Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: Murphy on June 18, 2006, 12:14:17 PM
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Hello everyone,
This is my first post.. I'm a newbie!!
I'm not much of a chemist and I need a bit of help with a project I am working on.
I am making diesel fuel from waste vegetable oil and need some directions on how to use one of my by-products of the process.
First, let me explain a bit.. The process is called "Base catalyst transesterfication".. This process results in some byproducts that must be disposed of properly. I am small time and don't produce much but I want to make sure I do it right.
Anyhow, the last part of my process requires that I "wash" the biodiesel by spraying the fuel with a very fine mist of water. The mist settles on top of the fuel and eventually ends up at the bottom of the tank. As the micro droplets of water travel down through the biofuel, it picks up the remaining contaminants in the fuel.
Here is my problem.
For every 50 gallons of fuel I make, I end up with about 50 gallons of this wash water. The wash water is at a PH of about 9.6 or so and as the processes progresses and wash water is drained off the bottom, its PH falls to around 7 or 7.5. I am using KOH (Potassium Hydroxide @ 90% purity) for my catalyst so this is the main ingredient in the wash water. There are some other things in there as well like soap (an undesired effect of the reaction), hard well water (not softened), and a few other minor things. The wash water appears a milky white color when first drained. By the end of the misting process, the wash water is clear as the incoming water and pretty much PH neutral.
I am on a large farm and I want to spread this was water out on the grass and maybe even some crops. (we grow a little bit of everything) How do I go about making this a poor-mans fertilizer?
Is there something simple that I can do to make this stuff plant friendly? I did a small control test on some grass / weeds by just hand pouring about 20 gallons into an area 10 x 10 feet.. After about 2 weeks, the grass is starting to turn brown.. Not exactly a quick death but none the less its dying..
Thanks,
Murphy
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You have in your wash water (at a minimum):
1. Glycerol reaction product
2. base (diluted KOH) catalyst
3. waste oil sludge and salts (from the free fatty acids)
4. methanol or ethanol, whatever you use
I would want to isolate what portion is responsible for browning the grass. One approach would be to see if it is simply a pH issue. Use the same amount of base and dilute with water (or scale it down in proportion to use less water). Pour it on the same size area of the grass and see if the grass dies just from the base (no biodiesel). If so, you might be able to get away with neutralizing the base with a weak acid (ie phosphoric acid).
I would do the same thing with the alcohol that you use to see if it is responsible. You can probably assume that all of the unreacted alcohol goes into the water phase.
If it isn't a simple pH issue, you are probably out of luck and will have to send it to wastewater or use it as a weedkiller. Another site you might want to ask.
http://forums.biodieselnow.com/topic.asp?TOPIC_ID=10431
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Dude,
Thanks for your response.. I was begining to think no one was going to even try to answer it..
Anyhow,
Glycerol, (we call it glycerin) is drained off at the reaction tank. While there may be some present in the wash water it would be a very small amount. The whole idea is to get the glycerol seperated from the bio that is to be washed before it gets transfered to the wash tank. Reaction tank designs are based on this fact..
Base (diluted KOH) catalyst is the big one.. There is left over catalyst.. This is why I decided to go with KOH instead of NaOH.. (NaOH is toxic to plants no matter what you do to it)
Waste oil sludge and salts from the free fatty acids end up in the glycerol by-product which is drained off before transfer to the wash tank. While they may be present in the wash water, they would also be in extremely small quantities.
Methanol or ethanol could be there also.. I use Methanol instead of ethanol.. Most of the left over methanol that is not used up in the reaction is also drained off in the glycerol layer.. So much of it that many biodiesel makers set up revovery stills to get it back from the glycerine. However, there is some left in the biodiesel and I could get this out if required.
Lets assume for the sake of this discussion that I am just dealing with diluted KOH left-over catalyst..
You are suggestin phosphoric acid? What about nitric acid?
Is there more involved in making potassium phosphate than just neutralizing with phos acid? Or is it really that simple for a poor-mans fertilizer?
I'd rather use the phosphate road than use nitric acid.. I buy KOH in 50lb bags and would hate to end up on some FBI watchlist for buying nitric acid along with it..
Thanks very much for your input..
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So my question has been moved to a forum section that no one visits?
Great...
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Is there any reason why you would not let the water evaporate and reuse the KOH catalyst?
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billnotgatez,
Thanks for your response.. I didnt think anyone was ever going to see my topic being that it's been moved to an almost non-active forum section...
Evaporating the water is not really an option as I generate so much of it.. A 50 gallon batch of bio will generate at least that much in wash water.. sometimes even more. Also, there are other things in the wash water like soap. Evaporation would require either lots of energy, or lots of space to hold the large volumes.
It just seems better to turn it into fertilizer if I can..
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Maybe I don't completely understand your process, but I don't see the logic in turning the wastewater into fertilizer. What kind of nutrients are in the wastewater that will be beneficial to the plants?
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There is left over catylist in the waste water.. The catylist is potassium hydroxide.. This also makes a small bit of soap but not a allot..
There is also methanol in the waste water but I can get rid of that pretty easy before using it for fertilizer.
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The death of the plants might be because of the alkalinity of the water. I'm not sure what could be done to remove that. http://www.wqa.org/glossary.cfm?gl=663
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A suggestion is nitrating the KOH with nitric acid, but the nitric acid is hard to get, and to much would make the solution acidic.
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What about phosphoric acid? Isnt that a very environmentaly safe stuff? Combined with KOH rich waste water solution, would that not make a poor-mans potassium phosphate?
I can get any chemical I want.. I've been doing business with a large industrial chemical supplier for 15 years and they know who I am..
I'm not crazy about using nitric acid.. While it might make a poor-mans potassium nitrate fertilizer, the problem is that one of my major by-products is glycerine.. I'm not interested in having glycerine and nitric acid in the same building.. Nor do I think purchasing the 2 at the same time is a good idea.. I might as well call the FBI myself... ;D
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If you are on such great terms with the chemical company have you thought about maybe giving them the waste to dispose of?
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I was studying about fertilizers at http://en.wikipedia.org/wiki/Fertilizer after your posts. I am not certain that just because you have a compound with potassium in it that that element will be available as a nutrient to plants. For instance it appears that potassium sulfate is used rather than potassium nitrate as a fertilizer. Also, I seem to recollect that buffers have phosphorous compounds in them. Still I am not sure potassium phosphate would act as a nutrient.
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Murphy-
Is there such a thing as using too much fertilizer?
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Murphy-
Is there such a thing as using too much fertilizer?
Of course.. to much of anything is bad...
I think my problem is mostly pH as later wash batches have a lower pH value and dont seem to kill the grass no matter how much I dump on it.. The first 5 gallon batch I remove is usually up around 9.5.. Second batch falls to around 9.2, and so on until my 6th or 7th batch is barely above incoming water pH... (7.5 or so).. That means that first batch has something like 10,000 times more caustic in it than the last batch.. Is that correct? pH is X10 for each number higher?
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The first 5 gallon batch I remove is usually up around 9.5.. Second batch falls to around 9.2, and so on until my 6th or 7th batch is barely above incoming water pH... (7.5 or so).. That means that first batch has something like 10,000 times more caustic in it than the last batch.. Is that correct? pH is X10 for each number higher?
Check you math - while you are right about 1 pH unit meaning 10 times difference, you start with 9.5 and end with 7.5, that's two units - so 100, not 10000.
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Not being an agricultural chemist, but looking at various pieces of information about fertilizers, it looks like salts of potassium created using phosphoric, sulfuric, and / or nitric acids would work. I lean towards the phosphoric acid and potassium hydroxide combination because it may have a more buffering activity. The sulfuric acid and potassium hydroxide combination may participate out initially and then dissolve as the pH gets closer to neutral. I do not think hydrochloric acid would be a good option.
You still might get fertilizer burn should you just dump it one small area. Actually had you spread the potassium hydroxide at the pH level you have over a wide area it would probably not have shown the browning effect, especially after a rain.
One side note, you are using potassium hydroxide with methanol and I thought most suggest you use ethanol.
Murphy – a question for you – which do you think is better, slightly alkaline soil or slightly acid soil?
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Borek,
You are correct.. Thanks.. 100 is much better than 10,000!!!! LOL
billnotgatez,
Thanks for the information you have provided. I'm going to try the phosphoric acid as soon as I can find a few gallons of it. Isnt there some product called "Rust Mort" or something that is used to turn rusted car part into a black oxide or something that contains a high concentration of phosphoric acid?
As for the soil.... I have NO idea what so ever on what side of the pH scale is better. My "uneducated" guess would be to say that acidic is better. I only say this because in my limited experience with chemicals (15 years industrial processing), I am a lot less afraid of acidic stuff than I am of caustic stuff.. Acid is way over-rated as dangerous while caustic materials can cause massive damage with little or no warning. Given the choice, I'd rather spill acid on myself than caustic soda.. Of course, like I said, I have no idea.. Its just a guess out of the blue.
It seems to me from my very limited knowledge, Acid dissolves metals and minerals in the soil while caustic tends to destroy biological things. I would think a plant would be able to deal with a dissolved metal much better than a caustic attacking its root.. Also, as I understand it, septic systems dont like soap (which is on the caustic side).. Being that a septic system is basically a miniature eco-system in itself and that they dont like caustic stuff, I'd have to say acid would be better for a plant.
Do you know the answer? Am I right or wrong?
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As for the soil.... I have NO idea what so ever on what side of the pH scale is better. My "uneducated" guess would be to say that acidic is better. I only say this because in my limited experience with chemicals (15 years industrial processing), I am a lot less afraid of acidic stuff than I am of caustic stuff.. Acid is way over-rated as dangerous while caustic materials can cause massive damage with little or no warning. Given the choice, I'd rather spill acid on myself than caustic soda.. Of course, like I said, I have no idea.. Its just a guess out of the blue.
It all depends on the plants - and pH. Some plants prefer slightly acidic soil, some prefer slightly basic one. Note it is "slightly" - I believe pH 5 to 8 is the range occuring in natural soils (but better check me on this, it is 50% guess). But just because these occurs naturally, doesn't mean every plant will survive them. pH control of soils is an important part of tending your crops (AFAIK most often CaCO3 is used to raise pH of acidic soils).
As for acid/base dangers - while (if given a choice) I would rather wash my hands in 1M HCl than in 1M NaOH (which supports your approach) they can be both dangerous when concentrated - so it is better to not underestimate either.
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which do you think is better, slightly alkaline soil or slightly acid soil?
Is there such a thing as using too much fertilizer?
The reason I posed the questions was to get us thinking about the effect of using fertilizer. Just because we make some chemical into a fertilizer does not mean we could have desired results. The question about acid / base status of a soil was a trick question. This is because some plants like acid soil and some like alkaline soil. But, I actually fooled myself. I know that in this area farmers are typically amending the soil with lime. So I assume very slightly alkaline was optimum, which is not entirely true. In most cases it seems that they are just raising it far enough to be very slightly acid or neutral. I base this on the below links.
http://en.wikipedia.org/wiki/Soil_pH
http://www.esf.edu/PUBPROG/brochure/soilph/soilph.htm
http://www.ext.colostate.edu/pubs/garden/07727.html
http://www.donnan.com/soilph.htm
The upshot of this means that you want to convert your highly alkaline potassium hydroxide to near neutral to keep the soil at the pH it is already at. It seems that most plants will tolerate 6.8 to 7.2 pH. Also remember that most fertilizer has various components so you might also want to add something like urea to the soil where you put the neutralized potassium hydroxide, but still make an effort to maintain the appropriate pH after any addition.
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I got the below information from various web sites
phosphoric acid H3PO4 pH Down Some pH reducers (available at pet stores) used in fish tanks are simply dilute solutions (up to 30%) of phosphoric acid. Also available in gel form at hardware stores as a rust remover. "Naval Jelly" in a spray bottle at hardware stores. Also used as a solder flux.
Phosphoric Acid
Formula: H3PO4
Synonyms: –
Suppliers:
1. It is sold by some hardware stores as a rust remover, sometimes by the name "Naval Jelly".
2. Some hydroponics suppliers sell it as a "pH Minus" (i.e. an agent to decrease the pH of water).
Atlantis Hydroponics (USA)
Elements Hydroponics Centre (UK)
GroWell Hydroponics (UK)
Hydro Gardens (USA)
HydroHobby (UK)
3. Some food suppliers sell it
4. Some alternative photographic suppliers sell it.
Bostick and Sullivan (USA)
Photographers' Formulary (USA)
5. Some brewing and winemaking suppliers sell it.
Beer Beer and More Beer (USA)
Defalco's (USA)
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Damn Bill, You're "the man".. Thanks for all your help..
I completely agree with you about some plants liking acidic and some liking caustic..
Some of the guys who make bio use NaOH instead of KOH.. NaOH is toxic to almost all plants.. This raised the discussion of constructing a poor-mans wetlands of plants that like the salty / high pH waste water we generate. After 20 min of reading, I quickly realized it would be a project to large for me to take on and not very compatible with Michigan environment. Thus, I started searching for a better way.
I think I need to get myself a soil type pH meter This entire project of mine was taken on with the understanding that with a little research and work, I could completely recycle all of my product and by-products with a positive influence. I'm holding true to that so far.. Things are looking good.. I just need to fine tune everything.
I think that before I go neutralizing things with acid, I better check soil pH then. I'm not much of a farmer :o
Thanks again for all your help.
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I think I need to get myself a soil type pH meter
http://www.ph-meter.info/pH-measurements-other-procedures
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If you search this forum you will find several entries involving bio-diesel (use the word diesel). I usually do not suggest using the search engine here because I find it challenging, but others more adept than me get results. In any case there is a thread by me that suggest an experiment which I have not done yet.
http://www.chemicalforums.com/index.php?topic=7087.0
My suggestion was to use ethanol and potassium hydroxide, which is more difficult. The reason was I wanted to stay away from buying methanol. But I suppose the home chemist could make methanol even though it is not as easy as ethanol. There is a web site that I read from time to time to keep thinking on this experiment.
http://journeytoforever.org/biodiesel_make.html
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Bill,
Please, do not point people to journeytoforever...
People experienced in biodiesel production will tell you that site is filled with inaccurate information. Some of the information is so off that you can damage your engine.
Journeytoforever is a joke site among biodiesel producers.
Just to give you one example: Journey to forever suggest using 3.5g of lye as base.. Anyone following this instruction will be producing bio with unreacted oil dissolved within it.. The minimum amount of base catalyst should be 5 grams. Commercial producers use up to 9 grams. That site is filled with misleading, inaccurate and some just-out-right-false statements and instructions. The real problem is that anyone making bio from that information wont know there is a problem until they have already put 10,000 miles on their engine, at which time your fuel injector pump fails or you find out your engine is gunked up with unreacted bio deposits. Something I find even more interesting is the folks who run straight veggy oil. As far as that's concerned, bring your cell phone cause your gonna need it..
Thanks again for all your help..
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Murphy –
Suggest another site with all the same information, but corrected and I will edit my entries. For instance oil content of various plant products etc.
Some sources seem short on biology and others seem short on mechanical and others are short on chemistry. Is there a site that has all accurately?
I am always willing to correct my entries.
Regards,
Bill
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Try these:
A newbie guide http://www.biodieselcommunity.org
Best Forum http://biodiesel.infopop.cc/
Those two sites above can take a newbie all the way from their first 1 liter test batch to becoming a commercial producer. There are even a few commercial producers who participate in the forums and we have one phd chemical engineer.. (although he doesn't post nearly often enough, when he does, we listen intently)
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Best Forum http://biodiesel.infopop.cc/
I doubt the biodiessel forum will be helpful since the threadstarter intends to convert waste stream into a fertiliser.
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Murphy –
What do you plan on doing with the glycerol / glycerin side product?
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Murphy –
What do you plan on doing with the glycerol / glycerin side product?
There are many uses for it. Currently I am storing it.. I am in the process of building a reflux still to distill the glycerin and recover my methanol from it. This protects the environment and gets my money back.. (meth is expensive).
Once this is done, part of the glycerin will go though soaponification to make soap for my shop floor, drive way, etc etc. While making soap from glycerin is a cool thing to do, one five gallon bucket of it will make more soap than I can probably use in my lifetime!! Great idea but it sure wont get rid of all my byproduct. I'm looking into purifying it to a commercial grade product. As I understand, its not that hard to do.. If that doesn't work out, I'll burn it for heat. Glycerin has a pretty good btu content and I am building an outdoor wood burning boiler for winter heating.. (High natural gas prices and all)..
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Murphy -
Would you use glycerol / glycerin to run your still as well?
I am contemplating the energy production minus the energy cost of this process.
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Those sites listed above are old. The best sites to use now are:
A biofuel/biodiesel newbie guide - http://biofuelbay.com/ (http://biofuelbay.com/)
Best BioFuel Forum - http://www.BioFuelDebate.com/ (http://www.BioFuelDebate.com/)
:)
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Just out of curiosity, you wouldn't happen to be JFox on the second forum would you (one of the administrators)?
Add to it that the two sites are related, sounds more like an ad...
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Those sites listed above are old. The best sites to use now are:
A biofuel/biodiesel newbie guide - http://biofuelbay.com/ (http:// biofuelbay.com/)
Best BioFuel Forum - http://www.BioFuelDebate.com/ (http:// www.BioFuelDebate.com/)
These are both your sites, so your opinion about their credibility doesn't matter. And please stop spamming our forums with links to your sites, or you will be banned. You may post links in Free Chemistry Advertising forum, that'll be enough.
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I think this depends on the grass.You get alkaline soils in desert conditions.I know this because my mother is an indoor cactus gardener.I have never seen much grass in the desert (or any other plant for that matter)
Now here in washington state we have very acidic soil especially at higher elevations.There is also no grass (but plenty of trees and shrubs)
This leads me to believe grass needs neutral to slightly acidic conditions to grow.It will not grow in probably even 7 very well.Think 6 most likely.Biological things are very sensitive to ph changes.Now if you took a bath in your wastewater or even some other water that had a similar ph I bet your skin would not be very happy after a short time.All plants need to be in water that wouldn't ever harm your skin even cacti.