Amine-Functionalized Lignin for CO₂ CapturePart 2: A Double Amine Grafting Strategy

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Global warming is driven by greenhouse gas emissions, necessitating effective carbon dioxide (CO2) capture technologies.
• Amine-based materials are crucial for post-combustion CO2 capture, but sustainable and biodegradable options are underexplored.
• Lignin, a sustainable biopolymer, offers potential for CO2 adsorption due to its tunable surface chemistry.

Purpose of the Study:

• To valorize lignin for enhanced CO2 capture through a double amine functionalization strategy.
• To investigate the CO2 adsorption performance of modified lignin materials under varying conditions.

Main Methods:

• Lignin was functionalized with diethylenetriamine (DETA) to create DETA-aminated lignin (DAL).
• A subsequent grafting procedure with triaminosilane (TRI) was performed on DAL to yield TRI/DAL.
• CO2 uptake, amine efficiency, and cyclic stability of the modified materials were evaluated.

Main Results:

• TRI/DAL exhibited significantly higher CO2 uptake (1.31 mmol/g) compared to individually modified lignin.
• CO2 capture was enhanced by humidity, reaching 1.84 mmol/g at 55% relative humidity.
• The material demonstrated excellent cyclic stability, retaining over 95% of its capacity after ten cycles.

Conclusions:

• Double amine functionalization of lignin is a promising approach for developing efficient and sustainable CO2 adsorbents.
• The developed TRI/DAL material shows potential for industrial applications in mitigating CO2 emissions.
• Moisture positively influences both CO2 capture capacity and the material's long-term performance.