Can you titrate all at once slowly adding the right amount of lye solution to the whole batch? (slowing down as you got close)

What I am imagineing is an electronic PH tester attached to the tank, and continualy adding lye solution until the right PH is hit.
(possibly makeing it automatic if I can find the right automation tools.)

do you see any problems with this idea?

Thanks

Also I have seen the "PH Meters don't work" in this forum ... however a source I think reliable says they do, so please counter with your source if telling me PH Meters don't work.

(So I can evaluate which source I trust more.)

Thanks

P.S. My source for PH Meters being said to work is:
http://journeytoforever.org/biodiesel_make2.html#pHmeters

JTF is famous for wrong info here.

I would say that pH meters may have, under some conditions, if there is enough water in the oil, given some kind or reading, at times.

I don't say pH meters don't work. Just that oil has no pH. pH by definition is aqueous.

Since oil has no pH, reading the pH of the dissolved ,or entrained water seems like it would vary in accuracy.

Also, decent pH meters are costly, require upkeep and need constant calibration.

Titration is easy and cheap. And, accurate enough.

A PH meter will not give any kind of useful reading on oil, the idea you are kicking around will not work at all.

Ok I did some research and I think I see what the issue is with measure "ph" of oil this page frames the arguement well:

http://www.noria.com/learning_center/category_article.a...okgroup=Lubrication2


Really what I should be talking about measureing is the "apparent pH" of oil (as ph implies an aquious solution)

I will have to do some research as to if "apparent pH" and aquious pH match in either a standard ratio or exactly.

ok I think I just went way over my head ...

but this is a paper on doing something like what I was saying .. not sure if it exactly maps to what i was saying because its a little too heavy a read for me:

http://www.iupac.org/publications/pac/1998/pdf/7007x1419.pdf

"
Abstract: Predictive equations for estimating pH(PS) (PS = Primary Standard) of the
potassium hydrogen phthalate buffer in any aqueous-alcoholic mixture are given as functions
of the alcoholic moiety mole fraction, x, in the mixture and of the relative permittivity, E, and
the autoprotolysis constant, pK,,, of the pure alcohol at 298.15 K. The two equations, one
valid for 298.15 K and the other covering the 263 - 318 K temperature range, have been
optimized by using the experimental data of pH(PS) in aqueous mixtures with the following
alcohols: methanol, ethanol, propan-2-01, ethane-I ,2-diol, 2-methoxyethanol (“methylcellosolve”).
The equations, tested on subsets generated from the full-set by removing an entire cosolvent
at a time, provide predicted pH(PS) values which differ from the “true” ones by less
than 0.1 pH over the entire range of co-solvent composition: 0 < x I 0.75. The predictive
equations are recommended for calculating pH(PS) only in those aqueous-alcoholic media for
which the corresponding experimental values are not available, and not as smoothing
equations for water and its mixtures with the above-mentioned solvents"

and here is a ph trode for non-aqueous acid/base titrations

http://news.directindustry.com/press/metrohm/ph-electro...ons-15372-21475.html

"Non-aqueous titrations play a key role in monitoring product quality in many areas, including the pharmaceutical, oil, and plastics industries, as well as the edible oils and fats industries."

John,

If you still think it is a good idea, go for it. Spend the $. Then, you will still need to check your results against titration, since they will be, at best, inconsistent.

How much do they want for a pH meter that they claim will give good readings on:

quote:

"Non-aqueous titrations

?

Good luck. Why not try out the base # suggested on JTF while you are at it?

Let us know what happens.

Just a question sort of related to this, if a continuous titration reading/testing is not possible somehow to allow for continuous "dozing" how do the continuous biodiesel plants work with regards titration testing and methoxide injection?

I have no knowledge of continuous plants so I am assuming that continuous plants would have to continuously add methoxide.

Continuous plants, (commercially made BD) use virgin oil. FFA's are consistant, they use the same amount of caustic for all their batches. I also must agree, pH meters do not work well in oil. While WVO is acidic, it is NOT aqueous acidity, the very definition of pH. Which stands for 'power of Hydrion' BTW. HTH