Recycling Polyethylene terephthalate (PET) by hydrolysis using excess citric acid molecules as catalysts to generate H+ protonic acid sites had been undertaken. The products of this recycling process are PolyEster Citric Acid (PEAc), formed by the polyesterification of two citric acid molecules, Ethane Diol (ED) or ethylene glycol, and a new solid material called PAT-Ac, whose molecular formula is made up of one molecule of pure terephthalic acid (PAT) and two molecules of citric acid. Two procedures had been established, one for extracting the PEAc solution and the Ethane diol in acetone solution (AED-solution) using the usual organic solvents dichloromethane and acetone, and the second for extracting pure Ethane diol (ED) by vacuum evaporation using a rotavapor. This recycling was carried out in a laboratory glassware reactor, in a 1000ml cylindrical beaker covered by a funnel with a conical lid, capped but non-watertight, and therefore under atmospheric pressure at a temperature of 150°C. A kinetic study of this recycling process was carried out, using an acid-base assay with HF-0.0026N to follow the progress of the recycled TAP and deduce the evolution of PET conversion with reaction time; and an acid-base titration with NaOH-0.05N to quantify the H+ protonic acid sites coming from the acid catalysts of the citric acid molecules and deduce the evolution of the citric acid quantity in the reaction medium. This latter assay also enabled the determination of the PAT-Ac molecular structure. A reaction mechanism for this recycling of PET by hydrolysis, using excess citric acid molecules as a catalyst source of H+ proton active sites, is proposed and validated by the kinetic data collected during the various acid-base assays mentioned above. The maximum conversion of PET to PAT and ED recorded during the kinetic study is 34.49% after 20mn reaction time or 1.5114×10-3 [moles of PAT regenerated per Gram of PET load], or 7.5572×10-5 [moles of PAT regenerated per Gram of PET and per Minute]. In addition, the volume of ED collected is 17ml and the mass of PAT-Ac synthesized is 2.6 [g].
| Published in | American Journal of Applied Chemistry (Volume 13, Issue 3) |
| DOI | 10.11648/j.ajac.20251303.13 |
| Page(s) | 73-90 |
| Creative Commons |
This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited. |
| Copyright |
Copyright © The Author(s), 2025. Published by Science Publishing Group |
Recycling, Polyethylene Terephthalate (PET), Procedure, Kinetics, Mechanism, Pure Citric Terephthalic Acid (PAT-Ac), Ethane Diol (ED), Polyester Citric Acid (PEAc)
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APA Style
Tahina, R. A., Joachim, R., Baholy, R., Hanitriniaina, R. M. (2025). Process and Kinetic Study of PET Recycling Into PAT-Ac Ethanediol and PEAc by Hydrolysis Catalyzed by Excess Citric Acid Protonic Acid H+. American Journal of Applied Chemistry, 13(3), 73-90. https://doi.org/10.11648/j.ajac.20251303.13
ACS Style
Tahina, R. A.; Joachim, R.; Baholy, R.; Hanitriniaina, R. M. Process and Kinetic Study of PET Recycling Into PAT-Ac Ethanediol and PEAc by Hydrolysis Catalyzed by Excess Citric Acid Protonic Acid H+. Am. J. Appl. Chem. 2025, 13(3), 73-90. doi: 10.11648/j.ajac.20251303.13
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Download@article{10.11648/j.ajac.20251303.13,
author = {Rabeharitsara Andry Tahina and Raherimandimby Joachim and Robijaona Baholy and Ratsimba Marie Hanitriniaina},
title = {Process and Kinetic Study of PET Recycling Into PAT-Ac Ethanediol and PEAc by Hydrolysis Catalyzed by Excess Citric Acid Protonic Acid H+},
journal = {American Journal of Applied Chemistry},
volume = {13},
number = {3},
pages = {73-90},
doi = {10.11648/j.ajac.20251303.13},
url = {https://doi.org/10.11648/j.ajac.20251303.13},
eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajac.20251303.13},
abstract = {Recycling Polyethylene terephthalate (PET) by hydrolysis using excess citric acid molecules as catalysts to generate H+ protonic acid sites had been undertaken. The products of this recycling process are PolyEster Citric Acid (PEAc), formed by the polyesterification of two citric acid molecules, Ethane Diol (ED) or ethylene glycol, and a new solid material called PAT-Ac, whose molecular formula is made up of one molecule of pure terephthalic acid (PAT) and two molecules of citric acid. Two procedures had been established, one for extracting the PEAc solution and the Ethane diol in acetone solution (AED-solution) using the usual organic solvents dichloromethane and acetone, and the second for extracting pure Ethane diol (ED) by vacuum evaporation using a rotavapor. This recycling was carried out in a laboratory glassware reactor, in a 1000ml cylindrical beaker covered by a funnel with a conical lid, capped but non-watertight, and therefore under atmospheric pressure at a temperature of 150°C. A kinetic study of this recycling process was carried out, using an acid-base assay with HF-0.0026N to follow the progress of the recycled TAP and deduce the evolution of PET conversion with reaction time; and an acid-base titration with NaOH-0.05N to quantify the H+ protonic acid sites coming from the acid catalysts of the citric acid molecules and deduce the evolution of the citric acid quantity in the reaction medium. This latter assay also enabled the determination of the PAT-Ac molecular structure. A reaction mechanism for this recycling of PET by hydrolysis, using excess citric acid molecules as a catalyst source of H+ proton active sites, is proposed and validated by the kinetic data collected during the various acid-base assays mentioned above. The maximum conversion of PET to PAT and ED recorded during the kinetic study is 34.49% after 20mn reaction time or 1.5114×10-3 [moles of PAT regenerated per Gram of PET load], or 7.5572×10-5 [moles of PAT regenerated per Gram of PET and per Minute]. In addition, the volume of ED collected is 17ml and the mass of PAT-Ac synthesized is 2.6 [g].},
year = {2025}
}
TY - JOUR T1 - Process and Kinetic Study of PET Recycling Into PAT-Ac Ethanediol and PEAc by Hydrolysis Catalyzed by Excess Citric Acid Protonic Acid H+ AU - Rabeharitsara Andry Tahina AU - Raherimandimby Joachim AU - Robijaona Baholy AU - Ratsimba Marie Hanitriniaina Y1 - 2025/06/25 PY - 2025 N1 - https://doi.org/10.11648/j.ajac.20251303.13 DO - 10.11648/j.ajac.20251303.13 T2 - American Journal of Applied Chemistry JF - American Journal of Applied Chemistry JO - American Journal of Applied Chemistry SP - 73 EP - 90 PB - Science Publishing Group SN - 2330-8745 UR - https://doi.org/10.11648/j.ajac.20251303.13 AB - Recycling Polyethylene terephthalate (PET) by hydrolysis using excess citric acid molecules as catalysts to generate H+ protonic acid sites had been undertaken. The products of this recycling process are PolyEster Citric Acid (PEAc), formed by the polyesterification of two citric acid molecules, Ethane Diol (ED) or ethylene glycol, and a new solid material called PAT-Ac, whose molecular formula is made up of one molecule of pure terephthalic acid (PAT) and two molecules of citric acid. Two procedures had been established, one for extracting the PEAc solution and the Ethane diol in acetone solution (AED-solution) using the usual organic solvents dichloromethane and acetone, and the second for extracting pure Ethane diol (ED) by vacuum evaporation using a rotavapor. This recycling was carried out in a laboratory glassware reactor, in a 1000ml cylindrical beaker covered by a funnel with a conical lid, capped but non-watertight, and therefore under atmospheric pressure at a temperature of 150°C. A kinetic study of this recycling process was carried out, using an acid-base assay with HF-0.0026N to follow the progress of the recycled TAP and deduce the evolution of PET conversion with reaction time; and an acid-base titration with NaOH-0.05N to quantify the H+ protonic acid sites coming from the acid catalysts of the citric acid molecules and deduce the evolution of the citric acid quantity in the reaction medium. This latter assay also enabled the determination of the PAT-Ac molecular structure. A reaction mechanism for this recycling of PET by hydrolysis, using excess citric acid molecules as a catalyst source of H+ proton active sites, is proposed and validated by the kinetic data collected during the various acid-base assays mentioned above. The maximum conversion of PET to PAT and ED recorded during the kinetic study is 34.49% after 20mn reaction time or 1.5114×10-3 [moles of PAT regenerated per Gram of PET load], or 7.5572×10-5 [moles of PAT regenerated per Gram of PET and per Minute]. In addition, the volume of ED collected is 17ml and the mass of PAT-Ac synthesized is 2.6 [g]. VL - 13 IS - 3 ER -
Chemical And Industrial Process Engineering-GPCI Department, Ecole Supérieure Polytechnique Antananarivo–ESPA, Antananarivo University, Madagascar
Chemical And Industrial Process Engineering-GPCI Department, Ecole Supérieure Polytechnique Antananarivo–ESPA, Antananarivo University, Madagascar
Chemical And Industrial Process Engineering-GPCI Department, Ecole Supérieure Polytechnique Antananarivo–ESPA, Antananarivo University, Madagascar
Chemical And Industrial Process Engineering-GPCI Department, Ecole Supérieure Polytechnique Antananarivo–ESPA, Antananarivo University, Madagascar
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