Carbonyl compound leaching from polyethylene terephthalate into bottled water under sunlight exposure

Abstract

Polyethylene terephthalate bottles containing natural spring water were used to study the leaching effect of carbonyl compounds after one year storage under real conditions of exposure. Ultraviolet-B and ultraviolet-A spectra of direct sunlight were acquired during the experiment. Leaching of acetone, acetaldehyde, and formaldehyde reached steady state after 210 days of outdoor storage, with the following concentrations: 434 ± 22, 345 ± 18, and 94 ± 5 µg/L, respectively. The increase due to sunlight exposure in comparison with laboratory storage in the dark was around 10%, 16%, and 36%. The leaching process of all three carbonyl compounds was found to follow the first-order kinetics. Photo-degradation of Polyethylene terephthalate bottles and the appearance of carboxyl end-groups were followed by attenuated total reflectance infrared spectra. After 313 days of storage under direct sunlight, new peaks appeared in the regions of 1770–1920 cm⁻¹ and 1685–1490 cm⁻¹. Cations, anions, total dissolved solids, pH, and conductivity were also measured during the storage period. Additionally, microbiological measurements as well as statistical analyses were also carefully discussed.

Keywords:

• PET-bottled water
• acetone
• acetaldehyde
• formaldehyde
• FTIR
• photo-degradation

Acknowledgment

The authors would like to express their deep appreciation to Prof. I. Othman (DG of AECS) for his encouragement. Thanks are also extended to Dr A.A. Allaf and S. Rihawy for their highly appreciated help in language editing.

Disclosure statement

No potential conflict of interest was reported by the authors.