New method reduces toxic dyes in the water by 80 percent

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Published 24 March 2023 at 13.16

Domestic. Researchers at Chalmers have developed a new method that can easily clean polluted water using a cellulose-based material. The discovery is believed to be able to counter the widespread problem of the textile industry's release of toxic dyes.

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The scientists have built up knowledge about nanocrystals of cellulose – and that is where the key to the water treatment plant. These extremely small nanoparticles have an outstanding absorption capacity, which the researchers have now found a way to take advantage of.

– We have taken a unique overall approach to these cellulose nanocrystals, and reviewed properties and possible areas of use. Now we have created a bio-based material, a form of cellulose powder with excellent cleaning properties that we can adapt and modify depending on the types of contaminants to be removed, says Gunnar Westman, assistant professor of organic chemistry, in a press release

< p>In a study, which was recently published in the scientific journal Industrial & Engineering Chemistry Research, the researchers show how toxic dyes can be filtered out of wastewater using the method and material developed by the group. The research has taken place in collaboration with the Malaviya National Institute of Technology Jaipur in India, where pollution from dyes in textile industry wastewater is a widespread problem.

The purification requires neither pressure nor heat, and uses sunlight to catalyze the process. Gunnar Westman likens the method to pouring raspberry juice into a glass with rice grains, which absorb the juice so that the water becomes transparent again.

– Imagine a simple purification system, like a portable box that is connected to the drain pipe. When the polluted water passes through the filter with cellulose powder, the pollutants are absorbed, and the sunlight that is allowed into the purification system causes them to break down quickly and efficiently. It is a cost-effective and simple system to set up and use, and we see that it could be of great benefit in countries that currently have poor or non-existent water treatment, he says.

India is one of several countries in Asia with extensive textile production, where large amounts of dyes are released into lakes, rivers and streams every year. The consequences for people and the environment are serious. The dyes contain chemicals and heavy metals that can cause skin damage to people upon direct contact and increase the risk of cancer and organ damage when the toxic substances enter the food chain. Nature is affected in several ways, among other things pollution impairs photosynthesis and plant growth.

Conducting field studies in India is an important next step, and the Chalmers researchers are now supporting their Indian colleagues in the work so that some of the country's small-scale industries can test the method in real life. So far, laboratory tests with industrial water have shown that more than 80 percent of the color pollution disappears with the new method, and Gunnar Westman sees good opportunities to increase the degree of purification even further.

– Going from the release of completely unclean water to removing 80 percent of the pollution is a huge improvement, and means significantly less destruction of nature and damage to people. With optimization of pH and purification time, we also see an opportunity to further improve the process, so that we can produce both irrigation and drinking water. It would be fantastic if we could help these industries get a water treatment that works, so that people in the surroundings can use the water without risking their health, he says.

Gunnar Westman also sees great opportunities to use nanocrystals of cellulose for purification of water pollutants other than dyes. In a previous study, the research team showed that contamination of so-called toxic hexavalent chromium, which is common in wastewater from mining and metal industries, could be successfully removed with a similar cellulose-based material. The group is also investigating how the research area can contribute to the purification of antibiotic residues.

– There is great potential to find good water purification possibilities with this material and in addition to the basic knowledge we have built up at Chalmers is an important key to success combined expertise that exists within the Wallenberg Wood Science Center, he says.