CAN ANYONE TELL ME IF BIODIESEL CAN HAVE TO LOW A P.H. MY BD HAS A P.H. OF 7 BUT IF I WASH IT, THAN IT DROPS TO 6. THE WASH WATER HAS A P.H. OF 5 BEFORE I WASH THE BD, THAN AFTER THE FIRST WASH THE WATER REGISTERS A P.H. OF 6 AND IF I WASH A SECOND TIME IT THAN REGISTERS 5. I NORMALY DON'T WASH BUT THOUGHT I MIGHT TRY IT BUT I AM CONCERNED THAT THE BD COULD BE TO ACIDIC IF I WASH. ANY THOUGHTS OUT THERE.
YOur water is acidic but you could avoid getting the BD acidic by stopping washing while a little soap is still there, when the water is still hazy. With trial and error you will soon find out how much to wash it. But make sure your your pH meter is calibrated. Check it against swimming pool indicator, phenol red - your last wash water should not turn the indicator yellow but orangey red.
You say your unwashed BD has a pH of 7. This makes me suspect your meter is not functioning correctly. To determine the pH you should shake a sample of BD with a similar amount of water and then check the pH of the water that settles out. Confirm the pH reading of the water with phenol red indicator.
I was using litmas paper for testing my P.H. but I guess it was giving me a false reading.I have rechecked my first wash water,which was a test and had equal water and BD, with Phenol red, pool and soil test strips and they all return a P.H. of 8 and the second wash, equal parts also, a P.H. 6.5. Would this make my unwashed BD P.H. 11 if my wash water started with a P.H. of 5.
No it wouldn't be that high. Best way to estimate the "pH" of unwashed BD is to shake some with about 1/10th the amount of water. Then let it settle and test the water.
I put the pH in inverted commas because an oil doesn't really have a pH as it has no easily released hydrogen atoms. It can certainly cause water it comes in contact with to have a high pH however, if it contains soap. Soap has to be alkaline because it is the salt of a weak acid and a strong alkali. Unwashed BD must contain some soap. The amount depends on the amount of FFA present in the original oil.
OK we seem to be getting closer now, there seems that everyone has diferent ways to test the PH of BD. I added 100mls of water to 1ltr of BD mixed it and let it settle and than tesled the water and got a PH of 8.5-9 so this would look about right.
I've given some more thought to the question of how much water to use when testing the pH. Bearing in mind the relative solubility of soap in water and BD I now think that, no matter whether it is washed or unwashed, the best amount of water will be a bit less than the amount of BD, say about 80%.
Soap is much more soluble in BD which contains methanol, but when you shake the BD with water most of the methanol will go into the water so it makes little difference whether methanol was there or not.
Because of the buffering capacity of the soap in water the amount of water will not be critical, but if you are trying to compare different procedures it would be as well to keep the proportion of water about the same.
