Technology alert: MOF water purification system

Monash University researchers have developed a revolutionary new water treatment technology that has the potential to provide cheap, sustainable, drinking water to millions of people around the world.

The world-first study, recently published in the Nature Sustainability journal, uses metal-organic frameworks (MOFs) and natural sunlight to convert brackish water and seawater into clean drinking water.

The study shows MOFs could transform the water treatment industry – which currently uses technologies that consume a significant amount of power and chemicals.

MOFs are a new group of materials made by combining metals and plastics (polymers) at the molecular level. By experimenting with different metal/polymer combinations, researchers can invent new materials with interesting and highly useful properties. These materials have applications in many engineering fields – such as hydrogen gas storage, carbon capturing and semi-conductor design.

The team at Monash University, led by Professor Huanting Wang, have created an MOF with the ability to remove contaminants from water when placed in a dark environment. The MOF then discharges those contaminants when placed in sunlight.

A diagram of the new process is shown below:

New MOF water treatment technology uses natural sunlight instead of power or chemicals.

As water passes through the MOF material, dissolved contaminants are attached to charged sites via a process called adsorption, safely removing them from the water.

Once the MOF has exhausted all of its sites, it is placed in sunlight, changing the state of the material and causing the MOF to discharge the contaminants. This regenerates the MOF back to a state suitable for reuse in further water treatment operations.

The process of adsorption is not uncommon in water treatment. Many different types of adsorbents are used today – such as resins, zeolites, rice husks, and sands. However, these materials either have a one-time use or require strong chemicals for regeneration – which is both costly and environmentally unsustainable.

The ability to regenerate an adsorbent using only sunlight is an extraordinary technological advancement, and could significantly reduce the amount of power and chemicals consumed by the water treatment industry.