I believe in the old days ethanol was dried in the lab by the addition of a piece of metallic sodium.
Kirk -----Original Message----- From: Ehren Bucholtz [mailto:[EMAIL PROTECTED] Sent: Thursday, August 29, 2002 4:54 PM To: biofuel@yahoogroups.com Subject: Re: [biofuel] Rock salt to dehydrate water-alcohol mixture While I haven't fully tested this idea yet on my own, I have had some observations. In my lab I threw some "table salt" which is just somewhat purer than rock salt, into some 95% ethanol, and came up with a big gloppy mess. Probably due to a couple of reasons. 1) salt by weight only will absorb about 1/10th its weight in water before it starts to dissolve in water,. 2) sodium chloride is slightly soluble in alcohol anyway. BTW the alcohol solution also had a yellow hue probably due to impurities in the salt. I have yet to try this, but I will try to dry some 95% ethanol with sodium sulfate, which is insoluble in ethanol. Initial outlay in cost of materials will be more expensive than rock salt, but all the sodium sulfate is recoverable in the end anyway. At any rate, a large amount of any salt that is insoluble in ethanol would be required. Lets say that sodium sulfate can absorb 1g of water per 10g of this salt. For 100 mL of 85% ethanol, 15 ml or 15 g would be water. That means that I need 150 g of sodium sulfate for my 100 mL sample, or about a 1.5:1 w/v ratio of sodium sulfate to 85% ethanol. The key is that we don't want the salt to start dissolving in water, because it would then go into solution. Then we would have a real mess as above, because ethanol and water are miscible probably bringing the salt into solution with them. So, for 30L of dry ethanol required to make 100L of biodiesel, I would need ~35L of 85% ethanol. For that 35L of wet ethanol I would need 52.5 kg of sodium sulfate. The density of anhydrous sodium sulfate is ~2.5 g/mL so that works out to 21 L volume of sodium sulfate. So I guess I need a container that can hold 60L of volume and be able to filter/pump off the liquid. Of course this is all highly speculative untill I actually do any of the experiments. I may be completely wrong on this, but just going with past experience dealing with drying other solvents. If anyone else has some ideas about the chemistry, or has practical experience on this please let me know what you think. Ehren >>> [EMAIL PROTECTED] 08/29/02 03:32PM >>> Is it really as simple as filling a barrel with rock salt, and pouring the alcohol-water solution into the top, with almost pure alcohol dribbling out the bottom? Is some alcohol lost in the process? This is a great idea because a solar furnace can't control the temperature well enough for distillation, but could easily be used to dry rock salt! I imaging one would simply set the solar furnace on HOT to accomplish the task. Am I correct? ------------------------ Yahoo! Groups Sponsor Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.384 / Virus Database: 216 - Release Date: 8/21/2002 ------------------------ Yahoo! Groups Sponsor ---------------------~--> 4 DVDs Free +s&p Join Now http://us.click.yahoo.com/pt6YBB/NXiEAA/MVfIAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
