[keerthana]

Please kindly help me in getting clarifying my doubt. I am having a solution containing benzene,toluene,ethyl benzene and xylene dissolved in methanol and it was then dissolved in water to prepare stock solution. Now i am doubting that any reaction could occur among these compounds? will any of these volatile compounds react with other compounds in the solution?

[rolnor]

What type of reaction could occur do you think?

[keerthana]

Thank you for your reply. I don't have chemical background. so I would wish to clarify a little more. Like, whether the volatilization of each compound might be hindered by the presence of other compounds in the mixture. say I have only benzene, it has some volatilization rate at room temperature. Now, if a mixture of BTEX is there, whether the volatilization rate of benzene in the mixture will be the same as we compare it with the benzene alone (former).

[wildfyr]

Unless they are a small amount of each of those in a large amount of methanol, I sort of doubt they are soluble in water. All of those would likely float on top.

And yes, the volatility of solvents is affected by the presence of other solvents, but it is not very predictable.

[keerthana]

I need to prepare 1 ppm aqueous BTEX solution. It has been dissolved in methanol first and then the aqueous standard for BTEX is prepared. I guess it is because of solubility they have first made it dissolve in methanol and then preparing the same in water.

[rolnor]

These compounds are not going to react with each other, no problem.

[keerthana]

whether the methanol used here is because of the solubility issue? By, using methanol, can we dissolve BTEX and methanol mixture in water?

[Enthalpy]

The solubility of benzene in water is nearly 2g/L, of toluene 0.5g/L, of xylenes 0.1-0.2g/L, of ethylbenzene 0.15g/L. So 1ppm would dissolve in water without methanol. Does methanol accelerate the dissolution?

[keerthana]

we will be preparing solutions of higher concentration which then eventually diluted to lesser amount due to accumulation of error. so for that higher concentration values, we may require methanol to dissolve BTEX in water. Is this correct?

[wildfyr]

Yes, this is a reasonable approach.

[keerthana]

benzene is a non polar liquid. methanol is a polar solvent. Then how benzene is dissolving in methanol?

[wildfyr]

Very small molecule solvents are unique, they have broad solubility properties.

[Enthalpy]

Some research papers treat methanol as a tiny "soap" than enables nano-emulsions of non-polar molecules (here benzene et al) in polar liquids (here water).

[keerthana]

can you please say the paper name for my reference.

[Enthalpy]

I don't have the paper. I just stumbled on it when searching for something else, as usual.

For instance that one
https://www.jstage.jst.go.jp/article/jsfe/15/3/15_119/_pdf
tells on page 8
"Spontaneous emulsion was observed in the aqueous phase when toluene containing a sufficient amount of ethanol came into contact with water."