"Our Neighborhood Clothing Collection Bins Will Be Empty"

KRICT Develops Low-Cost, High-Efficiency, Eco-Friendly Waste Clothing Collection and Recycling Technology

[Asia Economy Reporter Kim Bong-su] Most clothing waste, made primarily from chemical substances, is a major headache. It does not decompose well and threatens the environment when discarded in nature. Even when collected through clothing collection bins, recycling costs are high because the materials are varied and difficult to sort. Amid this, a domestic research team has attracted attention by developing a world-first technology that can quickly and efficiently sort waste synthetic fibers and recycle them as plastic raw materials.

The Korea Research Institute of Chemical Technology announced on the 18th that Dr. Jo Jeong-mo's research team developed a sorting technology that can separate recycling raw materials by utilizing the chemical properties of dyes in waste clothing. The team also devised a chemical recycling technology that simultaneously converts the sorted waste synthetic fibers back into monomer raw materials prior to synthesis.

Waste clothing that was discarded in nature or incinerated can be chemically recycled, meaning colored fibers or blended fibers can be converted back into raw materials prior to synthesis. This is expected to drastically reduce the amount of clothing waste generated.

Schematic diagram of chemical sorting and recycling technology for waste fibers. Image courtesy of Korea Research Institute of Chemical Technology

Greenhouse gases emitted by the clothing industry account for 10% of the total global emissions. Global clothing production is on the rise every year, and most of it is incinerated or discarded in nature, threatening the environment. In particular, synthetic fibers, which are cheap and durable and account for more than 60% of clothing production, are identified as one of the main culprits causing serious environmental pollution because they do not decompose easily like plastics.

The textile industry is increasingly interested in technologies that recycle waste resources or replace petroleum-based synthetic materials with sustainable raw materials. Currently, most (99%) of the fibers produced from recycled raw materials are recycled from transparent and clean waste PET bottles. The problem is that textile waste is discarded mixed with various materials without separate collection methods, so sorting by material type is essential for recycling. Most sorting is done manually or by separating materials based on density by floating or sinking in water, which is very inefficient. Even after sorting, many foreign substances remain, limiting physical or chemical recycling.

The research team developed a 'chemical sorting technology' that selectively acts only on specific materials using low-cost compounds to pick out only 'polyester (PET)' from mixed waste fibers, and simultaneously developed a 'chemical recycling technology' that decomposes the sorted polyester fibers at low temperatures to revert them to monomer raw materials prior to synthesis.

The sorting technology is very economical and innovative because it can easily and accurately distinguish fiber materials using a simple chemical principle. They developed an 'extractant' that acts only on polyester. The method involves contacting mixed waste fibers with the extractant, causing a color change in polyester fibers to select them. Specifically, first, fibers with color are separated from mixed waste fibers, and then the extractant developed by the team is applied to identify and separate only the fibers that undergo decolorization as polyester. At this time, the dye wastewater generated is applied to fibers that originally had no color, and conversely, only fibers that become dyed are separated as polyester. This method has a very low error rate and can remove dyes that were previously difficult to separate, allowing only high-quality polyester materials to be sorted. Biodegradable compounds are used in the waste fiber sorting and de-dyeing process, and the extractant containing dyes is recovered and reused after use, making it an economical and environmentally friendly sorting technology.

Along with this, the research team succeeded in developing a low-temperature glycolysis reaction technology that can rapidly decompose colored waste PET or waste polyester fibers to produce high-value monomers. Unlike the waste PET decomposition process at high temperatures above 200°C, this low-temperature reaction at 150°C can completely decompose the raw materials within 2 hours regardless of their structure or form. When linked with the chemical sorting technology, this can greatly reduce the burden of reaction and purification and drastically lower energy consumption, making it highly competitive for commercialization.

Im Mi-hye, President of the Korea Research Institute of Chemical Technology, said, "This achievement allows even low-grade colored waste fibers, which were difficult to recycle until now, to be used as raw materials for producing high-quality monomers," adding, "It is expected to become a resource-circulating recycling technology that can drastically reduce the amount of clothing waste generated."

The institute has already transferred the related technology to private companies and is promoting the establishment and commercialization of depolymerization facilities. They are pushing to build a demonstration plant with an annual PET processing capacity of 10,000 tons by the end of 2024. From 2025, they plan to begin full-scale mass production of recycled monomers and enter the global market.

The research results were published in the journal 'ACS Sustainable Chemistry & Engineering,' published by the American Chemical Society (ACS). It was selected as the cover paper of the December issue last year.

This content was produced with the assistance of AI translation services.