Glycolytic aminolysis of poly(ethylene terephthalate) waste for recovery of value‐added comonomer at atmospheric pressure

Abstract

Reaction of poly(ethylene terephthalate) waste (PETW) powder with ethylene glycol (EG) using 0.003 mol lead acetate as a catalyst was carried out in a batch reactor at 470 K under atmospheric pressure. Reactions were undertaken with various particle sizes ranging from 50 to 512.5 m and reaction times ranging from 10 to 60 min at 10-min intervals. A low molecular weight product of PETW was obtained using this reaction. Then hydrazine monohydrate, chlorobenzene, and cyclohexylamine (CHA) were introduced to convert the low molecular weight product of PETW into terephthalohydrazide (TPHD). To increase the PETW conversion rate, an external catalyst (lead acetate) was introduced during the reaction. The reaction product was deposited onto the surface of unreacted PETW that was removed from the surface by introducing dimethyl sulfoxide. To accelerate the reaction rate CHA was introduced during the second stage of reaction, which has industrial significance. Depolymerization of PETW was proportional to the reaction time and inversely proportional to the particle size of PETW. Analyses of value-added products (TPHD and EG) as well as PETW were undertaken. A kinetic model was developed and experimental data were simulated consistent with the model. A thermodynamic study was undertaken because this is required during the transfer of laboratory data through the pilot plant for commercialization.

Synthesis, spectral properties and application of novel disazo disperse dyes derived from polyester waste

“…The 13 C spectrum of compound 3 shows peaks at δ 126.9, 135.4 and 165.1 ppm for the aromatic CH, ArCCO and CO groups, respectively. These spectral values of synthesised compound 3 are in good agreement with those reported in the literature [30].…”

Synthesis and antibacterial activity of some novel bis-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and bis-4-thiazolidinone derivatives from terephthalic dihydrazide

“…13 C spectra of 1 shows peak at d 126.9, 135.4 and 165.1 for aromatic CH, Ar-C-CO and CO groups respectively. These spectral values of synthesized terephthalic dihydrazide are in good agreement with those reported in the literature [30]. The IR spectrum of compound 2a showed absorption peak at 1676 cm À1 due to C]N streching vibrations.…”

Depolymerization of poly(ethylene terephthalate) in dilute aqueous ammonia solution under hydrothermal conditions

“…Many attempts have been made to depolymerize PET for chemical recycling and to obtain the monomers of terephthalic acid (TPA) and ethylene glycol (EG) or their derivatives by hydrolysis with alkali, 1 -4 alkali and organic solvents, 5 high-pressure water including supercritical water, 6 -9 and acid, 10 -12 or by glycolysis 13 -21 or methanolysis with supercritical (SC) methanol, 22 -25 or aminolysis. 26 Mild recycling conditions are preferred to obtain higher recovery of monomers, easier separation of products, lower environmental impact, and simpler or more economical processes. Supercritical fluids such as SC water and SC methanol have been examined as environmentally benign reaction media because they do not require significant amounts of alkali or additives; however, reactions are conducted at high temperatures.…”