Fibres / Textiles /
Fibres / Textiles / Nonwovens Upcycling process for PAN from textile waste Most synthetic fibres are made from fossil material sources. Since these are only available in finite quantities and their use is not always compatible with today’s environmental goals, it is necessary to develop an innovative recycling process and close material cycles. Currently, polyacrylonitrile (PAN)-containing waste from production and end-of-use waste is sent for thermal waste treatment, used as a filler, or processed into lowvalue blended yarns. Although energy recovery is possible, incineration also releases harmful emissions, and the material can no longer be fed into a cycle [1]. At the ITA of the RWTH Aachen University, approaches to the chemical recycling of PAN fibres are being pursued under the project name industrial RePAN, as a step towards a closed-loop economy. The technical feasibility along the entire process chain from polymer recovery and fibre production up until the finished product (blankets) is being mapped. By: S. Schonauer & T. Gries Institute of Textile Technology, RWTH Aachen University Aachen, Germany Figure 2: Small scarf containing 50 % recycled PAN Assuming that newly acquired products replace old textiles, around 24,500 tonnes of end-of-use waste is annually generated in the house and home textiles sector in Germany. Even if only half of this waste could be recycled, it would offer 12,250 tonnes of new resources. During the production of PAN staple fibres, about 1 % by weight, and additionally during processing up to 10 % by weight, of fibre materials are generated as production waste [2, 3]. This type of waste served as a secondary raw material source for these research trials. The individual stages of the process are presented in Figure 1, starting with the collection of textile waste from the blanket production. The waste is dissolved in DMSO (dimethyl sulphoxide) and chemically precipitated to produce RePAN-pellets. During the preparation of the spinning solution, RePANpellets are mixed with new PAN-powder to equal parts, resulting in a 50 % – RePAN solution. These fibres with 50 % recycled material could be spun into yarns that could meet the same requirements as virgin material. These characteristics of the produced RePAN fibres, therefore, lead to the assumption that an industrial feasibility of recycled fibres is possible. The scientists are now proofing the processability of the yarns and upscaling to semiindustrial scale. Figure 2 shows a product using RePAN fibres. [1] Gries, T.: Fibre-tables based on P.-A. Koch, Polyacrylic fibres, 6. Issue, 2002 [2] Herbert, C. (Research and development at Dralon GmbH): Interview, 25.05.2016 [3] Rensmann, R. (managing director of Hermann Biederlack GmbH + Co KG): Interview, 25.05.2016 www.ita.rwth-aachen.de Figure 1: Recycling process from waste to new yarn Textile waste RePAN-pellets Spinning solution Staple fibres 32 bioplastics MAGAZINE [06/22] Vol. 17
Biogenic carbon dioxide (CO 2 ) for plastic production Materials manufacturer Covestro (Leverkusen, Germany) and SOL Kohlensäure (Burgbrohl, Germany) have concluded a framework agreement for a supply partnership for biogenic carbon dioxide (CO 2 ). With immediate effect, SOL, as one of the most important European suppliers of gases and gas services, will supply the liquefied gas to Covestro sites in North Rhine-Westphalia, where it will be used to produce plastics such as MDI (methylene diphenyl diisocyanate) and polycarbonate. Under the terms of the framework agreement, SOL Kohlensäure will already supply up to 1,000 tonnes of biogenic CO 2 this year. From 2023, the supply volume is to be further increased substantially, enabling Covestro to save the same amount of CO 2 from fossil sources at its NRW sites. “We have set ourselves the goal to become fully circular. To this end, we want to convert our raw material base to 100 % renewable sources. We are very pleased to have found a partner in SOL Kohlensäure who will support us in this transformation with a pioneering spirit”, explains Daniel Koch, Head of NRW Plants at Covestro. “We at SOL Kohlensäure are advancing the shift to more sustainable CO 2 sources. In this way, we are increasing security of supply, becoming independent of fossil raw materials, and reducing our environmental footprint at the same time”, emphasizes Falko Probst, Sales Manager at SOL Kohlensäure. From waste product to raw material The CO 2 used is obtained by SOL Kohlensäure from various sources, such as bioethanol and biogas plants. In these plants, CO 2 is produced as a by-product during the treatment of various biomasses, such as plant residues. This is separated by SOL Kohlensäure, purified and then made available to Covestro production as a raw material. In this way, the supply partnership supports the circular concept and contributes to reducing emissions. Covestro’s Lower Rhine sites in Leverkusen, Dormagen, and Krefeld-Uerdingen are ISCC PLUS certified and can supply their customers with more sustainable products made from renewable raw materials. Goal of climate neutrality by 2035 Covestro has set itself the goal of becoming fully circular. This also includes using alternative raw materials. Biomass, CO 2 , as well as end-of-life materials and waste replace fossil raw materials such as crude oil or natural gas. Carbon is managed in a circular way. In realizing these ambitions, both companies are relying on long-term supply partnerships. In addition to biogenic CO 2 , Covestro is investigating the use of other technical gases from renewable sources. The materials manufacturer is already offering its customers its first sustainable products, such as climate-neutral MDI. With the expansion of its alternative raw material base, this portfolio is set to grow further in the coming years. ISCC (“International Sustainability and Carbon Certification”) is an internationally recognized system for the sustainability certification of biomass and bioenergy, among others. The standard applies to all stages of the value chain and is recognized worldwide. ISCC Plus also encompasses other certification options for instance for technical-chemical applications, such as plastics from biomass (see pp. 52). AT https://www.covestro.com/ Biogenic gas being delivered, Luis Da Poca (SOL) connects the tank Delivery of biogenic CO 2 to Covestro site in NRW Inspection and acceptance of the delivery, from left to right: Katharina Rudel, Chemical Technician Covestro; Marcus Ney, Plant Manager Covestro; René Theisejans, Production Expert Covestro CCU / Feedstock bioplastics MAGAZINE [06/22] Vol. 17 33
