Page 2 of 2 FirstFirst 12
Results 11 to 20 of 20

Thread: Drying NaOH

  1. #11
    Join Date
    Dec 2016
    Location
    York UK
    Posts
    100

    Re: Drying NaOH

    Oh Dear Wesley, be careful. Shame you arn't closer, I have plenty of 1 litre round bottom flasks with the ground tapered tops.

    A few years ago I bought an amount of bankrupt stock from a chemical/lab glassware supplier, I have sold most of it but have a few bits and pieces left.

  2. #12
    Join Date
    Nov 2010
    Location
    Fort Worth, Texas, USA
    Posts
    273

    Re: Drying NaOH

    This morning I looked at my glassware I used to remove water from technical grade sodium hydroxide (drain cleaner). Under vaccum of 86 milliliters of pressure above zero at elevated temperature the hot sodium hydroxide went over the still head some of it was in the condenser. I saw a clear liquid in the receiving flask last night. I might not have applied enough stop cock grease to the ground glass joints to cause the easy separation of the glass ware components. I applied a lot of force to it to cause it to separate into pieces. I will do this again. This experiment is not as easy as I thought it would be, the sodium hydroxide foams across the still head upon heating. I did not put a thermometer into the hot sodium hydroxide while I was heating it. Thermometers with ground glass joints on them are expensive 100-150 USA dollars and it might ruin it. I will do this experiment again. I have other one liter round bottom boiling flasks to use in place of the one I broke. Technical grade sodium hydroxide turns into a liquid upon heating. It burned my heating mantel a little that I heated it so hot. I guess I heated the sodium hydroxide to 250 degrees centigrade or more to get that result. In making biodiesel, the less water that is in the starting materials, the better. Sodium hydroxide can have water removed from it by heating and high vaccum.

  3. #13
    Join Date
    Sep 2005
    Location
    WA
    Posts
    4,111

    Re: Drying NaOH

    Wesley,
    Surely you don't need to heat past 100C? Or does the water combine chemically with the NaOH and so needs a higher temperature to separate it?
    I don't like the thought of 250C NaOH getting splashed around the floor if the flask breaks. You would need effective PPE (personal protective equipment) to prevent serious injury.
    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


  4. #14
    Join Date
    Nov 2010
    Location
    Fort Worth, Texas, USA
    Posts
    273

    Re: Drying NaOH

    I did the experiment again. I put 157.3 grams technical grade sodium hydroxide into a 1 liter round bottom boiling flask , weighed it with a greased glass stopper in it. I heated the flask using a heating mantel under 99.5 millimeters of pressure (vacuum). Previously I wrote it was 86 millimeters of vacuum pressure. I read the guage wrong and did the math incorrectly to figure the pressure. I did not put a thermometer into the 1 liter flask since it might ruim my thermometer. That equipment is expensive and difficult to replace here. During heating the technical grade sodium hydroxide became a clear boiling liquid. I expect the temperature was over 200 degrees centigrade, that's a guess. The next day after cooling I reweighed the flask stopper and sodium hydroxide contents. 3.9 grams of mass was lost from heating the sodium hydroxide under 99.5 millimeters pressure (vacuum). I heated the sodium hydroxide for about 1 hour at the highest temperature under vacuum. In making biodiesel using sodium hydroxide dissolved in methanol to make methoxide, less water produces a higher concentration of methoxide for the reaction. There might be an advantage to drying the sodium hydroxide prior to making the alcohol methoxide solution.

  5. #15
    Join Date
    Sep 2005
    Location
    WA
    Posts
    4,111

    Re: Drying NaOH

    Were you able to test the water for pH?
    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


  6. #16
    Join Date
    Dec 2016
    Location
    York UK
    Posts
    100

    Re: Drying NaOH

    Hi Wesley and Tony,

    Your experiment Wesley showed a water content of the NaOH of 2.48%

    For those of us that use KOH the reduction in weight after drying would presumably be considerably more. I wonder if the KOH would dry efficiently if left in a 105 degree oven for a while.

  7. #17
    Join Date
    Nov 2010
    Location
    Fort Worth, Texas, USA
    Posts
    273

    Re: Drying NaOH

    I did not test the pH of the clear colorless liquid that went into the receiving flask. It surely was distilled water. Drying sodium or potassium hydroxide at 100 degrees centigrade probably would not work. There is a forceful chemical/physical attraction between water and the ionic caustic solid. I did an experiment decomposing the insecticide DDT that I found in my Grandmother's shed, storage building. I made fairly concentrated sodium hydroxide in water solution, part of the experiment was heating the aqueous caustic solution hot. The temperature of the strong technical grade sodium hydroxide solutuion exceeded 100 degrees centigrade without boiling. I don't remember the exact temperature. Epsom salt can be dried at something like 160 degrees centigrade to force water out of it. I'm not sure how to explain it correctly but heating it up under vacuum works to remove water from the caustic catalyst. In making biodiesel the drier the better. Removing water from all starting materials is good in hopefully a cost effective manner. The saponification reaction where triglyceride fatty acids react with sodium and potassium hydroxide is slower in the absence of water. The reaction was NaOH + Triglyceride fatty acids (vegetable oil, grease from cooking) in the presence of water produces soap plus heat (the reaction is exothermic). I don't remember the reaction mechanism, but I believe the water is regenerated during the reaction. I made potassium soap previously without adding any water. I heated it hot, maybe 150 degrees centigrade. It did react in the presence of very little water, but I expect the reaction was slower than if more water would have been present. Removing 2.48% water by mass from the catalyst might be significant in the probable increase in concentration of methoxide in the alcohol/catalyst solution. I have seen a book telling how to make super dry methanol, or ethanol indicating methanol as it is sold is not perfectly anhydrous (dry, without water). I don't know the specifications on common comercial grade methanol, I expect it has some water in it, so that might be another consideration in improving biodiesel production by in a cost effective manner, perfectly drying methanol. In addition to drying the oil, catalyst and what ever type of alcohol you choose to use. Methanol is not the only choice of alcohol to use in making biodiesel.

  8. #18
    Join Date
    Sep 2009
    Location
    Brisbane (North Side)
    Posts
    693

    Re: Drying NaOH

    Wesley,

    without steering the conversation from the very interesting topic it is, you can easily separate ground glass stoppers from the flask by using a wooden spoon believe it or not. just carefully rap the stopper with the wooden spoon (you wont be able to break it with a wooden spoon - thats why you use it) from side to side and the stopper will come loose very easily. I did do with the flask laying on its side, but it should work equally as well standing upright.

    I used this technique to open some old crystal decanters we were handed down. they had been stopped for 20 plus years.

    back to the chemistry lesson.......
    Regards,

    Cade.

    2002 100 series Landcruiser
    240,000 Km and counting on B100, 330,000km total on car.
    Naturally aspirated, Walbro Pusher pump just upstream of tank switch valves, Cav filter with reversed fuel flow direction.
    At 160,000 km Rebuilt pump, Reconditioned head and manifolds, glow plugs. Injectors all good after 160,000 km on B100.

  9. #19
    Join Date
    Nov 2010
    Location
    Fort Worth, Texas, USA
    Posts
    273

    Re: Drying NaOH

    Years ago, maybe in the late 1980ts there was an issue of disposal of styrofoan drinking cups here in the USA. I ground up some styrofoam , made concentrated aqueous sodium hydroxide (technical grade drain cleaner), and put the styrofoam with the caustic into a 1 litre round bottom boiling flask to react, if it would at room temperature. I made the mistake of not putting enough stopcock grease into the ground glass joint. The clear colorless transparent liquid took on a light yellowish brown color after one month or so. There was a reaction, but it was very slow. I tried to remove the ground glass stopper, but it was stuck into the joint permanently. I ended up discarding the flask and stopper in garbage that was buried in a land fill here. The best way to separate ground glass joints is to use more than enough stop cock grease, initially.

  10. #20
    Join Date
    Feb 2007
    Location
    Natone, Tasmania
    Posts
    77

    Re: Drying NaOH

    The best reagent to remove water from NaOH is obviously Na. Putting some in your sealed flask will extract every bit of oxygen and moisture from the contained air. I would first flush it with argon for economy sake; how fast water vapour will diffuse from the particles I have no idea but it will obviously be a function of heat and time, perhaps measured in years at room temperature. Perhaps a sealed ceramic ball mill or stainless steel? Note that hydrogen gas will be generated and you don't want another Fukushima in your reactor.

    Just measuring catalyst is not pleasant, there is quite a bit of the stuff fuming into the air even at room temperature, and did you guys measure that?

    Personally I find commercial grades of methanol and KOH satisfactory with careful washing. I start with a mist - after adding about 20% water and decanting the liquid; indicator paper after a little bit more mist suggests most of the caustic is gone, and it is really easy from there. Meanwhile, back at the lab....

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •