Light-Harvesting Membranes Heat, Desalinate Water in One Step

A Rice University-led team will conduct further development and field testing of a desalination technology that uses nanoparticles and sunlight to treat water, with help from a $1.7 million grant from the Department of Energy (DOE).

The technology, called NESMD, for nanophotonics-enabled solar membrane distillation, builds on membrane distillation by incorporating light-capturing nanoparticles directly into the membrane.

A scaled-up nanophotonics-enabled solar membrane distillation (NESMD) test bed during a 2017 demonstration at the Center for Nanotechnology Enabled Water Treatment, an National Science Foundation-funded engineering research center at Rice University. Courtesy of Jeff Fitlow/Rice University.

Membrane distillation is a lower-energy desalination alternative to boiling brine and capturing the steam. Instead, hot brine is flowed across one side of a porous membrane, and water vapor is drawn through the membrane naturally. When nanoparticles are added to the membrane, it essentially becomes a one-sided heating element that drives distillation. The nanoparticles used for this process are low-cost and commercially available.

Results from testing on laboratory-scale prototypes showed that NESMD could desalinate water at a rate of up to six liters per hour per square meter of light-harvesting membrane. NESMD inventor Qilin Li said that many parts of the technology could be optimized to improve upon these results when the system is scaled up for operational field tests.

“We’re creating off-grid systems to provide water anywhere it’s needed,” said Li.

The desalination system is the first major innovation from the Center for Nanotechnology Enabled Water Treatment (NEWT), based at Rice University.

The desalination system, which uses a combination of membrane distillation technology and light-harvesting nanophotonics, is the first major innovation from the Center for Nanotechnology Enabled Water Treatment (NEWT), based at Rice University. Courtesy of Rice University.