Effect of quaternary ammonium salt as a phase transfer catalyst for the microwave depolymerization of polyethylene terephthalate waste bottles

Abstract

Poly(ethylene terephthalate) (PET) obtained from waste bottle product was depolymerized under microwave irradiation in open vessel equipment. PET bottle was shredded and ground to <0.5mm particle size and subjected to basic hydrolysis to terephthalic acid (TPA) and ethylene glycol using 10% NaOH under the influence of microwave irradiation (200W) in the presence of quaternary ammonium salt as a phase transfer catalyst (PTC). The effect of irradiation time, base concentration, particle size, PTC quantity, and microwave irradiation power on the extent of depolymerization was investigated. Results show that the optimum conditions to give ∼99% of TPA were 10% NaOH, 60min, 200W power, and 3% wt./wt. PTC/PET. This process is viable economically and interesting, since that PTC could be recovered and the side products after acidification are glycol and sodium chloride.