| dc.description.abstract | Poly(ethylene 2,5-furandicarboxylate) (PEF) is a new type of plastic made from bio-based raw materials. Compared to the widely used poly(ethylene terephthalate) (PET), PEF has better mechanical properties, oxygen barrier performance, and thermal stability. With the increasing environmental awareness and the development of related technologies, PEF is regarded as an important alternative to traditional plastics and is expected to be more widely used in the future. Although PEF is biodegradable, its degradation process requires specific environmental conditions, so studying its recycling strategies remains crucial. Among various plastic recycling methods, alkaline hydrolysis is a simple and commercially viable method. Currently, the literature on exploring PEF alkaline hydrolysis is still limited. Therefore, this study mainly investigates the impact of various experimental parameters on the process and final products of PEF alkaline hydrolysis.
The alkaline hydrolysis of PEF was carried out in an autoclave, which was then placed in an oven set to specific reaction temperatures and times. After alkaline hydrolysis, PEF generated disodium furanoate (DSF), which was subsequently converted into the final product, 2,5-furandicarboxylic acid (FDCA) monomer, by adding sulfuric acid aqueous solution (H₂SO₄(aq)). In the first part of this study, different bases (NaOH and KOH), reaction temperatures (80°, 100°, 120°, and 160 °C), reaction times (4, 6, and 8 h), and molar ratio of NaOH per PEF repeating unit (2.2 and 6.6) were used to preliminarily investigate the effects of each parameter on the conversion of PEF, the yield of FDCA, and the assay of FDCA. This provided a basis for subsequent the design of experimental (DoE).
In the second part, Minitab 19 software was used to perform experimental design and analysis using the Full Factorial Design (FFD) method. This was done to investigate the effects of single experimental factors (reaction temperature, reaction time, and molar ratio of NaOH per PEF repeating unit) and the interaction between two factors on the reaction outcomes (the conversion of PEF, the yield of FDCA, and the assay of FDCA) during the alkaline hydrolysis process. Based on the analysis results of the FFD, identify the significant factors affecting the experimental results and establish the mathematical model equations for each experimental result. Finally, the optimal conditions (reaction temperature of 160 °C, reaction time of 6 h, and molar ratio of NaOH per PEF repeating unit of 2.2) were used to verify the mathematical model. Under the optimal conditions, the average experimental results obtained were the PEF conversion of 97.7 %, the FDCA yield of 84.5 %, and the FDCA assay of 97.2 %. The relative prediction error between the model′s predicted values and the experimental values was within ± 3.5 %, indicating that the model had high accuracy. | en_US |