H2O Titanuim - New Tech?

Randy Holmes-Farley · Apr 28, 2018

Thanks.

Jose Mayo · Apr 28, 2018

Scott Weinrich said:
AOP=Advanced oxidation processes. Its a term of art in the water treatment industry.

I think a better approach to creating the TiO2 surface would be to coat the inside of a tube with powdered anatase and then sinter it in place rather than chemically create a oxide layer. You'd have better control of crystalline form although I think some of the anatase would undergo a phase change to rutile at temperatures high enough to sinter. Rutile still has reasonable catalytic efficiency though.

You'd likely want a coating thick enough to be periodically resurfaced as the catalyst will likely eventually foul.

Yes. The sintering of microcrystalline anatase is possible and has already been done on several surfaces, heating the deposited film of a suspension of TiO2 at a maximum of 400ºC, above that the change to rutile can occur. The problem is to be able to coat the interior of the tube uniformly with the anatase film, and then heat it. On flat surfaces it is much easier.

But again, if the anatase coating is obtained and kept permanently irradiated, it will hardly accumulate debris due to its "self-cleaning" effect and maintenance may perhaps be given with periodic flow increases on the reaction surface, para drag larger particles eventually adhered.

Regards

Randy Holmes-Farley · Apr 28, 2018

Jose Mayo said:
Yes. The sintering of microcrystalline anatase is possible and has already been done on several surfaces, heating the deposited film of a solution of TiO2 at a maximum of 400ºC, above that the change to rutile can occur. The problem is to be able to coat the interior of the tube uniformly with the anatase film, and then heat it. On flat surfaces it is much easier.

But again, if the anatase coating is obtained and kept permanently irradiated, it will hardly accumulate debris due to its "self-cleaning" effect and maintenance may perhaps be given with periodic flow increases on the reaction surface, para drag larger particles eventually adhered.

Regards

It is self cleaning to organics, but what about deposition of inorganic minerals, such as calcium carbonate, or, if you accept that it happens even in seawater, the calcium hydroxyapatite?

Jose Mayo · Apr 28, 2018

Randy Holmes-Farley said:
It is self cleaning to organics, but what about deposition of inorganic minerals, such as calcium carbonate, or, if you accept that it happens even in seawater, the calcium hydroxyapatite?

In order for there to be a real detriment to the catalytic action of the irradiated anatase, the carbonate deposit would have to be thick enough to be opaque to UV light and impervious to water, otherwise it would continue to function.

This is the case, for example, in building blocks (bricks), which have been made with mortar doped with TiO2 anatase to coat monuments, and continue to operate, outdoors and only under solar irradiation, after several years, without any deposit of fungi or algae on them.

Regards

Jose Mayo · Apr 28, 2018

I, one of my first experiments, prepared a fine mass of structural white cement with anatase (half to half by volume, measured by spoonfuls) and spread it on a glass surface previously sandblasted to adhere.

I waited for it to dry and simply put the coated plate in the sump under irradiation of a 45W UVA lamp so that a thin layer of water, 6.0 millimeters thick, flowed over the plate. Never created algae.

Regards

Scott Weinrich · Apr 28, 2018

Randy Holmes-Farley said:
It is self cleaning to organics, but what about deposition of inorganic minerals, such as calcium carbonate, or, if you accept that it happens even in seawater, the calcium hydroxyapatite?

Yea, I agree. I'd expect a decrease in efficiency due to fouling from abiotic sources but also perhaps some organics that are refractory to degredation by hydroxyl radicals. From prior lab research I worked on, I know things with aromatics like humic/fulvic acid can be pretty stubborn toward reactive oxygen species.

edosan · Apr 29, 2018

Thanks for sharing guys!

kecked · Jun 4, 2018

How about putting the titanium dioxide in a pvc Binder. The surface would be less reactive but you’d have a reactive surface of oxide. Can the oxide be formed into a ceramic sleeve? I just added titanium sheet to my UV to stop the plastic breaking down. So far it works for that purpose and I see no other changes.

Scott Weinrich · Jun 5, 2018

kecked said:
How about putting the titanium dioxide in a pvc Binder. The surface would be less reactive but you’d have a reactive surface of oxide. Can the oxide be formed into a ceramic sleeve? I just added titanium sheet to my UV to stop the plastic breaking down. So far it works for that purpose and I see no other changes.

There might be problems with the hydroxyl radicals attacking the PVC over time. Incorporation in a ceramic sleeve might work, but the process of firing the ceramic might cause a phase change to a crystal form with a lower catalytic efficiency. It depends on the temperature at which the ceramic is fired. I would not expect titanium sheet to exhibit this sort of chemistry to any appreciable extent.

kecked · Jun 5, 2018

So then what would be a good sleeve material to block uv and not get killed itself and also not poison the tank.

how about this https://www.ebay.com/i/111815964657?chn=ps

Or can i just run the output over GAC.

Scott Weinrich · Jun 5, 2018

kecked said:
So then what would be a good sleeve material to block uv and not get killed itself and also not poison the tank.

how about this https://www.ebay.com/i/111815964657?chn=ps

Or can i just run the output over GAC.

I assume the titanium sheet you added would probably be fine to just shield the housing from UV. I have the same problem of the plastic breaking down in my UV unit. I've seen a bunch of different methods of immobilizing TiO2: sintering, impregnating concrete, etc.

Cory · Jun 5, 2018

Cool thread. Following

kecked · Jun 5, 2018

I have one more idea....glass tube if I can find the right size. Regular boro glass should filter well. Can I find 4-6" tube though! Bet it restricts flow a lot as well.
No dead fish yet and orp looks the same. Lets see if the tube gets less fouled or the tube gets plated. AHHHH. wonder if I ground the titanium if it would draw the charge away and stop the oxide /hydroxide formation. Might work....or make it dissolve. Ok thread hijack over.