Synergistic co-catalysis by seawater salts and CO2 for degradation of marine microplastics in hydrothermal gasification: Mechanism and modeling based on ReaxFF molecular dynamics

Shaoqiang Nie, Zihui Xiao, Tugui Yuan, Wenwei Zhong and Wenxiang Zhang

Energy, 2025, vol. 341, issue C

Abstract: To advance the resource utilization of microplastics in marine environments via hydrothermal gasification, this work investigates the catalytic effects of individual and combined additions of chloride salts (KCl and NaCl) and CO2. The role of these salts, naturally present in seawater, in promoting the gasification of polyethylene terephthalate (PET) and polyethylene (PE) was evaluated using reactive force field molecular dynamics (ReaxFF-MD) simulations. Results demonstrate that KCl significantly enhances the degradation efficiency and H2 yield for both individual and mixed PE/PET plastics. Furthermore, the introduction of CO2 strengthens the catalytic performance by reacting with KCl to form K2CO3 during the process. The hydrothermal gasification of PE/PET mixtures also shows considerable potential for the recovery of valuable products, such as terephthalic acid (TPA) and ethylene, with TPA recovery rates reaching up to 95 % at a simulated temperature of 2000 K (corresponding to an actual temperature of 640 K). The apparent activation energy for gasification of the plastic mixture was approximately 219 kJ/mol; the addition of KCl reduced it to about 62 kJ/mol, while the combined introduction of KCl and CO2 further decreased it to around 60 kJ/mol. This work provides essential theoretical insights and fundamental data for deploying seawater-based hydrothermal gasification as a sustainable technology for recovering mixed plastic waste.

Keywords: Hydrothermal gasification; H2; Marine microplastics; Chloride salts; Kinetics; ReaxFF-MD (search for similar items in EconPapers)
Date: 2025
References: View references in EconPapers View complete reference list from CitEc
Citations:

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S036054422505131X
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:341:y:2025:i:c:s036054422505131x

DOI: 10.1016/j.energy.2025.139489

Access Statistics for this article

Energy is currently edited by Henrik Lund and Mark J. Kaiser

More articles in Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().