recently i have studied articles about biodiesel wastewater. we are producing large amount of waste waster in water washing of biodiesel. we can reduced waste water by adding some percentage of distilled water 10 or 5 min before ending transesterification process as prewash.
you read the article again and highlight the question you question is not good during transesterification no one using water , waste water produced in some reactions especially when using acid catalyst with WCO. the final product (biodiesel) should be washed with deionised water.
Dear sir please see this
http://biodieseltutorial.utahbiodieselsupply.com/waterprewash/
i got this idea from here
Dear colleague,
You are using WCO (high FFA%) as feedstock oil and you chosen base homogeneous catalyst (KOH) for this reaction. In my opinion, you were not right in this case because the saponification reaction is very easy to occur and lead to form soap. The big amount of soap make the transeserification stop soon.
So you need do esterification reaction first by using acid catalyst (H2SO4). After finished this step (FFA% will significant decrease), you can use KOH for next step (transesterification).
About washing process, your idea is not good. Because the hydrolysis reaction can occur if you use distilled water soon. For this reason, the amount of ester (ester content) will unexpected decrease.
For the better idea, after finished reaction, glycerol phase should be removed from biodiesel phase. After that, you can wash biodiesel phase by distillated water. This process should be repeated 6 times (3 times without stirring and 3 times for stirring or slow shaking).
I hope this comment will be useful for you.
Residual water may be removed by heating under vacuum. In small quantities it can be used sodium sulfate. The biodiesel washing must be done not only with water but with dilute acetic acid to remove any quantities of catalysts
i am not using water and methoxide together, when oil reach to 60 degree i add methoxide in it and after 1 hour and 50 min. when transesetrification process is almost completed i added 5% De ionized water to stops the transesterification reaction. it also give a pre-wash ,reduce soap, inhibit emulsion formation, and make further washing easier.
my aim of these experiments is to reduce the amount of waste water we produce in water washing and keep the quality of biodiesel same. Because Biodiesel wash water has extremely high biochemical oxygen demand (BOD), total dissolved solids (TDS), glycerin and residual fats, oils and greases (FOG), as well as highly acidic and basic conditions based on the generating process. Untreated wash water has been found to have concentrations in excess of 75,000 ppm BOD and very high concentrations of FOG with a very basic pH.
after my experiments i will show GC MS analysis results of bio-diesel
Dang Nguyen Thoai i am using different types of oil
oil with (0.3% ffa)
oil with (0.5% ffa) as well
Dear Muhammad Aamir Bashir,
Actually, I have understood your idea. This method can be applied for feedstock oil with low FFA. You are using oil with 0.3% FFA and 0.5 % FFA, for me, this oil could not called as waste cooking oil (WCO). Therefore, firstly I was quite confused about the word "used oil" that you were using.
However, by using oil (0.3 - 0.5 %FFA) I think that you can do transesterification right now. You also should test the methyl ester content by GC or GC-MS both of cases: no and adding de-ionized waster to check as if water influence or not.
Good luck to your research
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