Here we go again…. this time with a change to
the team. Mikey Leahy’s place has been taken by
Iain Stewart (an Earth Scientist) who, even within a
few minutes of meeting him, I knew was going to fit
in well. I arrived in LA from Perth (Western Australia)
just under a week ago, and three days ago I had to pick
the other four scientists and film crew up from Las
Vegas where they’d flown to from Heathrow. We’ve
all now spent a few days together, and it looks like
it’s going to be a good team all-round.
Anyway, it’s the first day of filming, and there’s
a lot to do. My challenge for programme one is to purify
various samples of ‘impure’ water which
Iain and Ellen are to collect from a variety of botanical
and geological sources. Sounds easy enough, but where
to start, given the limited resources I have at my disposal?
I settle on charcoal (made from burning wood). In fact,
I think NASA actually use charcoal filters to purify
the air and water systems in their spacecraft. Charcoal
is also used in domestic water filters. I suspect that
ordinary charcoal will do, but there’s a chance
I can make it an even more effective filter by ‘activating’
it – to do this I’ll need to blow air or
‘superheated’ steam through the hot charcoal,
neither of which processes will be easy, or even possible,
under Rough Science conditions.
My plan is to pack some two and a half centimetre diameter
PVC tubing with plugs of charcoal and trickle the impure
water samples (when I eventually get them) down the
columns, under gravity. The charcoal is acting as more
than just a physical filter to the impurities in the
water. It’s an extremely porous material, containing,
as it does, lots of tiny cavities, channels and pores.
These all go to increase the material's surface area
quite significantly. Incredibly, just one gramme of
activated charcoal can have an internal surface area
equivalent to five or six tennis courts. As the impure
water works its way down the column, many of the impurities
will bind weakly to the charcoal surfaces (a process
called adsorption). The slower the trickle, the more
efficient the purification process. The purified water
should pass through unhindered, for collection at the
bottom of the column.
Today’s goal will therefore be to make some charcoal.