I have been seeing, what appears to me, conflicting posts on the use of KOH instead of NaOH as a catalyst. One post states that girl_mark has switched to using KOH while I think I saw a post where Tilly said that he would not use KOH.
Have there been some changes in thought about which catalyst to use and if so, why?
One of the stated reasons for KOH is that the by product does not solidify. Recent threads on a pre-wash wash also prevent the by product from going solid.
I am still somewhat a rookie in this but I am very picky about what I produce. There are always trade offs for any decision. If there are good reasons to switch catalyst, I would appreciate hearing the rationale.
Hello Bobby S
I think I have said I have not used KOH. That was completely because of a lack of availability.
Now i live in ลึก ประเทศอินเดีย and am flat out making official made in Australia souvenirs.
I would never dream of making biodiesel ever again in Australia.
I have no opinions with refrence to the use of KOH
Bobby, I used NaOH at first because I could get it at the grocery store and being new at it, I could experiment without purchasing large amounts of anything. Then I tried KOH. That was that, it's like night and day. Much easier to work with, faster reaction time (in my experience anyway), it disolves in methanol much much faster, it doesn't solidify, it's more forgiving in case of slight measurement error and also in that it seems to tolerate water in the oil and still make good fuel. Again, this is only in my experience and not submited as fact.
I love it but one thing to watch out for is that because it disolves so fast in methanol it's easy to, if you pour a lot into a collapsable carboy all at once, get hot spots. This is where the disolving process causes heat. If large amounts of KOH are all in one place it can creat a substantial amount of heat. Enough to melt right through those thin crappy carboys.
But a little care is all that is needed to avoid issues with melting your carboys.
All in all, NaOH would have to be all but free before I would use it again.
That's my opinion of it and from what I've read about it, most seem to feel this way about KOH as opposed to NaOH. It just seems to be a much better version of caustic to use in BD processing.
Ok, I'll step down off the soap box now. LOL
PS, it's damn good stuff!
Tilly, why not? (I would never dream of making biodiesel ever again in Australia.)
Just curious, if it's because of personal reasons feel free to tell me to mind my own f@%#ing business. LOL
Very funny Scottie, now beam down my clothes.
Exciting new laws in Australia make it illegal to make biodiesel
unless you are licensed,pay taxes, keep records etc.
Being law-abiding citizens, noone is now making biodiesel for personal use.
I vote for KOH, too.
the same reasons Wayne mentioned.. it is a little more expensive, but worth it, in my mind..
aussie biodiesel bob...
I'm with Wayne on this one. Bought KOH because it was cheaper and easier to get in large quantity from my supplier.
Very happy with how user friendly it is. Will not go back to Naoh unless I had to.
The KOH I use is flakes, 90% pure. The only complaint is the dust when I am moving the stuff from larger conatainers to smaller ones and when measuring. It makes me cough and burns my skin. A dust mask and long sleeves, along with the usual rubber gloves and glasses took care of that.Kevin
Does KOH have a longer storage life than NaOH?
Will it pick up water as easily and loose it's effectiveness?
No clue, but I suspect it would be more to do with flake vs. bead than NaOH vs. KOH in terms of water absorbsion and so on. If any of it is sealled up good you really should not have a problem. I bought a 50 lb bag and put it in plastic 5 gallon buckets. It took two buckets to hold it. I found a 2 gallon bucket that I'm going to clean out and fill so that the stuff isn't getting exposed every time the lid is off to remove enough for a batch.
First I had filled up a couple of Red Devil Lye containers, thinking this would be enough for an average batch and I could avoild unecessary opening and closing of the bucket. Because it takes more KOH than NaOH, it wasn't enough and had to open the bucket anyway. I think the two gallon bucket option will be a nice compromise.
Very funny Scottie, now beam down my clothes.
Who do you use for your supplier for the KOH?
My first bag of Lye was 50lbs of KOH. I took another local guy's advice on that. I found that for my particular circumstances, KOH wasn't ideal. I have soft water and the KOH doesn't want to wash out without a fight.
I want to make bar soap from the glycerin and NaOH is more conducive to making solid soap. I switched to NaOH and found that washing became easier. Less NaOH is necessary for the base amount (500g/L vs 700g/L). The only drawback I can see is that NaOH is more of a pain to mix into Methanol. I'm in Texas so the weather is warmer here for me than say UTAH or Wyoming so every situation is a bit different.
I made beautiful biodiesel from KOH and NaOH. I probably won't go back unless something substantial comes up. For me, I'm using NaOH.
I am happy to report that I have another successful batch in the drying tank. For me, water washing biodiesel made with NaOH requires half the effort that KOH does. I should note that I remove Methanol using the Graham Laming plumbers delight condenser setup.
This time, I took extra care to squeeze out as much methanol from the biodiesel as possible. It appears that the soap already began to fall out in my appleseed (water heater) setup even with the pump running. Because the drain of the water heater isn't at the true bottom, this soap was able to accumulate at the bottom. If I had a fully draining setup, I would probably be able to drain off the gel soap at the bottom, making water washing even easier. WOOHOO!!!
My preference is NaOH
Like kd460, I find the dust from KOH is troublesome and a terrible irritant. Just a light breeze back in summer and I got some of it down behind my neck, where it dissolved in the sweat and it stung like *!^%6$% crazy.
NaOH gives off minimal dust.
Also, the purity of KOH seems more variable than that of NaOH, which can lead to inconsistent batches, unless you add a fair bit more than the prescribed base amount.
The soap from NaOH processed biodiesel is much easier to filter in a waterless, no-resin wash system, which I use (The EcoProcessor)
NaOH certainly does have downsides too, so you need to weigh up which benefits outweigh which disadvantages, for your way of operating, and then make up your mind which way to go.
NaOH takes a little longer to dissolve in methanol (though it has never been a problem for me)
NaOH derived glycerol can set solid if allowed to cool, so must be drained from pipework before that happens.
Some say NaOH is less environmentally friendly, whereas KOH can be used to make fertiliser, but I do not entirely agree with this generalisation.
My reasoning is that KOH processing-residues can dramatically promote the wrong sort of organism to grow, particularly if it runs of into rivers, streams, lakes, where it can accelerate algal blooms which most often adversely affect the natural balance of other water life in that environment.
That is not to say that NaOH products can be allowed to run into streams, simply to point out that KOH products are not without their risks.
There is no clear 'better' catalyst, from what I can tell - I guess you must make up your mind based on how the pros and cons of each catalyst affect you and your environment, based on the type of processing you intend to do.
Hope that helps,
The other NaOH issue is that you just often can't work with oil over a titration of 5-7 with it because it begins to make soap that gels unlike the soap made from KOH, which does not. That's a really big issue when oil demand is high and people end up with crappy sources of oil.
Are you talking about the use of phosphoric acid and the resulting phosphates? Most people don't use phosphoric since it's so expensive compared to the other options.
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