I have never seen the word “partition” used in this way before. Hard to search for examples because unrelated computer graphics articles about surface partitioning dominate. I did find this:
Partitioning is the distribution of a solute, S, between two immiscible solvents (such as aqueous and organic phases). It is an equilibrium condition that is described by the following equation:
S(aq) ⇄ S(org)
Interesting to think that a surface can play a role comparable to a solvent. I wonder what a chemist would have to say about it.
In separation science a partitioning coefficient can be described for an undesirable contaminant, inbetween a solid adsorbent having a certain degree of retention, versus a solvent where it is soluble to its own certain degree, under static equilibrium conditions.
IOW the smoke will have different affinity for different types of furniture, carpets, and window coverings, and when it comes in contact with these they soak it up like a sponge. Because the adsorbent materials are physically like a sponge more often than not, whether on a macro, micro, or molecular level.
The solvent is plain air, but the "solubility" of the raw smoke in air is not a factor because the smoke is not actually dissolved in the solvent (air) at this point, or ever really. The smoke consists of a lot of solid particles that have been forcefully dispersed into the air at uneven concentrations. The smoke itself is not a chemical contaminant that dissolves in the air, it's just dispersed in the air not much differently than an unwanted chemical, for a least a good period of time.
But the solids will eventually settle if they are not purged beforehand. What you're left with after that is then chemical equilibrium.
In a confined enclosure, static equilibrium will eventually be reached between the amount of chemical contaminants dissolved in the air at that temperature, versus the amount adsorbed onto available surfaces. After which no more odor can be released from the furniture once the air is saturated. To really get rid of the smell you're going to have to replace the saturated air with fresh air and one compete air exchange is not usually enough. Also the more efficient air exchange the better, and the fresher the better. If one person smoked one time, or you burned some popcorn and did not let out the smoke right away, that's not much contamination and it's not constant, but it's also not unusual to still smell it a week later when you first walk in from a fresh outdoor air environment. But just don't open the windows when something like a diesel truck is idling outside, new odor could then be coming in in greater quantities than the old odor can escape, one roomful at a time.
You may have grams of "odor" soaked into the carpet along with 100 grams of dirt & dust. But what if the chemical causing the odor only "evaporates" into the air a few milligrams at a time? Because the heavier the liquid, the slower the evaporation and the resulting partitioning coefficient using air as a solvent is such a low number. And it's not too unintuitive to figure that things which are semi-solid like tars or true solids like some pesticides hardly evaporate at all, but can really stink when there's only a few milligrams in the air.
Stuff like that is not going away without a solvent much stronger than air, and also a more concentrated solvent than a gaseous fluid can make contact by the gram much faster than a gram of fresh air can eventually flow by the unwanted material to be removed.
Plain water may not be any better as a solvent at dissolving cooking oils and tars than air is a solvent, but you sure can get a lot more grams into contact with a surface or macro adsorbent quicker compared to air as a gas.
Plain steam dissolves things so much better just from the added heat of the liquid turning it into a stronger solvent, plus so much of the water evaporates so fast at that temperature there is also a purging effect.
Then there's the carpet-cleaning liquids that can improve the partitioning coefficient of water so it will dissolve otherwise insoluble materials without nearly as much heat as steam. Like grams of detergent added to volumes of water to clean a certain area of carpet, or hundreds of grams of water-soluble organic solvent over the same area instead. Or both, simultaneously, or sequentially. Then when you do the math you see how much more effective sequentially is.
Now without doing any carpet cleaning, when you...
Interesting, it seems that the actual surface material of walls and/or furniture makes a large difference in how long VOCs stick around, due to differences in surface area at the microscopic scale.
I have a couple HEPA filters in my house that hopefully keep particulate exposure down. Does this mean that I have to run them longer? That I need more of them continuously running to keep exposure to VOCs low?
The proper way to get rid of smells from a smoker is to wash all of the paintable surfaces with trisodium phosphate, paint all of the walls and ceilings with Kilz primer, and then clean the floors, doors, and woodwork (and everything, windows, etc) with a solvent that removes the tar and resin (or paint them with Kilz too). If there is carpet, remove the carpet and pad and install new carpet. Might need to replace fixtures and furnishings depending on how bad it is.
So yeah, smoking in a house is insanely destructive and takes a long time to actually remove the odor forever.
Also, check all of the drains (including floor drains) to ensure there is water in the trap.
For inhabited spaces there are ionizers available optimized to produce negligible amounts of ozone. They produce O2- and N2- ions instead, which are much safer, even beneficial. They help not only with VOCs but dust too unlike ozone which is a neutral molecule.
The confusion with ozone generators is understandable but very unfortunate here.
That thread is illuminating. I see two serious problems.
- - -
First, the quality of a modern American education.
Let's assume 2000sqft house with 8.5ft ceilings = 17k cu ft or ~500 m3, 1-0.1 μmol/mol ozone produces irritation to respiratory passages, so we need 1-0.1g total ozone left in 500m3 of house.
"170g of a highly reactive gas is generated over two days in a house full of organic materials. The windows are open and the heat is on; after what time will less than 0.1g gas remain?"
Make virtually _any_ assumptions and the answer could not possibly be longer than "minutes."
Mind you, I used very generous numbers and assumptions here. Mexico City averages over 0.1 μmol/mol and seconds of Mexico City air does not "totally destroy" anyone's lungs or cause you to cough up green phlegm.
In other words, with a few seconds of basic math and two basic facts about ozone it is trivial to see that the ozone is effectively gone. This guy has a university biochem degree and experience with organic synthesis? He's on there calling for an "atmospheric chemist" and thinking up ideas to fill the entire house with aerosolized cooking oil (!?!?!?) What is it that makes so many people today entirely incapable of critical thinking? Mind you, this guy literally once had a professor give him a hands-on demonstration of the rapid reaction of ozone - the sort of hint you would give if a student somehow failed the above question - and he still somehow couldn't get it after a week of Googling and reading "the literature."
How do we teach critical thinking?
- - -
Second, the modern synthetic chemicals we live with.
Ozone is always present around us, sometimes at quite high concentrations, depending on your environment. Obviously (... perhaps not always too obviously ...) it is always reacting around us. Most people own hundreds to thousands of pounds of modern synthetic materials. Innovative new chemistries. Formulas changed yearly. Those things are not static, they are off-gassing, they are reacting, they are releasing compounds unknown into the air we breathe. Just your mattress alone might have a hundred pounds of polyurethane foam, the precise composition of which is unknown to any one individual. Perhaps it is enclosed in a polyester cover, and then likely one treated with a fire retardant. Perhaps the corner protectors are recycled plastic of unknown origin, and then maybe they contain an odor-reducing additive. How do all these things react with the air around us? How do they interact with each other? I suspect that when we eventually study this better we are not going to like what we find - but for now, why do we allow plastics manufacturers to use us all as guinea pigs?
Replication and peer review are required to be very careful about believing small effect sizes that are inconsistent across populations which are so common with papers in biology and medicine measuring the effect of X on Y when it's entirely believable that the study might just be statistical error or cherry picking.
This study is measuring something pretty obvious and it's more akin to you demanding replication and peer review to your bathroom scale. There might be room for some additional studies but the conclusions here "surface areas for VOCs to stick to are much bigger than this simplified model" don't really need to be doubted all that much.
There's actually a decent amount of work recently in this space, some of it motivated by the wildfires.
Here's another recent paper with similar findings.
The persistence of smoke VOCs indoors: Partitioning, surface cleaning, and air cleaning in a smoke-contaminated house
https://pmc.ncbi.nlm.nih.gov/articles/PMC10575580/
Does this mean the Germans are right with Lüften!? I habitually have done this as an American in the morning for my office, something about morning fresh air after the night seems right?
I always thought the American meme about Lüften / Stoßlüften was just about the fact that people like exotic names for normal behaviours. Are you telling me that there is a significant percentage of people in the US who don't fully open two or more windows to get the air completely exchanged about three times a day in the winter?
I know you have AC for the summer, where we use Lüften during the night and then close our exterior blinds. And that makes sense, as your summers are hotter in many areas and it doesn't get cool enough at night for our strategy to work consistently. But I have always assumed that everyone does Lüften in the winter, and that you guys just like the funny sounding word we use for it.
>Our estimates of the total surface partitioning capacity are much larger than if the reservoirs are taken to be thin organic films on smooth, impermeable surfaces.
... so is "smooth, impermeable surfaces" the current begrudgingly-accepted model or something? because there's no way any person who has ever been in a house would think that's a reasonable model. permeable surfaces are all over the place, literally most of the place because it includes essentially all walls and therefore wall interiors. managing that for e.g. humidity is a significant part of building design because it's completely inescapable... and that's before even touching stuff like fabric where your average couch probably has more surface area than all structural surfaces combined.
That reminds me of when I was living right by the BLM protests/CHOP [0] in Seattle and got tear gas in my condo. I had just bought some new coffee beans to try out and when I did the next morning, thought they tasted super "chemical-y" and immediately threw them aways.
Turns out tear gas is known to seep into food items, especially porous food like coffee and bread [1]. Not surprised at all that VOCs linger in reservoirs as mentioned in the article.
> That reminds me of when I was living right by the BLM protests/CHOP [0] in Seattle and got tear gas in my condo. I had just bought some new coffee beans to try out and when I did the next morning, thought they tasted super "chemical-y" and immediately threw them aways.
This is by far the most Seattle thing I have ever read.
16 comments
[ 311 ms ] story [ 892 ms ] threadPartitioning is the distribution of a solute, S, between two immiscible solvents (such as aqueous and organic phases). It is an equilibrium condition that is described by the following equation:
S(aq) ⇄ S(org)
Interesting to think that a surface can play a role comparable to a solvent. I wonder what a chemist would have to say about it.
https://www.chemicool.com/definition/partitioning.html
IOW the smoke will have different affinity for different types of furniture, carpets, and window coverings, and when it comes in contact with these they soak it up like a sponge. Because the adsorbent materials are physically like a sponge more often than not, whether on a macro, micro, or molecular level.
The solvent is plain air, but the "solubility" of the raw smoke in air is not a factor because the smoke is not actually dissolved in the solvent (air) at this point, or ever really. The smoke consists of a lot of solid particles that have been forcefully dispersed into the air at uneven concentrations. The smoke itself is not a chemical contaminant that dissolves in the air, it's just dispersed in the air not much differently than an unwanted chemical, for a least a good period of time.
But the solids will eventually settle if they are not purged beforehand. What you're left with after that is then chemical equilibrium.
In a confined enclosure, static equilibrium will eventually be reached between the amount of chemical contaminants dissolved in the air at that temperature, versus the amount adsorbed onto available surfaces. After which no more odor can be released from the furniture once the air is saturated. To really get rid of the smell you're going to have to replace the saturated air with fresh air and one compete air exchange is not usually enough. Also the more efficient air exchange the better, and the fresher the better. If one person smoked one time, or you burned some popcorn and did not let out the smoke right away, that's not much contamination and it's not constant, but it's also not unusual to still smell it a week later when you first walk in from a fresh outdoor air environment. But just don't open the windows when something like a diesel truck is idling outside, new odor could then be coming in in greater quantities than the old odor can escape, one roomful at a time.
You may have grams of "odor" soaked into the carpet along with 100 grams of dirt & dust. But what if the chemical causing the odor only "evaporates" into the air a few milligrams at a time? Because the heavier the liquid, the slower the evaporation and the resulting partitioning coefficient using air as a solvent is such a low number. And it's not too unintuitive to figure that things which are semi-solid like tars or true solids like some pesticides hardly evaporate at all, but can really stink when there's only a few milligrams in the air.
Stuff like that is not going away without a solvent much stronger than air, and also a more concentrated solvent than a gaseous fluid can make contact by the gram much faster than a gram of fresh air can eventually flow by the unwanted material to be removed.
Plain water may not be any better as a solvent at dissolving cooking oils and tars than air is a solvent, but you sure can get a lot more grams into contact with a surface or macro adsorbent quicker compared to air as a gas.
Plain steam dissolves things so much better just from the added heat of the liquid turning it into a stronger solvent, plus so much of the water evaporates so fast at that temperature there is also a purging effect.
Then there's the carpet-cleaning liquids that can improve the partitioning coefficient of water so it will dissolve otherwise insoluble materials without nearly as much heat as steam. Like grams of detergent added to volumes of water to clean a certain area of carpet, or hundreds of grams of water-soluble organic solvent over the same area instead. Or both, simultaneously, or sequentially. Then when you do the math you see how much more effective sequentially is.
Now without doing any carpet cleaning, when you...
I have a couple HEPA filters in my house that hopefully keep particulate exposure down. Does this mean that I have to run them longer? That I need more of them continuously running to keep exposure to VOCs low?
VOCs getting absorbed by surfaces was the most plausible theory in the comments there as well. Interesting to see more evidence for it.
So yeah, smoking in a house is insanely destructive and takes a long time to actually remove the odor forever.
Also, check all of the drains (including floor drains) to ensure there is water in the trap.
The confusion with ozone generators is understandable but very unfortunate here.
- - -
First, the quality of a modern American education.
Let's assume 2000sqft house with 8.5ft ceilings = 17k cu ft or ~500 m3, 1-0.1 μmol/mol ozone produces irritation to respiratory passages, so we need 1-0.1g total ozone left in 500m3 of house.
"170g of a highly reactive gas is generated over two days in a house full of organic materials. The windows are open and the heat is on; after what time will less than 0.1g gas remain?"
Make virtually _any_ assumptions and the answer could not possibly be longer than "minutes."
Mind you, I used very generous numbers and assumptions here. Mexico City averages over 0.1 μmol/mol and seconds of Mexico City air does not "totally destroy" anyone's lungs or cause you to cough up green phlegm.
In other words, with a few seconds of basic math and two basic facts about ozone it is trivial to see that the ozone is effectively gone. This guy has a university biochem degree and experience with organic synthesis? He's on there calling for an "atmospheric chemist" and thinking up ideas to fill the entire house with aerosolized cooking oil (!?!?!?) What is it that makes so many people today entirely incapable of critical thinking? Mind you, this guy literally once had a professor give him a hands-on demonstration of the rapid reaction of ozone - the sort of hint you would give if a student somehow failed the above question - and he still somehow couldn't get it after a week of Googling and reading "the literature."
How do we teach critical thinking?
- - -
Second, the modern synthetic chemicals we live with.
Ozone is always present around us, sometimes at quite high concentrations, depending on your environment. Obviously (... perhaps not always too obviously ...) it is always reacting around us. Most people own hundreds to thousands of pounds of modern synthetic materials. Innovative new chemistries. Formulas changed yearly. Those things are not static, they are off-gassing, they are reacting, they are releasing compounds unknown into the air we breathe. Just your mattress alone might have a hundred pounds of polyurethane foam, the precise composition of which is unknown to any one individual. Perhaps it is enclosed in a polyester cover, and then likely one treated with a fire retardant. Perhaps the corner protectors are recycled plastic of unknown origin, and then maybe they contain an odor-reducing additive. How do all these things react with the air around us? How do they interact with each other? I suspect that when we eventually study this better we are not going to like what we find - but for now, why do we allow plastics manufacturers to use us all as guinea pigs?
Replication and peer review are required to be very careful about believing small effect sizes that are inconsistent across populations which are so common with papers in biology and medicine measuring the effect of X on Y when it's entirely believable that the study might just be statistical error or cherry picking.
This study is measuring something pretty obvious and it's more akin to you demanding replication and peer review to your bathroom scale. There might be room for some additional studies but the conclusions here "surface areas for VOCs to stick to are much bigger than this simplified model" don't really need to be doubted all that much.
Here's another recent paper with similar findings. The persistence of smoke VOCs indoors: Partitioning, surface cleaning, and air cleaning in a smoke-contaminated house https://pmc.ncbi.nlm.nih.gov/articles/PMC10575580/
I know you have AC for the summer, where we use Lüften during the night and then close our exterior blinds. And that makes sense, as your summers are hotter in many areas and it doesn't get cool enough at night for our strategy to work consistently. But I have always assumed that everyone does Lüften in the winter, and that you guys just like the funny sounding word we use for it.
... so is "smooth, impermeable surfaces" the current begrudgingly-accepted model or something? because there's no way any person who has ever been in a house would think that's a reasonable model. permeable surfaces are all over the place, literally most of the place because it includes essentially all walls and therefore wall interiors. managing that for e.g. humidity is a significant part of building design because it's completely inescapable... and that's before even touching stuff like fabric where your average couch probably has more surface area than all structural surfaces combined.
Turns out tear gas is known to seep into food items, especially porous food like coffee and bread [1]. Not surprised at all that VOCs linger in reservoirs as mentioned in the article.
[0]: https://en.wikipedia.org/wiki/Capitol_Hill_Occupied_Protest
[1]: https://www.propublica.org/article/tear-gas-is-way-more-dang...
This is by far the most Seattle thing I have ever read.