I was told something today that I thought was very interesting, but have not heard of it done, and that is to place rock salt on the bottom of a container where wet oil will go and the salt will draw down the water and leave clear oil over it.
For me to try this I would have to intentionally wet some oil as what I get is already dry, so if someone has a wet oil problem and wants to experiment and maybe report back the results.
Could turn out to be what hard wood chips did to dry washing as a ground breaking method?
** Biodiesel Glycerine Soap - The Guide
- on 5 continents helping people make & sell soap from the Biodiesel Glycerine.
Salt might absorb some of the bulk water that drops to the bottom of the container. However once water settles out it's no longer a big problem. Salt on the bottom is not going to extract dissolved or suspended water which is the real problem. If the salt was in a column it might draw water out of the UVO that passes through.
I use a column with a water absorbing polymer to 'polish' my fuel to < 300ppm water, and it works very well as shown by tests with a carbide manometer.
Wha kind of material are you using in your colum ?
I used rock salt one time to try absorbing water and break a water/veg emulsion made when I used water and baking soda to wash unused-but-old high FFA sunflower oil, really didn't see that it helped at all. I poured about 10 pounds of water softener salt in the bottom of the barrel and let it stand for a couple days, still had the emulsion, and when I finally drained the barrel I still had the chunks of salt?
I finally cleared the emulsion by well-stirring 4 cups of dry kitchen flour into the oil to absorb enough water to upset the equilibrium and allow separation, I have done this over a dozen times and it has worked every time after a couple days, the wet flour always ends up on the bottom of the barrel
This might sound a bit out there but some of the available brands of kitty litter are now actually 100% synthetic molecular sieve material, and cheap. I use packets of this as humidity absorbers when I do plastic wrapped long turm storage of tools or guns or whatever. I forget the brand I bought but the info can be found with a web search, I think I paid about ten bucks for a 15 pound bag at Target.
This experiment was inspired by the following thread:
I was actually about to start a thread to show my results but lo and behold, this thread had been recently start.
Background: I decided to give this a try for myself and those who are not fortunate enough to be able to get into the dry wash biz. My goal was to shorten the length of time required to dry, water washed bio and to lessen the energy expenditure to do so, i.e., heating, stirring, pumping, blowers, etc.
Set up: I took an ~ 1L sample of freshly washed bio and set up staged vessels fed via gravity. The top vessel holds the wet bio, the next vessel down holds the rock salt and the final vessel is the collection vessel.The vessels holding the wet bio and the rock salt are identical. The vessels are vacuum flasks with the hose barb at the bottom. (No vacuum is used here). Each is connected via clear plastic tubing and the flow of bio is controlled via laboratory hose clamps. It took two passes through the salt to attain the desired result; HOWEVER, the salt was not changed out. After the first pass I returned the bio to the top vessel and repeated. After the first past you could see a marked difference in water content but still wasn't perfect. The 2nd pass, through the same salt, yielded crystal clear bio. I'm going to run an addition ~ liter through that same salt to see if it still has any capacity left. I was going to post pics, but apparently my camera will not take POOR enough quality pics to meet the minimum file size. So I tried my phone, but my work computer will not allow me to connect periphery devices. Sorry. When I get home I'll try to upload the pics from my phone. Hopefully they'll be small enough of a file. If none if this works, and anyone would like pics, PM me your email and I'll be glad to send them.
Additionally, I will be contact one of our contract labs to see if they can run an NaCl analysis on bio/oils. If they can, I'll post the results.
Thoughts, suggestions, comments? All welcome. I hope this is helpful to someone. Thanks for having me on the forum!
FYI: I've already started running another Liter of wet bio through this same salt bed. Its clearing up nicely. I believe if I had a vessel to hold about twice the salt it would work in one pass or perhaps more detention/contact time with the salt. Both passes took an hour, combined with no energy expenditure at all.
Sorry...finally managed to get the phone to cooperate and pics are still too big. PM me if you want the pics.
I've used this technique to break emulsions several times. Dissolved the rock salt into boiling water until I reached saturation point then poured into the emulsion, mixed and let stand. Voila. Worked great for me every time.
What method do you use to measure the water content of the BD before and after the salt column?
Didn't. Although I don't have exact #s as to water/moisture content, I did put water in the fuel as I water washed it an hour prior to the experiment. After the salt, the fuel was crystal clear at room temps which should generally at least indicate very low level of water??? I would do the "hot pan" test but I don't have anything handy here at work to do so. Can you offer any suggestions of how to proceed to verify your query? Thanks
Ok, so I'm about to run a water weight analysis on the bio before and after the salt column. I will be using a laboratory grade digital Denver Inst scale with capacity to 1/10,000th of a gram. Will tare the vessel weight and measure out 50mL of "before and after" to get % removal of water. Stay tuned.
Weighed a 50mL pyrex beaker on scale and tared the weight. It weighed 29.3362g
Added 50mL of wet bio to the beaker while on the scaled, tared: 14.6762
" " dry " ": 14.6508
A bit disconcerting to say the least with a difference of 0.0254g and a 0.173% difference in weight.
I took the bio sample to the heat/stir plate and ran the temp up to 100C. No bubbles, no boiling, no steam, no vapor, no condensation. So that's enough for me to dispel whether or not any water is present.
One caveat: I had used all of the original wet sample in my experiment so I went down and grabbed some more but I had already started the drying process but the bio was still very cloudy and hazy. But apparently that means nothing. I realize the use of the original sample would have been optimal but like I said, I had already ran it all through the salt column.
Obviously I need to modify and improve this test. This first go around was simply to see if any visual improvement, i.e., increased clarity of bio from the haziness and cloudiness associated with water washing. I'll be washing a new batch next week and I'll give this a go one more time for the weighing aspect anyway. Again, thoughts? Thanks for reading.
Your equipment is likely accurate enough to make the 'weigh-heat-weigh' method valid.
I use a carbide manometer to measure water content in my fuel.
Just to clarify, I didn't use weigh heat weigh. Instead of heating, I supplemented the heated sample for the the bio I had passed through the salt.
Yes, I reference your site extensively! LOL! Loads of fantastic info there and I greatly appreciate you keeping that site up and going. It's a great resource!
All of our equipment is calibrated daily. We're a wastewater treatment facility and so must therefore meet state and fed guidelines for laboratory equipment. I am by no means a stranger to laboratory analysis procedures, QA/QC, and precise and accurate measurements.
With your precision equipment the 'w-h-w' method would be more accurate.
Thanks for the compliment on the site, I'm just a contributor. The real credit goes to site owner Rickdatech.
Salt has been used by commercial producers to dry biodiesel in the past. But, when the ASTM standards changed a few years back reducing the metal content allowed in biodiesel, commercial producers stopped using salt columns to dry biodiesel because the technique left too much metal (Na) in the biodiesel to meet the new ASTM standards.
Thanks for the input guys. I really appreciate it. Not sure if "updated ASTM standards" would push me away from my own private use of biodiesel and its being dried via salt. I contacted my contract lab to see if they could perform an Na analysis for me. No go, but I have a request in for them to locate another entity who can perform the analysis. I'm just not convinced of salt's solubility in oil. Once/if I get some numbers in hand I'll post them up.
Rick, allow my to direct my compliments on the site to the proper person for upkeep! As I stated earlier, I love your site and use it often.
John, not to take anything away from you, I still appreciate your contributions to said site and to this discussion.
If I can ever be of help to either of you, I'm at your service.
Thanks for the kind words.
I've learned a lot over the years about biodiesel and WVO and created make-biodiesel.org and svotutorial.org to help out those that want to learn. I was heavily involved with the original "Collaborative Biodiesel Tutorial" and when it stalled out, decided to start my own tutorial web sites. The SVO Tutorial is less than a year old, while I've been working on make-biodiesel.org for over six years. Like with the original "Collaborative Biodiesel Tutorial", guest authors are welcome. More than a few people have helped me with the site, from article submissions to providing inspiration. Without them the site wouldn't be as far along as it is.
The great thing about making biodiesel for personal use is that you don't have to meet any standards other than your own.
Well everybody stay tuned if you've been paying attention to this. I've found a lab to run the Na analysis. After reading about the ASTM standard, which is EN 14538, for sodium, its actually a test for sodium and potassium which leads me to believe that this test is used primarily to detect residual catalyst. And since I use KOH in the transesterification process, if any Na shows up it will most definitely be from the salt column. The ASTM max limit for Na is 5 ppm. If simply passing the BD through a salt column can raise sodium levels that high, I'm gonna be shocked. Anyways, results should be forth coming; hopefully within the next couple of weeks.
One other note regarding the original experiment. I've continued to run wet BD through the original column and to date have run ~ 2 gallons of wet BD through ~ a quart of salt. Should have weighed the salt first and then ran a water weight test via "heat weigh heat." At that point I could calculate the pounds of water a pound of salt would remove. I'll do that next time. But the original salt is still drying down the wet BD. Also, I should have used a larger bed of salt which I will also do when I "reset" this experiment. Going to wait on Na analysis before I start getting more involved....no sense in proceeding if the BD is chocked full of Na.
Sample is being shipped out today. Should have results in ~ a week.