A Study of the Alkaline Solvolysis of Postconsumer Polyethylene Terephthalate in Primary C1 – C3 Aliphatic Alcohols

Abstract

This study was carried out to examine the thermo-chemical decomposition of postconsumer polyethylene terephthalate (PET) in alkaline solutions of C1 – C3 primary alcohols with a view to developing a simple, yet effective method for the chemical recycling of post-consumer PET. The effect of various process parameters such as temperature, time and sodium hydroxide concentration on the degree of PET degradation and products yield were studied for each alcohol. Response surface methodology (RSM) was used for predicting the optimal conditions for the alkaline solvolysis of PET scrap, with Box-Benkhen design for the three variables chosen as the experimental design. The data obtained from measurement of properties were fitted as second-order equations. The optimum sodium hydroxide concentration, reaction temperature and time were 32.5 g/l, 100°C and 46.8 min, respectively for methanol; 32.6 g/l, 94.3°C and 40.9 min, respectively for ethanol and 31.4 g/l, 120°C and 40.0 min, respectively for propan-1-ol. Under these optimum conditions, the percentage decomposition of PET was 92.22 for methanol, 91.65 for ethanol and 44.50 for propan-1-ol. The findings of this study showed that chemical reprocessing of postconsumer PET could be achieved under the relatively simple conditions of alkaline solvolysis, with terephthalic acid being one of the end products.