Ion-specific capacity–rate–energy trade-offs in graphite-based capacitive deionization: Beyond gravimetric performance ranking
Desalination, cilt.643, 2027 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 643
- Basım Tarihi: 2027
- Doi Numarası: 10.1016/j.desal.2026.120951
- Dergi Adı: Desalination
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, Environment Index, Geobase, INSPEC, Public Affairs Index, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Capacitive deionization, Capacity–rate–energy trade-off, Cation-equivalent normalization, Cross-electrolyte comparison, Graphite-based electrode, Ion-specific electrosorption
- Ondokuz Mayıs Üniversitesi Adresli: Evet
Özet
This study systematically compares NaCl, NH4Cl, and CaCl2 on the same graphite-based electrode platform using a consistently defined operational endpoint and complementary gravimetric, molar, cation-equivalent, rate, and cell-electrical energy descriptors. The comparison addresses a key limitation of conventional capacitive deionization (CDI) benchmarking: although gravimetric salt adsorption capacity (SAC) is widely used as a performance metric, direct cross-electrolyte comparisons can be misleading when salts differ in molar mass and ionic valence. Moreover, SAC alone does not capture adsorption rate or electrical-energy demand, potentially altering the interpretation of electrolyte performance. At the reference condition of 0.10 N, 1.2 V, and 15 mL min−1, the 30-min mean SAC values were 64.87, 116.07, and 73.18 mg g−1 for NaCl, NH4Cl, and CaCl2, respectively. The corresponding operational endpoints occurred at 15, 10, and 30 min, yielding cation-equivalent uptake (qeq,op) values of 1.120, 2.170, and 1.319 meq g−1 and equivalent-normalized adsorption rates (ASAReq,op) of 0.075, 0.217, and 0.044 meq g−1 min−1, respectively. The corresponding cell-electrical specific energy consumption (SEC) values were 0.0212, 0.0153, and 0.0391 Wh L−1. Machine learning was retained as a secondary exploratory analysis, revealing strong observation-level interpolation but substantially weaker leave-one-condition-out transferability, thereby indicating limited generalization to unseen operating conditions. Overall, electrolyte performance depended on both the selected benchmarking metric and operating condition, demonstrating that gravimetric SAC alone is insufficient for robust cross-electrolyte evaluation. The coordinated assessment of adsorption capacity, equivalent-normalized uptake and rate, operational endpoint, and cell-electrical energy provides a more physically meaningful framework for CDI performance benchmarking across electrolytes.