Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: Beau1k on August 01, 2016, 05:28:36 PM
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Hello Chemical Forum,
I want to create non-toxic, inexpensive, heavier than water solution to perform density separation tests on different materials.
A saline solution is typical for this task, usually as far as I understand it, but I want to reach SG of over 1.45 for some of the trials.
Firstly...how much salt would I need to add to water to reach this SG.
Secondly...is there a better way!?
Thank you in advance chemical forum Citizen Chemists! ;D
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Welcome, Beau1k!
Water dissolves only 359g/L table salt, so even if the volume remained constant you wouldn't achieve the density 1.45. You need other compounds.
The short list of Engineeringtoolbox
http://www.engineeringtoolbox.com/liquids-densities-d_743.html
shows no safe dense liquid, but some exist. Maybe chlorocarbons with molecules bigger than CCl4?
I made a dense suspension (not a solution) of MoS2 nanopowder in water+glycol. Not a first choice for density separation. And it was dirty for real.
Did you check what's used in mining industry? Such a process is pretty common, including around 1450kg/m3.
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I only took a quick look
Am I misunderstanding the SG table.
Chloroform 1.469
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Yes, but Beau1k wanted a "nontoxic" compound. Then it's a matter of how toxic, in which quantity, to how well trained people with what equipment.
If the driver dumps a truck load in a pool of dense liquid and people around carry only a helmet, then chloroform and CCl4 are already too toxic.
Maybe Beau1k can tell us more about how nontoxic the liquid shall be?
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CHI3 in organic solvents. CsI in water.
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Hey everybody! Thanks for the input so far. Regarding the toxicity...I mean TOTALLY non-toxic...which is why I wanted to go with salt, but it appears that's a no-go. CsI is also a no-go :"Although caesium is only mildly toxic, it is a hazardous material as a metal and its radioisotopes present a high health risk if released into the environment."
This seems to be the HOT ticket: https://en.wikipedia.org/wiki/Sodium_polytungstate Na6[H2W12O40] or 3Na2WO4 9WO3 H2O but it's super expensive and only available in Germany so it seems :/ Maybe I could have some lab make it for me or how does that work?
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Welcome, Beau1k!
Water dissolves only 359g/L table salt, so even if the volume remained constant you wouldn't achieve the density 1.45. You need other compounds.
Did you check what's used in mining industry? Such a process is pretty common, including around 1450kg/m3.
What would the SG be if you added 359g to an L of table salt?
I have not checked into the mining industry angle...I'll look into that, good idea.
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I mean TOTALLY non-toxic...
No such thing. It is a dose that makes a poison, every substance is toxic this or another way.
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I mean TOTALLY non-toxic...
No such thing. It is a dose that makes a poison, every substance is toxic this or another way.
We don't intend on drinking it ;D
I mean toxic in the normal sense...like if we are handling it, breathing in any vapors from the process etc. I wouldn't want anything that requires any permitting or special safety equipment to use. Ideally something as innocuous as saltwater.
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"Although caesium is only mildly toxic, it is a hazardous material as a metal and its radioisotopes present a high health risk if released into the environment."
And fortunately, Cs is not metallic in CsI, nor does it contain radioisotopes unless you make big efforts.
Barium salts and solutions use to be dense too but I have no clue about their toxicity. Some are used as mud to drill oilwells.
I've just checked that C2Cl6 weighs 2t/m3 but it's a carcinogen. Similar compounds, dense but healthy?
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Sodium polytungstate is probably the best choice in use now for making an aqueous solution of very high density. You can make solutions with up to 3x the density of water. This would be an overkill for what you need but it is radically less toxic than some of the older heavy liquids.
The most relevant wikipedia page for this topic is a near orphan, with only one link. I could barely find it.
https://en.wikipedia.org/wiki/Heavy_liquid
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Calcium chloride would be less overkill for your need. Plus I randomly found a web based solution density calculator for it. ;D
http://www.tetrachemicalseurope.com/index.asp?page_ID=658
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Sodium polytungstate is probably the best choice in use now for making an aqueous solution of very high density. You can make solutions with up to 3x the density of water. This would be an overkill for what you need but it is radically less toxic than some of the older heavy liquids.
The most relevant wikipedia page for this topic is a near orphan, with only one link. I could barely find it.
https://en.wikipedia.org/wiki/Heavy_liquid
So I have looked into SPT...the viscosity is high which is a bummer. There is also LPT it is less viscous so that's encouraging...BUT...the problem with both is they say "REACTS WITH COPPER" in my application there can be small copper dust particles so I'm wondering...what is the reaction? What would the reaction be?
Can you tell what the reaction to Cu would be by the formula of the compound?
SPT: Na6[H2W12O40] or 3Na2WO4·9WO3·H2O.
( https://en.wikipedia.org/wiki/Sodium_polytungstate )
LPT: Li2WO4 ( https://en.wikipedia.org/wiki/Lithium_tungstate )
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Sugar
I got this table from
http://wiki.chemprime.chemeddl.org/index.php/Sugar_Solution_Density:_Canning,_Maple_Syrup,_and_Pousse_Cafes
It might be viscous.
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Calcium chloride would be less overkill for your need. Plus I randomly found a web based solution density calculator for it. ;D
http://www.tetrachemicalseurope.com/index.asp?page_ID=658
This calculator is cool but only goes to 1.5 for whatever reason. Maybe that's the max amount of Calcium Chloride that can be dissolved in water?
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Sugar
I got this table from
http://wiki.chemprime.chemeddl.org/index.php/Sugar_Solution_Density:_Canning,_Maple_Syrup,_and_Pousse_Cafes
It might be viscous.
What would the viscosity be (centipoise) if we added enough sugar to make a 1.5 solution?
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OK...so what about Sodium Sulphate?
Solubility is 13.9 g/100 mL (20 °C)
SG is 2.66-2.75
Could I get this to dissolve and reach a SG of 1.8?
And at that point...what'd the ventipoise # be?
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Never, max 1.2106 for 22 %.
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@Beau1k
As a teaching forum we encourage people to develop learning skills by giving hints and pointers.
Have you tried to find the centipoise of the items you asked about using a search engine like GOOGLE.
We understand you may have limited experience with chemistry but some work by you is also expected.
Reflect on our forum rules
Click on the link near the top center of the forum page.
Forum Rules: Read This Before Posting.
http://www.chemicalforums.com/index.php?topic=65859.0 (http://www.chemicalforums.com/index.php?topic=65859.0)
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@Beau1k
Many of us here like to solve interesting problems like yours.
But, since we do not know the specific application we are hampered.
This has been mentioned earlier in the thread.
If for some reason you can not share the specifics, it still would be helpful with parameters.
For instance -
Can your process be heated?
That would allow greater solubility although it would increase evaporation. It could also reduce viscosity.
Try to think of other parameters that would be applicable or share the exact application for your need.
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So I have looked into SPT...the viscosity is high which is a bummer. There is also LPT it is less viscous so that's encouraging...BUT...the problem with both is they say "REACTS WITH COPPER" in my application there can be small copper dust particles so I'm wondering...what is the reaction? What would the reaction be?
I think you might be confused a bit about viscosity numbers. A moderate concentration SPT solution would have a low viscosity of only a few centipoise and even a high concentration solution would only be around 10 cP. While these numbers are several fold higher than water you would not readily notice the difference. It would probably be better for our intuition if viscosity was reported on a logarithmic scale like decibels. Anyways, milk has a viscosity of 3 cP which is probably a bit above what SPT would have with a specific gravity of 1.45. On the other hand, a sugar solution at such a density would be a syrup with a viscosity higher by a couple orders of magnitude.
As for tungstate's incompatibility with copper presumably the copper just replaces the sodium and the resulting copper tungstate wouldn't be soluble. You would almost certainly have the same sort of problem with most non-alkali metal ions. This is not a significant problem for your application unless you somehow have large amounts of dissolved metal ions. The copper is not going to be dissolved unless your pH is acidic and I doubt that the tungstate would be soluble at acidic pH.
You would have no such problems with chlorides or nitrates. These anions are highly hydrophilic and form many deliquescent salts. I picked calcium chloride because it was deliquescent and its two ions are unequivocally benign and it can achieve an SG just barely above your stated number. Calcium nitrate would be able to get a higher SG than the chloride and while nitrate isn't something we evolved to consume in large quantities, it isn't particularly toxic.
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@Beau1k
As a teaching forum we encourage people to develop learning skills by giving hints and pointers.
Have you tried to find the centipoise of the items you asked about using a search engine like GOOGLE.
We understand you may have limited experience with chemistry but some work by you is also expected.
Reflect on our forum rules
Click on the link near the top center of the forum page.
Forum Rules: Read This Before Posting.
http://www.chemicalforums.com/index.php?topic=65859.0 (http://www.chemicalforums.com/index.php?topic=65859.0)
Yeah absolutely! That's how I learned about centipoise in the first place ;D
I'm tryin...I only ask when I've exhausted my capability to calculate or understand the effects.
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@Beau1k
Many of us here like to solve interesting problems like yours.
But, since we do not know the specific application we are hampered.
This has been mentioned earlier in the thread.
If for some reason you can not share the specifics, it still would be helpful with parameters.
For instance -
Can your process be heated?
That would allow greater solubility although it would increase evaporation. It could also reduce viscosity.
Try to think of other parameters that would be applicable or share the exact application for your need.
Can't share too much sorry. Temperature would be ambient...heating would increase energy costs too much.
Basically a non-viscous solution anywhere above 1.5 would work...I figured 1.8 would be better but I think I can live with 1.5 - It must be low cost because of the loss of the mixture on the material being treated in the mixutre.
Right now I'm looking at Calcium Nitrate. Looks promising but I cannot determine how much I can dissolve in water, what that SG would be, and then ultimately what viscosity I end up with. These formulas elude me.
All the properties are here: https://en.wikipedia.org/wiki/Calcium_nitrate but how to calc that into the results I'm looking for is my problem.
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So I have looked into SPT...the viscosity is high which is a bummer. There is also LPT it is less viscous so that's encouraging...BUT...the problem with both is they say "REACTS WITH COPPER" in my application there can be small copper dust particles so I'm wondering...what is the reaction? What would the reaction be?
I think you might be confused a bit about viscosity numbers. A moderate concentration SPT solution would have a low viscosity of only a few centipoise and even a high concentration solution would only be around 10 cP. While these numbers are several fold higher than water you would not readily notice the difference. It would probably be better for our intuition if viscosity was reported on a logarithmic scale like decibels. Anyways, milk has a viscosity of 3 cP which is probably a bit above what SPT would have with a specific gravity of 1.45. On the other hand, a sugar solution at such a density would be a syrup with a viscosity higher by a couple orders of magnitude.
As for tungstate's incompatibility with copper presumably the copper just replaces the sodium and the resulting copper tungstate wouldn't be soluble. You would almost certainly have the same sort of problem with most non-alkali metal ions. This is not a significant problem for your application unless you somehow have large amounts of dissolved metal ions. The copper is not going to be dissolved unless your pH is acidic and I doubt that the tungstate would be soluble at acidic pH.
You would have no such problems with chlorides or nitrates. These anions are highly hydrophilic and form many deliquescent salts. I picked calcium chloride because it was deliquescent and its two ions are unequivocally benign and it can achieve an SG just barely above your stated number. Calcium nitrate would be able to get a higher SG than the chloride and while nitrate isn't something we evolved to consume in large quantities, it isn't particularly toxic.
For sure I'm confused ??? :o ;D But story of my life :P
Calcium Nitrate looks very promising. Just, as stated above, need to figure out how much CAN be dissolved in water and what the SG would be, and then what the viscosity would be of that. ???
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Ca(NO3)2 is soluble to at least 45% w/w and such solution has a density of 1.423 g/mL.
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Ca(NO3)2 is soluble to at least 45% w/w and such solution has a density of 1.423 g/mL.
Thanks for that!! Can you tell me how to make this calculation?
Also...how do I determine the viscosity of this mixture at 1.423?
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In general, you cannot simply calculate either solubility or density. These are determined through experiment and we normally have to look them up. However, you should be able to estimate a rough lower bound for the density of a mixture by assuming that the volume of the mixture is not larger than the sum of the volumes of the constituents. Also, for a dilute solution you might assume that the volume of the mixture is not less than the volume of the solvent and this would give you a rough upper bound. Of course your application is far from dilute so I only mentioned that for completeness.
So you might see if you can work out a lower bound for Borek's case.
BTW, assume he has there a 45%w/w solution of the tetrahydrate of calcium nitrate (which has a density of 1.9 g/cm3)
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Ca(NO3)2 is soluble to at least 45% w/w and such solution has a density of 1.423 g/mL.
Thanks for that!! Can you tell me how to make this calculation?
As Itanjir wrote - I have not calculated these, I took them from tables (built into CASC - I have nothing else at hand).
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Oh. You guys are using software...smart. OK thanks everybody...off to the fertilizer store to do some experiments. Wish me luck :o
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The rubber Industry typically uses zinc chloride solutions. Sometimes HCl is needed to help solution. These went to sp gr 2.0 easy. Should find a reference in the astm. Its a question of toxicity, although rinsing on removal will help a lot.
Good luck