{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,5]],"date-time":"2026-03-05T14:36:04Z","timestamp":1772721364182,"version":"3.50.1"},"reference-count":57,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,3,5]],"date-time":"2026-03-05T00:00:00Z","timestamp":1772668800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT\/MCTES","award":["UID\/50011\/2025"],"award-info":[{"award-number":["UID\/50011\/2025"]}]},{"name":"FCT\/MCTES","award":["LA\/P\/0006\/2020"],"award-info":[{"award-number":["LA\/P\/0006\/2020"]}]},{"name":"FCT\/MCTES","award":["UIDB\/00102\/2020"],"award-info":[{"award-number":["UIDB\/00102\/2020"]}]},{"name":"FCT\/MCTES","award":["UIDB\/00511\/2020"],"award-info":[{"award-number":["UIDB\/00511\/2020"]}]},{"name":"FCT\/MCTES","award":["UIDP\/00511\/2020"],"award-info":[{"award-number":["UIDP\/00511\/2020"]}]},{"name":"ALiCE","award":["LA\/P\/0045\/2020"],"award-info":[{"award-number":["LA\/P\/0045\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Multilayer plastic packaging waste (MPPW) represents a major challenge for waste management due to its widespread use in single-use applications and its complex, heterogeneous structure. Variations in polymer composition, layer thickness and number of layers significantly hinder conventional recycling processes, leading most MPPW to be disposed of through landfilling or incineration. This study presents the development and optimization of a dissolution\u2013precipitation process using toluene to recover polyethylene (PE) from MPPW. The proposed method successfully produced PE with less than 5 wt% polypropylene (PP), meeting common recycling quality requirements. Design of experiments (DoEs) combined with response surface methodology (RSM) was applied to evaluate the influence of key operating parameters, including temperature, dissolution time, solvent to waste ratio and agitation speed, to identify optimal processing conditions. The results demonstrated that temperature had the most significant influence on both dissolution yield and polymer purity. Optimal conditions of 100 \u00b0C, 30 min, 400 rpm, and a solvent-to-waste ratio of 15 mL\/g resulted in a total recovery yield of 39.1% with a polymer composition of 97.7 wt% PE and 2.3 wt% PP. Owing to the use of established and scalable unit operations, the process shows strong potential for industrial-scale implementation without requiring complex or specialized infrastructure.<\/jats:p>","DOI":"10.3390\/polym18050638","type":"journal-article","created":{"date-parts":[[2026,3,5]],"date-time":"2026-03-05T13:11:22Z","timestamp":1772716282000},"page":"638","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Polyethylene Recovery from Multilayer Plastic Packaging Waste"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8350-4794","authenticated-orcid":false,"given":"Anareth","family":"Cavuquila","sequence":"first","affiliation":[{"name":"CICECO\u2014Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7281-3903","authenticated-orcid":false,"given":"Luanna","family":"Maia","sequence":"additional","affiliation":[{"name":"CICECO\u2014Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"},{"name":"LEPABE, ALiCE, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"},{"name":"CERES, Department of Chemical Engineering, Faculty of Sciences and Technology, University of Coimbra, Rua S\u00edlvio Lima, Polo II, 3030-790 Coimbra, Portugal"}]},{"given":"Germano A.","family":"Carreira","sequence":"additional","affiliation":[{"name":"i9Green, Av. 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Jos\u00e9 Alves Correia da Silva, Edif\u00edcio Vela Sul 2\u00b0 D, Rotunda Sul, Cova da Iria, 2495-402 F\u00e1tima, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0767-721X","authenticated-orcid":false,"given":"In\u00eas","family":"Portugal","sequence":"additional","affiliation":[{"name":"CICECO\u2014Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9310-2457","authenticated-orcid":false,"given":"Carlos M.","family":"Silva","sequence":"additional","affiliation":[{"name":"CERES, Department of Chemical Engineering, Faculty of Sciences and Technology, University of Coimbra, Rua S\u00edlvio Lima, Polo II, 3030-790 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6462-8679","authenticated-orcid":false,"given":"Ana","family":"Barros-Timmons","sequence":"additional","affiliation":[{"name":"CICECO\u2014Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,5]]},"reference":[{"key":"#cr-split#-ref_1.1","unstructured":"European Union (2025). Regulation"},{"key":"#cr-split#-ref_1.2","unstructured":"(EU) 2025\/40 of the European Parliament and of the Council of 17 January 2025 on Packaging and Packaging Waste. Off. J. Eur. Union, 40, 1-202."},{"key":"ref_2","unstructured":"Eurostat (2024, June 12). Recycling Rate of Packaging Waste by Type of Packaging. Available online: https:\/\/ec.europa.eu\/eurostat\/databrowser\/view\/cei_wm020\/default\/table?lang=en."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Schmidt, J., Grau, L., Auer, M., Maletz, R., and Woidasky, J. (2022). Multilayer Packaging in a Circular Economy. Polymers, 14.","DOI":"10.3390\/polym14091825"},{"key":"ref_4","unstructured":"Warner, J.R. (2010). Multilayer Flexible Packaging: Technology and Applications for the Food, Personal Care and Over-the-Counter Pharmaceutical Industries, William Andrew."},{"key":"ref_5","unstructured":"Dixon, J. (2011). Packaging Materials: Multilayer Packaging for Food and Beverages, Woodhead Publishing."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"13282","DOI":"10.1021\/acs.est.0c03371","article-title":"Detailed Analysis of the Composition of Selected Plastic Packaging Waste Products and Its Implications for Mechanical and Thermochemical Recycling","volume":"54","author":"Roosen","year":"2020","journal-title":"Environ. Sci. Technol."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Cabrera, G., Li, J., Maazouz, A., and Lamnawar, K. (2022). A Journey from Processing to Recycling of Multilayer Waste Films: A Review of Main Challenges and Prospects. Polymers, 14.","DOI":"10.3390\/polym14122319"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Bernat, K. (2023). Post-Consumer Plastic Waste Management: From Collection and Sortation to Mechanical Recycling. Energies, 16.","DOI":"10.3390\/en16083504"},{"key":"ref_9","unstructured":"Aymonier, C., and Slostowski, C. (2017). Method and Device for Dismantling Multilayer Systems Including at Least One Organic Component. WO2017037260A1. (10,507,597), U.S. Patent."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"6867","DOI":"10.1039\/D2GC01531E","article-title":"Delamination of Polyamide\/Polyolefin Multilayer Films by Selective Glycolysis of Polyurethane Adhesive","volume":"24","author":"Houbrechts","year":"2022","journal-title":"Green Chem."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"4198","DOI":"10.1002\/cssc.202002877","article-title":"Towards a Better Understanding of Delamination of Multilayer Flexible Packaging Films by Carboxylic Acids","volume":"14","author":"Mys","year":"2021","journal-title":"ChemSusChem"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"105268","DOI":"10.1016\/j.resconrec.2020.105268","article-title":"Recycling of Post-Consumer Multilayer Tetra Pak\u00ae Packaging with the Selective Dissolution-Precipitation Process","volume":"165","author":"Georgiopoulou","year":"2021","journal-title":"Resour. Conserv. Recycl."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"449","DOI":"10.1007\/s00289-009-0104-5","article-title":"Recycling of Polymers from Plastic Packaging Materials Using the Dissolution\u2013Reprecipitation Technique","volume":"63","author":"Achilias","year":"2009","journal-title":"Polym. Bull."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"eaba7599","DOI":"10.1126\/sciadv.aba7599","article-title":"Recycling of Multilayer Plastic Packaging Materials by Solvent-Targeted Recovery and Precipitation","volume":"6","author":"Walker","year":"2020","journal-title":"Sci. Adv."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1016\/j.supflu.2012.12.015","article-title":"PET and Aluminum Recycling from Multilayer Food Packaging Using Supercritical Ethanol","volume":"75","author":"Sayer","year":"2013","journal-title":"J. Supercrit. Fluids"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"5376","DOI":"10.1039\/D0GC00894J","article-title":"Towards Closed-Loop Recycling of Multilayer and Coloured PET Plastic Waste by Alkaline Hydrolysis","volume":"22","author":"Denolf","year":"2020","journal-title":"Green Chem."},{"key":"ref_17","unstructured":"De Schrijver, I., Desplentere, F., Delva, L., De Tandt, E., and Ragaert, K. (2018, January 7\u20139). Open-Loop Recycling of PET-PE Post-Industrial Multi-Layered Plastic Waste. Proceedings of the International Conference on Polymers and Moulds Innovations-PMI 2018, Lisbon, Portugal."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"030005","DOI":"10.1063\/1.5084815","article-title":"Compatibilization of PET-PE Blends for the Recycling of Multilayer Packaging Foils","volume":"2055","author":"Delva","year":"2019","journal-title":"AIP Conf. Proc."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1016\/j.fuel.2014.04.092","article-title":"Fuel from Microwave Assisted Pyrolysis of Waste Multilayer Packaging Beverage","volume":"133","author":"Undri","year":"2014","journal-title":"Fuel"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"497","DOI":"10.1016\/j.psep.2020.10.038","article-title":"Catalytic Pyrolysis of Polyolefin and Multilayer Packaging Based Waste Plastics: A Pilot Scale Study","volume":"149","author":"Sivagami","year":"2021","journal-title":"Process Saf. Environ. Prot."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1038\/s44286-025-00247-1","article-title":"Solvent-Based Plastic Recycling Technologies","volume":"2","author":"Xu","year":"2025","journal-title":"Nat. Chem. Eng."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e202500018","DOI":"10.1002\/cssc.202500018","article-title":"Dissolution\u2013Precipitation of Plastic Waste: Current Position and Opportunities","volume":"18","author":"Resende","year":"2025","journal-title":"ChemSusChem"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"371","DOI":"10.1590\/0104-1428.1965","article-title":"Recycling Assessment of Multilayer Flexible Packaging Films Using Design of Experiments","volume":"25","author":"Uehara","year":"2015","journal-title":"Pol\u00edmeros"},{"key":"ref_24","unstructured":"(2021, September 24). Start-Up of LyondellBasell\u2019s MoReTec Plant Underlines Ambitious Plastic Waste Targets. Available online: https:\/\/cefic.org\/a-solution-provider-for-sustainability\/chemical-recycling-making-plastics-circular\/chemical-recycling-via-conversion-to-feedstock\/start-up-of-lyondellbasells-moretec-plant-underlines-ambitious-plastic-waste-targets."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Kaiser, K., Schmid, M., and Schlummer, M. (2018). Recycling of Polymer-Based Multilayer Packaging: A Review. Recycling, 3.","DOI":"10.3390\/recycling3010001"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"105905","DOI":"10.1016\/j.resconrec.2021.105905","article-title":"Recycling of Multi-Material Multilayer Plastic Packaging: Current Trends and Future Scenarios","volume":"176","author":"Ek","year":"2022","journal-title":"Resour. Conserv. Recycl."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1223","DOI":"10.1016\/S0079-6700(03)00045-5","article-title":"A Review of Polymer Dissolution","volume":"28","author":"Koenig","year":"2003","journal-title":"Prog. Polym. Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"707","DOI":"10.1016\/j.chemosphere.2018.06.095","article-title":"Solvent-Based Separation and Recycling of Waste Plastics: A Review","volume":"209","author":"Zhao","year":"2018","journal-title":"Chemosphere"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1016\/j.jenvman.2019.05.021","article-title":"Dissolution of Adhesive Resins Present in Plastic Waste to Recover Polyolefin by Sink-Float Separation Processes","volume":"243","author":"Mumbach","year":"2019","journal-title":"J. Environ. Manag."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"163","DOI":"10.2298\/CICEQ120526119H","article-title":"Quality Restoration of Waste Polyolefin Plastic Material Through the Dissolution-Reprecipitation Technique","volume":"20","author":"Hadi","year":"2014","journal-title":"Chem. Ind. Chem. Eng. Q."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Julie Anne, R.B., Esteven, E.G., David Manfred, S.P., Michael Sean, P.D., and Terence, P.T. (2021, January 22\u201323). Dissolution Kinetics of Low-Density Polyethylene in D-Limonene\/Xylene Solutions for the Chemical Recycling of Waste Plastic Laminates. Proceedings of the 7th GoGreen Summit 2021, Virtual.","DOI":"10.36647\/978-93-92106-02-6.11"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"863","DOI":"10.1002\/pen.21598","article-title":"Dissolution of Waste Plastics in Biodiesel","volume":"50","author":"Zhang","year":"2010","journal-title":"Polym. Eng. Sci."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"536","DOI":"10.1016\/j.jhazmat.2007.06.076","article-title":"Chemical Recycling of Plastic Wastes Made from Polyethylene (LDPE and HDPE) and Polypropylene (PP)","volume":"149","author":"Achilias","year":"2007","journal-title":"J. Hazard. Mater."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"4619","DOI":"10.1021\/acssuschemeng.3c08154","article-title":"Increasing the Dissolution Rate of Polystyrene Waste in Solvent-Based Recycling","volume":"12","author":"Kol","year":"2024","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Ferreira, A.M., Sucena, I., Otero, V., Angelin, E.M., Melo, M.J., and Coutinho, J.A.P. (2021). Pretreatment of Plastic Waste: Removal of Colorants from HDPE Using Biosolvents. Molecules, 27.","DOI":"10.3390\/molecules27010098"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"171","DOI":"10.33003\/fjs-2023-0703-1774","article-title":"Process Optimization of Solvents Assisted Polyethylene Waste Recycling","volume":"7","author":"Abdullahi","year":"2023","journal-title":"FUDMA J. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"2729","DOI":"10.1016\/j.matpr.2020.02.572","article-title":"Process Parameter Optimization Study on Thermolytic Polystyrene Liquid Fuel Using Response Surface Methodology (RSM)","volume":"26","author":"Selvaganapathy","year":"2020","journal-title":"Mater. Today Proc."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"285","DOI":"10.1016\/j.wasman.2020.10.011","article-title":"The Effect of PP Contamination in Recycled High-Density Polyethylene (rPE-HD) from Post-Consumer Bottle Waste and Their Compatibilization with Olefin Block Copolymer (OBC)","volume":"119","author":"Karaagac","year":"2021","journal-title":"Waste Manag."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Karaagac, E., Jones, M.P., Koch, T., and Archodoulaki, V.-M. (2021). Polypropylene Contamination in Post-Consumer Polyolefin Waste: Characterisation, Consequences and Compatibilisation. Polymers, 13.","DOI":"10.3390\/polym13162618"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"100252","DOI":"10.1016\/j.wmb.2025.100252","article-title":"Valorization of Mixed Multilayer Plastic Waste: An Exploratory Study","volume":"3","author":"Cavuquila","year":"2025","journal-title":"Waste Manag. Bull."},{"key":"ref_41","unstructured":"(2024, July 01). Portaria n.\u00b0 851\/2009, de 7 de Agosto. Available online: https:\/\/diariodarepublica.pt\/dr\/detalhe\/portaria\/851-2009-494002."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"107058","DOI":"10.1016\/j.polymertesting.2021.107058","article-title":"Determining the PE Fraction in Recycled PP","volume":"96","author":"Larsen","year":"2021","journal-title":"Polym. Test."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"108353","DOI":"10.1016\/j.polymertesting.2024.108353","article-title":"Accurate Determination of Polyethylene (PE) and Polypropylene (PP) Content in Polyolefin Blends Using Machine Learning-Assisted Differential Scanning Calorimetry (DSC) Analysis","volume":"131","author":"Bashirgonbadi","year":"2024","journal-title":"Polym. Test."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Hansen, C.M. (2007). Hansen Solubility Parameters: A User\u2019s Handbook, CRC Press.","DOI":"10.1201\/9781420006834"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"602","DOI":"10.1002\/pen.21313","article-title":"Dissolution Mechanism of Polymers in High Pressure\u2013High Temperature n-Alkanes\u2014Application to Blends Separation","volume":"49","author":"Martini","year":"2009","journal-title":"Polym. Eng. Sci."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"90","DOI":"10.1002\/pen.10168","article-title":"Experimental Investigation and Modeling of the Dissolution of Polymers and Filled Polymers","volume":"38","author":"Cao","year":"1998","journal-title":"Polym. Eng. Sci."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1007\/s12649-012-9131-9","article-title":"The Selective Dissolution Technique as Initial Step for Polystyrene Recycling","volume":"4","author":"Gracia","year":"2013","journal-title":"Waste Biomass Valorizat."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1002\/app.30533","article-title":"Chemical Recycling of Polymers from Waste Electric and Electronic Equipment","volume":"114","author":"Achilias","year":"2009","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"122940","DOI":"10.1016\/j.polymer.2020.122940","article-title":"A Closed-Loop Process Design for Recycling Expanded Polystyrene Waste by Dissolution and Polymerization","volume":"209","author":"Mumbach","year":"2020","journal-title":"Polymer"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1134\/S0040579519010068","article-title":"Modified Correlation for Low-Density Polyethylene (LDPE) Solubility in Several Organic Solvents","volume":"53","author":"Hadi","year":"2019","journal-title":"Theor. Found. Chem. Eng."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"2542","DOI":"10.1002\/app.20767","article-title":"Study of Polyethylene Solution Fractionation and Resulting Fractional Crystallization Behavior","volume":"93","author":"Kong","year":"2004","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_52","unstructured":"Mark, J.E. (1999). Polymer Data Handbook, Oxford University Press."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"8143","DOI":"10.1039\/C6SM01206J","article-title":"Understanding the role of molar mass and stirring in polymer dissolution","volume":"12","author":"Valois","year":"2016","journal-title":"Soft Matter"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"585","DOI":"10.1515\/polyeng-2012-0081","article-title":"Potential Solvent for Reconditioning Polyolefin Waste Materials","volume":"32","author":"Hadi","year":"2012","journal-title":"J. Polym. Eng."},{"key":"ref_55","doi-asserted-by":"crossref","unstructured":"Alexandridis, P., Ghasemi, A., and Tsianou, M. (2025). Polypropylene Dissolution Kinetics: Effects of Solvent, Temperature, and Particle Size. Polymers, 17.","DOI":"10.3390\/polym17233213"},{"key":"ref_56","unstructured":"Seider, W.D., Seader, J.D., Lewin, D.R., and Widagdo, S. (2017). Product and Process Design Principles: Synthesis, Analysis, and Evaluation, Wiley. [4th ed.]."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/18\/5\/638\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,5]],"date-time":"2026-03-05T13:25:31Z","timestamp":1772717131000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/18\/5\/638"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,5]]},"references-count":57,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["polym18050638"],"URL":"https:\/\/doi.org\/10.3390\/polym18050638","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,5]]}}}