Decomposition of the Bis(2-Hydroxyethyl) Terephthalate (Bhet) by Atmospheric Nonthermal Plasma

Abstract

The waste polyethylene terephthalate (PET) recycling technology using plasma has been studied for reasons of low pollution and high resource yield[1]. The microwave-excited atmospheric pressure plasma jet (ME-APPJ) provides high electron density and abundant active species[2]. For those reasons, the ME-APPJ is suitable for bis(2-hydroxyethyl) terephthalate (BHET) decomposition as a plasma source. The BHET that basic component of PET is a monomer produced by depolymerizing the PET[3]. The boiling point of BHET is about 317 at 1 atm. Also, the gas temperature of ME-APPJ did not exceed 310 revealing that the results are not by the thermal decomposition. In this study, the reaction between ME-APPJ and BHET was analyzed by using optical emission spectroscopy, intensified charge coupled device and Fourier- transform infrared spectroscopy. The gas of double bonded CO and single bonded OH were produced from the BHET during reactions. The electron energy of ME-APPJ was estimated by comparing bonding energy of BHET with CO and OH which were experimentally produced. The electron energy of ME-APPJ is 347 – 467 kJ/mol. The concentration of CO gas was measured by reaction of BHET with ME-APPJ according to input power. In this study, CO gas was obtained from BHET decomposition through the ME-APPJ. These result can be used as basic study for the development of high value-added technology for recycled waste using plasma.