiratory distress occurred about 4 hours after the accident. He died soon afterward. Autopsy findings revealed dilatation of the heart and an acutely inflamed bronchial tree with partially ulcerated mucosa. The lungs showed severe hemorrhagic edema.
      [Greendyke RM, Hodge HC; J Forensic Sci 9: 383-90 (1964) as cited in NIOSH; Criteria Document: Hydrogen Fluoride p.44-5 (1976) DHEW Pub. NIOSH 76-143] **PEER REVIEWED**

      The National Library of Medicine Search gave me these and more are at the link located below.

      http://toxnet.nlm.nih.gov/cgi-bin/sis/search2/f?./temp/~EZ4oDV:1

      I would add the caution that toxicological "cause and effect" are notoriously unreliable BUT, the evidence becomes more compelling when the details are consistent with a known mechanism of action ie hypocalcemia due to Fluoride Ion exposure.

      Of course I often get accused of "fear mongering" in these sort of things. Hopefully that's not how this is coming across. I've used HF in the distant past: anything can be handled "safely" but that doesn't eliminate intrinsic risk. In my opinion, HF has a lot of intrinsic risk.

      I agree with you though that this is hardly a "spooky" chemical! :)

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    3. Here is a link to an article that cites some useful information about HF toxicity. there is a fairly recent Occupational Exposure Death from Australia.

      http://ehs.unc.edu/environmental/docs/hydrofluoricacid.pdf

      As a general rule, when numerical limits are cited, they are based on "best evidence" rather than "SWAG" reports ie scientific, wild-assed guesses which the internet is rife with. :)

      Doug

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  4. The other thing, just as a follow up is that even if there is only a possibility of HF exposure, that needs to be mentioned in the Emergency Room (and the prudent thing to do is to err on the side of caution and to go to the ER) as soon as you get there is that that Hydrogen Fluoride exposure is possible/probable/definite.

    The topical treatment for HF burns is immediate application of topical Calcium Gluconate Gel. The systemic treatment is IV Calcium Gluconate plus supportive care. If the absorbed F ion level is too high, the die, as they say is cast. The treatment at that point is symptomatic. What will be, will be :(

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  5. I worked at a lab that used HF at a near-industrial scale. They had annual simulated emergency exercises, and one of the points was to train the local emergency room to have Calcium Gluconate available, and know how to use it. I was there for over a decade, everyone treated HF with respect, and never got hurt (well... not hurt enough for me to know about, at least).

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