As important a technology as water filters are, they get less effective as bacteria builds up on their surface.
To make the new membrane, the researchers first feed a sugary substance to Gluconacetobacter hansenii.
The bacteria then use that substance to produce cellulose nanofibers in water.
While those fibers are growing, the team adds graphene oxide flakes to add stability and durability to the membrane.
"We can add whatever we like to the bacteria nanocellulose during its growth.
We looked at it under different pH conditions similar to what we encounter in the environment, and these membranes are much more stable compared to membranes prepared by vacuum filtration or spin-coating of graphene oxide."
"If you want to purify water with microorganisms in it, the reduced graphene oxide in the membrane can absorb the sunlight, heat the membrane and kill the bacteria," says Srikanth Singamaneni, co-lead author of the study.
Three minutes of exposure to light was enough to heat the membrane to over 70° C (158° F), hot enough to kill the bugs.
Tests of membranes made without the reduced graphene oxide found that, predictably, the E. coli survived.
That said, it may be tricky to implement in current water filtration systems, but the team suggests that future designs could be made to use LEDs or tiny generators that produce light and heat from the flow of the water itself.