[constant thinker]

I'm sorry to be blunt but you are naive. I know this because I was the same way at one point but I learnt quickly and thankfully before I ever seriously hurt myself.

I know people keep warning you this and that, and you think you have everything good, but you've only been lucky so far. I'm shocked you haven't received chemical burns yet. 

Strong bases HURT... A LOTTTT. And the pain isn't always instantaneous so quite a bit of damage can be done before you realize it.
I know this from experience making soap the old fashioned way.

I'm glad you said you're using gloves but you missed 4 other important things for safety.

1. Lab coats aren't just for good looks. If someone wearing a lab coat spilled chemicals on themselves, odds are it'd wind up on their lab coat. They can quickly yank of the lab coat and separate it from themselves preventing chemical burns. I guess an apron that covers your full front may act as a stand in.

2. Maybe I missed something, but something like this REALLY REALLY needs goggles at the very least. You won't be able to do too much chemistry if your blind or your vision is really blurry. Eye damage is permanent.
     You actually should have a face shield on along with the goggles.

3. You said nothing about having any weak acids nearby in the even you manage to spill it on yourself or anywhere else. I always make sure I have baking soda and vinegar nearby.

4. You've said nothing about having good ventilation. It doesn't take much to be overwhelmed by fumes. Also just throwing open a window and calling it good doesn't always work. Trust me I figured that one out when I through open my bathroom window and then poured bleach into my bathtub. Within a few minutes my eyes were very irritated and it was difficult to breathe.

5. (I know I said 4 things) I do hope you aren't using things that you use to cook with! Never mix labware and cookware. Do yourself and family a favor and invest in some Pyrex beakers, flasks, test tubes, etc. [u=http://www.unitednuclear.com/]United Nuclear[/u] has a lot of good and in my opinion fairly priced lab equipment and glassware for the lab.

And no I'm not just some adult that is telling you what to do, I'm only 17, a teenager like you. So please just take the safety precautions we've all told you. Not just for you, but for everyone you live with, and trust people when they say what you're doing is dangerous. Just because you haven't had an accident yet, doesn't mean what you're doing is safe.

Good luck with experiment. Maybe I'll do the same one you're doing now sometime over the summer.

[macman104]

3. You said nothing about having any weak acids nearby in the even you manage to spill it on yourself or anywhere else. I always make sure I have baking soda and vinegar nearby.

That caught my attention too.  He said that he had towels, and I was trying to figure out what exactly he was hoping the towels would do against the hot caustic base...

[BlueTheCow]

In reviewing this post, I just realized it was giant... BEAR(sp? originally I had bear, then bare, now bear... lets not bare  ) WITH ME:

Hello BlueTheCow,

My first comment is ... WOW .. quite unsafe. I need to start this comment with a legal statement: this mechanism and reaction in the manner you are planning is extremely unsafe. Do not perform the test or reactions, please, for your own safety.

Ah, right. Well, ignore the bayer process part of it. I take full responsibility and am completely self-liable for my actions and so on. Any information I acquire here could be acquired on my own in other ways, etc.

But in any case, lets just talk about filters. Nothing dangerous about theorizing about filters, right?

From a theoretical perspective, a really inexpensive filter can be created from various cloths ...yep, the kind that you use to clean dishes. Folding the cloth on top of itself, along with putting it on the bottom of an old soup can can form a very good filter. If the material passes through the filter with particles, add a little sand in the bottom of the filter can before pouring your ingredients into it. Finer sand = finer filter.

Hm... I'm not entirely sure what you're talking about. Would you cut a hole in the bottom of the can and flow water through? Or what? Are you talking about a sand filter as described here http://en.wikipedia.org/wiki/Sand_filter? As I said, I'm not entirely sure I understand this (it's not described very well on wikipedia at the moment).

Also, a NaOH solution dissolves SiO₂/silica/sand, especially in my case. Would there perhaps be some alternative to using sand? Or is the sand not entirely necessary for what you described?

Lastly, do you have an idea of what sizes of particles would be filtered out? As far as I know, I need most of the particles size 0.5-1.0 microns (diameter I believe) and up filtered out. It might still work with less fine filtering, but I'm not entirely sure.







As to the next post that was posted while I was typing this one:   

I'm sorry to be blunt but you are naive. I know this because I was the same way at one point but I learnt quickly and thankfully before I ever seriously hurt myself.

I tend to appreciate bluntness for its efficiency (though I tend to not use it much myself because most people are not as understanding as I am). And good for you, not hurting yourself seriously and all!

I know people keep warning you this and that, and you think you have everything good, but you've only been lucky so far. I'm shocked you haven't received chemical burns yet.

Well... I've been really careful and such. Even with my shakey hands. Looking at your post though, I really have to say thank you for finally giving some constructive safety arguments (that is, stuff not meant to deter as the others posted, more meant to help; that's nice of you).

Strong bases HURT... A LOTTTT. And the pain isn't always instantaneous so quite a bit of damage can be done before you realize it.
I know this from experience making soap the old fashioned way.

Yeah, I heard about that soapmaking stuff when I was searching for a supply of NaOH (I finally settled on using Roebic "Crystal Drain Opener" from Home Depot/Lowes, but I'm not sure it's the best solution; I only bought one 908g/2lb bottle, and I won't need more for a while).

I'm glad you said you're using gloves but you missed 4 other important things for safety.

1. Lab coats aren't just for good looks. If someone wearing a lab coat spilled chemicals on themselves, odds are it'd wind up on their lab coat. They can quickly yank of the lab coat and separate it from themselves preventing chemical burns. I guess an apron that covers your full front may act as a stand in.

I it sounds kinda silly, but I bought a pair of welding gloves to handle the hot reaction chamber (the teakettle, or for now the measuring cup). Whenever I'm near the solution, I guard myself by putting my hands up. They are very large.
But yes, I do think I'll get a lab coat before I do any more experiments. Stylish and protective; I don't know how I forgot about those.

2. Maybe I missed something, but something like this REALLY REALLY needs goggles at the very least. You won't be able to do too much chemistry if your blind or your vision is really blurry. Eye damage is permanent.
     You actually should have a face shield on along with the goggles.

Yeppers, definitely. That's one thing I was extremely concerned about. I have a pair of impact and chemical protecting goggles. I don't have a faceshield yet, but I'll make sure I get one before I increase the size of my experiments from the measuring cup reaction chamber to the teakettle.

3. You said nothing about having any weak acids nearby in the even you manage to spill it on yourself or anywhere else. I always make sure I have baking soda and vinegar nearby.

Does HCl count? No...?  Oh dear. I'll get some baking soda before I do another trial as well. I'm not sure about the vinegar; if you have baking soda, why do you need the vinegar as well?

Recently posted while I was typing (it happened again, sheesh):

That caught my attention too.  He said that he had towels, and I was trying to figure out what exactly he was hoping the towels would do against the hot caustic base...

Well, basically, I'm using such small amounts at the moment, that a big towel absorbed and contained everything (when it spilled over as I mentioned in a previous post). It had some (what looked like) temperature burns, and of course I am not reusing that towel for anything as it contains the mixture, but it didn't ignite or get eaten through by the hot caustic mixture... not exactly a standard solution, but it took care of the mess (and further cleaning of the table took care of the residue, as far as I can tell). So... I'm for keeping the towels nearby, just in case.

4. You've said nothing about having good ventilation. It doesn't take much to be overwhelmed by fumes. Also just throwing open a window and calling it good doesn't always work. Trust me I figured that one out when I through open my bathroom window and then poured bleach into my bathtub. Within a few minutes my eyes were very irritated and it was difficult to breathe.

Hm... well, it is right next to a wide open window; the table is literally sitting along the window...  And along with the goggles I wear one of those 3M respirator masks. Further than that, I'm not sure what I would do... place a fan on one side of the experiment and the window on the other, and have the fan blow across the experiment and out the window? Or what?

5. (I know I said 4 things) I do hope you aren't using things that you use to cook with! Never mix labware and cookware. Do yourself and family a favor and invest in some Pyrex beakers, flasks, test tubes, etc. [u=http://www.unitednuclear.com/]United Nuclear[/u] has a lot of good and in my opinion fairly priced lab equipment and glassware for the lab.

Heh, of course not. All the cookware that I hijacked from my mum, I told her I would keep (I only took 1 steel measuring cup and a plastic teaspoon, which she has plenty more of; I'm planning on replacing them anyway, of course). All the rest of the stuff, I've either bought from Wal-mart, Home Depot, Lowes, or acquired from my (old) high school chemistry lab kit (it had some test tubes, a graduated cylinder, a spring scale and some other stuff).
At the moment, I'm not really interested in beakers, test tubes, etc, as all that is glass and most of my experiments currently involve NaOH, for which glass is a bad container.
In any case, no, I'm not eating out of the chemistry equipment.

And no I'm not just some adult that is telling you what to do, I'm only 17, a teenager like you.

I don't remember mentioning I was a teenager... Is it that obvious? Maybe it was the really old posts from when I was distraught (my first thread etc).

So please just take the safety precautions we've all told you. Not just for you, but for everyone you live with, and trust people when they say what you're doing is dangerous. Just because you haven't had an accident yet, doesn't mean what you're doing is safe.

Right, it's not safe. And I have had accidents, I've just managed them properly. I will take the safety precautions, but I will not, of course, desist (that would be against my values).

Good luck with experiment. Maybe I'll do the same one you're doing now sometime over the summer.

Hehe, cool. If you need any information about the specifics, lemme know (I went through a lot of information finding the specifics I needed; then again, as my experiments are part of a larger project, you may not need to go through as much stuff). Or just ask on the forums and if I'm there, I'll reply.

Post Note:
By the way, do you have any suggestions for sources of a full face chemical shield and a labcoat?

Also, if there are typos, errors, etc. in this post... gimme a break. It's giant, and hard to review.

[macman104]

Just wanted to say until you get the faceshield, the goggles you are talking about are they "glasses" or "goggles", the ones that have a elastic band around the back of the head.  I would recommend those if you have the glasses instead.

[BlueTheCow]

Just wanted to say until you get the faceshield, the goggles you are talking about are they "glasses" or "goggles", the ones that have a elastic band around the back of the head.  I would recommend those if you have the glasses instead.

They are goggles with the elastic band around the head. Sides, top, bottom, and frontal coverage of the eyes (basically, fully covering my eyes).

[eugenedakin]

Hello BlueTheCow,

Hm... I'm not entirely sure what you're talking about. Would you cut a hole in the bottom of the can and flow water through? Or what? Are you talking about a sand filter as described here http://en.wikipedia.org/wiki/Sand_filter? As I said, I'm not entirely sure I understand this (it's not described very well on wikipedia at the moment).

Also, a NaOH solution dissolves SiO2/silica/sand, especially in my case. Would there perhaps be some alternative to using sand? Or is the sand not entirely necessary for what you described?

Lastly, do you have an idea of what sizes of particles would be filtered out? As far as I know, I need most of the particles size 0.5-1.0 microns (diameter I believe) and up filtered out. It might still work with less fine filtering, but I'm not entirely sure.

My apologies about the instructions, I will try and clarify (pun intended) the instructions on the filter. Yes, the Sand filter works quite well, and can filter to below 40 microns. I doubt that a 1 micron filter would work without the need for pressure to force the fluid through the filter.

Instructions for a makeshift fine-filter:

Take a tomato can and cut both end off of the can, leaving a circular tube. Clean the tube with water and soap. Place a clean, folded cloth over one side of the empty tube and fasten it with rubber-bands. On the inside of the tube, place some fine-grain-sand (1 inch or 2.2 centimeters). Place a coarse cloth above the layer of sand. Take one last cloth and form it into a 2 inch loose ball with your hands and place it in the container. Pour the content that you need to filter on the 2 inch loose ball.

Functionality: The 2 inch loose ball slows down the speed of the fluid entering the filter, preventing dispersion of the sand in the filter. The coarse cloth directly above the layer of sand is your coarsest filter, to catch large particles. The sand catches most of the fine particles, and the last cloth (with the rubber band) just holds the filter together.

I hope this helps visualize a filter.

Sincerely,

Eugene

[BlueTheCow]

Hello BlueTheCow,
[snippet snipped]
I hope this helps visualize a filter.

Sincerely,

Eugene

It does, quite so. Thank you very much for clarifying () it for me.

However, I do have a question about the actual sand. I won't be able to use sand in my specific process as it would dissolve and pass through the filter (leaving a can with a couple rags in it... could be a great archaeological mystery someday...).

So anyway, I was thinking that if I use some other particle instead of SiO₂, it might work. Unless there are any suggestions/objections, I'll go ahead and test a few materials myself.

[eugenedakin]

Hello BlueTheCow,

Yes, you are correct. When you bring sand to a very high temperature, and then add caustic soda you can dissolve sand to make sodium silicate. It is very difficult to make sodium silicate under laboratory conditions, let alone the theoretical conditions both you and I are talking. 

Just for your own enjoyment, put sand in a jar, add water and caustic, mark the side of the glass jar with a felt marker and wait. If the sand dissolves, there should be a space in between the layer of sand and the mark you made on the outside of the glass. 

If you have sodium silicate already, then yes, sodium silicate dissolves relatively quickly with the addition of caustic soda. Sand is not sodium silicate  .

Sincerely,

Eugene

[nj_bartel]

Does HCl count? No...?  Shocked Oh dear. I'll get some baking soda before I do another trial as well. I'm not sure about the vinegar; if you have baking soda, why do you need the vinegar as well?
---------------------------------------------


Just got a wonderful image of some faceless person screaming with hot NaOH solution in his face grabbing for muriatic and pouring it in his eyes.

Oh, and there are more reasons to use Pyrex than you think, for example the fact that it's heat/shatter resistant.  BUY PYREX.

[billnotgatez]

I would think that a good metal container that is not effected by the corrosive nature of sodium hydroxide is a reasonable choice.

As to safety

A standard lab has several setups to help with this

A fume hood
A special shower that you just pull the handle down and it does the rest
Eye washing station

After that the experimenter uses
Face shields
Lab coats
Gloves
Maybe even special boots


I for one support citizen science especially when it is done on a very small scale.

[BlueTheCow]

Whew! The forum monster ate my post (my login cookie expired while I was typing, and then when I tried to go back, the text box for the message body was empty, and reposting was giving me the Already Posted error....), but LUCKILY I was able to cut him open and recover my post using Wireshark (a packet sniffer). That was a close one. Here's the post:

Alright, I'm back, and I think I've come up with a solution to my coffee filter problem. Essentially, I'll buy a pack of "0.22 micron Pore Size, 13mm diameter, 50 micron thick Sterlitech PTFE (Teflon) Unlaminated Membrane" (which is shaped like a circle) from http://www.sterlitech.com/products/membranes/PTFE/ptfeunlaminated.htm.

I'll take one of these PTFE membrane filters, stick it in-between two 3/8 inch galvanized steel pipe flange fittings, making essentially a steel pipe coupling with a filter squished in between (the diameter of the flow is 9.525mm, but the flange itself is about 4 times this diameter, allowing the filter to fit in nicely), and then seal it with pipe thread sealant (which also contains PTFE).

So I'll have my own little filter frame, which I can connect to any reactor contraption I come up with. It will require me to wet the filter with Isopropyl Alcohol before use, due to the hydrophobic property of PTFE. Also, I'll have to come up with some way to push the mixture through at 40 PSI. (I'm not actually sure if I need both the pre-wetting with alcohol and the pressure, or if either one would work; I'll test this myself, as it seems a trivial thing to consider at the moment: if both are needed, then I'll buy the supplies for both; there won't be much wasted if only one is needed, as I would prefer the more expensive pressure method, which excludes alcohol; the only wasted supply could be the Isopropyl Alcohol, which is inexpensive.)

In actuality, I'll probably need 2 or more of such filter frame contraptions, as I'll most likely need to filter in a step down manner in order to not clog the pores too quickly. That is, I'll most likely need to use similar 5.0 micron and/or 10 micron pore size membranes and filter through these before I filter with the fine 0.22 micron pore size membrane.
(This part where I have to use multiple filter sizes scares me, as I can already see the hundreds of membrane filters stacking up in cost... I think I'll email one of the suppliers to see if they can split packages for "sampling"...)



In any case, the next problem I'm working to solve is creating the pressure necessary to push the mixture through the filter (>=40 PSI). If anyone has any ideas, feel free to share (keep in mind that the mixture is extremely caustic and at around 170-210C, and may have fair sized particles, perhaps up to a few mm in diameter). Currently, I'm trying to figure out a way to build my own pump that will work in this situation.

[Borek]

In most cases pump just speeds the filtration. No pump - it still goes, just slowly. Remember that pressure can accidentally squeeze your liquid into any direction, that's not what you want.

[BlueTheCow]

In most cases pump just speeds the filtration. No pump - it still goes, just slowly. Remember that pressure can accidentally squeeze your liquid into any direction, that's not what you want.

Are you sure I won't need a pump? While that will make it much easier to design, the following is from the manufacturer's FAQ section:

EDIT2: SKIP THIS PART, as I made a mistake. I'm leaving it here so there's no confuzzling of anyone who already read it.

Q. Why is my flow rate low?  Little or no liquid is seen to pass through the membrane, what could be the problem?
A. There could be a number of things going on to restrict the flow through the membrane.

[first part removed to condense post]
Another thing to consider is if the liquid is being properly prefiltered.  With such small pore sizes, 0.05-0.01, you need to filter in a step down manner so as not to plug the pores.  Step down means a series of filters with decreasing pore sizes.  This can even happen with DI water, bacteria or other particles can be introduced to the process and cause problems with blinding or plugging the filter.

So... would I just have to wait longer? Or clean the filter more often? Or...?

Edit: Re-reading my post, is it possible that this information does not apply to the pore size I will be using (0.22 microns)?
EDIT2: This is the end of the skippable part.
Edit2: I'm going bonkers; this quote doesn't even concern the pump...

This one does:

Q. What membrane has been used to prevent water vapor from passing, but would allow regular air to pass?

A.  The common membranes used for gas/air filtration are our hydrophobic Polypropylene and PTFE Membranes.  They both inhibit the flow of water vapors (hydrophilic) while allowing regular air molecules (such as oxygen) to pass.

For the PTFE membrane the water intrusion pressure (which is inversely related to pore size) is greatest with the smaller sizes:

Water Intrusion of PTFE 

Pore Size (um)	Water Intrusion Pressure (psi)
0.2	40
0.45	20
1.0	7
3.0	2
5.0	1

So what I meant to ask was: if I don't use a pump, where does the 40 PSI intrusion pressure come from?

[Borek]

OK, for such small pore size you may need external pressure just to wet the filter. But I still don't like the idea. OTOH - 40 psi you will get from tyre pump.

[enahs]

Do you really need super filtration? I mean, if this is just to see if you can do it, does it need to be super pure?

Insert obligatory safety warning, which you have gotten a lot, and should read carefully.

I would go to your local hardware store. Go to the window section. Look at the window screening. They make some out of metal. Find one with a metal that will not react with hot NaOH (they are not all pure metals, and some can be aluminum!) Buy a little. Cut a bunch of circles out, lay them on top of one another in alternating patterns so you make really tiny holes, and shape it like a funnel. You now have a metal screen that should filter pretty decently.

And while you are at the hardware store, get a face shield and really good gloves, pretty please. And maybe a cheap piece of plexi-glass to screw into a wood frame and put between you and the reaction.