“Make mine seawater” (petrochemicals make desalinization practical)

Technology |  2 min. read

“Water, water every where,

Nor any drop to drink”

(Which, as it turns out, is how the Rime of the Ancient Mariner actually puts it – though most of us have probably heard it as “and not a drop to drink”.)

In the poem, it’s the plight of sailors adrift in the ocean, literally on a sea of water, but suffering from thirst, because you can’t drink seawater.

But that was then (1797, to be exact).

Now we can (thanks to desalinization, taking the salt out of sea water).  And that is a good thing, because now it isn’t just sailors at sea who need water – it’s hundreds of millions of us on land too – people who live in places where traditional sources of water are falling short.

But desalinization traditionally uses massive amounts of energy (which also makes it massively expensive).  And that, is why even in cities by the sea, we don’t see much desalinization today.

Now comes a new technology, a membrane for filtering seawater that mimics the membrane of a living cell.  This new filter doesn’t require forcing the water through it (which is what takes all that energy and costs all that money) – but still does the work of producing clean, drinkable water – straight out of the sea.

But this new membrane has another plus as well.  It turns out that seawater has a lot of lithium in it, and this new process can filter out that lithium.  That’s good because this is the same lithium that goes into lithium-ion (Li-ion) batteries – the batteries that run laptops when they’re not plugged.  Also cell phones, tablets, digital cameras, and cordless power tools (like sanders, drills, hedge trimmers).  And yes, electric car batteries too.  Which means, like clean drinking water, the demand for lithium is also putting pressure on the supply.

So you might say truly, this is a magic membrane, that might be the answer to two critical shortages at once.  And the starting point for this magic – is toluene.  Now, if you don’t know what that is, you’re not alone.  Toluene is a petrochemical, made from petroleum, working quietly in the background.  In this case, toluene is used in step one of a series of chemical reactions, which eventually gets us to a zeolitic imidazolate framework, which is the basis of the new membrane filter.

And that – could get us to a virtually inexhaustible source of fresh drinking water (and a lifetime supply of cellphone batteries).  Guess it’s a good thing oil and water don’t mix.