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Polímeros

versão impressa ISSN 0104-1428versão On-line ISSN 1678-5169

Resumo

CURTI, Priscila S.  e  RUVOLO Fº, Adhemar. Kinetics study of the heterogeneous depolymerization of waste PET in alkaline medium: stirring rate effect. Polímeros [online]. 2006, vol.16, n.4, pp.276-285. ISSN 1678-5169.  https://doi.org/10.1590/S0104-14282006000400006.

There is an environmental and economic concern related to recycling waste polymers, due to its high accumulation in the domiciliary urban waste and due to the aggregated value of these materials. Thus, many studies of mechanical and chemical recycling of waste plastics, mainly PET, have been proposed. In this work, waste PET obtained from bottles was submitted to chemical recycling using a solution of sodium hydroxide in ethylene glycol. The reaction extent and the kinetics were seen to be influenced by the stirring rate in the solution. At 1360 rpm, the mass transfer resistance of the product from the unreacted PET surface to the solution was eliminated, and the reaction rate became controlled by the chemical process. The kinetic equation derived from a model with a heterogeneous medium fitted the experimental results well, and the apparent rate constants were higher than those cited in the literature. These results suggest that the alkaline medium used is very efficient and only 6 minutes were sufficient to obtain 100% of sodium terephthalate yield at 1360 rpm and 170 °C.

Palavras-chave : PET waste; depolymerization; alkaline medium; kinetics; heterogeneous medium.

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