ElizabethGreene
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Poor Yields of Elemental Sulfur extraction with Xylene from Encap™ Fast Acting™ Sulfur Plus AST™
Poor Yields of Elemental Sulfur extraction with Xylene from Encap™ Fast Acting™ Sulfur Plus AST™
Abstract: A procedure is presented for the extraction of elemental Sulfur from the Encap™ Fast Acting™ Sulfur Plus AST™ garden
product. Sulfur yield was a disappointing 10% of the initial mass, approximately 25% of the amount expected. Suggestions for future work are
included.
Background: A damaged bag of Encap™ Fast Acting™ Sulfur Plus AST™ was obtained containing 1.08kg of product. This was opened
and dispensed into a Ziploc Bag for storage and the damaged packaging discarded. The material consists of roughly even proportions of dark brown
pebbles and light-brown chocolate chip shaped pieces approximately 3 mm in diameter.
Source Material
The packaging indicates that the product contains 49.72% Sulfur, 54.25% Gypsum, and 5.6% other. This must be a remarkably effective fertilizer as it
gives 110%. The author took great delight in this, and theorizes that the Encap marketing department may have had some involvement in this packaging
design.
Package Label
The author assumed the following composition
40% Elemental Sulfur (S)
54% Gypsum (CaSO4-2H2O)
6% other including Bentonite Clay and Lignosulfonates
Procedure: 20 grams of product were placed in a 250ml beaker and 50mL of Klean-Strip Xylene added. This was covered with a round
bottom flask to prevent excessive evaporation and heated to 60°C with an electric hot plate. The mixture was held at this temperature for 5 minutes
with vigorous agitation by glass rod. The chocolate-chip shaped pieces were observed to break apart into a fine powder and the solvent became cloudy
with particulates. The dark brown pebbles appeared unaffected. This was decanted through an unbleached coffee filter into a clean flask to cool. As
the product cooled, many small crystals were observed setting out of the clear-yellow filtrate solution.
The wet source product was weighed and found to be heavier than expected, with an estimated yield under one gram. 50mL of additional Xylene was
added, covered, and heated to 75°C for 5 minutes with glass-rod agitation. This was decanted through the filter into the beaker with the previous
filtrate and placed on a shelf to recrystallize. A significant portion, possibly up to a half gram of the light-brown chocolate-chip shaped piece
powder was captured in the filter.
After three days, the majority of the sulfur-bearing Xylene solvent was lost in a lab spill, but most of the sulfur crystals remained. The dry source
material was weighed at 17g. The remaining Sulfur/Xylene mixture was heated to 100°C to evaporate the remaining Xylene. 2g of small yellow sulfur
crystals were collected and placed in a vial labeled “Sulfur”. This product contains a very small number (2-3?) of brown fibers which are assumed
to be from the filter.
Product
Discussion:
Those purchasing garden products as a source of elemental sulfur should avoid products with large percentages of Gypsum. The sulfur in Gypsum is not
available for simple solvent extraction.
The author suspects that her coffee filters “shed” a small number of brown fibers. Search for new filter material is underway.
The theoretical yield of this procedure was 40% x 20 grams = 8 grams. The actual yield was 2 grams. Assuming that the portion lost with the spilled
solvent would have been completely recovered, the yield could have been as much as 3 grams. This is between 1/4th and 1/3rd of the theoretical yield.
This is disappointing.
Self-Criticism:
Use of a mechanical stirrer could improve the repeatability of the procedure.
Cats have no place in the lab, especially not knocking experiments off the damn shelf. Future in-progress experiments will be kept in a lidded
plastic bin.
Future Work:
The author now has a quantity of reasonably pure Sulfur available, and will work up a solubility curve for Sulfur in Xylene as a function of
temperature in the future. Examples of the specific procedure to follow would be appreciated.
The yield of this procedure was disappointing. The experiment will be repeated to determine if powdering and/or washing the source material prior to
extraction increases the yield. Other variations could include increasing the solvent temperature or extraction time.
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ElizabethGreene
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Addendum:
The author has a free long-haired cat available named Blue. Smells slightly of Xylene, but appears undamaged.
Note: Cat does not appear to care for author's attempts at paw cleaning.
Note: Feline claws are an effective tool for placing small groups of holes in author.
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sargent1015
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God these are a delight to read  Keep on doing science, I love reading your
posts!
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watson.fawkes
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Quote: Originally posted by ElizabethGreene  | This must be a remarkably effective fertilizer as it gives 110%.
[...]
Those purchasing garden products as a source of elemental sulfur should avoid products with large percentages of Gypsum. |
The sulfur percentage is high, since it includes the sulfur within the sulfate. Under the fertilizer analysis, there's a heading for
"combined sulfur" at 9.22%. Subtracting that off gives a result close to correct within rounding error.
I suspect the polyacrylamides (see "Active Ingredients") were as much responsible as the gypsum. They're used in various time-release products. I'm
assuming here their purpose is to encapsulate, which would definitely make extraction harder. Look up the patents listed at the bottom to be sure.
Grinding the material to powder should help recovery.
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Funkerman23
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Pardon my asking but: was there any particular reason you chose xylene for the sulfur extractions? I know sulfur will dissolve in Carbon disulfide
but ethanol & ether will dissolve it a little as well( CRC handbook is a nice reference but slightly soluble isn't to precise of a description)
but digress.
" the Modern Chemist is inundated with literature"-Unknown
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unionised
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Powdering the material might help. So might pre-extraction with boiling water to remove some of the other components which might occlude the sulphur.
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papaya
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Couldn't you just distill sulfur from powder in a proper setup ?
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ElizabethGreene
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| Quote: Originally posted by watson.fawkes | | [...]I suspect the polyacrylamides (see "Active Ingredients") were as much responsible as the gypsum. They're used in various time-release products.
I'm assuming here their purpose is to encapsulate, which would definitely make extraction harder. Look up the patents listed at the bottom to be sure.
Grinding the material to powder should help recovery. |
Sadly, I hadn't noticed those until I was resizing the image for posting. <stern voice> Bad Chemist, Bad!</stern voice> I'll look them
up.
| Quote: Originally posted by Funkerman23 | | Pardon my asking but: was there any particular reason you chose xylene for the sulfur extractions? I know sulfur will dissolve in Carbon disulfide
but ethanol & ether will dissolve it a little as well( CRC handbook is a nice reference but slightly soluble isn't to precise of a description)
but digress. |
No pardon required, I'm posting these here because I'm a complete chemistry noob and I lack a proper instructor to critique my work. I want people to
ask questions and tell me when I'm doing something foolish.
Xylene is available at my local Home Depot. The choice was based on easy availability. My source of diethyl ether would be from truck starting fluid
and these all seem to be mixtures containing hexane as well. Denatured alchohol has the same problem. It is a mixture of different substances
introducing another component to the experiment.
I don't have a ready source for Carbon Disulfide and have not researched its synthesis. Do you have a procedure for it? I have Carbon and Sulfur
now. 
My local McKay's Used books has a 1989 copy of the CRC for $5.00. Is that new enough to have IUPAC names in it?
I believe that is possible. The boiling point is 445°C (Wikipedia, "Sulfur") though, and I would have to rig some sort of torch fired apparatus to
reach that temperature. Would it spontaneously form Sulfur Dioxide with atmospheric Oxygen at that temperature?
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woelen
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A nice solvent for sulphur is toluene. I once did an experiment with that and quite some sulphur can be dissolved in hot toluene, while its solubility
is low in cold toluene. Toluene is available in many countries as paint thinner, maybe it is available for you as well. I wrote a web page about this:
http://woelen.homescience.net/science/chem/exps/S+toluene/in...
For me, this was just a curiousity. I can buy very pure sulphur, but I just liked to try making the pure chemical from raw materials.
-------------------------------------------------------------
Synthesizing CS2 in a home lab is not easy at all. You need very high temperatures and you need to work in perfectly sealed apparatus and have to deal
with its extreme flammability and the problem of clogging of tubes with condensed sulphur. Synthesis of CS2 is done at temperatures, much higher than
its ignition temperature (which is as low as appr. 100 C). Buying it is not easy, I do not know of any OTC source for this chemical. I have some of
this, but I purchased it from a chemical supply store, which sells to individuals in the Netherlands.
[Edited on 24-6-13 by woelen]
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watson.fawkes
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| Quote: Originally posted by ElizabethGreene | | The boiling point is 445°C (Wikipedia, "Sulfur") though, and I would have to rig some sort of torch fired apparatus to reach that temperature. Would
it spontaneously form Sulfur Dioxide with atmospheric Oxygen at that temperature? |
Yes, you'll get lots of
SO2 coming off the hot sulfur surface in the presence of atmosphere. Combustion not required. Pulling vacuum is one method to prevent this;
purging with an inert gas would also work.
Distilling sulfur requires more attention to temperature control than you might guess. Sulfur polymerizes in its liquid phase within a certain
temperature range. While still technically liquid, the viscosity shoots way up. If you want liquid sulfur to fall off the condenser, you can't cool it
down too much. Thus water is likely not a good working fluid. Monitoring the outgoing temperature of the condenser coolant and keeping it above the
polymerization threshold is the goal.
All told, an interesting project, but not a simple one.
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ElizabethGreene
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Yes! Your and GarageChemist's discussion on this. (http://www.sciencemadness.org/talk/viewthread.php?tid=3902) was the inspiration for this procedure. There was also an anecdotal report mentioning
Xylene, but I can't find the thread for that.
I'll include references from now on.
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papaya
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Maybe I wanted to say "sublimation" rather than "distillation", because with the first (if it works at all) one probably can escape complexities (high
viscosity, etc). Like you put the powder in the bottom of a tower and the vapors condense on top being periodically harvested. As of solvents for
sulfur, once I noticed that hot DMSO will dissolve sulfur and on cooling you get a parafine-like substance with sulfur crystals in frozen DMSO. I
don't know much about solubility though, just that I could etch copper parts in that hot DMSO sulfur solution in the course of miuntes (I discovered
to my surprise).
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vmelkon
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Yes, it is possible. I did it in 2010.
http://www.youtube.com/watch?v=T3jWbCChHzw
I'm using a long neon tube, that is slightly bent.
I'm using a propane torch.
Any vapor that goes past the bent part of the tube, cools down, and liquid sulfur flows down a bit and solidifies.
The reason : my sulfur had be contaminated by some organic stuff because of a previous experiment. It looked dirty yellow.
Danger : the neon tube is ordinary glass and can crack because of uneven heating.
As for SO2, don't worry. There isn't much contact between the air and the sulfur.
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bfesser
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<strong>ElizabethGreene</strong>, your write-up was again a delight to read. If I were you, I would purchase the CRC Handbook you
mentioned. Five dollars is a fair price for that edition, provided it's in acceptable condition. I'm sure it uses systematic naming, it may not be a
perfect match for the current revisions of the IUPAC nomenclatures, but I doubt you'll ever encounter a difference. If nothing else, they make a
handy 'lab jack'.
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papaya
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Another method came to my mind. Yes, like in industry!
https://en.wikipedia.org/wiki/Froth_flotation
Aquarium pump must suffice?
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DraconicAcid
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| Quote: Originally posted by ElizabethGreene | Addendum:
The author has a free long-haired cat available named Blue. Smells slightly of Xylene, but appears undamaged.
Note: Cat does not appear to care for author's attempts at paw cleaning.
Note: Feline claws are an effective tool for placing small groups of holes in author. |
Love the write-up.
My father used to have a dog named "Blue", do to an unfortunate incident involving a can of spray paint, a puppy that would chew on everything on
sight, and a book that claimed that puppies can be broken of this habit if you take what they are chewing on and force it into their mouths so that
they gag.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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ElizabethGreene
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I reattempted this today, with several notable changes.
1. The product was powdered in a dedicated lab blender prior to extraction. The powder was screened through fiberglass window screen and the larger
material reground until it all passed through.
2. The solution was heated hotter, longer, and with mechanical agitation.
3. An Ice bath was used to expedite crystallization.
4. More source material was used in relation to solvent.
5. I "recycled" the Xylene, reducing the amount of Product lost in solution.
#5 requires some explanation.
The Xylene still had a strong yellow color even after chilling in the ice bath. I decanted the cold clear yellow solvent back into a beaker, added
make-up solvent, and stir-bar and put it back on the heat. Then I added fresh source material. My working theory was that this solvent was saturated
with the sulfur that would not recrystallize out, so any more that dissolved into it would come straight out in the end product. Theoretically this
technique would allow one to trade time for better yield and reduced solvent use when crystallizing out a substance with a small difference in hot and
cold solubility. There was a visible significant difference in yield between the first and subsequent rounds of extraction, indicating that this
technique has some merit.
The final product is still drying, but I'm estimating the yield at ~45%. This is a notable improvement.
EDIT: Yield, 58grams, 37% of theoretical. Sodding pusspockets.
Lessons learned:
If the solution in a flask is at 90c, the cool-to-the-touch neck of the flask will get "hot" when one starts pouring the
solution out.
Turn on the magnetic stirrer -before- adding the powder to the flask. or it will get buried and stuck.
Any interruption in stirring (i.e. if the hot plate pops a circuit breaker) will allow insolubles to settle out. These insulate the bottom of
the flask and can cause a significant temperature gradient between the bottom and top of the solution. I saw a difference of 20c and localized
boiling at one point.
I need to get a fire extinguisher for the lab. The current response plan of "scream" then "run" is insufficient.
The hot Sulfur-Xylene clouded my plastic filter funnel. If I had it to do again I'd use the glass one for the hot filtration and the plastic
one for adding the cold source material to the extraction flask.
The blender works much better at dry grinding if it's less than 1/4th full.
Get some spoons or scoops for the lab for transferring dry materials.
Prolonged usage of the electric-skillet-turned-hot-plate at high temperatures causes it to smell. It came from goodwill so this could be old
grease cooking off. Alternately it could be the teflon letting go and giving me cancer. The non-stick coating needs to come off for safety.
A dust mask is required for safety when grinding, sifting, and transferring powdered materials.
Need to add a weight to the magnetic stirrer to help reduce walk at high speeds.
The cat appears to have learned a lesson, and remained a respectful distance away while watching the procedure.
Future Work:
I still have a pound and a half of source material, and am considering trying to distill it next.
[Edited on 30-7-2013 by ElizabethGreene]
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Varmint
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I took an entirely different approach, I washed the entire bag in a large plastic tub (20 gal) with plain old tap water.
The prills of sulfur did not dissolve of course, so long as you work fast they hold their prill shape.
Take a kitchen screen strainer and a scoop of the sludge from the large container, wash it with the water hose back into the tub, virtually all that
is left in the screen is sulfur prills.
Repeat until you have most if not all the prills separated and drying, then prop the screen by some means and pour the contents of the bucket through
the screen into another large bucket or series of smaller ones to recover the last of the prills.
Then dry the prills collected, pick out the occassional stone or whatnot, and NOW you have prills ready for purification via whatever solvent you
choose.
In my 6lb bag, the sulfur content was listed as 33 % total, my dried prills weighed 685g, or abour 25%. This means about 5-6% is locked up in the
other components in the bucket wash, but I was happy with the yield as it was, and simply let the bucket wash evaporate in the sun on a large plastic
sheet propped up to form an impromptu "kiddie pool", then saved it back in the original bag.
If your variety doesn't have the yellow sulfur prills of course my approach is useless!
DAS
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bfesser
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Thread Moved
11-8-2013 at 07:55 |
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