You’ve been using alcohol for years and now you are thinking about recycling it. Great idea. You use a lot of alcohol and it would be good to save money by buying less. It doesn’t take a lot of training or special knowledge to recycle alcohol. But for those who are curious about the details of alcohol recycling anyway, this post is for you.
When we say alcohol we really mean ethanol. It is used to dehydrate and rehydrate tissue in tissue processing and staining. It is preferred over other alcohols (methanol and isopropanol) for dehydration because it is not harsh and preserves cell morphology well.
Because ethanol is heavily taxed, it is not always used in its pure form.
Fully denatured ethanol is most often contains methanol, isopropanol and MIBK (methyl isobutyl ketone). The denaturing agents make the ethanol complete unpalatable and people cannot tolerate the taste. There are no limits on the size of containers for fully denatured ethanol and it is not taxed in most locations.
Partially denatured ethanol most often contains methanol and isopropanol. Being partially denatured, it is somewhat unpalatable but supposedly a determined person could still consume it. Partially denatured alcohol can be purchased in containers up to 20 liters (5 gallons) and is moderately taxed.
Pure ethanol does not contain any denaturants. Since it could potentially be consumed it is highly taxed. The largest size container is 4 liters (1 gallon).
The contaminants in alcohol include excess water, stain, fat, paraffin, protein, and biological materials.
Alcohol is the most demanding solvent to recycle and this is where you will really see a difference between recyclers.
To recycle alcohol you should choose a solvent recycler that uses fractional distillation by temperature and that has a well-designed distillation column.
The main challenge is to separate alcohol from the water contamination.
The pure alcohol will distill over next. Once all the useable alcohol has been distilled into the pure alcohol container the recycler will automatically stop and cool down.
Left behind in the boiler is a little alcohol along with fat, paraffin, protein and some biological materials.
Recycled alcohol should be perfectly clear and should not have any color at all. The alcohol will be 99.9% pure but the concentration will be a maximum of 95%.
The recovery rate for alcohol is about 85% on average. Since the recovery is 85%, you will still need to buy some alcohol.
The boiler residue is mostly water, with some alcohol, fat, protein, stain and biologicals. The alcohol is very dilute, so this waste is suitable for drain disposal.
Don’t recycled alcohol contaminated with xylene. Alcohol stations that follow a xylene stations are usually contaminated with xylene due to “carryover” from the xylene station. A simple test for xylene contamination in alcohol is to pour a few drops of water into the alcohol. If it gets cloudy (milky), then it is contaminated with xylene and should not be recycled.
Alcohol purity is simple to test. Just let the alcohol come to room temperature and then use a hydrometer to measure the alcohol content. You can buy a hydrometer from a local scientific equipment supply house or from B/R.
The hydrometer test is very sensitive to temperature. Hot alcohol will appear to have a much higher concentration than it really does. Don’t fool yourself. Let the alcohol come to room temperature before performing the hydrometer test.
We recommend hydrometers made by companies the Fischer Scientific and VWR. They have been making them for decades and are real experts.
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