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Thread: Drying NaOH

  1. #1
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    Drying NaOH

    If you care to know to make anhydrtous sodium methylate (methoxide), you obtain anhydrous methanol, then add sodium metal to it. Hydrogen is evolved and released from the reaction but I believe you get a quanitative yield of anhydrous sodium methoxide solution in anhydrous methanol. That's expensive to do on a large scale.

  2. #2
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    Re: Drying NaOH

    Tilly mentioning that my 85% KOH has about 15% water impurity (that's imporatant) , caused me to remember something I did years ago. I don't remember why I did it, just that it happened. There is/was a name brand of technical grade sodium hydroxide drain cleaner called Red Devil Lye sold in the United States. Years ago I put maybe 100 grams of that type of inexpensive sodium hydroxide into a big enough beaker and put it into a hot oven, maybe 150 degrees centigrade or more. Probably, due to the water present the white solid caustic became hot thick liquid. Maybe the oven temperature was 200 degrees centigrade, I don't remember and I did not write it down. I had not thought about it for years. To produce the highest amount of methoxide, the starting materials should be as dry (anhydrous) as possible. Tilly said the caustic had water in it, so removing all the water in the the sodium hydroxide or potassium hydroxide would increase the concentration of methoxide or ethoxide in alcohol solution resulting from dissolving dried caustic in anhydrous alcohols. The increased methoxide concentration would cause a faster more complete reaction (transesterification) in forming the fatty acid esters , biodiesel from vegetable oils. The methanol should be as dry as possible. Drying the caustic would cause a better reaction to occur and diminish saponification soap production from glyceryl trifatty acids (vegetable oil) during the transesterification process. Free fatty acids would still neutralize caustic present at some rate (not immediately). Catalyst is removed from being available by free fatty acid + caustic to form soap + water + heat (exothermic reaction, heat given off). The significant amount of water present in the caustic solid may be removed prior to making the methoxide alcoholic solution by heating way above the boiling point of water to vaporize it, remove it from the caustic solid material. Two problems in doing that, drying solid caustic in a gas oven is carbon dioxide reacts with sodium hydroxide and potassium hydroxide to degrade the caustic a bit to sodium carbonate and potassium carbonate, but if it's done right it's not a problem. The other slight problem is that the caustic becomes a liquid while the water boils off, when it cools, it's one solid block in the bottom of a large enough glass beaker. I broke the solid caustic block apart with a stainless steel screw driver , without breaking the glass beaker, to get anhydrous sodium hydroxide mixed with some sodium carbonate. Technical grade sodium hydroxide already has some sodium carbonate in it. Drying the sodium hydroxide catalyst introduces a bit more sodium carbonate into the solid, but it's probably a better starting material for use in making the methoxide solution, with much less water in it. A Spectral absorption/emission study would be required to determine the increase in methoxide or ethoxide concentration resulting from drying the catalyst prior to dissolving/reacting in dry methoxide or anhydrous ethanol. Drying the caustic in an appropriate oven prior to mixing with anhydrous alcohol will improve the biodiesel manufacturing process. Oh yes, boiling the water out of the caustic solid at elevated temperature 150-200 degrees centigrade frosts the glass on the inside of the beaker where the hot liquid caustic touched the heat shock resistant glass. Thanks
    Last edited by Tony From West Oz; 26th December 2016 at 04:48 PM. Reason: mis spelled four words

  3. #3
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    Re: Drying NaOH

    Wesley,
    Were you able to quantify the amount of water present after your NaOH drying experiment?
    What would have been the amount of Sodium Carbonate prior to the NaOH drying experiment
    If an electric oven were used, what amount of reduction of Sodium Carbonate production would you expect?
    How would one test for the amount of Sodium Carbonate in the NAOH before and after the drying process?
    So many questions, so few answers. Hopefully the above Q will find their A.

    Thanks,
    Tony
    Last edited by Tony From West Oz; 26th December 2016 at 04:49 PM. Reason: Moved to new thread - changed title
    Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

    Current Vehicles in stable:
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    '06 Musso Sports Crew Cab. Running on used cooking oil with 5% to 10% misfuel.
    Toyota Camry Hybrid - (Wife's Car)

    Previous Vehicles:
    '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup. Died when supercharger stuck at max boost for weeks. Stretched head bolts.
    '80 Mercedes 300D. 2 tank conversion [Sold]
    '84 Mercedes 300D. 1 tank, no conversion. Replaced engine with rebuilt OM617A turbodiesel engine. Finally had good power. Donor for current Fatmobile coupe. (body parted out and carcass sold for scrap.)
    '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
    '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
    Parts Car C220 1993 All body panels, headlights, interior engine and ECU available.


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  4. #4
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    Re: Drying NaOH

    I did not weigh the beaker before and after to determine change in mass of the beaker. I used a natural gas powered oven. If a heat shock resistant watch glass on top of the beaker is used in an effort to slow carbon dioxide gas exchange touching the hot liquid caustic then that might help diminish sodium or potassium hydroxide degrading into sodium carbonate. An electrric oven would be better since it doesn't produce carbon dioxide gas that reacts with hot liquid caustic being dried. Also the density of hot air in a 200 degree centigrade oven is less than air at 20 degrees centigrade. It takes a few short minutes to do this drying, so probably not much sodium or potassium hydroxide becomes the carbonate. I expect it's worth doing. I had never thought of it untill Tilly mentioned caustic solid material has a lot of water present. I did dry sodium hydroxide years ago. I don't remember why I did it though and I didn't write it down in a lab notebook. My bottle of potassium hydroxide says it's 85% KOH on the assay listed on the side of the bottle and it says it's 2.0% K2CO3 (potassium carbonate) that leaves about 13% which is probably mostly water. Drying the solid caustic would be of benifit so when dissolving caustic in dry methanol or anhydrous ethanol to produce a methoxide or ethoxide solution the starting materials contain as little water as possible. Water decomposes methoxide. More water pushes the reaction to the reactants side of the equation, to the left. Removing water from the starting materials will push the reactants to the product side of the equation, to the right.
    Last edited by Tony From West Oz; 26th December 2016 at 04:50 PM. Reason: moved to new threaD - CHANGED TITLE

  5. #5
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    Re: Drying NaOH

    I did an experiment, Drying Technical Grade Sodium Hydroxide. I weighed a 600 ml beaker with a watch glass on top of it. It weighed 278.9 grams. I added technical grade sodium hydroxide (drain cleaner) the inexpensive kind. I reweighed the beaker + watch glass + sodium hydroxide. It weighed 432.1 grams. I preheated the natural gas powered kitchen oven to 160 degrees centigrade or 320 degrees fahrenheit. I put the beaker into the oven on top of a hot sheet of metal for twenty minutes. I removed the hot beaker from the oven and put it inside a heat shock resistant glass dessicator to cool. Upon cooling I reweighed the beaker + watch glass + sodium hydroxide , it was 431.7 grams. 0.4 grams less than it was initially. The lost mass was surely water. But being hot the sodium hydroxide took on carbon dioxide from the atmosphere making sodium carbonate. But there was still a net mass loss as a result of heating. The sodium hydroxide product was not one solid peice as it was when I did this before. A higher temperature would work better to force water out of the caustic quickly. An electric oven would work better. Figuring a way to seal a container to not allow carbon dioxide from the atmosphere to touch the hot drying sodium hydroxide would work better. In 100 grams of technical grade sodium hydroxide there might be 15 grams/milliliters of water present that could be removed by some modification of this process, so the methoxide methanol solution produced would have a higher concentration of methoxide, due to less water being present in the starting materials.
    Last edited by Tony From West Oz; 26th December 2016 at 04:51 PM. Reason: moved to new thread - CHANGED TITLE

  6. #6
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    Re:Drying NaOH

    Thanks for conducting this test. It helps to see what is possible and to work out the cost/benefit of performing it.
    0.1434% reduction in weight.
    Unless we can quantify the Na2Co3 in the dried NaOH, we cannot identify the actual reduction of water in the NaOH.
    if 15% of the 278.9g was H20 (1g/ml), the water would weigh 36.2g and 50% of it removed by heating, you would have a reduction in weight of 18.1g
    What is the weight of Na2CO3?
    Can we calculate the proportion of Water and Na2CO3 from the weight reduction?
    Last edited by Tony From West Oz; 26th December 2016 at 04:51 PM. Reason: moved to new thread - CHANGED TITLE
    Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

    Current Vehicles in stable:
    '85 Mercedes Benz W123 300CD Turbodiesel single tank using 95% used cooking oil and 5% to 10% misfuel (where someone had filled diesel vehicle with petrol).
    '06 Musso Sports Crew Cab. Running on used cooking oil with 5% to 10% misfuel.
    Toyota Camry Hybrid - (Wife's Car)

    Previous Vehicles:
    '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup. Died when supercharger stuck at max boost for weeks. Stretched head bolts.
    '80 Mercedes 300D. 2 tank conversion [Sold]
    '84 Mercedes 300D. 1 tank, no conversion. Replaced engine with rebuilt OM617A turbodiesel engine. Finally had good power. Donor for current Fatmobile coupe. (body parted out and carcass sold for scrap.)
    '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
    '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
    Parts Car C220 1993 All body panels, headlights, interior engine and ECU available.


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  7. #7
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    Re: Drying NaOH

    Tony,
    I did some water tests on KOH methoxide, both as mixed and dried with CaO, I'll see if I can dig them out.

    As said the calcium soap formed couldn't be washed out (virtually insoluble in water) I tried to use magnesol and that also didn't work. Even centrifuging didn't work. It was only the oak chips that eventually got the soap to zero after 3 passes, changing the oak each time.

    As per others that have tried this our conclusion is that the extra yield isn't worth all the extra time.
    Last edited by Tony From West Oz; 26th December 2016 at 04:52 PM. Reason: moved to new thread - CHANGED TITLE

  8. #8
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    Re:Drying NaOH

    Hello there; I did the experiment that was a total failure. I weighed a one litre round bottom flask with a greazed stopper in it. I heated the flask hot under 86 millimeters of vacuum pressure. I saw liquid in the receiving flask from the vacuum still. Then when I disconnected/ disassembled the vacuum still I dropped the 1 litre flask with the dried technical grade sodium hydroxide solid. I did not gtet a mass reduction measurement on how much water was removed from heating the sodium hydroxide under vacuum, but water was removed, I saw it in the recieving flask That cost me a lot of money plus calling the crushers tio authorise me to purchase another 1 liter flask. The government people here are bad.
    Last edited by Tony From West Oz; 26th December 2016 at 04:52 PM. Reason: moved to new thread - CHANGED TITLE

  9. #9
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    Re: Drying NaOH

    What a disappointment! I hope that you and anyone nearby were not hurt. The cost of replacing the glassware and the NaOH just rubs salt (or is is NaOH?) into the wound.

    Thanks for your research.

    In Australia, purchase of litre sized analytical glassware will raise the interest of the authorities.
    Merry Christmas,
    Tony
    Last edited by Tony From West Oz; 26th December 2016 at 04:53 PM. Reason: moved to new thread - CHANGED TITLE
    Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

    Current Vehicles in stable:
    '85 Mercedes Benz W123 300CD Turbodiesel single tank using 95% used cooking oil and 5% to 10% misfuel (where someone had filled diesel vehicle with petrol).
    '06 Musso Sports Crew Cab. Running on used cooking oil with 5% to 10% misfuel.
    Toyota Camry Hybrid - (Wife's Car)

    Previous Vehicles:
    '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup. Died when supercharger stuck at max boost for weeks. Stretched head bolts.
    '80 Mercedes 300D. 2 tank conversion [Sold]
    '84 Mercedes 300D. 1 tank, no conversion. Replaced engine with rebuilt OM617A turbodiesel engine. Finally had good power. Donor for current Fatmobile coupe. (body parted out and carcass sold for scrap.)
    '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
    '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
    Parts Car C220 1993 All body panels, headlights, interior engine and ECU available.


    Searching the Biofuels Forum using Google
    Adding images and/or documents to your posts


  10. #10
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    Re: Drying NaOH

    I have moved these posts from "Drying WVO" to a new thread "Drying NaOH" to make the subject match the discussion
    Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

    Current Vehicles in stable:
    '85 Mercedes Benz W123 300CD Turbodiesel single tank using 95% used cooking oil and 5% to 10% misfuel (where someone had filled diesel vehicle with petrol).
    '06 Musso Sports Crew Cab. Running on used cooking oil with 5% to 10% misfuel.
    Toyota Camry Hybrid - (Wife's Car)

    Previous Vehicles:
    '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup. Died when supercharger stuck at max boost for weeks. Stretched head bolts.
    '80 Mercedes 300D. 2 tank conversion [Sold]
    '84 Mercedes 300D. 1 tank, no conversion. Replaced engine with rebuilt OM617A turbodiesel engine. Finally had good power. Donor for current Fatmobile coupe. (body parted out and carcass sold for scrap.)
    '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
    '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
    Parts Car C220 1993 All body panels, headlights, interior engine and ECU available.


    Searching the Biofuels Forum using Google
    Adding images and/or documents to your posts


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