Sciencemadness Discussion Board

Cerium Oxide

Bromomethane - 23-10-2010 at 14:43

I have an opportunity to purchase 1 pound of cerium oxide from a local business for $10, but have no thoughts on what to do with it, so I am not sure if I should buy it. Does anyone have any suggestions for the moderately equipped home chemist? (other than polishing rocks)

Thanks

Bromomethane

not_important - 23-10-2010 at 14:56

Enter into Google "cerium oxide" site:sciencemadness.org

morrie - 16-11-2010 at 06:07

I have kilo of nano cerium oxide. I have had it for years. Not much use for anything that I can think of.

a_bab - 16-11-2010 at 07:24

Unless you'll ever need it for glass polishing (as in telecope mirror making), there is no point in getting it IMO.

Simply too inert to make anything usefull out of it.

The WiZard is In - 17-11-2010 at 12:16

Quote: Originally posted by Bromomethane  
I have an opportunity to purchase 1 pound of cerium oxide from a local business for $10, but have no thoughts on what to do with it, so I am not sure if I should buy it. Does anyone have any suggestions for the moderately equipped home chemist? (other than polishing rocks)

Thanks

Bromomethane



Well as previously mentioned it was (sez Ullmann) used to
polish glass or to decolour glass. With considerable effort
it could be reduced to cerium metal. Mellor's opus - V p 626
quotes M Moldenhauer cerium oxide is not reduced by
applying the thermite process.

Mellor cites - Alcan Hirsch, J. Soc. Chem Ind. 31 [10] 477, 1912.
Metallic Cerium: Its Preparation and Properties, with Special
Reference to its Commercial Applications. I pulled my copy off
the JSCI off the shelf - this paper was Hirsch's 1911 U of Wisconsin
thesis for his doctor's degree and was published in Trans. Amer.
Electrochem. Soc. 1911, 20, 57-104. You can read it or
DL'd it @ google.com/books. Either convert to text then cut &
paste or DL the complete PDF and print at will.

Sedit - 17-11-2010 at 13:50

I say use it to polish rocks. However I feel tin oxide works much better in this respect for polishing efforts but I know commerially that cerium oxide is normally used. I used to practice Lapidary as a hobby and use to use cerium oxide for the final polish thats until I decided to substitute tin oxide one day and was astounded by the results. One day the grinder had enough and decided to fight back taking the tip of my finger with it. Needless to say I don't really enjoy that hobby as much anymore.

Its only 10$ for a pound of the stuff so why not. A quick look around the web tells me it has a variety of catalytical activity and is able to absorb oxygen and release it so I would say scoop it up and see if you find a use for it down the line.

The WiZard is In - 17-11-2010 at 14:41

Quote: Originally posted by Sedit  
I say use it to polish rocks. However I feel tin oxide works much better in this respect for polishing efforts but I know commerially that cerium oxide is normally used. [snip]


-----
Ullmann's 4th A6:149. ... has now replaced other polishing
oxides [correcting what I previously posted] ... almost completely.
The special merits of cerium oxide are its 100% faster polishing
speed and it cleanliness.



Sedit - 17-11-2010 at 15:43

Yup but the luster you get from tin oxide can't be matched by cerium oxide on most stones. I was polishing by hand using leather and oxide slurry so time was no kind of a commercial factor.

a_bab - 17-11-2010 at 21:26

Sedit, in telescopes and optics in general the finish needs to be quite high as you can imagine. Cerium oxide is the commercial solution; red iron oxide Fe2O3 is another option (at least for amateur use). Before the actual polishing the oxide particles needs to be sieved, and only the smallest fractions are used. In practice very little is needed for a lens or a mirror. The sieving is actually done by a decantation process, and it goes in several steps taking days. The last decantation products will stay suspended for 24 hours or more, making the water suspension turbid. This "turbidity" is the stuff needed for the final finish, so it's obviously these particles ought to be really fine.

Cerium oxide crystals are very tough, harder than tin oxide for sure. This gives superior speed in polishing. The largest abrasive particle size gives the final finish, so it's obviously your tin oxide was "finer" then the cerium oxide you had used, which explains your results. But I can't imagine even a hardcore lapidary hobbist would do the tedious decantations in order to achieve a luster down to almost molecular level as required in optics.

Copenhagen - 17-11-2010 at 21:51

You can dissolve cerium oxide into hot 50% sulfuric acid over 2 hours and decant off the liquid layer to get cerium IV sulfate solution a useful oxidizer in aqueous solutions for synthesis of beta amido ketones and also a useful titrating agent that converts Iodide ion into iodine.

Copenhagen - 17-11-2010 at 21:55

And a journal article for the beta amido ketones.

Attachment: Beta_Amido_Ketones_Cerium_IV_Sulfate.pdf (368kB)
This file has been downloaded 648 times

Copenhagen - 17-11-2010 at 22:07

https://www.sciencemadness.org/whisper/viewthread.php?tid=95...

See this thread for a download of volumetric analysis that discusses the conversion of cerium oxide to cerium IV sulfate.

a_bab - 17-11-2010 at 22:30

Dear Copenhagen, there's a button called "EDIT" which allows you to add new stuff to your post instead of making consecutive posts. This helps reducing the long threads.

Sedit - 17-11-2010 at 23:43

Quote: Originally posted by a_bab  
Sedit, in telescopes and optics in general the finish needs to be quite high as you can imagine. Cerium oxide is the commercial solution; red iron oxide Fe2O3 is another option (at least for amateur use). Before the actual polishing the oxide particles needs to be sieved, and only the smallest fractions are used. In practice very little is needed for a lens or a mirror. The sieving is actually done by a decantation process, and it goes in several steps taking days. The last decantation products will stay suspended for 24 hours or more, making the water suspension turbid. This "turbidity" is the stuff needed for the final finish, so it's obviously these particles ought to be really fine.

Cerium oxide crystals are very tough, harder than tin oxide for sure. This gives superior speed in polishing. The largest abrasive particle size gives the final finish, so it's obviously your tin oxide was "finer" then the cerium oxide you had used, which explains your results. But I can't imagine even a hardcore lapidary hobbist would do the tedious decantations in order to achieve a luster down to almost molecular level as required in optics.



I repeat.... I know all of this and speed does not always equat to quality.... look at anything made in china for an example.

I say what I say from YEARS of personal experiance in polishing and cutting, by hand I might add. Semi precious stones using a bench grinder, a jig, and various oxides to get the final polish....

You think Cerium is better because Wiki says so then try for yourself. Get tin oxide and cerium oxide and do a side by side and see which is FASTER and which is more lusterus. You will see without a doubt Tin tops cerium ten fold!

I cant argue the point anymore until someone proves me wrong with first hand experiance which seems to be HIGHLY lacking here other then me and my missing finger and we both know Tin rules cerium!

a_bab - 18-11-2010 at 09:21

There may be a possibility that tin oxide is harder then cerium oxide. I have no data concerning the durity of the discussed oxides. So I'm opened to facts such as tin oxide polishes faster then cerium oxide, and I believe your report.

Yet I'm wondering why is cerium oxide prefered to the tin oxide by the industry? Could be one of these "traditional" reasons?

Sedit - 18-11-2010 at 10:06

Sorry if my last post was a little harse been having some personal issues that got me a little on edge lately.

Anyway the fact that tin oxide produces the luster it does might not have to do with it being harder then cerium but may have to do with it being softer. If the grit is to hard you fracture and scratch the crystal facets instead of "shaving them" so to speak which causes the luster to appear. The effect can be seen by ball milling sand for days on end which leads to a very fine grit yet for polishing efforts this is pretty useless as a final polish even though it is without a doubt harder then the stone being polished. The only gem I ever had a problem with which also happens to be the one I was working on at the time I had the accident was a blue/purple star sapphire. No matter what I did I could not get this damn stone to take a high polish and eventially tossed it, literally tossed it because it was pissing me off and was already on edge working with one hand at the time.

The Cerium oxide I used was made just for final polishing but my Tin oxide came for use in ceramic glazes so perhaps there was a difference in partical size or something, I am more then willing to admit that.

This site here might help explain why Cerium is used more often then tin in industrial setting

http://www.covington-engineering.com/Lapidary_Polishing_Powd...

Notice the relatively large difference in price for the tin oxide compaired to the cerium oxide.

Copenhagen - 18-11-2010 at 15:55

Dear a_bab,

Really? I've never heard of this "Edit" button before. What is this new creation?

You know to be honest, I'm a closet post-whore. But you caught me red-handed. I apologize for my blatant transparence and I will not pollute this thread further.

[Edited on 19-11-2010 by Copenhagen]