Use of deep eutectic solvents in the degradation of PET
Project no. 1211 · Status: Kapanmış · 2018
Summary
In this study, depolymerization of polyethylene terephthalate (PET) was carried out by glycolysis method. The reaction was performed between PET and ethylene glycol catalyzed by deep eutectic solvents (DES). Polyethylene terephthalate (PET) a polyester material that is formed by the condensation of terephthalic acid and ethylene glycol. Due to the low cost, excellent tensile strength, chemical resistance, clarity, processability, and reasonable thermal stability, there are many usage area of PET. PET is mainly used in the production of fiber, packing, containers, building materials. Because of waste PET cannot be decomposed rapidly in ecosystem, it is necessitated to focus on the the recycling process. For this purpose, physical and chemical recycling processes have been investigated in literature. Tendency to chemical recycling process increased day by day because by applying this process, virgin monomer products such as bis (2-hydroxyethyl) terephthalate (BHET) can be produced. In this study, glycolysis of PET into BHET in the presence of DESs as catalyst was investigated. DES can be synthesized with the mixing of two components, one of them is a hydrogen bond donor (HBD) and the other is a hydrogen bond acceptor (HBA). The main properties of these components are being cheap, biodegradable, and renewable. With the simple mixing of these two components using a specified ratio, a eutectic mixture is formed. DES has a melting point that is lower than the individual components. The eutectic mixtures are generally characterized by a very large depression of freezing point During the study, five different DESs were used as catalyst; these are Potassiumcarbonate+Ethylene glycol, Choline chloride (ChCl) +DimethylUrea (DES 3), Choline chloride +Urea (DES 2), Choline chloride +Ethylene glycol (DES 4), Choline chloride (ChCl) +Glycerol (DES 5) and bis (hydroxyethyl terephthalate) (BHET) was obtained as product. The catalyst screening was performed among five different DESs by considering conversion of PET and the yield of BHET. Among used DESs, the most efficient catalyst was found as DES comprising potassium carbonate and ethylene glycol as hydrogen bond acceptor and hydrogen bond donor. Ethylene glycol/polyethylene terephthalate (EG/PET), Deep eutectic solvents/Polyethylene terephthalate (DES/PET), and temperature are decided as parameter. The parametric study was carried out. Characterization was performed by FTIR analysis and it is compared with literature to determine the presence of product.