Degradation of poly(ethylene terephthalate) using ionic liquids

Abstract

The degradation of poly(ethylene terephthalate) (PET) was successfully achieved using ionic liquids. The products were separated according to their solubilities in boiling water. Average molecular weights of the main product were determined by gel permeation chromatography (GPC). The physicochemical properties of the product have been characterized by scanning electron microscopy equipped with an energy dispersive X-ray analyzer (SEM/EDX), X-ray diffractometer, infrared spectrometric analyzer, differential scanning calorimeter, and thermogravimetric analysis instrument. The influences of experimental parameters, such as the reaction time, reaction temperature, and addition of different catalysts on the solubility of PET were investigated. A study on the recycling of the ionic liquid shows that ionic liquid could be used repeatedly. Moreover, the solubility of PET in the recycled ionic liquid is higher than that in fresh ionic liquid. Further study shows that the increase of solubility in the recycled ionic liquid is attributable to the presence of a minor amount of water. A mechanism of the degradation of PET in 1-butyl-3-methylimidazolium chloride ([bmim]Cl) was proposed. In addition, the kinetics of this reaction was investigated. Results show that this degradation process is a first-order kinetic reaction and the activation energy is 232.79 kJ mol -1 .

Effect of temperature management on the hydrolytic degradation of PET in a calcium oxide filled tube reactor

“…Solvolysis processes using water, methanol and glycol can be used to gain terephthalic acid [5][6][7][8][9], dimethyl terephthalate (DMT) [10,11], bishydroxyethyl-terephthalate (BHET) [12][13][14] and glycol from bottle PET, which has a high purity. It may well prove possible to make use of ionic liquids as an alternative for the depolymerisation of PET [15]. Any of the products recovered can be employed in the production of new PET.…”

Recent Developments in the Chemical Recycling of PET

“…It has not been long since ionic liquids were applied as catalyst for PET glycolysis when Wang et al initiated the study and first reported its use in 2009 (Wang et al, 2009a). The main advantage of ionic liquids over conventional catalysts like metal acetates is that the purification of the glycolysis products is simpler.…”

The Glycolysis of Poly(ethylene terephthalate) Waste: Lewis Acidic Ionic Liquids as High Efficient Catalysts

“…It has been reported that ionic liquids were used as solvents and/or catalysts in polymer depolymerization [11,12]. In 2009, Wang [13] found that ionic liquids could catalyze the depolymerization of PET in ethylene glycol.…”