Login With Google
Green process cuts water use, pollution in textile industry
Why is it in news?
- A completely green method developed by researchers from the University of Calicut, Kerala, can potentially do away with using water for sizing and desizing cotton and polyester yarn. Textile industry is highly water-intensive and also one of the biggest water polluters.
More in news
- By using liquid and supercritical carbon dioxide instead of water, and sucrose octaacetate in place of starch, has made the sizing and desizing process eco-friendly.
- Before the yarn is woven into fabric, it is coated with sizing agents to strengthen the yarn (to decrease breakages on the loom) and protect it from damage and reduce friction. Sizing also removes or smoothens the projecting microfibres that might interfere with the weaving process.
- Traditionally, starch mixed in water is used for the sizing process, and this requires plenty of water. The used water is disposed of, leading to water pollution.
- The researchers used liquid carbon dioxide as solvent and tested three agents that easily dissolve in carbon dioxide for sizing both cotton and polyester yarn.
- The yarn after sizing has to be dried when water is used, making the entire process energy-intensive. But no drying is needed when liquid carbon dioxide is used as it is an inherently dry process.
- When the pressure of carbon dioxide is reduced to gas phase pressure, the carbon dioxide changes its state from a liquid to gas leaving the yarn dry.
- Once the weaving is completed, the sizing agent has to be completely removed from the yarn as it might resist dyes and chemicals commonly used in textile processing.
- In the conventional desizing process, large volume of water is used for desizing or washing the fabric to remove the sizing agent from the yarn, which generates lots of waste water.
- Instead of water, the researchers used supercritical carbon dioxide for desizing. “While both liquid and supercritical carbon dioxide have lower viscosity and surface tension compared with water, the molecular diffusion of supercritical carbon dioxide is 10 times more than liquid carbon dioxide
Source
The Hindu