Alcohols are used to remove impurities on the surface of semiconductors or electronics during manufacturing. Wastewater containing alcohol is treated using reverse osmosis, ozone, and biological decomposition.
Such methods can lower the alcohol concentration in wastewater. However, they are ineffective at completely decomposing alcohol in wastewater with a low alcohol concentration. This is because alcohol is miscible in water. That makes it impossible to completely separate from alcohol using physical methods. Chemical or biological treatments are highly inefficient. For this reason, wastewater with a low alcohol concentration is primarily treated by diluting it with a large amount of clean water before its discharge.
The Korea Institute of Science and Technology (KIST) has announced that a research team led by Dr Sang Hoon Kim and Dr Gun-hee Moon of Extreme Materials Research Center developed a photocatalyst that can completely decompose a trace amount of alcohol in water within a short duration by adding a very trace amount of copper to iron oxide, which is used as a catalyst during the advanced oxidation process.
The paper, “Control of copper element in mesoporous iron oxide photocatalysts towards UV light-assisted superfast mineralisation of isopropyl alcohol with peroxydisulfate,” was published in Chemical Engineering Journal.
Treating semiconductor wastewater important
The research team employed Fenton oxidation, which uses oxidising agents and catalysts for water treatment during the advanced oxidation process. Usually, alcohols were used as reagents to verify radical production during Fenton oxidation in other advanced oxidation processes (AOP) studies. They were the target for removal from semiconductor wastewater in this research.
This water treatment technology is expected to dramatically reduce the cost and water resources invested into semiconductor wastewater treatment. In the past, clean water with a volume 10 times higher than that of the wastewater under treatment was required to dilute the wastewater to reduce the alcohol concentration of 10 ppm in the wastewater to less than one ppm.
Water resources can be saved if the photocatalyst developed by the KIST is used for water treatment. The research team applied the photocatalyst to wastewater from a semiconductor factory. They proved that alcohol decomposition levels similar to those observed in the laboratory could be achieved in industrial practice.
“As large-scale semiconductor production lines are established, we expect that there will be a rapid increase in the demand for the treatment of semiconductor wastewater,” said Dr Kim. “The results of our research will provide a solution to treat semiconductor wastewater using fewer resources effectively and at a lower cost,” he added.
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