Breakthrough in filtering salt and metal ions from seawater Thursday, 01 March 2018

Australian chemical engineers have found an efficient and sustainable way to filter salt and metal ions from seawater that could mean a breakthrough for safe drinking water for billions of people, and benefits for the water and mining industries.

Dr Huacheng Zhang, Professor Huanting Wang and Associate Professor Zhe Liu at Monash University are part of the team comprising the University of Texas and CSIRO that has discovered metal-organic framework (MOF) membranes can mimic the filtering function (ion selectivity) of organic cell membranes.

The results of the team’s research have just been published in Science Advances and revealed that with further development, these MOF membranes have “significant potential”. They could perform the dual functions of removing salts from seawater and separating metal ions in a highly efficient, environmentally sustainable, and cost-effective manner, according to the engineering team.

The MOF membranes are ‘next gen’ material that have the largest internal surface area of any known substance. Sponge-like crystals can be used to capture, store and release chemical compounds like salt and ions in seawater.

While reverse osmosis membranes are currently responsible for more than half the world’s desalination – and the last stage of most water treatment processes – they have limitations, the team says. In fact, they believe there is room for improvement by a factor of two to three in energy consumption.

And in the mining industry, these membrane processes could not only reduce water pollution but could be used as a way of recovering valuable metals. With the rising demand of lithium-ion batteries in electronics, if this new process turns out to be economically and technologically feasible, direct extraction and purification of lithium from seawater could be performed instead of from rocks and brines.


Image: Monash University.