Drying WVO

[smithy Senior Member Find all posts View Profile Close smithy]

Re: Drying WVO

Hi Wesley,

I think the chemical you are referring to is Sodium (or Potassium) Methylate. As you say it is anhydrous and when mixed with methanol also 'consumes' water that is in the methanol, so gives a totally water free methoxide.

Under these circumstances as long as the oil is dry yeilds of over 100% (by volume) can be achieved with reduced soap production.

Many of us here in the UK use it. One drawbrack is that the glycerol sets 'like a brick'. I use various combinations of all three catalysts depending on time of year. I find it gives the best combination of yield, economy and liquid glycerol.

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Drying WVO

Hi smithy, welcome to the forum!

Hi Wesley,
I think the chemical you are referring to is Sodium (or Potassium) Methylate.
As you say it is anhydrous and when mixed with methanol also 'consumes' water that is in the methanol, so gives a totally water free methoxide.

Wesley is talking about making methoxide by mixing KOH with Methanol which was what you were talking about, not purchasing Sodium (or Potassium) Methylate.
Wesley did not say it was anhydrous, he only pointed out that mixing KOH with methanol does not make the full 320g H2O per kg of KOH used in the reaction you said was produced. Wesley explained that this lesser H2O production is due to variables such as the purity of the KOH involved and how much methoxide is actually produced when the KOH is mixed with the methanol.

Typically new methanol is 99.9% purity or greater.
Can you explain what you mean by "consumes" when you said "...when mixed with methanol also 'consumes' water that is in the methanol"

Under these circumstances as long as the oil is dry yeilds of over 100% (by volume) can be achieved with reduced soap production.

There is a bit more to it than that.
The maximum theoretical yield is about 100% by mass which, depending on the oil being used, equates to something like 104.5% yield by volume
However, to achieve this high yield in a straight base reaction requires that the oil must also not contain any FFA's.
FFA's do not convert into biodiesel in a base reaction, they convert into soap.

I have noticed on other websites, people will sometimes include the biodiesel that drops out of the glycerine during a glycerine prewash as part of their claimed yield.

[WesleyB Donating Member Find all posts View Profile Close WesleyB]

Re: Drying WVO

A few points I noticed. Free fatty acids have a carboxylic acid functional group on the end of a carbon 12 to carbon 22 or so chain. A carboxylic acid is a carbon bonded in this case to another carbon ( the long chain connection) and to two oxygen atoms. One of the oxygen atoms has a double bond the other has a single bond. The single bond oxygen also has a single bond to a hydrogen, being a hydroxide (alcohol group). The free fatty acids have a functional group (caroxylic acid) that is the same as vinegar ( dilute aqueous acetic acid). The issue about that as it relates to this issue is water is strongly attacted to the acid group on free fatty acids. So a centrifuge will not remove all the water, hydrogen bonded to the carboxylic acid end of a free fatty acid molecule. Sodium methylate or sodium methoxide (a chemical may have several names designating it that are valid) is an anhydrous solid, but I believe it ignites when exposed to air. So it is sold I believe in solution in anhydrous methanol. Being dissolved in anhydrous methanol it is not as dangerous. Using solid sodium or potassium methoxide would have to be done in a glove box under inert atmosphere, which would be expensive. So the without water (anhydrous) chemical is available somewhere in the United States as an anhydrous (without water) alcohol solution, so that it can be carefully used outside a glove box with a nitrogen atmosphere inside it. Tilly I did not know the 15% percent inpurity in my KOH is water. I'll look at the assay printed on the label of my bottle when I get home later. Free fatty acids are a product of hydrolysis, that's water plus vegetable oil triglycerides yields free fatty acids plus mono, di or glycerine. The water inserts it self at the bond between the fatty acid and glycerine to produce two different molecules. After wards the water does not exist. The molecule has separated at the atomic level. OH- goes with the glycerine, H- goes with the free fatty acid. A general priniciple in organic chemistry that for every 10 degrees centigrade increase in an endothermic reaction as opposed to an exothermic reaction (heat given off) a doubling of the reaction rate occurs. So the lower temperature vaccum assisted removal of water from oil will allow less free fatty acids to form during drying. The longer the wet oil is kept hot the more hydrolysis will occur and the higher titration results. Maybe centrifuge the wet oil then using a flash evaporator then acid base proceedure might be best but might not be cost effective and a lot of equipment and a lot of trouble. Magnesium silicate or wood chips might be the most cost effective way to remove almost all the soap produced.

[horseflybiodiesel Biofuels Forum Newbie Find all posts View Profile Close horseflybiodiesel]

Re: Drying WVO

Yum.....so bubbles are ok? hahaha, man do I have a lot to learn about this hobby

[smithy Senior Member Find all posts View Profile Close smithy]

Re: Drying WVO

About a year ago I did a process using KOH methoxide that had beed dried using CaO (quicklime) The yeild was noticeably higher and the amount of Potassium soaps were very low. The big disadvantage was that some calcium soaps were produced during the process which were difficult to remove. I ended up filtering the dried biodiesel 3 times through hardwood to get rid if the calcium soap.

For convenience I now use a blend of Potassium and ASM (anhydrous sodium methylate) whenever I can, using as much ASM as is practical for the time of year. At the moment I can't use any ASM as using just 1/3 will result in solid glycerol. In Summer I can go up to 2/3 ASM and 1/3 KOH where the glycerol still remains liquid.

[WesleyB Donating Member Find all posts View Profile Close WesleyB]

Re: Drying WVO

etI remember reading about using quick lime CaO calcium oxide to assist in making methoxide in methanol solution. The idea was that when sodium or potassium hydroxide reacts/ dissolves in dry methanol to form methoxide plus water, that the calcium oxide would react with the water to form calcium hydroxide. Calcium forms two bonds , so calcium hydroxide is HOCaOH one hydrogen from the water bonds with the one oxygen in calcium oxide the hydroxide left from HOH, H two O, dihydrogen oxide, one oxygen bonded to two hydrogens, Subtract one hydrogen atom from two hydrogen atoms plus one oxygen atom bonded to each other, that leaves one hydrogen atom bonded to one oxygen atom and the oxygen atom forms two bonds, one to hydrogen, one to calcium. So the hydroxide functional group bonds to the other side of the calcium atom from where the oxygen in calcium oxide was. The water no longer exists. It was broken into two pieces. But there is an equilibrium. Calcium oxide will not dry ethanol perfectly. I believe calcium oxide will only dry 95% ethanol to 99.5%. Then the dried (commercial anhydrous) ethanol may be distilled off in a special distillation set up. So in making methoxide with caustic solid, removing the water produced from the reaction of sodium hydroxide and methanol is removing a chemical from the right side of the reaction equation, water. Water decomposes methoxide. The more water present the less methoxide can exist. Using Calcium Oxide to remove water from the solution causes the equilibrium to shift to the right, the products side of the equation . The less water the better. Drying the sodium or potassium hydroxide prior to making the methoxide in methanol solution as I described previously probably would improve what someone called The Imisides Method. I'm not sure Mark imisides actually produced that process completely by himself. I suppose that doesn't matter it's in the public domaine to be post on the internet. Dry the solid caustic in an oven at 160 degrees centigrade. Let it cool . With a metal screwdriver break up the solid caustic. Dissolve in dry methanol. Then if you care to add enough calcium oxide. That might increase the concentration in methanol of methoxide, but them there's the calcium soap produced that might be a problem. Calcium oxide does not completely perfectly dry alcohol solutions.

[smithy Senior Member Find all posts View Profile Close smithy]

Re: Drying WVO

I found the results I did a year ago. KOH methoxide was 3.12% water. After adding an excess of CaO and left to settle the water content was 0.42% These tests were done using Trinity reclaimed methanol with a water content of 2600ppm.

The concentration of methoxide used for the test was 50gms KOH in 400mls of Methanol.

[WesleyB Donating Member Find all posts View Profile Close WesleyB]

Re: Drying WVO

The concentration of methoxide used for the test was 50gms KOH in 400mls of Methanol. There is an equilibrium. Tilly said the remainer of the pertcentage of 85% or 90 % KOH is water. Water decomposes methoxide. The production of methoxide from Hydroxide ion plucking the hydrogen off methanol to produce methoxide ion is not 100% it's not quantitative. I've reqognized a method to dry caustic solid in the absence of carbon dioxide from the air adding to the hot potassium or sodium hydroxide, In a laboratory appartus. Weigh a single neck round bottom flask, add sodium or potassium hydroxide reweigh. Set up a vaccuum still. With a heating mantle heat the caustic hot to possibly over 200 degrees centigrade. Pull a strong vaccuum on the caustic during heating. Heating it hotter probably wouldn't hurt. It will frost the inside of the heat shock resistant lab glass flask. After heating maybe 30 minutes or an hour allow the flask to cool, then reweigh. I've got the equipment to do this, I just haven't done it yet. Starting with drier caustic solid would be better in making biodiesel.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Drying WVO

Wesley, Looking forward to your test results.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Drying WVO

I have moved some posts from this topic "Drying WVO" to a new thread "Drying NaOH" to make the subject match the discussion.
All posts on this topic should now be related to Drying WVO.

[Harvey Member Find all posts View Profile Close Harvey]

Re: Drying WVO

Dear Brains Trust
I'm looking at solar heating my wvo to assist drying, utilising some black irrigation pipe as solar collector, little dc pump and solar panel to circulate water, and utilise an aircon evaporator coil from an old split aircon for the heat transfer into the oil. With the coil being copper pipe with aluminium fins, dropped into a 200 litre steel drum of oil I wonder as to any problems such as polymerisation (which I'm not scientific enough to understand). ???
Kind regards Harvey

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Drying WVO

Great idea. By circulating water, you overcome the biggest disadvantage of plumbing WVO systems - Leaks are a PITA to clean up. Water has a higher specific heat than oil and a lower viscosity, so it makes sense to move the heat from the collector to the oil using water.
The dissimilar metals in contact with moist WVO could facilitate corrosion of the aluminum / copper.
I have used copper pipes in my early WVO conversion and it did not seem to impact on the oil at all. I did note that the copper pipe, where it was submerged in the oil was bright clean copper. The copper which never was submerged in WVO did get a verdigris coating.
I have not used aluminum in WVO at all so cannot comment there.

Another option is to use a plate heat exchanger (MPHE - SS ones are readily available) and a second DC pump to circulate the oil thru it.
You could also consider getting some SS pipe and having it bent to suit your oil heating vessel. That way you minimise any chances of reaction occurring, the oil remains in the heating vessel and the water cannot get into the oil. A Win - Win situation and much cheaper than a MPHE.

Please post photos of your progress and some numbers to show how well it works.

[WesleyB Donating Member Find all posts View Profile Close WesleyB]

Re: Drying WVO

Heating/drying waste vegetable oil with solar assisted power. On cloudy days not much would occur. Several mirrors reflecting light from the sun onto metal tubing with water slowly circulating through it would be good. I recall seeing a photograph of the very stylish solar energy cells on the roof of the White House while Obama was President of the United States. I expect the first time a big hail storm occurred those solar cells were smahed and the money to put them there was wasted. I don't know if you all have occassional hail storms there, but if you do it might smash glass solar reflector mirrors and solar electric cells.

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Drying WVO

Wesley,
We have a large solar array on our home and have has several heavy hail storms. There has been no damage to the panels from hail, despite some large hail in recent years, even on our old 17 year old panels.
Solar panels are designed to withstand very high impact events. Not bullets though - they will cause significant damage.
You might look up Brisbane in your atlas. There is no need for mirrors to help the solar heating or power generation on most days.

Tony

[Harvey Member Find all posts View Profile Close Harvey]

Re: Drying WVO

Hi Wesley
My design has a few simple requirements:
Total cost less than $60 (cheap irrigation pipe, Ebay pump and panel ala China, scavenged copper for heat exchanger).
As I collect oil I place it in my 200lt cone bottom reactor, over time it settles most of the water and crud out. Then I usually heat it with a 3.6kw heater for about 3hrs to 95C, and spray it across a fan. On frypan bubble test I get no bubbles.
I'm just looking at reducing my 3hr electric heat time. If it's cloudy for a week, it's ok as I have time, being a low consumption fuel baron of only 40-50lt/week.
Thank you for your valued input to the forum.