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Author: Subject: Sulfur from Sulfuric acid?
Orenousername
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[*] posted on 6-5-2016 at 00:43
Sulfur from Sulfuric acid?


I was tinkering with the purification and concentration of hydrochloric acid as the only muriatic acid i can obtain is a bright yellow color and I do not trust its' purity. I added ~200mL of the muriatic acid to an addition(separatory) funnel and dripped it slowly into about 100mL of rooto sulfuric acid drain opener and bubbling the gas produced into 100mL of distilled water in an ice bath.

I should mention that I added some aluminum to the reaction flask because my previous attempts always had problems with suck-back, I thought the H2 generated might sort of push the HCl along into the water.

All was going well and I was getting a steady rate of HCl dissolving in the water, but the bubbling started to die down so I added another piece of aluminum to the flask and almost immediately i noticed the water go cloudy. I shut off the addition of muriatic acid and i saw that some yellow percipitate had formed in the water and noticed a strong smell of sulfur. The entire apparatus was also covered in what I believe to be elemental sulfur.

So my question to you guys is: what the hell happened?




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hissingnoise
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[*] posted on 6-5-2016 at 03:27


Quote:
So my question to you guys is: what the hell happened?

Your H2SO4 was reduced to sulphur by nascent hydrogen!

The inverted funnel method is best for preventing suckback . . . ?

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[*] posted on 6-5-2016 at 04:14


Would this be an effective way of making sulphur?
So basically the H2SO4 gets reduced to SO2 and the SO2 to elemental sulphur?


[Edited on 6-5-2016 by TinSandwich]
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[*] posted on 6-5-2016 at 06:41


Quote:
Would this be an effective way of making sulphur?

If you couldn't obtain sulphur by any other method, yes!

But H2S is the product of the reduction and sulphur forms by its oxidation by SO2, in situ . . .

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[*] posted on 6-5-2016 at 06:49


http://www.skylighter.com/sulfur.htm



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Orenousername
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[*] posted on 6-5-2016 at 11:30


Quote: Originally posted by hissingnoise  
Quote:
So my question to you guys is: what the hell happened?

Your H2SO4 was reduced to sulphur by nascent hydrogen!

The inverted funnel method is best for preventing suckback . . . ?



Ah I see, but what is oxidizing the h2s into s? Dissolved oxygen?
But yes the inverted funnel method would be ideal but i do not have a funnel that fits in my beakers :(




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Orenousername
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[*] posted on 6-5-2016 at 12:02


Quote: Originally posted by TinSandwich  
Would this be an effective way of making sulphur?
So basically the H2SO4 gets reduced to SO2 and the SO2 to elemental sulphur?


[Edited on 6-5-2016 by TinSandwich]


I don't know where you live but elemental sulfur is readily available almost everywhere where gardening is legal.




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[*] posted on 6-5-2016 at 22:35


Quote: Originally posted by Orenousername  
Quote: Originally posted by TinSandwich  
Would this be an effective way of making sulphur?
So basically the H2SO4 gets reduced to SO2 and the SO2 to elemental sulphur?


[Edited on 6-5-2016 by TinSandwich]


I don't know where you live but elemental sulfur is readily available almost everywhere where gardening is legal.


Yeah, I can probably buy it OTC, I just haven't bothered looking for it (never really needed it). It's just fun to look for alternative ways to make stuff that's all.
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[*] posted on 7-5-2016 at 00:53


Quote:
Ah I see, but what is oxidizing the h2s into s?

In this case, dioxide oxidises sulphide; 2H2S + SO2 ─> 3S + 2H2O.

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[*] posted on 8-5-2016 at 14:43


Quote: Originally posted by hissingnoise  
Quote:
Ah I see, but what is oxidizing the h2s into s?

In this case, dioxide oxidises sulphide; 2H2S + SO2 ─> 3S + 2H2O.



Per this source to quote (link: https://www.google.com/url?sa=t&source=web&rct=j&... ):

"Hydrogen sulfide is an undesirable component found in many industrial process streams. Traditionally its removal and recovery have been accomplished in an absorber-stripper operation, followed by the Claus process in which the H2S is reacted over alumina catalyst with SO2 obtained by burning a portion of the inlet stream. The gas-phase reaction to produce sulfur is

2 H2S + SO2 = 3/x Sx + 2H20

This reaction is equilibrium-limited to 95 to 97% conversion in 2 to 4 stages because the temperature must be kept above the dewpoint of sulfur. Additional processing must be provided to reduce the concentration of sulfurous compounds in the effluent to environmentally acceptable levels. "

So, I am not sure if reaction conditions (temperature, catalyst,..) are met here. [Edit] Found a video on the aqueous reaction of these dissolved gases which apparently proceeds. Link: https://m.youtube.com/watch?v=XdGyiDu8xb0 . I also came across a claimed reaction between H2S and H2SO4 forming SO2, H2O and S.

Also, nascent hydrogen does not exist being an historical substitute for more complex processes. For example, the action of passing H2 gas on a newly formed hydroxyl radical, may react as follows forming the reactive hydrogen radical:

.OH + H2 = H2O + .H (see, for example, http://www.rrjournal.org/doi/abs/10.2307/3571093 )

Hydroxyl radicals may be present due to transition metal impurities in the muriatic acid (especially Fe and Cu) or from a Fenton-like reaction via elemental Al in the presence of H2SO4 (more research needed).

There could be the following reaction between SO2 and .H :

SO2 + .H = .HO2 + S

.HO2 + .HO2 = H2O2 + O2

where hydrogen peroxide could further reduce H2S:

H2O2 + H2S = 2 H2O + S
----------------------------------------------------
Here is an extract from a paper where ZVAl stands for zero valence aluminum (elemental Al):

"Using bifunctional aluminum prepared by sulfated ZVAl with sulfuric acid, electron transfer to molecular oxygen (O2) generated reactive oxygen species (ROS) for the oxidation of methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME). The sulfate species on the ZVAl surface enhanced the oxidation efficiency by first stabilizing the ROS on the active sites and then adsorbing the organic substrate to initiate oxidation (Fig. 2a).Although both these reports established that ZVAl-mediated AOPs can be initiated by electron transfer, the exact identification of ROS and the main oxidant (H2O2 and/or HO•) remained unconfirmed. The use of bare ZVAl (without surface modificationor pre-treatment) as Fenton-type catalyst to generate HO• was first demonstrated by Bokare and Choi [86]. In the presence of O2, in situ generation of H2O2 and the subsequent decomposition into HO• was achieved by electron transfer from commercial ZVAl samples under acidic condition (Fig. 2b). After the dissolution of the native surface oxide (Al2O3) layer on ZVAl at acidic pH(pH ≤ 4) to expose the bare Al metal surface, the sequential generation of H2O2 and HO• was utilized for the oxidative mineralization of organic pollutants (4-chlorophenol, phenol, nitrobenzene andsodium dichloroacetate) [86]. Subsequently, the ZVAl/O2 system has been used as a heterogeneous AOP for the removal of bisphenol A [87], acetaminophen [88] and arsenite [89] from aqueous solultions."

Source: Bokare & Choi, " Review of iron-free Fenton-like systems for activating H2O2 in advanced oxidation Review processes", Journal of Hazardous Materials 275 (2014) 121–135. Link: http://www.sciencedirect.com/science/article/pii/S0304389414...

[Edited on 8-5-2016 by AJKOER]

[Edited on 9-5-2016 by AJKOER]
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[*] posted on 8-5-2016 at 18:00


This is good. Sulfur miticides have been phased out and replaced by some blue spray at my local stores. For anyone who isn't me, this would provide a good Sulfur source.

I, on the other hand, still have my 15 pounds of sulfur, and I don't think I'll need this procedure for quite a while. Good work though.
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[*] posted on 9-5-2016 at 00:49


Kinda like using MDMA as a source for safrole . . . :D

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[*] posted on 10-5-2016 at 22:21


My OTC HCl also has the yellow impurity. I think it's FeCl<sub>2</sub>. Regardless, you can distill it and get colorless, pure HCl solution in your receiving flask and the yellow impurity will remain in the boiling flask.
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[*] posted on 12-5-2016 at 07:31



Upon further research, my prior speculation that the following reaction sequence between SO2 and .H occurs:

SO2 + .H = .HO2 + S

.HO2 + .HO2 = H2O2 + O2

is not precisely correct. My understanding is now the following:

SO2 + .H (+ M) = .HOSO (+M)

.HOSO + .H = H2O + SO

if the reaction temperature is sufficient to support the heat of formation of SO, otherwise I suspect a reduction to sulfur and oxygen. Reference : "MECHANISMS OF RADICAL REMOVAL BY SO2", available at https://www.google.com/url?sa=t&source=web&rct=j&... and also, the article abstract available at http://pubs.rsc.org/en/content/articlelanding/1969/tf/tf9696...

[Edited on 12-5-2016 by AJKOER]
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