VERY HIGH CAPACITY
Mezzenga is enthusiastic about the hybrid membrane’s filter capacity. In tests with mercury chloride, for example, the mercury concentration present in the filtrate fell by more than 99.5 percent.
The efficiency was even higher with a toxic potassium gold cyanide compound, where 99.98 percent of the compound was bound to the membrane, or with lead salts, where the efficiency was larger than 99.97 percent. And with radioactive uranium, 99.4 percent of the original concentration was bound during filtration.
“We achieved these high values in just a single pass,” says Bolisetty.
Even over multiple passes, the hybrid membrane filters out toxic substances with a high degree of reliability. Although the mercury concentration in the filtrate increased by a factor of 10 from 0.4 ppm (parts per millions) to 4.2 ppm after 10 passes, the quantity of protein used was extremely low.
To filter half a liter of contaminated water, the researchers used a membrane weighing just a 10th of a gram, of which 7 percent by weight was made up of protein fibers.
“One kilo of whey protein would be enough to purify 90,000 liters of water,” says Mezzenga.
This suggests the efficiency can be increased by adding more protein content in the membrane, he adds, emphasizing the flexibility of this new approach.
Mezzenga, who has patented the technology, is confident the filter will find its way onto the market.
“There are numerous applications for it, and water is one of the most pressing problems we face today,” he adds.
Featured Photo Credit: ETH Zurich