Sciencemadness Discussion Board - Airborne release of Sodium Hydroxide pellets

Airborne release of Sodium Hydroxide pellets

Doc B - 1-8-2017 at 23:56

I've noticed a respiratory irritation when dispensing NaOH pellets in STP conditions. There is no visible dust or fine particulate matter present in any such instances, however the irritation is comparable to that from inhalation when making an aqueous NaOH solution. I've heard of the ARF from such solutions explaining the irritant but I'm curious if it is caused by the same phenomena just how it can't be explained?

I considered that there may be fine particulate matter but I've not seen any nor detected any by placing containers of water around the work space, from which I've measured an initial pH prior to dispensing and compared a post dispensing pH measurement.

Has anyone noticed the irritant or can explain it?

JJay - 2-8-2017 at 00:24

I've noticed it before... I figure it is from NaOH particulates... these days I simply handle NaOH in my fume enclosure, but goggles and a dust mask worked ok for me when I didn't have one.

LearnedAmateur - 19-9-2017 at 13:32

I commonly notice a peculiar odour when working with reagent grade NaOH (ruling out discernible contamination), solid or in solution, so it seems as if it somehow reacts with the air, physically or chemically. Due to its strong hygroscopicity and high enthalpy of solution, I'd put my money on microscopic droplets of hydroxide solution being emitted which are easily breathed in. However, I don't get any irritation from being near it, that's probably down to individual differences regarding detection thresholds.

Doc B - 3-10-2017 at 04:30

Fine particulates does seem to be the most elegant explanation, however the pH test of the surrounds, after dispensing approximately 10kg in 4 to 5 molar lots, indicated that there was insufficient particulate matter dissolved to elevate the surrounding water. As such I am not sure if it's an accurate explaination to the phenomenon.

Morgan - 3-10-2017 at 05:52

Maybe off topic but it's amazing how much you can't see that's going on with everyday items. If you pull a Kleenex from a box or clean the lint from a clothes dryer screen outdoors in bright sunlight, there's a virtual blizzard of particles launched into the air that you get to breathe. Sunlight does for dust what schlieren photography does for studying airflow.

symboom - 3-10-2017 at 08:34

The same particular dust is observed with lithium into water while hydrogen is given off some lithium hydroxide becomes airborne in the stream of hydrogen gas and its really choking gas. Same with sodium metal and water forms a cloud of hydrogen and sodium hydroxide

NEMO-Chemistry - 3-10-2017 at 16:11

I buy 25Kg of sodium Hydroxide at a time, some for soap and some for Bio Diesel. It comes in a kind of plastic sack, i separate it into two plastic containers when I get it. I noticed the irritation when doing this.

But I also notice when making soap, the solution of hydroxide gives off fumes when first mixed, so i had always assumed that when pouring the prills out into the store bins, the irritation was due to the fumes given off from the tiny amounts of sodium hydroxide solution produced as it sucks water from the air.

I havnt really noticed any dust, but the irritation is the same as i get when making solution of hydroxide up for soap making.

zed - 9-10-2017 at 18:16

NaOH effect on respiration? Oh yeah! I've noticed it. It hits the sinuses and soft palate pretty hard. Doesn't seem to effect Ph paper. Can't see dust, mist, or spatter. But, something is going on.

LearnedAmateur - 10-10-2017 at 10:59

I've set up an experiment which I'm going to conduct over the next week. On the left is a beaker of 0.8g (0.02 mol) hydroxide pellets and the same amount in 20mL distilled water, making a concentration of 1M. The pH strips are held in place by the cling film so any microscopic droplets should be able to travel up and make contact without escaping. Hopefully enough will be absorbed by this time next week to show a result, and if not then we'll need to find another mechanism.

gatosgr - 22-12-2017 at 16:26

I get the same irritation form NaOH pellets and eye irritation as well. The culprit is dried 1M NaOH solution on latex gloves I think, when you continue to do work with these gloves dust particles travel in the air. I have safety glasses on but the plastic attracts the NaOH dust by electrostatic attraction. I have never been told anything about the dust of dried solution of chemicals in my chemistry lab courses maybe some more experienced chemist can elaborate on this?

Do you think fine aerosol is emitted from NaOH solutions? I got some hydrogen evolution from NaOH today, didn't notice any aerosol, it should be really fine if it exists.

Quote:

This alkaline substance does not form vapors but may form aerosol dust which can be inhaled. Reports from cases of inhalation of caustic soda suggest that this compound has the ability to irritate the respiratory tract lining. A lung injury known as pulmonary edema or the accumulation of fluid in the lungs may happen. Workers exposed to a hot mist of this compound in unventilated area will experience tightness of chest, difficulty in breathing, and cough. This is due to the bodys defense mechanism against the irritant. There was a reported case of a man who sustained severe pulmonary injury due to inhalation of aerosol containing the substance. This happened when water was poured onto sodium hydroxide pellets.

So maybe fine aerosol is emitted from NaOH pellets when exposed to air moisture.

It seems that soap makers experience this kind of trouble: http://www.tikvah.com/medical/lye.html

http://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC12854...

It's pretty self-explanatory that if you heat NaOH solution the evaporated water will contain NaOH but aerosol from just dissolution is a first for me.

Do you guys get eye irritation as well or just respiratory irritation?

Someone told me that NaOH aerosols are forming from stirring, bubbling and pouring (which I did all three at once) causing eye irritation, has anyone experienced any of that?

[Edited on 23-12-2017 by gatosgr]