HI!!

In the esterification you have the production of water but is water with sulfuric acid so....what can we do with that water??? There's any kind of easy treatment for it?? What happen If I evaporate it??

Evaporate the water, which also evaporates excess methanol. Then, add extra catalyst to neutralize sulfuric acid left in oil.

hi
I was thinking in evaporating but if I evaporate the excess methanol would it have any effect in the transesterificaton???

Evaporating the excess methanol will not have a negative effect on the transesterification process. But, once evaporated it is no longer available in the base (transesterification) reaction. You will have to add additional methanol in the base step.

The drawback to the esterification (acid) process is the production of water as a byproduct of the reaction. If the water is allowed to enter the transesterification process, excess soap will be formed.

You must remove the water. This means, unfortunately, that the excess methanol is also removed.

Hello quemala

Most people just leave the water and the methanol and the H2SO4 in the oil at the end of the acid stage and perform the base reaction by using 5g NaOH+ titration mixed into the remainder of the methanol to make a total of 200ml methanol per litre WVO reacted.

hi!!

I am making esterification in the lab...so I just eliminate the water that usually is in the botton or in a upper layer....but if I am going to star bigger batches I will probably have a lot of litters of this water....so that's why I ask about....is any good thing to do with this water once I separate it from the esterificate oil????

I don't want to evaporate it because as producer says I will have to add extra methanol and it's not cheap for me .....
And as Tilly said if I keep water in the process I will have problems with tranesterification because of the formation of soaps....

For my part, I had issues with the water causing soap problems as well.

I finally just settled on a full drying of the oil after the acid stage. I have a methanol recovery system so all this costs me is the energy to do it. If I watch the temperature I can seperate the methanol from the water during the distillation process. The methanol gets re-added during the base stage.

that would be a good alternative.....i will have to built a condenser to keep the methanol in the process......

quemala,

Water and methanol are miscible. Add a small amount of water to methanol the two will completely mix. Add a small amount of methanol to water and the two will completely mix. Add any amount of water to any amount of methanol and the two will completely mix.

An esterification reaction starts with dry oil, methanol, and acid. As esterification progresses, water is produced as a by-product of the chemical reaction. The "chemical" water mixes with the methanol. At first only a small amount of water is produced. As the reaction progresses more and more water is produced. The build up of water eventually is enough to dilute enough of the methanol to the point where the methanol is no longer active in esterification, and the reaction stops.

The two main ways to counteract this are to either: one - add overwhelming amounts of excess methanol to reduce the effects of dilution; or, two - stop the process periodically and drain off the water/methanol mixture. Option one is very expensive without methanol recovery. Option two requires adding more reactants to continue the reaction.

The specific gravity water is greater than the SG of oil. The SG of oil is greater than the SG of methanol. A solution of a small amount of water and a lot of methanol has a SG less than oil, so the water/methanol mixture will float in the oil. As the amount of water in the mixture increases, the SG of the mixture will increase until it is greater than the SG of the oil, so the water/methanol mixture will then settle in the oil.

quote:

Originally posted by producer:
The two main ways to counteract this are to either: one - add overwhelming amounts of excess methanol to reduce the effects of dilution; or, two - stop the process periodically and drain off the water/methanol mixture. Option one is very expensive without methanol recovery. Option two requires adding more reactants to continue the reaction.

would it be possible to extract that water using anhydrous sodium sulphate? i'm sure the sodium would NOT form any soap, not with so many excess sulphate ions. besides, sulphuric acid is much stronger than FFAs, so any soap would be converted into FFA and sodium sulphate. all AFAIK, of course.

hi!!

Producer I got a question....you said that first the water-methanol mix is going to be above the oil and since the reaction get complete it would be more water so it finish at the bottom......

Sometimes I get water at the bottom and sometimes in a upper layer....so if I get water in the upper layer it's because the reaction is not complete...that I need more time for the esterification??

harry747,

I have no experience or knowledge about using sodium sulfate as a drying agent, so I can't help.

quemala,

My comment about the methanol/water mixture was to explain why it is possible to see the layer on top of the oil and later below the oil. The comment did not address completeness of reaction. I did not mean to imply you could use this phenomenon as an indicater of reaction completeness. This may be possible. I don't know.

quote:

Originally posted by producer:
harry747,

I have no experience or knowledge about using sodium sulfate as a drying agent, so I can't help.

i think it's worth a test. any volunteers?

Producer,

I know you didn't say the position of the water layer is an indicator of complete or incomplete reaction....but I just want to figure out if it could be possible to predict when the reaction is done base in the production of water....thanks for the explanation it's very useful!

I have another question....does all the methanol in the esterification reacts with the water ??....f I drain the water I am draining all the methanol too....so in the transesterification I would have to put extra methanol??

acid process is easy to figure out completeness without having to try and measure SG's just titrate it and assume all your acid level is ffa which should be less than .5%. if your using the same process over and over with the same oil and same reaction conditions in the same sized reactor maybe you could tell if it was done by when and where it seperated if you could see it. but then youd want to check if below your target or below .5% done anyways. im gonna try to work at getting tilly's viscosity test to work consistantly for predicting how much TG's are left after all acid processes. iv'e forgetten how i made clear orange biodiesel out of my trap grease while we've been building the winterized feedstock tanks and methanol recovery unit. only thing that seems to work lately is 10 g/ liter (total oil/esters base, and 15 % methanol. this after acid reacting down to 1% ffa

hello!!

I was reading some information and talk about an acid stage in two steps like two steps transesterification....have someone do it?? or get better results than with one step??

Why not just use a molecular seive (rated for water removal - i think that's either 3 or 4A size) in series with your circulation pump? Since methanol is close to the same size that a water molecule is, you could simply add a small amount of excess methanol at the beginning of the esterfication reaction to make up for any that happens to accidently get sucked out by the mole seive.

The best part is that the mole seive media can be regenerated and re-used.

hi Dogma....

Sorry but could you tell me where can I find information about that kind of molecular seive??....what are them made of that are re-used??....sorry if it's a dump question but I did not know about it!

You can go to:
http://www.sciencelab.com/page/S/PVAR/23014/SLM2959

for pricing. Its about 200 bucks for 3kg.
You may be able to find it cheaper though.
This would require a mesh size smaller than I think 8 (in order to retain the media).

At one point, i saw a vessel for around 600 bucks. It had a heater and various ports for vents/drains etc to allow for regeneration.