IIT Guwahati researchers develop microfiltration process to remove microplastics from sea water

The researchers claimed that while there have been many studies to identify and quantify microplastics in various food products, including salt, there have been fewer attempts at finding ways to remove them.

A team of researchers at the Indian Institute of Technology (IIT), Guwahati has developed a microfiltration process to remove microplastics from seawater in order to prevent the inclusion of plastic residues in edible salt extracted from it. The research has been published in the journal "Environmental Technology and Innovation".
According to the team, plastic pollution is rampant all over the world and while there is some level of awareness, the seriousness is not yet understood. "Microplastics -- plastic pieces smaller than one-fifth of an inch -- are now found in almost all oceans and marine animals. What's worse, sea salt has been found to have considerable amounts of microplastic.

"Research performed in East Asia has shown that 90 per cent of the table salt brands sampled worldwide have microplastics. Microplastics ingested by human beings can disrupt hormones, leading to infertility, and cause nervous system problems, and even cancer," said Kaustubha Mohanty, Department of Chemical Engineering, IIT Guwahati.

The researchers claimed that while there have been many studies to identify and quantify microplastics in various food products, including salt, there have been fewer attempts at finding ways to remove them.

The IIT Guwahati team, for the first time, showed efficient removal of microplastics from synthetic seawater using hollow fiber microfiltration (HF-MF) membranes, they said.

"In our hollow fiber membrane filter, hundreds of tiny straw-like tubes are bundled together to create a filter matrix. The walls of these tubes are filled with microscopic pores, and when water is passed through the tubes, the microplastics are trapped inside, thus freeing water of this pollutant," explained Mr Mohanty.

Hollow fiber membranes are already used extensively in daily life applications such as RO pretreatment, industrial water or wastewater, juice processing, and other biotech applications, including in dialysis membranes used for kidney ailments.

"The hollow fibers are made of many kinds of materials and the ones used by the IITG team were made of polypropylene and a silk protein called sericin. We were able to remove 99.3 per cent of the microplastics present in seawater, without any reduction in the salt contents. If this filtered water is used to extract salt, it would be free from microplastics," he said.

The researchers, however, clarified that this can only remove microplastics from seawater before salt extraction, and obviously cannot remove microplastics that get added during salt production, such as through the use of descaling agents in the desalination process itself.

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