Comparative kinetics and enhanced desalination efficiency of hydrate-based desalination using HFC-125a, HFC-134a, and HFC-152a through hydrate pelletization and induced melting

• Published in: Desalination 2024-12, Vol.592, p.118176, Article 118176
• Main Authors: Hong, Sohee, Cho, Sang-Gyu, Burla, Sai Kiran, Seo, Seong Deok, Han, Jihoon, Won, Yong Sun, Lee, Ju Dong
• Format: Article
• Language: English
• Subjects: Gas hydrate desalination; HFC gas hydrates; Hydrate pelletization; Induced hydrate melting; Salt removal efficiency
• ISSN: 0011-9164
• DOI: 10.1016/j.desal.2024.118176

The present study demonstrates the feasibility of gas hydrate technology for effective desalination of salt water without requiring pre- or post-treatment. The research highlights two main aspects: the thermodynamic and comparative kinetic properties of hydrofluorocarbon (HFC) gases, and the novel concept of hydrate pelletization enhanced by an induced pellet melting procedure. The thermodynamic viability of HFC gases such as HFC-125a, HFC-134a, and HFC-152a for hydrate formation in both saline and non-saline conditions is underscored. For the first time, a comparative analysis of the gas uptake kinetics for these three gases is presented under 0, 3.5, and 8.0 wt% NaCl conditions. Results indicate that HFC-134a and HFC-152a exhibit rapid gas uptake kinetics, while HFC-125a shows sluggish kinetics, attributed to the effective pressure driving force and subcooling temperature. Regardless of the guest gas, the chosen experimental conditions achieved salt removal efficiency of ~70 % in 3.5 wt% NaCl and ~ 75 % in 8.0 wt% NaCl. The novel induced hydrate pellet melting approach significantly improved salt removal efficiency, exhibiting a nonlinear behavior where the rate of salt removal efficiency increases asymptotically as more hydrate melts. New insights into salt distribution within the hydrate pellet reveal that the core contains higher salinity, than the outer layer. •Gas hydrate technology desalinates seawater efficiently without the need for pre- or post-treatment processes.•First comparative analysis of gas uptake kinetics for HFC-125a, HFC-134a, and HFC-152a at varying salinity levels.•Hydrate-based desalination removes ~70 % salt in 3.5 wt% NaCl and ~75 % in 8.0 wt% NaCl in a single-stage process.•A novel hydrate pelletization and induced melting method enhance salt removal to ~95 % and ~97 % for 3.5 and 8.0 wt% NaCl.•Mechanical compaction during pelletization creates a higher salt concentration in the core than in the outer layers.