Chemical Forums
Specialty Chemistry Forums => Chemical Engineering Forum => Topic started by: levi0709 on September 08, 2009, 01:29:25 AM
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hello, i recently have been working with polyvinyl alcohol, and i was wondering, i mixed the polyvinyl alcohol with water that contained a dye that was water soluble, the polyvinyl alcohol hardened and it got painted with the dye, but now i want to separate the dye from the polyvinyl alcohol, i tried soaking it in water until the polyvinyl alcohol dissolved again, but now how can i separate the dye from the polyvinyl alcohol?
thanks for your time
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I also experienced that situation in which i mixed a polyvinyl alcohol with a stained ionized water. check if the dye is also oil soluble or grease soluble, you can use this as a solvent to separate the dye from the PVA.
Try completely hydrolyzing the PVA before mixing in the oil or grease..
(DO NOT AT ALL COST EXPOSE YOUR PVA TO TEMPERATURE NEAR 200 DEGREES CENTIGRADE)
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hello, the dye is alcohol soluble, but not oil or grease soluble...
can anyone help me please?
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Maybe try hexanol?
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you mean mix hexanol with the mixture already in water? or do i mix it in solid state?
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Mix in the water. Hopefully you will get phase separation between hexanol and water. I'm not sure if PVA will also go into the hexanol phase. Your yield may not be so good, but it might be worth a try.
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ok, ill try that and post the result as soon as posible.
really thanks for taking the time to answer my post and help me!!!!
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if you have access to octanol, that might be better.
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Send the dye/alcohol solution through a gram or two of silica gel. The dye will stick and the alcohol should pass through. The more diluted it is with water the better this should work.
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greetings, as it turns out, the dye was water soluble, so i tried sticking the hardened mixture into the water and letting the polyvinyl alcohol dissolve, but when i tried to decant the dye from the blob of polyvinyl alcohol it just made a big mess, does anyone have a good method of getting rid of the polyvinyl alcohol and separating the dye?
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so, there is no way to separate the polyvinil alcohol from the dye stained water without making a mess?
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Hello levi0709,
When you said when i tried to decant the dye from the blob of polyvinyl alcohol it just made a big mess
, could you please describe to the group what a 'big mess' is? Could you describe physical properties, colour, and any other description that may help the viewer understand what you are seeing.
Thanks for your help,
Eugene
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of course, the polivynil alcohol/water mixture became almost the same color, clumps of polyvinil got loose on the water, it looked like a blob as it was completely saturated by the water, i tossed that experiment and tried another with smaller amounts of water to prevent it from becoming blobish, the polyvinyl alcohol clump could be seen as a whole, but smaller clumps became loose on the water, so to separate the dye i tried squeezing the bigger clump like squeezing the juice out of a fruit, some of the dye mixed with the water but most of it remained within the larger clump.
hope anyone can help me with this, and thanks for your reply!!!
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Hello levi0709,
Here is where some chemistry experience - and digging for some information - will help you out.
What you need to research, is to find a chemical (solvent?) that is soluble for your dye and is insoluble for PVA. You have already tried water (as the solvent) and realized that the dye and polyvinyl alcohol (PVA) are both soluble in water.
By either searching on the internet or looking in your favorite library, look up the solubilities of PVA and your dye. This information will help you select the solvent.
Best wishes,
Eugene
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ok, i'll guess ill start testing the solvents;
i'll post the results when i have them;
thanks for answering my posts!!
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hello, after one year of testing (i did a LOT of testing) i found out that the best solvent was ethanol at 96%, but still some of the polyvinyl alcohol got mixed with the dye and when i heated it burned into a gelatinous substance, of six attempts using the ethanol i only got it completely right once, completely separating the dye and not getting it burned; the other five however got transformed into the gelatin i wrote about.
I read somewhere that some persons used borax in the polyvinil alcohol containing solution to have it completely removed.
any ideas?
thanks