Self-Assembling Membrane Purifies Water

The two-layer material may suit industrial water-purification applications

By Chemical Processing Staff

An “aqua material” membrane that can operate at high pressures provides outstanding performance in removing small organic molecules and heavy metals from water, report researchers at the Weizmann Institute of Science, Rehovot, Israel. Called an aqua material because water is its major component, the membrane boasts unprecedented robustness as well as valuable functionality that make it promising for demanding industrial applications, they add. Moreover, the membrane is easily fabricated and readily disassembled when fouled, the researchers say.

The membrane (Figure 1) consists of a Nafion polymer structure on a PP2b amphiphile layer. Its metal retention reaches 99.98%, the researchers note. More details appear in an article in Angewandte Chemie International.

The next step in the development is scale-up and automation of membrane fabrication, says Boris Rybtchinski, a professor in Weizmann’s organic chemistry dept., and leader of the research team. Once funding is obtained, this should take one to two years. Then, the team hopes to run pilot-plant scale trials. “I expect that in a couple of years we will have some prototypes for industrial applications,” he predicts.

The key challenges remaining to be addressed are the cost of the organic material, he notes. “But if produced in high amounts, it may be economical,” Rybtchinski adds.

Dealing with a fouled membrane involves disassembling it, cleaning the two solutions, and then reassembling. “This is a short process. Takes hours. We still have to develop a better Nafion recycling procedure,” he explains. “We can retrieve 90% or more of PP2b. Nafion is more challenging but most of it can be recycled as well.”

Yeda Research and Development, Rehovot, which specializes in technology transfer of work done at the Weizmann Institute, now is working to bring the technology to market.

Industrial implementation might involve either an operating company handling the assembly, disassembly and reassembly of the membranes it is using, or this being done by a vendor selling the separation system. “[It’s] too early to tell. I think that both options are conceivable,” says Rybtchinski.

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