(3,3)-Connected Triazine-Based Covalent Organic Frameworks for Efficient CO₂ Separation over N₂ and Dye Adsorption

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) are advanced porous materials with tunable properties.
• Ecological sustainability demands efficient methods for CO2 capture and pollutant removal.
• Triazine-based COFs offer potential due to their structural stability and high surface area.

Purpose of the Study:

• To synthesize and characterize novel (3,3)-connected triazine-based COFs.
• To evaluate the COF materials for CO2 adsorption and separation.
• To assess the COF materials' performance in removing organic dyes from aqueous solutions.

Main Methods:

• Synthesis of two triazine-based COFs with (3,3)-connectivity.
• Gas adsorption measurements at 273 K and 1 bar to determine CO2 selectivity and capacity.
• Batch adsorption experiments to evaluate dye removal efficiency (MB, GV, RhB).
• Analysis of adsorption behavior using Langmuir isotherms and quasi-secondary kinetics.

Main Results:

• The synthesized COFs exhibit high specific surface area and excellent thermal/chemical stability.
• COFZ1 demonstrated a CO2 selectivity of 35.09 and a CO2 capacity of 24.21 cm3 g-1 for simulated flue gas.
• Maximum adsorption capacities for methylene blue (MB) and gentian violet (GV) were 510 and 564 mg g-1, respectively.
• Adsorption performance remained stable across varying pH and salt concentrations, with high recyclability.

Conclusions:

• The developed triazine-based COFs are effective for both CO2 capture and organic dye removal.
• These materials exhibit robust adsorption properties, high selectivity, and excellent stability, making them suitable for environmental applications.
• The adsorption mechanism involves monolayer adsorption and chemisorption, following Langmuir and quasi-secondary kinetics.