The dyes that provide color to many objects in our world are also polluting our water, but there’s big news from researchers at Drexel University. According to a report from the laboratory, they have found a way to neutralize the dyes, which can be toxic and carry potentially cancer-causing substances.
Dyes are used in textile, cosmetic and paper industries among other industries. According to a CNN report, the textile industry uses approximately 1.3 trillion gallons of water each year to dye fabric. To put the volume in perspective, the story claims this is enough water to fill two million Olympic-sized pools and most of it is later, untreated, sent into rivers and streams.
That’s where the Drexel team – and its “tiny” one-dimensional, photocatalytic nanofilament – comes in.
In short (sans labspeak), microscopic dye particles stick to the nanofilament via adsorption. The nanofilament is exposed to light, which breaks down the dyes into carbon dioxide and water. There is a lot of chemistry involved in corrosion, including the formation of electron holes and radicals that help the illumination process purify the waste water.
Interestingly, according to the Drexel team, the dyes help sensitize the nanofilaments to light, aiding their self-destruction.
Experts were able to break down the two common colors using visible light. Using a 1:1 mass ratio of catalyst and dye reduced both pollutants by 90% and 64% in about half an hour.
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“We are just beginning to uncover the possibilities of this material,” said Professor Michel Barsoum, a study leader in the Drexel report.
The dye is difficult to purify from waste water, as it is not a solid that can be filtered. Drexel experts estimate that we generate about 380 billion cubic tons of wastewater each year, of which only 24% is adequately treated, due in part to the presence of irritants such as dyes.
A significant breakthrough in the Drexel process is the effectiveness of visible light, like sunlight. Similar de-dyeing methods until now have required UV treatment, which requires a lot of power. According to the research team, the experts’ light-sensitive nanofilament is more efficient.
“The use of visible light, like the sun or other simulated light sources, can significantly reduce the financial and energy consumption costs associated with treatment,” researcher Adam Walter said in the lab report.
Barsoum said in the report that the Drexel team is continuing their nanofilament research with the hope of finding new applications, helping to create a “sustainable future” and clean water.
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