Learn How To Test Biodiesel For Soap Content | Springboard Biodiesel

Learn how to test Biodiesel for soap!

Daniel Bowen from Springboard Biodiesel walks through how to properly test Biodiesel for soap content.

When making Biodiesel, it's often important to know what the total soap content in it is. For instance, when dry washing Biodiesel, you can test for soap to know if you have successfully removed all of it.

Items Required:
===========
100 mL Isopropyl Alcohol
10 mL Biodiesel to be tested
Bromophenol Blue pH Indicator
0.01 N Hydrochloric Acid
Beaker, (2) Pipettes, and a Pipette Pump
Magnetic Stirrer

The Method:
==========
1- Add 10 mL Biodiesel to 100 mL Isopropyl Alcohol
2- Add 15-20 drops Bromophenol Blue
3- Add measured amounts of Hydrochloric Acid until it turns yellow
4- Record the number of milliliters (mL) used

Calculating Soap Content:
=====================
mL of Acid Used x conversion factor = ppm's of soap

Conversion Factor
===============
NaOH reacted Biodiesel - 304
KOH reacted Biodiesel - 320

ASTM Acceptable Soap Levels
========================
NaOH Reacted Bio - No more than 41 PPM
KOH Reacted Bio - No more than 66 PPM

Check out our complete soap test kit:
http://utahbiodieselsupply.com/soaptestkit.php

We also carry magnetic stirrers:
http://utahbiodieselsupply.com/hannamagstirrerblack.php
http://utahbiodieselsupply.com/hannamagstirrerstainless.php
http://utahbiodieselsupply.com/hannamagstirrerstainless.php

And all the chemicals needed to perform soap tests:
http://utahbiodieselsupply.com/chemicals.php

To learn more, stop by our site!
http://www.utahbio.com
Utah Biodiesel Supply

Learn more about Springboard Biodiesel
http://www.springboardbiodiesel.com

Category:

Howto & Style

Tags:

• biodiesel
• soap
• test
• utahbio
• dry
• wash
• springboard

[redblue18700]

When I add the bromoblue drops, my acetone or isopropanol turn yellow to begin with. I add my biodiesel and it stays turned yellow.

if i add only a tiny amount of naoh solution it turns blue so i know the indicator is accurate.

[UtahBiodiesel]

@redblue18700 It means your alcohol is acidic. I'd recommend getting new Isopropyl Alcohol.

[greengineers]

After the conversion is shown, the ASTM limit for NaOH is shown to be <41ppm, and for KOH, <66ppm. However, in the review, these numbers are reversed.  What are the correct values?

[UtahBiodiesel]

@greengineers

For Potassium Hydroxide reacted Biodiesel - No more than 66 PPM

For Sodium Hydroxide reacted Biodiesel - No more than 41 PPM

[graydonblair]

It's possible that that can occur but the catalyst will normally fall out in the glycerin. Be sure to stop by biodieseldiscussion [dot] com and visit the dry washing section as they've been discussing soap testing at great length including this potential issue. Great question by the way!

[fuze59]

If you have residual catalyst in your biodiesel won't this effect the amount of HCL that you will need to add?

Therefore you're initially neutralizing catalyst not the soaps.