Sciencemadness Discussion Board - Working with lead compounds

Working with lead compounds

Refinery - 25-6-2020 at 11:20

When working with metallic lead and it's chemical derivatives which may or may not be water soluble, what general precautions and gear should be taken in order to minimize or eliminate exposure to lead? The most dangerous part of lead appears to be it's bio-accumulation, so even minimal amounts of exposure over time can cause health issues.

Exposure routes can be inhalation, ingestion and possibly transdermal route with low molecular weight water soluble compounds. Lead compounds have a very low vapor pressure and temps below 400C should produce insignificant amount of vapors, but solutions can splash, soak surfaces and dry forms will dust, which will fall on surfaces.

phlogiston - 25-6-2020 at 13:41

I use a combination of:
(1) Extra regard to lab hygiene. Work as cleanly and neatly as possible. Clean often.
(2) Use at least two layers of containment. I.e. if a container breaks, make sure the spill will be contained.
(3) think through/plan experiments well
(5) protective gear: gloves and a labcoat. Facemask that blocks aerosols possibly useful too, but I personally don't use them.

Also, after working with soluble lead compounds, I wet surfaces with a dilute solution of magnesium sulfate, which should convert small contamination that went unnoticed to nearly insoluble lead sulfate (which is less toxic than soluble lead salts). Then I clean with regular water to flush the magnesium sulfate away.

A problem that I noticed seems to be disregarded often is the formation of aerosols when bubbles break (e.g. during electrolysis, or when bubbles form in an acid when it dissolves something, or during boiling, etc).
When you dissolve something in acid or boil a solution, ever noticed the layer of tiny droplets that appears over time on the surface around the container? A common solution in the case of a beaker is to place a watch glass on top, but mist usually still escapes from the opening at the beak.

Ubya - 25-6-2020 at 14:53

i've recently worked with lead metal and salts, just yesterday i'm pretty sure i got quite of a dose of lead oxide vapours while trying to reduce lead oxides to the metal in a coal furnace.

if you need to boil down a solution containing lead ions, use an a distillation apparatus, beakers and flasks alone don't block the spray formed by popping bubbles.

i had to convert some soluble lead acetate to the carbonate, the solution was still acidic so by adding sodium carbonate the solution fizzed a bit. i used a flask and a liebig condenser mounted over it vertically, the droplets would appear below mid condenser, but not over, so i knew that i wasn't getting too much contamination in my workplace.

how to clean and deal with dirty glassware or surfaces?
for dirty glassware i used a bleach solution, it converts any soluble salt (even not so soluble lead chloride) to the oxides (colored dark brown)i would then filter or decant the now safe water layer and store the wet oxide for future use or disposal.
for surfaces i used moist paper towels to grab any particulates, and instead of throwing them i'm just keeping them in a bag, then i apply a dilute bleach solution to again form dark insoluble oxides, and then i wipe those (if i see any) the same way.

[Edited on 25-6-2020 by Ubya]

wg48temp9 - 25-6-2020 at 16:16

Quote: Originally posted by phlogiston

A problem that I noticed seems to be disregarded often is the formation of aerosols when bubbles break (e.g. during electrolysis, or when bubbles form in an acid when it dissolves something, or during boiling, etc).
When you dissolve something in acid or boil a solution, ever noticed the layer of tiny droplets that appears over time on the surface around the container? A common solution in the case of a beaker is to place a watch glass on top, but mist usually still escapes from the opening at the beak.

If your boil a solution containing sodium in an open beaker or better dissolve aluminium in sodium hydroxide solution in an open beaker in a small room. With a blue burning gas flame in the room you will see flashes of yellow in the flame as aerosol particles containing sodium enter the flame. Its a good visual demonstration of how easily an aerosol can contaminate the room and anyone in it.

woelen - 25-6-2020 at 23:13

When I have a solution of a toxic metal (which leaves dry toxic particles on evaporation) and I perform a reaction with it in which lots of gas bubbles are produced, then I cover the beaker, flask or test tube with a loosely fitting piece of paper tissue. The gas can easily escape, but the droplets are absorbed by the paper.
The same can be done, when boiling such solutions.

Cou - 25-6-2020 at 23:21

Quote: Originally posted by Ubya

if you need to boil down a solution containing lead ions, use an a distillation apparatus, beakers and flasks alone don't block the spray formed by popping bubbles.

in 2015, when I had much less chemistry education, I had a beaker full of a solution of copper ii sulfate and zinc sulfate, and I tried to recover the solids by boiling away all the water. I had it held in front of me the whole time.

That night I had severe chills, and I woke up in the morning with the most wicked flu in my life. Fever, cramps, chest pain, metallic taste in mouth, etc. I thought maybe I got "metal fume fever" from the mists of zinc compounds. Once the fever went away, I had a very runny nose and a metallic taste in my mouth for a week.

I still don't know if that was related to zinc exposure, or if I just got the flu by coincidence. I don't know if runny nose is a symptom of metal fume fever.

[Edited on 26-6-2020 by Cou]

nitro-genes - 26-6-2020 at 11:58

Working with large amounts of lead really isn't much fun, and Phlogiston pretty much summed up most of the precautions to be taken. Of course, best would be doing these things in a fumehood or downwind and outside. From what I've read, the half life of internalized lead salts for most soft tissues of the body is about 15 days. Not sure if the health damage resulting from very low levels of lead are also cumulative. If not, it seems another good precaution may be to limit the frequency of experimenting with lead salts and leave many months/weeks in between experiments involving lead salts.

Although definitely advisable, I'm not sure if gloves are a real necessity, especially if you wash hands frequently and immediately after working with lead salts. From what I've read, lead salts are not easily taken up by your skin, although some controversy seems to exist around this. Many people actually handle soldering tin without any notion that they are handling lead for which the oxide layer seems to come off very easily and contaminate your hands with lead salts. Sometimes it also seems that working with slippery gloves can seem more of a danger than just using bare hands.

From what I've read, aerosolization of lead salts (especially when using lead carbonate) is THE single most prominent danger of working with solutions of lead salts. Apparently, wheares only about 10-15% of any ingested lead salt is absorbed by the body, almost 40% of the lead that is inhaled as fume or aerosol is absorbed for adults, to an estimate of almost 80-100% for children. And aerosols are easily produced indeed. The most commonly used method for producing lead acetate is the hydrogenperoxide/acetic method as desribed here on SMDB. This method works great, though when used to make other lead salts can produce large amounts of aerosols. Not only if the acetic is neutralized using carbonates or bicarbonates, but also when using NaOH for the neutralization. When unreacted hydrogen peroxide is still present, the addition of NaOH will precipitate orange Pb3O4, which catalyses the extremely rapid decomposition of the remaining H2O2, producing large amounts of aerosols for example.

[Edited on 26-6-2020 by nitro-genes]

Refinery - 27-6-2020 at 08:10

Does it make difference in aerosol formation if the lead salt is soluble or non soluble to water?

Does passive evaporation also cause aerosol formation?

Ubya - 27-6-2020 at 12:23

Quote: Originally posted by Refinery

Does it make difference in aerosol formation if the lead salt is soluble or non soluble to water?

Does passive evaporation also cause aerosol formation?

if the salt is not soluble it is a bit better, but not by much, particles can still be carried over.

passive evaporation is safe, no popping bubbles

Refinery - 7-7-2020 at 11:29

Evaporation sounds good, then. And so, if concentration by boiling is performed, the liquid should be condensed and the system put under water trap to eliminate aerosols and particles.

wg48temp9 - 30-7-2020 at 03:02

Quote: Originally posted by wg48temp9

Quote: Originally posted by phlogiston

Below is a snip of a video one of our members made doing experiments next to their kitchen stove. The color of the flame of the gas burner indicates the air is contaminated by dust or an aerosol from his experiments which would also contaminate the kitchen and would have been inhaled if he had no protection.

B(a)P - 30-7-2020 at 03:16

I haven't seen the clip that you got that from, but what makes you conclude it is their kitchen?
Is it an air contaminant or something on the burner?
Does the video indicate the level of ventilation?
Did this experiment include lead?
Please note this is not an attack on your post wg48temp9. I am just a little confused how you drew your conclusions. I am clearly missing something.

unionised - 30-7-2020 at 07:37

"Lead compounds have a very low vapor pressure and temps below 400C should produce insignificant amount of vapors,"

Unless you are unlucky...
https://en.wikipedia.org/wiki/Tetraethyllead

Another important factor- make sure you don't accidentally make organo-lead compounds. It's not very likely, but it's worth thinking about.

wg48temp9 - 30-7-2020 at 16:54

Quote: Originally posted by B(a)P

I haven't seen the clip that you got that from, but what makes you conclude it is their kitchen?
Is it an air contaminant or something on the burner?
Does the video indicate the level of ventilation?
Did this experiment include lead?
Please note this is not an attack on your post wg48temp9. I am just a little confused how you drew your conclusions. I am clearly missing something.

The purpose of my post was to show what a gas flame looks like when its sucking in airborne particles that may not visible. It was in support of my original post.

Below is a pic of a gas flame that is not sucking in airborne particles or if it is they are spectroscopically not contaminated with sodium so the sodium yellow emission is not observed.

Its not important if it is a kitchen or not or what the level of ventilation was
or if the particles are contaminated with lead.

As described in my original post its a demonstration of how readily air can be contaminated by the regents used in an experiment, in particular when boiling liquids.

An other demonstration is shake a bottle powdered rhodamine then open it over a sheet of damp white paper.