This article is significant news in the MENA region; the most water-scarce region in the world, where desalination plants are for some time now ‘run of the mill’ urban furniture. An improvement in the filtering membrane would have a financial impact on the running costs of these plants. It could encourage the inception of more especially in those other and remote areas with limited finances. A new filter turning saltwater into freshwater upgrade would undoubtedly impact not only this water industry but also all those linked with the region’s agriculture and food production.
“Making the material smoother prevents it from getting gunked up quickly”, as per Maria Temming, author of this article posted on August 16, 2018, by ScienceNews would certainly not fall in deaf ears whether from these last referred to countries but from all of the MENA region. The only snag would be that of whether sea water rising could suffice to feed all those prospective plants.
Smoothing out the rough patches of a material widely used to filter saltwater could make producing freshwater more affordable, researchers report in the Aug. 17 Science.
Desalination plants around the world typically strain salt out of seawater by pumping it through films made of polyamide — a synthetic polymer riddled with tiny pores that allow water molecules to squeeze through, but not sodium ions. But organic matter, along with some other waterborne particles like calcium sulfate, can accumulate in the pockmarked surfaces of those films, preventing water from passing through the pores (SN: 8/20/16, p. 22). Plant operators must replace the membranes frequently or install expensive equipment to remove these contaminants before they reach the filters.
Now researchers have made a super smooth version without the divots that trap troublesome particles. That could cut costs for producing freshwater, making desalination more broadly accessible. Hundreds of millions of people already rely on desalinated water for drinking, cooking and watering crops, and the need for freshwater is only increasing (SN: 8/18/18, p. 14).
Manufacturers normally create salt-filtering films by dipping porous plastic sheets into chemical baths that contain the molecular ingredients of polyamide. These molecules glom onto the sheet, building up a thin polymer membrane. But that technique doesn’t allow much control over the membrane’s texture, says Jeffrey McCutcheon, a chemical engineer at the University of Connecticut in Storrs.
McCutcheon and colleagues made their version by spraying the polyamide building blocks, molecular layer by layer, onto sheets of aluminium foil. These polyamide films can be up to 40 times smoother than their commercial counterparts.
Such ultra-smooth surfaces should reduce the amount of gunk that accumulates on the films, McCutcheon says, though his team has yet to test exactly how clean its films stay over time.
Typical polyamide films for filtering saltwater (shown in the scanning electron microscopy image to the left) have rugged, pockmarked surfaces that trap organic material and other particles, clogging the filter. New, ultrasmooth polyamide membranes (right) could avoid that problem.
M.R. Chowdhury. 3D printed polyamide membranes for desalination. Science. Vol. 361, August 17, 2018, p. 682. doi: 10.1126/science.aar2122.
- A. Witze. More than 2 billion people lack safe drinking water. That number will only grow. Science News. Vol. 194, August 18, 2018, p. 14.
- T. Sumner. New tech harvests drinking water from (relatively) dry air using only sunlight. Science News. Vol. 191, May 13, 2017, p. 10.
- T. Sumner. New desalination tech could help quench global thirst. Science News. Vol. 190, August 20, 2016, p. 22