Add some aluminum foil or steel nails to the copper sulfate solution.
The copper will plate out onto the more reactive metal.
The blue color goes away.
The iron sulfate or aluminum sulfate that remains in solution is not
harmful to wildlife in your sewer system.
-----
Get a free science project every week! "http://scitoys.com/newsletter.html"On Tue, Apr 24, 2012 at 1:11 AM, Cathal Garvey <cathalgarvey@gmail.com> wrote:
If you look up how HEPA filters tend to work, it's not actually by size
exclusion. Instead, the filters are engineered to attract and adsorb
particles as they pass through the mesh. So, the filter "pore" size
isn't so small as to impede flow. The disadvantage though is that you
can't just back-flush the filter to re-use it; adsorbed
dirt/spores/viruses are there to stay, more or less.
As to humidity control; I won't get into the mechanics, because it's not
something I know a great deal about. But, a cheap hack to avoid standing
water from getting contaminated is to add 1g/L CuSO4.7H20 (Blue Copper
Sulphate) to the water. Copper Sulphate is a pretty effective biocide,
so this tends to prevent anything growing in it.
However, reading through MSDSs one day, I discovered that copper
sulphate is considered "extremely toxic to the aquatic environment"; try
to avoid washing it down the sink. Just let it dry out and re-use if
possible after autoclaving.
www.indiebiotech.com
On 24/04/12 04:20, Daniel C. wrote:
> On Mon, Apr 23, 2012 at 11:03 PM, Simon Quellen Field
> <sfield@scitoys.com> wrote:
>> If we build the other device I was talking about, where we create air that
>> has the temperature and humidity we like, and then blow it through a
>> virus filter, we can also use a wet bulb hygrometer, since it is on the
>> non-sterile side of the filter.
>
> I've heard about filtering things to sterilize them a few times
> recently... is this a new thing? I don't recall it being possible to
> do this when I worked in a lab way back when, but maybe it was and I
> just never did it (or forgot). It seems like any filter small enough
> to get viruses out would also impede airflow so much that you'd need a
> tremendous pressure differential to get any throughput.
>
> -Dan
>
--
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