[Beau1k]

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!

[Enthalpy]

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.

[billnotgatez]

I only took a quick look
Am I misunderstanding the SG table.
Chloroform   1.469

[Enthalpy]

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?

[AWK]

CHI₃ in organic solvents. CsI in water.

[Beau1k]

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?

[Beau1k]

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.

[Borek]

I mean TOTALLY non-toxic...

No such thing. It is a dose that makes a poison, every substance is toxic this or another way.

[Beau1k]

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 

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. 

[Enthalpy]

"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?

[Intanjir]

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

[Intanjir]

Calcium chloride would be less overkill for your need. Plus I randomly found a web based solution density calculator for it. 

http://www.tetrachemicalseurope.com/index.asp?page_ID=658

[Beau1k]

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 )

[billnotgatez]

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.

[Beau1k]

Calcium chloride would be less overkill for your need. Plus I randomly found a web based solution density calculator for it. 

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?