Purolite vs. Amberlite
Purolite is very similar to the Amberlite dry wash resin which we sell. The properties are
similar and the way they operate are also similar. So what's the difference? Price is the main factor.
Picture of Amberlite & Purolite together
Most studies have shown that both dry wash resins do an excellent job of dry washing Biodiesel.
Purolite and Amberlite are both based on a gel-type resin that is built around the same chemical ion exchange resin
protocol. In other words, because they both are built similarly and function almost exactly the same, it comes
down to personal preference.
How Do You Use Resin To Purify (Dry Wash) Biodiesel?
The resin beads are placed inside of a holding vessel and unwashed Biodiesel is
flowed through the resin beads. Typically the vessel employed is tubular
and is referred to as an Ion Exchange Resin Column. The resin beads, when deposited in the
column, form a "resin bed" at the base of the vessel.
How Much Biodiesel Can The Resin Purify? Arbor Biofuels Company (ABC) indicates that 1 lb of Purolite can be expected to
treat approximately 100 gallons of home brewed Biodiesel made from used cooking oil.
They further indicated that to achieve these results, the resin should be
used according to manufacturer's recommendations.
Please see page 2 of Purolite PD206 FAQ
Examples of Purolite Recommendations
1- Depth of resin bed needs to be a minimum of 24"
2- Dry wash vessel's resin bed should be designed on a 1 to 3 aspect ratio.
For every width in diameter, the resin bed depth/height should be
three times the diameter. For example, the 24" deep resin bed
would have a maximum column diameter of 8".
3- Dry wash vessel should be capable of handling 100% resin bed expansion since the resin swells as
it adsorbs the impurities out of the Biodiesel. For example, the 24" deep resin bed
mentioned previously would need a resin vessel with a minimum height of 48"
4- There should be no more than 1000 ppm (Parts Per Million) of total impurities
(glycerin, soap, unused catalyst and other trace impurities) in the Biodiesel to be dry washed.
How Fast Should I Flow The Biodiesel Through The Towers?
Every tower is different in it's construction so flow rates will vary depending on the particular dry wash tower being used, but
Arbor Biofuels Company recommends the following flow rates
when using our Dry Wash Towers: 6" Tower - 9 Gallons Per Hour (0.15 GPM) 10" Tower - 25 Gallons Per Hour (0.42 GPM) 12" Tower - 50 Gallons Per Hour (0.83 GPM)
What Kind Of Pump Should I Use? Arbor Biofuels Company recommends using
a diaphragm style pump that can deliver a consistent flow through the towers for extended periods of time.
Being able to adjust the flow rate is also crucial.
Example Pumps include Milton Roy Series, Liquid Metronics Incorporated (LMI), and Pulsafeeder Click Here to learn more about diaphragm pumps
If you have trouble finding a pump, contact Arbor Biofuels Company
as they can often help you find a used one.
How Much Resin Should I Buy? (Example Sizing Requirements)
If you're producing 30 gallons a week, estimate roughly 50 weeks of production,
that's 1500 gallons per year. To get enough resin to last a year, we'd recommend
purchasing at least 20 lbs. While 20 lbs is a little more than may be needed,
ABC recommends over shooting estimates to take into account times when you run
"less than desirable" Biodiesel containing over 1000 PPM total impurities through the resin bed.
Again, every tower is different in it's construction so resin amounts used will vary depending on the particular dry wash tower being used,
however, listed below are the amounts of resin shipped with our Dry Wash Towers
6" Tower - 20 lbs Resin - Treats up to 2,000 gallons 10" Tower - 70 lbs Resin - Treats up to 7,000 gallons 12" Tower - 120 lbs Resin - Treats up to 12,000 gallons
How Do I Test For Contaminants?
ABC has put together a handy soap testing kit for determining the amount of
soaps and unused catalyst. If proper settling techniques are used, very little free
glycerin or only the soluble glycerin will ever remain in your Biodiesel.
Do I Have To Remove The Unreacted Methanol From The Biodiesel
Before It Is Dry Washed With Purolite? (De-methylating)
ABC has found that the un-reacted methanol can cause contaminants to stay suspended in the Biodiesel.
These initial levels of contamination may prematurely exhaust Purolite's resin capacity.
To help keep the system running properly, ABC recommends 3 different options for removing
residual methanol still left in Biodiesel prior to it being washed.
1- Utilize the 5% Water Pre-Wash Method.
This method is the easiest of the three and is extremely effective in helping remove gross glycerin,
excess methanol, soaps, catalyst and other impurities.
2- Utilize the GL 1 Day Process.
This method is based on the simple chemistry principle that
Biodiesel is immiscible with all these impurities if the un-reacted methanol is removed. Graham's process
removes the methanol and then allows the impurities to settle out naturally over 24 hours. At this point
the clear, clean Biodiesel can be sent through the resin for complete purification.
3- Centrifuge or settle the crude Biodiesel for as long as practical prior to running it through the
resin bed. The Purolite resin has an immense capacity for removing soap relative to its capacity for
absorbing glycerin - long settling times will help remove as much glycerin as possible and ensure
its most economical use.
How Do I Maintain The Resin? (Resin Clean-out)
The most common way to maintain your resin is by flushing it with methanol.
To do this, ABC recommends the resin column be filled with methanol until it completely covers the resin bed.
After the column is filled with methanol let the resin bed soak overnight (12 hours).
Then slowly pump methanol through the system until you've pumped approximately
5 vessel volumes through the column.
This "flooding with methanol" technique allows the glycerin and entrapped soaps
that have been absorbed by the resin bed to be flushed out by re-dissolving them into
methanol and moving them away from the resin beads.
Initially when flushing the impurities out of the resin bed, the outlet methanol will be dark
brown or at least very cloudy with these impurities until the column is totally flushed.
Once the beads are totally flushed, the methanol will be clear. At that point stop the flushing
and allow all the remaining methanol in the column to drain out. It may be best to let the unit
drain overnight to ensure as much methanol as possible to be removed.
How Do I Remove The Excess Methanol?
At this point the resin beads are still holding methanol and should be "dried" before reusing the resin.
Arbor Biofuels Company recommends drying the resin beads by using one of these three options:
1-Flush With Biodiesel The methanol in the resin bed can be flushed out by pumping Biodiesel through the column, however,
the Biodiesel used to flush the column will need to be demethylated before being used.
2-Remove Beads And Air Dry The beads can be removed from the vessel and air dried. To do this,
carefully remove the beads and place on a flat surface and allow to dry. Sunlight and a fan will greatly
speed up this process. When the resin beads are dry they can be re-installed in the dry
wash vessel and Biodiesel processing can begin again. CAUTION! If this method is used,
be sure to air dry the resin beads in a well ventilated area to avoid excessive methanol fume buildup.
3-Air Purge The Beads A dry air or gas purge system can be used to
force dry the methanol out of the resin beads.
What Do I Do With The Methanol Afterwards?
Methanol used to clean out the resin can be re-used in your next Biodiesel reaction without any problems.
Arbor Biofuels Company recommends using 32% by volume instead of 20% methanol if this is the only methanol being
used in a Biodiesel reaction.
Because Purolite recommends specific size requirements for the towers that the Purolite will be put into, we also
sell a great ion exchange tower kit and two pre-built ion exchange towers. As different sized towers have different
loading requirements, we're making our Purolite available in 20, 70, and 100 lb increments.