UT Austin develops hydrogels that desalt water with ambient sunlight

Researchers at the University of Texas at Austin, US, have developed a technology with gel-polymer hybrid materials that can desalinate water using ambient solar energy.

The research team led by Guihua Yu, associate professor of material science and mechanical engineering at the Cockrell School of Engineering, is using a combined gel-polymer hybrid, or hydrogel, that has hydrophilic (attraction to water) and semi-conducting (solar-absorbing) properties. These new hydrogels — networks of polymer chains known for their high water absorbency — enable production of clean water from seawater or contaminated waters.

The team developed a new hydrogel-based solar vapour generator that uses ambient solar energy to power evaporation for desalination.

The concept differs from existing solar steaming technologies, which are costly to run and require optical instruments to concentrate sunlight. The new nano-structured gels can run on naturally occurring levels of ambient sunlight, and increase the volume of water evaporated.

The hydrogels generate water vapour with direct sunlight, and the vapour is pumped to a condenser that collects the fresh water.

The desalinating properties of the hydrogels were tested on salt-rich water samples from the Dead Sea, and “passed with flying colours,” producing drinking water that meets World Health Organisation standards, the university said.

“Our outdoor tests showed daily distilled water production up to 25 litres per square metre, enough for household needs and even disaster areas. Better still, the hydrogels can be retrofitted to replace the core components in most existing solar desalination systems, thereby eliminating the need for a complete overhaul of systems already in use,” said Yu.

Phys.org has a short video of the process

The research was published in Nature Nanotechnology in April 2018