IIT uses nanotech for cheap textile wastewater cleanup

Indian Institute of Technology Madras said it has filed for two patents based on nanotechnology, including one for a nanocomposite adsorbent that could treat polluted wastewater from the textile and other industries.

S. Ramaprabhu, a professor at the school's Alternative Energy and Nanotechnology Laboratory and department of physics, led the research on the extensive surface area of nanomaterials.

Ramaprabhu found that nanocomposite adsorbents would remove dye molecules and odors from factory wastewater, making it suitable for industrial or agricultural use. The dye molecules could also be collected for re-use, the researchers said.

The other patent covers nanomaterials enabling efficient drug delivery in cancer treatment.

The water-intensive textile industry uses a number of flushing steps that add fat, oil chemicals and dye to the wastewater emitted from factories. The fixation rate of dye on cotton is about 70 percent, leaving significant amounts of dye in factory wastewater.

Ramaprabhu says the nanocomposite adsorbents would be inexpensive because they are made up of 90 percent graphite. The remainder is made up of carbon nanotubes, which have smooth, water-repellent interiors. Only water molecules can pass along the interior of carbon nanotubes, while viruses, bacteria, toxic metal ions and other organic molecules are kept out, according to nanotech researchers.

Carbon nanotubes were the focus of water purification studies last year by the Atomic Research Centre in Mumbai, India. Researchers there were investigating how water filtration systems based on carbon nanotubes could be used to remove arsenic, fluoride, heavy metals and toxic organic chemicals (see Indian water purification goes nano).

In January, Anaheim, Calif.-based cleantech incubator Catalyx said it developed a technology to purify heavily polluted wastewater from the textile and other industries using a low-cost, chemical-free process. The process incorporates desalination and forward osmosis, which uses the company’s proprietary 25-micron-thick, 85-percent porous, self-supporting, high-flux membrane with a semipermeable coating (see Catalyx develops two-way osmosis to purify wastewater).

And in August, researchers at Carnegie Mellon University said they discovered small molecule catalysts, Tetra-Amido Macrocyclic Ligands, to clean toxic substances like wastewater and fuel (see Researchers claim chemistry breakthrough for environmental cleanup).

Ramaprabhu says his nanomaterial-based process could be tweaked to have applications in wastewater treatment for industries other than textiles or in cleaning polluted water supplies.

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