Safe Water Delivery Using Artificial Porous Materials

We can have an endless, but not infinite, supply of safe drinking water if we could only extract the water in the air we breathe. 
Wiping Air with a Sponge or an Eraser

Source - redbookmag.com

This extraction of water can be visualized as a gizmo that acts like a sponge or a chalkboard eraser when we move it in the air where we need to extract safe water.
This gizmo would "clean" the air around us of water molecules, with the same motion that we use to wipe a blackboard clean of chalk!
Later, once the gizmo fills up with extracted water, we could squeeze out (literally speaking) this water.
Luckily, materials that may be very suitable for just such an action already exist.
MOFs - Metal-Organic Frameworks

Source - ucla.edu

Source - labroots.com

MOFs are structures consisting of organic molecules and metal ions. The organic molecules hold metal ions in a 3-D grid pattern that is porous to another, a third, material.
The structures can have virtually any 3-D configuration - the configuration essentially depends upon the organic molecules and the metal ions that comprise the structure.
As we may also expect, the combination of organic molecules and metal ions define what materials will be absorbed by a specific structure.
Cavity size, number of cavities and absorption rates can also all be controlled.
Water Absorption
Chemistry of organic molecules can, in the presence of moisture and under different ambient temperatures, get compromised but a list of water-stable combinations have been developed. The focus, however, has been on using MOFs for energy applications like hydrogen and other gas absorption, storage and release.
All that remains is to focus this research on water absorption, storage and release! 
A local supply of safe drinking water using a MOF that extracts moisture from the air we breathe can be a reality in our very near future!

Water Is Full of Holes

Water is known as a Universal Solvent, because it dissolves most everything. It can do this because water is full of holes.


Some Liquids have Structure
There are simplistically speaking, two kinds of liquids:

- Unstructured liquids have their molecules held together by relatively weak non-directional Van Del Waals forces. These molecules fill space fairly well. Liquid detergents are an example of a widely used unstructured liquid.

Unstructured Liquid
Source - sites.bergen.org

Structured Liquid
Source - ifm.liu.se

- Structured liquids have their molecules held together by relatively stronger forces that exhibit an orientation or direction (polarity) as hydrogen bonds do in water. These molecules do not fill space well - there are voids throughout these liquids that other materials can fill very well.


Water, a Structured Liquid, has Voids
As is obvious from the illustrations, unstructured liquids have very few voids, while structured liquids have voids. The more (and larger voids) a liquid has, the more molecules (and kinds of molecules) of other materials the liquid can absorb i.e. the more universally solvent the liquid is. 
A large part of the volume of liquid water is made up of voids


Water has voids because of Hydrogen Bonds

Source - science.csustan.edu

Hydrogen bonds, it is assumed, shown as grey lines between the water molecules, create the voids in water. The  water molecule,  which  contains two  hydrogen atoms  and  one  oxygen atom  in  a  nonlinear arrangement, is ideally  suited  to  engage  in  hydrogen bonding