Adsorption of Congo red on spinel CuCo2O4: Equilibrium, kinetic and thermodynamic studies
Journal of the Taiwan Institute of Chemical Engineers, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jtice.2026.107044
- Dergi Adı: Journal of the Taiwan Institute of Chemical Engineers
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Applied Science & Technology Source, Chemical Abstracts Core, Compendex, INSPEC, Engineering Source (EBSCO)
- Anahtar Kelimeler: Adsorption, Congo red, CuCo2O4, Isotherm, Kinetic, Thermodynamic
- Yıldız Teknik Üniversitesi Adresli: Evet
Özet
Background Congo red (CR) is a toxic anionic azo dye widely used in industrial applications and poses serious environmental and health risks due to its persistence and complex structure. Although CuCo₂O₄ has been extensively studied for photocatalytic dye degradation, batteries, and supercapacitors, its inherent adsorption capacity under non-catalytic circumstances has not been well explored. This study fills that gap by demonstrating dye-selective adsorption behavior across eight structurally diverse dyes, offering mechanistic insight not found in single-dye adsorption investigations. Methods CuCo₂O₄ was synthesized and characterized using XRD, SEM/EDS, FT-IR, and point of zero charge (pHpzc) analysis to determine its structural and surface properties. Interfacial interactions at the solid-liquid boundary were systematically probed through pH-dependent surface charge variation (pHpzc = 5.94), ionic shielding effects, and a broad 8-dye structure–selectivity screen to decouple the role of molecular geometry and functional group density on bimetallic Cu/Co active centers. Significant findings The adsorption process followed a pseudo-second order (PSO) kinetic, indicating surface-controlled interactions, while equilibrium data were best described by Langmuir and Redlich–Peterson models. The maximum adsorption capacity was determined as 115.2 mg/g at 298 K, demonstrating high efficiency. Thermodynamic results confirmed that the process was spontaneous (ΔG = −26.15 kJ/mol) and endothermic (ΔH = +38.46 kJ/mol). Adsorption was governed by multiple mechanisms, including electrostatic attraction, π–π interactions, hydrogen bonding, and weak surface complexation.