AsianScientist (May 19, 2020) – Scientists in South Korea have turned old plastic bottles into a material that can remove antibiotics from contaminated water, reducing the spread of multi-drug resistance bacteria while addressing plastic waste at the same time. Their findings have been published in Composites Part B: Engineering.
Excess antibiotics from agricultural run-offs can find their way into the water supply, where they encourage the development of multi-drug resistant bacteria. As the name suggests, these bacteria can withstand virtually all classes of antibiotics, making them potentially deadly pathogens.
Currently, the most well-known method of effectively removing antibiotics from water uses a porous carbon composite, which is made from metal-organic frameworks (MOFs), crystalline structures bonded in two or three dimensions though a coordination bond between metal ions and organic ligands. However, since the organic ligands used to synthesize MOFs are expensive, porous carbon composites are too costly for widespread use.
Instead of using organic ligands, a team of researchers at the Korea Institute of Science and Technology (KIST) turned to polyethylene terephthalate (PET), a material commonly used to make disposable drink bottles. The team, led by Professor Choi Jae-woo at KIST’s Water Cycle Research Center, extracted high-purity organic ligands from waste PET bottles, using them to synthesize an adsorbent material that could remove antibiotics from water.
To obtain pure terephthalic acid from the waste PET bottles, the team used a process called alkaline hydrolysis, enhancing the efficiency with ultrasound. They then used an iron-based MOF as a precursor to magnetise the terephthalic acid, creating a porous carbon composite that could later be easily separated out using an external magnetic field.
When the resulting porous carbon composite was tested for its ability to remove the antibiotic tetracycline from water, the team showed that it was able to remove all traces of the antibiotic within 90 minutes. The adsorption rate of 671.14 mg/g is superior to that of previously developed adsorbents.
To assess the reusability of the porous carbon composite, the adsorption-desorption process was conducted five times. Even after repeated use, the material maintained 90 percent of its adsorption properties, indicating a high degree of stability and wide applicability for water treatment.
“The porous carbon composite developed through this research is applicable to various fields, ranging from eco-materials to energy materials, and I expect that it will soon be highly regarded as a value-added eco-material,” Choi said.
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Source: National Research Council of Science & Technology; Photo: Shutterstock.
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