Colloidal particles all have a surface charge, called a zeta potential. This very surface charge is what keeps them in suspension in water.

As water runs through a diffusiophoretic water filter (DWF), an ion gradient pushes or pulls the colloidal particles due to their surface charge to one side of the DWF. This ion gradient can for example be imparted by carbon dioxide passing through a thin silicone membrane. The clean water, or filtrate, is split off, free of harmful colloidal particles.

What makes DWFs so amazing is that they are most effective on particles with a high surface charge or zeta potential: thus the very property that keeps colloidal particles in suspension in water allows them to be removed easily with DWFs.

DWFs are incredible for harmful chemicals as well. While harmful chemicals themselves often are not movable by a DWF, most of these chemicals can be adsorbed by micro- or nanoparticles (MNPs) such as iron oxides and carbon nanotubes. These MNPs with adsorbed chemicals can then be easily removed by DWFs, and even recycled. Up to now, the use of MNPs for adsorption has been limited because the MNPs are hard to separate and recover. DWFs solve this problem.

DWFs thus provide an inexpensive and efficient platform to remove the contaminants and chemicals of a specific water source.