Solubility Determination and Correlation for Bis(2-hydroxyethyl) Terephthalate (BHET) in Four Binary Solvents from 283.15 to 323.15 K

Abstract

The laser monitoring observation technique was used to study the solid−liquid equilibrium solubility data of bis(2-hydroxyethyl) terephthalate (BHET) in four binary mixed solvents (methanol + water, ethanol + water, ethylene glycol + water, and acetone + water) from 283.15 to 323.15 K at normal atmospheric pressure. Five thermodynamic models (the Apelblat model, the λh model, the Jouyban−Acree model, the Wilson model, and the NRTL model) were selected to correlate the experimental data. Based on the correlation index and the root-mean-square deviation, the Apelblat model and λh model were more suitable for fitting the BHET solubility data. According to the obtained Wilson model parameters, the thermodynamic properties during the dissolution of BHET were calculated. The results showed that the dissolution process of BHET in all mixed solvents was spontaneous.

Measurement and PC-SAFT Modeling of the Solubility of the BHET Monomer, the BHET Dimer, and PET in Single Solvents

“…Unfortunately, details on their applied method, which could shed light on the systematic differences, are unavailable. Concerning the solubility of the BHET monomer in EG, the data from Yao et al and Yuan et al are of a similar order of magnitude compared to our measurements but exhibit a lower slope, potentially explained by differences in their applied methods. Unfortunately, Huang et al did not measure the solubility in EG, which could have been valuable for validating our obtained data.…”

“…Figure presents a comparison between our measured BHET monomer solubilities in water (left) and EG (right) and the available literature data. Whereas the data obtained by Yao et al and Yuan et al are congruent for both solvents, there are noticeable differences when compared to our measurements. In terms of BHET monomer solubility in water, our results are approximately 1 order of magnitude greater.…”

“…Recently, Yao et al published solubility measurements of the BHET monomer in various solvents, including pure methanol, ethanol, EG and water, within a temperature range of 10 to 55 °C. These data are consistent with the results obtained by Yuan et al, who measured solubilities of the BHET monomer in pure methanol, ethanol, EG, acetone, and their aqueous mixtures between 10 and 50 °C. Additionally, Huang et al .…”

“…Whereas the data obtained by Yao 24 37.4 to 54.9 24 247 25 41 25 a Standard uncertainties u are u(T 0i SL ) = 1.12 K and u(h 0i SL ) = 5.1 J g −1 . Relative standard uncertainties u r are u r (T 0i SL ) = 0.0045 and u r (h 0i SL ) = 0.0393. et al 11 and Yuan et al 12 are congruent for both solvents, there are noticeable differences when compared to our measurements. In terms of BHET monomer solubility in water, our results are approximately 1 order of magnitude greater.…”

Chemical Recycling Development of Poly(ethylene terephthalate) by Glycolysis and Cooling Crystallization with Water

“…32 DSC scans of the in-house synthesized (a) α-form BHET monomer crystals and (b) δ-form BHET monomer crystals in Figure 6 show that the melting points of the two endotherms for αand δ-form BHET monomer crystals of 111.87 and 111.70 °C, respectively, were very close to each other. 42 However, their enthalpy of fusion values of 96.13 and 148.57 J/g, respectively, were quite different. Their crystal structures and crystallographic data are shown in Figure S4 and Table S3.…”