There is no doubt that laundry is our least favorite chore among all other works we have to do at home. Washing clothes is boring to us because it always takes so long to sort, wash, fold, and iron all of our clothes. This washing process requires soaps, detergents, bleach and water to remove dirt, malodor, stain from the clothes, then it requires a dryer or an afternoon on the clothesline to dry. It is a time and energy consuming process to turn a stack of dirty clothes into a pile of clean clothes and often it makes people wish for that the clothes just clean themselves. To cut down this tiring work from our daily chores two material engineers from China have made a great discovery.
Mingce Long and Deyong Wu, two material scientists from Donghua University of China have developed a special fabric that rids itself of dirt and bacteria when exposed to sunlight. They have done it by dunking cotton into a vat of specially crafted nanoparticles. The chemistry behind the self-cleaning fabric is titanium dioxide ( ) aka “titania”, a very cheap, nontoxic powder that is used in white paint and silver iodide (AgI) is yellow powder which is a type of photosensitive chemical used in film photography. Titanium dioxide can absorb ultraviolet light and oxidize organic compounds and silver iodide darkens with exposure to light. These properties are used to make this special fabric.
A chemical mixture coating on cotton yarns gives the fabric its self-cleaning abilities. The coating includes substances known as photo-catalyst which is a substance that starts a chemical reaction when exposed to light or triggers chemical reactions in light. Titanium dioxide and silver iodide are used as photo-catalyst. Scientists have previously shown that titanium dioxide mixtures could remove stains from clothes but it requires exposure to ultraviolet light and silver iodide can speed up chemical reactions in sunlight. The end result of the chemical processing is a cotton fabric with a coating that is insoluble in water and can repeatedly break down dirt and stains. To test the fabric’s self-cleaning abilities it was stained with an orange dye for 30 minutes then, under simulated sunlight, the dye was broken down and could be rinsed off using water.
The scientists said that the self-cleaning cotton is not marketable yet, they still need to make sure the coated cotton won’t harm those who wear it, because silver iodide is toxic when ingested and repeated contact with skin can turn the skin blue which is called ‘Argyrosis’. Titanium dioxide also can cause health problems if it gets in the lungs. Another problem of this fabric is that we don’t know the exact manufacturing cost and if it is a commercially viable process. Still, one of the scientists Mingce Long says that he hopes to wear self-cleaning clothes one day and avoid having to do laundry. “Someday in the future, when I walk on the street,” he says, “I hope people are wearing self-cleaning clothes that originated from my technology.”
