| dc.description.abstract | Recycling poly(ethylene terephthalate) (PET) bottles has been discussed widely since its omnipresence and non-biodegradable characteristics. It has been reported that PET can be chemically recycled by glycolysis. The bis(2-hydroxyethyl) terephthalate monomer was the desired product of glycolysis of PET. Previous studies mainly focused on reaction parameters such as catalyst type, amount of catalyst, reaction temperature, reaction time, stirring rate and volume of ethylene glycol (EG) to achieved the high yield of product.However, there were also other processing steps after glycolysis, BHET dimer filtration, crystallization, BHET monomer filtration and drying. The development of those steps is essential because each step can affect the product quality and the process efficiency. Therefore, the aim of my research is to explore the influence of each step from glycolysis to BHET dimer filtration to crystallization to BHET monomer filtration and finally to drying on the whole glycolysis process. Firstly, 10 g of PET flakes, EG (30 and 60 mL) and Na2CO3(0.0276, 0.0555 and 0.111 g) as catalyst were added into an autoclave containing a 100 mL of PEEK cup size and heated a given temperature with a stirring rate of 550 rpm. Then, the autoclave was cooled to room temperature overnight by turning off the autoclave. In glycolysis, the effects of the reaction temperature (165 °, 185 ° and 195 °C), reaction time (1, 2 and 3h), amount of catalyst (0.0276, 0.0555 and 0.111 g) and volume of EG (30 and 60 mL) on the yield of BHET monomer would be studied. After glycolysis, hot water was added and the product medium was kept at 65 °C for 1h and then filtered to separate BHET
monomer from dimer. In filtration, the effect of the different amount of hot water added (60, 120 and 240 mL) in filtration would be investigated. The filtrate was cooled form 65 ° to 25 °C, and white BHET monomer were crystallized. In crystallization, the effect of different stirring rates of 0 and 600 rpm, crystallization time of 4, 8 and 16h, cooling rate of 80 °C/h and 5 °C/h and initial of concentration of 110.24, 73.49 and 44.10 mg/mL of filtrate on yield, purity, polymorphism and crystal size distribution of BHET monomer. Finally, BHET monomer were filtered and oven dried at 40 °C. The characterizations for all BHET monomer by sieving, optical microscope (OM), Fourier transform infrared spectroscopy(FT-IR), powder X-ray diffractometer (PXRD), differential scanning calorimeter (DSC), nuclear magnetic resonance (NMR) and high performance liquid chromatography (HPLC) to ascertain their physicochemical and structural properties. | en_US |