Researchers develop method for extracting copper from wastewater

Photo of water droplets in a sink
Lisi Ludwig/Senior Staff
Researchers have found a way to remove copper ions from wastewater using zinc imidazole salicylaldoxime, or ZIOS, crystals at a rate that is 30 to 50 times faster than current adsorbents. ZIOS crystals are also able to maintain stability for up to 52 days of being submerged in water.

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An international team of researchers, including Lawrence Berkeley National Laboratory, or Berkeley Lab, researchers, has created a crystalline structure that can trap copper ions in wastewater.

The structure, called zinc imidazole salicylaldoxime, or ZIOS, could be a blueprint for water treatment that isolates heavy metals at the atomic level, according to a study published by Nature Communications. Theresa Duque, Berkeley Lab spokesperson, added in an email that further research will need to be conducted in order to selectively remove other pollutants.

“Today’s water treatment systems are ‘bulk separation technologies’ – they pull out all solutes, irrespective of their hazard or value,” said study co-author Peter Fiske in a Berkeley Lab press release. “Highly selective, durable materials that can capture specific trace constituents, or falling apart with time, will be critically important in lowering the cost and energy of water treatment.”

Researchers found that ZIOS crystals use a separation method called adsorption, which adheres the copper ions to their outer surface. ZIOS crystals were found to adsorb copper ions 30 to 50 times faster than current adsorbents.

ZIOS crystals also possess small pores, or nanochannels, that expand when submerged in water. According to Duque, this process allows the water carrying copper ions to “flow at a larger scale.”

Ngoc Bui, an assistant professor at the University of Oklahoma, said in the press release that ZIOS works like a “more structured” sponge. Instead of absorbing water and then expanding randomly, ZIOS absorbs water molecules and expands in specific directions.

Unique from current methods, ZIOS crystals can maintain stability after being submerged in water for up to 52 days and perform well in acidic conditions, which would be useful for adsorbing copper ions in acidic wastewater.

Duque said in the email that ZIOS is a new technology and is not currently commercially available. According to Duque, the researchers’ next steps are to develop the technology to remove other pollutants.

“This current study demonstrated a new material that can capture copper ions specifically,” Duque said in the email. “There currently isn’t an estimate for commercial availability — additional studies would be needed to demonstrate ZIOS as a scalable, commercial product.”

Contact Megha Krishnan at [email protected] and follow her on Twitter at @_meghakrishnan_.