GLYCOLYSIS OF WASTE PET BOTTLES USING ETHYLENE GLYCOL AS A SOLVENT AND A CALCINED SNAIL SHELL AS A CATALYST

Abstract

With the increasingly widespread use of polyethylene terephthalate (PET) bottles due to their cheap and robust nature, there has been an exponential increase in waste from these bottles in landfills, dumpsites, gutters, and roadsides, which has led to a negative effect on the environment, plants, animals, and human population with land and water pollution. Chemical recycling of the waste PET bottles would reduce the menace and recover the starting monomers for PET production. In this research, waste PET bottles were chemically recycled through glycolysis to produce bis-hydroxyethyl terephthalate (BHET) using ethyl glycol (EG) as a solvent and calcined snail shell as a catalyst within the temperature range of 180-200°C at different EG:PET ratios of 5:1, 6:1, and 6.5:1, while a constant catalyst:PET of 1:100 was used. After reaction and crystallization, a yield of the glycolysis product of 39.72% was obtained. This yield recorded is not as good as using oyster shell (68.6%), sodium acetate (72%), and calcium carbonate (69%) as catalysts. TGA and FTIR indicated that the samples were composed mainly of BHET monomers as functional groups. It is recommended that longer reaction time and varying catalyst:PET ratio be used to determine the optimum temperature and reaction. Keywords: Glycolysis, Bis-Hydroxyethyl Terephthalate, Chemical Recycling, Polyethylene Terephthalate Depolymerization, Snail Shell DOI： https://doi.org/10.35741/issn.0258-2724.58.3.28