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How do you prepare sodium polysulfide Na2Sx in aqueous solution?
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Martin Bullen
How do you prepare sodium polysulfide Na2Sx in aqueous solution?
Dear Prof. Sarkar, thank you very much. If I see the problem correctly, it lies in the quality of Na2S, which is not stored under Ar or N2 and is going hydrated in time to NaHS, which is not able to sequestrate the sulfur? It will be a bit challenging in my conditions (environmental chemistry lab, not a synthetic one), but I can obtain a new Na2S and plastic bag-glovebox and work with it.
Dear Prof. Sarkar, thank you very much. If I see the problem correctly, it lies in the quality of Na2S, which is not stored under Ar or N2 and is going hydrated in time to NaHS, which is not able to sequestrate the sulfur? It will be a bit challenging in my conditions (environmental chemistry lab, not a synthetic one), but I can obtain a new Na2S and plastic bag-glovebox and work with it.
I would like to have a one more question regarding on Na2Sx stability. Generally, the literature suggests to ultrasound and vortex Na2S and S in aqueous dispersion, both for 10 min, and then react the mixture at 80 °C for 12 hours. I have, by one replicate of the synthesis, obtained from the dispersion a clear bright yellow solution after about 4 hours, and when I left the reaction run further to the prescribed 12 hours, the mixture went back to clear Na2S probably and the S precipitated on the magnetic stirrer. - Is there some dynamic equlibrium in between the Na2S and Na2Sx states? - How can I avoid this in the future? Should I just stop the reaction after I get the yellow bright solution? The reaction runned in MilliQ-water in a well cleaned glass roundbottom flask with a reduction and Dimroth-cooler in an oil bath set at 80 °C.
I would like to have a one more question regarding on Na2Sx stability. Generally, the literature suggests to ultrasound and vortex Na2S and S in aqueous dispersion, both for 10 min, and then react the mixture at 80 °C for 12 hours. I have, by one replicate of the synthesis, obtained from the dispersion a clear bright yellow solution after about 4 hours, and when I left the reaction run further to the prescribed 12 hours, the mixture went back to clear Na2S probably and the S precipitated on the magnetic stirrer. - Is there some dynamic equlibrium in between the Na2S and Na2Sx states? - How can I avoid this in the future? Should I just stop the reaction after I get the yellow bright solution? The reaction runned in MilliQ-water in a well cleaned glass roundbottom flask with a reduction and Dimroth-cooler in an oil bath set at 80 °C.
You are absolutely correct as sealed bottle of Na2S is relatively pure but once opened then it starts decomposing under exposure with air.. Keeping it under cold condition(fridge) will enhance its stability. The dissolution of more Na2S into NaOH will not help . Had it been NaHS then addition of NaOH would have created fresh Na2S. Next time when you get a new pack of Na2S and when you first time opening it, you can distribute required amount of Na2S in several small vials for future use and the operation should be done in the absence of air and moisture and tightly closed vials to be stored in desiccator . The problem you face here is the basic chemistry of Na2S and in water it hydrolyses to produce NaHS and NaOH so the extra NaOH is not good for polysulfide generation.
You are absolutely correct as sealed bottle of Na2S is relatively pure but once opened then it starts decomposing under exposure with air.. Keeping it under cold condition(fridge) will enhance its stability. The dissolution of more Na2S into NaOH will not help . Had it been NaHS then addition of NaOH would have created fresh Na2S. Next time when you get a new pack of Na2S and when you first time opening it, you can distribute required amount of Na2S in several small vials for future use and the operation should be done in the absence of air and moisture and tightly closed vials to be stored in desiccator . The problem you face here is the basic chemistry of Na2S and in water it hydrolyses to produce NaHS and NaOH so the extra NaOH is not good for polysulfide generation.
After about 15 h of reaction, when trying to protect the reaction mixture from air (under Ar atmosphere from balloon) and from sunlight (Al foil), I am getting something like this. Clear bright yellow solution, but the sulfur seems not to be dissolved completely. Should I react further or try to filter the solution (the sulfur particles wir disturb inf further reaction of direct sulfidation of Ag0 nanoparticles).
After about 15 h of reaction, when trying to protect the reaction mixture from air (under Ar atmosphere from balloon) and from sunlight (Al foil), I am getting something like this. Clear bright yellow solution, but the sulfur seems not to be dissolved completely. Should I react further or try to filter the solution (the sulfur particles wir disturb inf further reaction of direct sulfidation of Ag0 nanoparticles).
You are correct, use sodium sulfide and add elemental sulfur into it and stir, the sulfur will go into solution in aqueous medium. Alternately you may take NaOH solution make it two halves. In one half pass hydrogen sulfide to get NaHS and then into it add the rest half of NaOH solution to create fresh Na2S . Into it you add elemental sulfur and stir. You will get polysulfide solution. Normally in Na2Sx , x varies from 2 to 5.
You are correct, use sodium sulfide and add elemental sulfur into it and stir, the sulfur will go into solution in aqueous medium. Alternately you may take NaOH solution make it two halves. In one half pass hydrogen sulfide to get NaHS and then into it add the rest half of NaOH solution to create fresh Na2S . Into it you add elemental sulfur and stir. You will get polysulfide solution. Normally in Na2Sx , x varies from 2 to 5.
I understand your problem. The concentration you are using for Na2S is not actually what you are using but less. This might happen if you use solid Na2S procured from the market as it may not be very pure or got decomposed on standing.. Best thing you should start with Known amount of NaOH dissolved in a fixed volume of water, using half of this volume to pass H2S to saturate, chase out the excess of H2S from the solution by Argon for a few minutes and then add the rest half volume of the NaOH solution to get pure Na2S of desired strength. Here you add the elemental sulfur and stir under inert atmosphere and this will go into solution to provide you pale yellow Na2S2 solution. In the present case , you decant the Na2S2 solution for your use, be careful to handle it in the absence of oxygen as more oxygen more it will get oxidized to more complex mixture of thiosulfate, sulfites etc You will succeed after couple of attempts. Go ahead and if anything more you require do ask me. Thanks
I understand your problem. The concentration you are using for Na2S is not actually what you are using but less. This might happen if you use solid Na2S procured from the market as it may not be very pure or got decomposed on standing.. Best thing you should start with Known amount of NaOH dissolved in a fixed volume of water, using half of this volume to pass H2S to saturate, chase out the excess of H2S from the solution by Argon for a few minutes and then add the rest half volume of the NaOH solution to get pure Na2S of desired strength. Here you add the elemental sulfur and stir under inert atmosphere and this will go into solution to provide you pale yellow Na2S2 solution. In the present case , you decant the Na2S2 solution for your use, be careful to handle it in the absence of oxygen as more oxygen more it will get oxidized to more complex mixture of thiosulfate, sulfites etc You will succeed after couple of attempts. Go ahead and if anything more you require do ask me. Thanks
The entire operation should have been done under oxygen free condition. One can preserve the yellow colored solution for days if it is stored under oxygen free condition.. Further light can catalyze the decomposition and if traces of metal ion (ppm or ppb) is present the reaction will be fast. Kindly adopt these precautions.
The entire operation should have been done under oxygen free condition. One can preserve the yellow colored solution for days if it is stored under oxygen free condition.. Further light can catalyze the decomposition and if traces of metal ion (ppm or ppb) is present the reaction will be fast. Kindly adopt these precautions.
Precisely such thing is happening. Use new and freshly open bottle then the problem can be minimized several folds. I wished that you had a small cylinder of H2S gas and some NaOH and good water to avoid such a problem permanently but with new bottle you will get your work.Best wishes, SS
Precisely such thing is happening. Use new and freshly open bottle then the problem can be minimized several folds. I wished that you had a small cylinder of H2S gas and some NaOH and good water to avoid such a problem permanently but with new bottle you will get your work.Best wishes, SS
Thank you. I have filtered it through 0,45 um syringe filter, and let stay in a vial under Ar (but it vas a normal vial and Ar dosed from a balloon), after two days the product is still yellow, but S is precipitating. Yes, I am usind solid Na2S, but I have not much further possibilities. I can try to dissolve the Na2S (and use it in surplus) in NaOH solution (which concentration?) and then add the S, everything under Ar, but that´s probably the best we can do here. Should I store the Na2Sx better in a refrigerator? Funny thing is, that for the first time it completely worked without Ar-atmosphere and the product seemed to be stable (clear and yellow) for months. So, it really might be that reason, that my bought Na2S is not so pure anymore?
Thank you. I have filtered it through 0,45 um syringe filter, and let stay in a vial under Ar (but it vas a normal vial and Ar dosed from a balloon), after two days the product is still yellow, but S is precipitating. Yes, I am usind solid Na2S, but I have not much further possibilities. I can try to dissolve the Na2S (and use it in surplus) in NaOH solution (which concentration?) and then add the S, everything under Ar, but that´s probably the best we can do here. Should I store the Na2Sx better in a refrigerator? Funny thing is, that for the first time it completely worked without Ar-atmosphere and the product seemed to be stable (clear and yellow) for months. So, it really might be that reason, that my bought Na2S is not so pure anymore?
Dear Prof. Sarkar,
thank you very much. If I see the problem correctly, it lies in the quality of Na2S, which is not stored under Ar or N2 and is going hydrated in time to NaHS, which is not able to sequestrate the sulfur?
It will be a bit challenging in my conditions (environmental chemistry lab, not a synthetic one), but I can obtain a new Na2S and plastic bag-glovebox and work with it.
Dear Prof. Sarkar,
thank you very much. If I see the problem correctly, it lies in the quality of Na2S, which is not stored under Ar or N2 and is going hydrated in time to NaHS, which is not able to sequestrate the sulfur?
It will be a bit challenging in my conditions (environmental chemistry lab, not a synthetic one), but I can obtain a new Na2S and plastic bag-glovebox and work with it.
More
VOTE
I would like to have a one more question regarding on Na2Sx stability. Generally, the literature suggests to ultrasound and vortex Na2S and S in aqueous dispersion, both for 10 min, and then react the mixture at 80 °C for 12 hours. I have, by one replicate of the synthesis, obtained from the dispersion a clear bright yellow solution after about 4 hours, and when I left the reaction run further to the prescribed 12 hours, the mixture went back to clear Na2S probably and the S precipitated on the magnetic stirrer.
- Is there some dynamic equlibrium in between the Na2S and Na2Sx states?
- How can I avoid this in the future? Should I just stop the reaction after I get the yellow bright solution?
The reaction runned in MilliQ-water in a well cleaned glass roundbottom flask with a reduction and Dimroth-cooler in an oil bath set at 80 °C.
I would like to have a one more question regarding on Na2Sx stability. Generally, the literature suggests to ultrasound and vortex Na2S and S in aqueous dispersion, both for 10 min, and then react the mixture at 80 °C for 12 hours. I have, by one replicate of the synthesis, obtained from the dispersion a clear bright yellow solution after about 4 hours, and when I left the reaction run further to the prescribed 12 hours, the mixture went back to clear Na2S probably and the S precipitated on the magnetic stirrer.
- Is there some dynamic equlibrium in between the Na2S and Na2Sx states?
- How can I avoid this in the future? Should I just stop the reaction after I get the yellow bright solution?
The reaction runned in MilliQ-water in a well cleaned glass roundbottom flask with a reduction and Dimroth-cooler in an oil bath set at 80 °C.
More
VOTE
You are absolutely correct as sealed bottle of Na2S is relatively pure but once opened then it starts decomposing under exposure with air.. Keeping it under cold condition(fridge) will enhance its stability. The dissolution of more Na2S into NaOH will not help . Had it been NaHS then addition of NaOH would have created fresh Na2S. Next time when you get a new pack of Na2S and when you first time opening it, you can distribute required amount of Na2S in several small vials for future use and the operation should be done in the absence of air and moisture and tightly closed vials to be stored in desiccator . The problem you face here is the basic chemistry of Na2S and in water it hydrolyses to produce NaHS and NaOH so the extra NaOH is not good for polysulfide generation.
You are absolutely correct as sealed bottle of Na2S is relatively pure but once opened then it starts decomposing under exposure with air.. Keeping it under cold condition(fridge) will enhance its stability. The dissolution of more Na2S into NaOH will not help . Had it been NaHS then addition of NaOH would have created fresh Na2S. Next time when you get a new pack of Na2S and when you first time opening it, you can distribute required amount of Na2S in several small vials for future use and the operation should be done in the absence of air and moisture and tightly closed vials to be stored in desiccator . The problem you face here is the basic chemistry of Na2S and in water it hydrolyses to produce NaHS and NaOH so the extra NaOH is not good for polysulfide generation.
More
VOTE
After about 15 h of reaction, when trying to protect the reaction mixture from air (under Ar atmosphere from balloon) and from sunlight (Al foil), I am getting something like this. Clear bright yellow solution, but the sulfur seems not to be dissolved completely. Should I react further or try to filter the solution (the sulfur particles wir disturb inf further reaction of direct sulfidation of Ag0 nanoparticles).
After about 15 h of reaction, when trying to protect the reaction mixture from air (under Ar atmosphere from balloon) and from sunlight (Al foil), I am getting something like this. Clear bright yellow solution, but the sulfur seems not to be dissolved completely. Should I react further or try to filter the solution (the sulfur particles wir disturb inf further reaction of direct sulfidation of Ag0 nanoparticles).
More
VOTE
You are correct, use sodium sulfide and add elemental sulfur into it and stir, the sulfur will go into solution in aqueous medium. Alternately you may take NaOH solution make it two halves. In one half pass hydrogen sulfide to get NaHS and then into it add the rest half of NaOH solution to create fresh Na2S . Into it you add elemental sulfur and stir. You will get polysulfide solution. Normally in Na2Sx , x varies from 2 to 5.
You are correct, use sodium sulfide and add elemental sulfur into it and stir, the sulfur will go into solution in aqueous medium. Alternately you may take NaOH solution make it two halves. In one half pass hydrogen sulfide to get NaHS and then into it add the rest half of NaOH solution to create fresh Na2S . Into it you add elemental sulfur and stir. You will get polysulfide solution. Normally in Na2Sx , x varies from 2 to 5.
More
VOTE
I understand your problem. The concentration you are using for Na2S is not actually what you are using but less. This might happen if you use solid Na2S procured from the market as it may not be very pure or got decomposed on standing.. Best thing you should start with Known amount of NaOH dissolved in a fixed volume of water, using half of this volume to pass H2S to saturate, chase out the excess of H2S from the solution by Argon for a few minutes and then add the rest half volume of the NaOH solution to get pure Na2S of desired strength. Here you add the elemental sulfur and stir under inert atmosphere and this will go into solution to provide you pale yellow Na2S2 solution.
In the present case , you decant the Na2S2 solution for your use, be careful to handle it in the absence of oxygen as more oxygen more it will get oxidized to more complex mixture of thiosulfate, sulfites etc You will succeed after couple of attempts. Go ahead and if anything more you require do ask me. Thanks
I understand your problem. The concentration you are using for Na2S is not actually what you are using but less. This might happen if you use solid Na2S procured from the market as it may not be very pure or got decomposed on standing.. Best thing you should start with Known amount of NaOH dissolved in a fixed volume of water, using half of this volume to pass H2S to saturate, chase out the excess of H2S from the solution by Argon for a few minutes and then add the rest half volume of the NaOH solution to get pure Na2S of desired strength. Here you add the elemental sulfur and stir under inert atmosphere and this will go into solution to provide you pale yellow Na2S2 solution.
In the present case , you decant the Na2S2 solution for your use, be careful to handle it in the absence of oxygen as more oxygen more it will get oxidized to more complex mixture of thiosulfate, sulfites etc You will succeed after couple of attempts. Go ahead and if anything more you require do ask me. Thanks
More
VOTE
The entire operation should have been done under oxygen free condition. One can preserve the yellow colored solution for days if it is stored under oxygen free condition.. Further light can catalyze the decomposition and if traces of metal ion (ppm or ppb) is present the reaction will be fast. Kindly adopt these precautions.
The entire operation should have been done under oxygen free condition. One can preserve the yellow colored solution for days if it is stored under oxygen free condition.. Further light can catalyze the decomposition and if traces of metal ion (ppm or ppb) is present the reaction will be fast. Kindly adopt these precautions.
More
VOTE
Jan David at what molar ratio you have prepared the polysulfide solution.
Jan David at what molar ratio you have prepared the polysulfide solution.
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Thank you :) .
Thank you :) .
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VOTE
Precisely such thing is happening. Use new and freshly open bottle then the problem can be minimized several folds. I wished that you had a small cylinder of H2S gas and some NaOH and good water to avoid such a problem permanently but with new bottle you will get your work.Best wishes,
SS
Precisely such thing is happening. Use new and freshly open bottle then the problem can be minimized several folds. I wished that you had a small cylinder of H2S gas and some NaOH and good water to avoid such a problem permanently but with new bottle you will get your work.Best wishes,
SS
More
VOTE
Thank you.
I have filtered it through 0,45 um syringe filter, and let stay in a vial under Ar (but it vas a normal vial and Ar dosed from a balloon), after two days the product is still yellow, but S is precipitating.
Yes, I am usind solid Na2S, but I have not much further possibilities. I can try to dissolve the Na2S (and use it in surplus) in NaOH solution (which concentration?) and then add the S, everything under Ar, but that´s probably the best we can do here.
Should I store the Na2Sx better in a refrigerator?
Funny thing is, that for the first time it completely worked without Ar-atmosphere and the product seemed to be stable (clear and yellow) for months. So, it really might be that reason, that my bought Na2S is not so pure anymore?
Thank you.
I have filtered it through 0,45 um syringe filter, and let stay in a vial under Ar (but it vas a normal vial and Ar dosed from a balloon), after two days the product is still yellow, but S is precipitating.
Yes, I am usind solid Na2S, but I have not much further possibilities. I can try to dissolve the Na2S (and use it in surplus) in NaOH solution (which concentration?) and then add the S, everything under Ar, but that´s probably the best we can do here.
Should I store the Na2Sx better in a refrigerator?
Funny thing is, that for the first time it completely worked without Ar-atmosphere and the product seemed to be stable (clear and yellow) for months. So, it really might be that reason, that my bought Na2S is not so pure anymore?
More
VOTE