In wine industry, people may use a copper wand to scrub sulfide out of solution. Using copper powder is more efficient, but more problematic as it tends to partly dissolve and form a greenish colloid wich needs to be further removed…
Sodium sulfite works as well as a sulfide scrubber, it is cheaper and simpler than copper I believe.
Still… elemental sulfur is anyway slightly soluble in most organic solvents (in the order heptane >ethanol >acetone > methanol for instance). Leftover non reacted elemental sulfur (coloidal) will be present in final product. Moreover, polysulfides which are eventually generated are not necessarily scrubbed as easily as hydrogen (mono)sulfide can be. As they oxidize, they produce more elemental sulfur.
Thus, although the bad sulfide smell might be gone., that leftover sulfur can react again with the final cannabinoid mixture if one apply sufficient heat (eg if attempting to distill) and produce H2S again. This further promotes mess in the vacuum line, condensers, pumps etc…
Cool stuff I’ll definitely give it a try in future setbacks. So in your opinion sulfur contaminated material is not fully remediate-able? My analytics labs don’t test for that specifically.
I think there are some pros to elemental copper though, such as no more additional infrastructure required just copper metal, the ability to both reflux and redistill continuously, a visual indicator that your distillate is contaminated with sulfur and not some other junk, a visual cue for when the majority has been removed (blackened copper slows in appearance on repacking), and last but not least easily attainable reagents (food stores).
I don’t like the philosophy of if it tests well and doesn’t smell, it sells. Especially when tens of thousands are on the line. But sometimes that’s what happens.
@Dr_Jebril your write ups are always very informative, thank you. Is it worthwhile to try ICP-OES or MS for residual sulfur or do you think there’s too much elemental sulfur normally to be worthwhile? Most cannabis labs already have the equipment
It hurts me to know someone actually paid for these teks. They ghosted you and didn’t provide support because these are SHIT reactions… (as far as CBD to d8/d9)
In the current state of the sufur based process described on the forum,I believe it is likely not remediated that easily. Unless we see a chemical analysis of the final product, I believe it is still present.
Yes copper present multiple advantages. I think copper flakes should be preferred regarding powders, because easier to retrieve, and less prone to dissolution. Still, the surface area is way smaller, so one need to use much higher amounts of material to ensure same efficiency. Once blacked, the spent copper flakes can be regenerated by a mild acidic treatment.
However, absence of partial dissolution of Copper (or other trace metals from the scrubber) forming mysterious colloids is still to be demonstrated as well…
That would be ok for the most reactive reduced sulfur species.
The elemental part (remains from reagent, or produced by the scrubbing) likely need more work to be remediated.
This should be perfectly fine for measuring total sulfur (and Cu) in the end product.
“The results—from a team led by Caltech and BP, and in collaboration with researchers at UCLA, ETH Zürich, and China’s Nanjing University—”
Let’s Future4200 stoners beat them.
In acqueous chemistry, the classic laboratory approach for trapping sulfide involves potassium, and a basic solution (e.g. KOH, or KCl +NaOH). Basic conditions make H2S soluble, and helps forming insoluble KHS and K2S. Still, his need to be further oxidized to avoid H2S escaping again… and this forms elemental sulfur for a part (plus eventually more soluble higher oxidation degree, eg. sulfite, sulfate, metabisulfite etc…)
If done well, reduced sulfur can be easily scrubbed out (primarly H2S/HS-/S2-).
The issue is all the elemental sulfur that is there.
Sulfide and elemental sulfur also react together to form polysulfide (the same series as monosulfide, with more S, in average 3 to 6). This further makes the thing more complex, as you think that all sulfide may be gone, but some may still be there… in fact that’s a field a chemistry which is still not that well understood, fundamentally. Still lot’s of magics in this domain of reduced sulfur.
They distill way below sulfur vaporisation temperature.
I think that’s what causes a mess when distilling sulfur rich products.
They evaporate and re condensate easily as a solid, lining tubes and glaswares.
Besides cannabis, this is my area of research, clay chemistry.
More from a geochemical point of view, investigating deeper the structure properties (related to structural Fe), how they influence this kind of redox processes, and in turns how such process affects them, trying to model it. I have been especially looking at sulfide-bentonite (natural, purified, also a list of (oxyhdr)oxides…) interactions for the last two years. The report on this topic will be out soon. I also have to write two articles now…
Without any modification, bentonites react with sulfide.
They oxidize sulfide to elemental sulfur (the clay gets reduced, and change color). That’s the basic process at play, although there are still other mysteries behind (using an excess sulfide promotes an excess consumption with clay, some suprise with the radical S internediate… while an excess blocks the reaction with oxides and forms a mysterious compound…).
If one uses enough clay, 100% sulfide can be reduced to elemental sulfur.
In this paper here, what they are doing is not that clear at all (it is more engineering kind)…
“Sulfur” is being removed from the crude oil, but its chemical and redoxspeciation (reduced, zero–valent, oxidised, chemical species…) is not dealt with.
Despite the title, the materials being employed are modified clay, either coated with Fe oxides (likely goethite/hematite), or acid-treated. Other process than reduction are likely also at play, at part precipitation, perhaps sorption as well…
Eventually, a notable portion of sulfur still remains in the crude oil (almost 1 wt.% ). My guess is that this is the elemental sulfur (at part generated upon remediation), still very difficult to deal with, very resilient.
That’s the piece of the puzzle which Future 4200 must solve now.
But would the FE and H imbedded clay remove most and using LLE with potassium chloride finish it off?
In theory?
I’m thinking staged filtration in a sense. I don’t think there will be one method use that’ll remove the elemental sulfur. Maybe a combo of the two would yield more positive results? Maybe multiple separate filtration set ups?
Spitballin here…
I need to set aside more time to R&D this method to see what it yields. The “recipe” to imbed the bentonite is there and all of those elements I have access to. Probably after the holiday season.
Edit… maybe a bed of copper flakes above the bentonite filters to neutralize the sulfur creating sulfides and using the clay beds to “capture” the sulfides?
It is slightly soluble in all known organic solvents, to various degrees.
The solubility drops with decreasing temperature.
In fact all these remediation methods revolve around similar principles, involving blocking reduced sulfur, and further oxidizing it to elemental sulfur. In some cases, the elemental sulfur is incorporated in another chemical insoluble species. But a portion always remains. I believe this is the portion from oxidation of polysulfides (all the involved S does not get trapped).
I believe the ultimate method might be in this list:
-membrane filtration
-multiple recrystallization
-finding a way to “overoxidize” specifically sulfur (to higher oxidation degrees)
In well water where sulfur is more prominent, and you add water softeners and filtration, are you just removing the rotten egg smell and leaving behind the elemental sulfur?
I understood it that the hydrogen sulfide is oxidized and then removed through filtration.
I know there is a difference between elemental and hydrogen sulfur, just trying to wrap my head around a method that could work.
Would oxidizing the sulfur then filtering it work then?
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