Polyethyleneimine-Based Cryogels Enabling the Selective and Reversible Adsorption of Chlorine

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Chemistry

Background:

• Elemental chlorine (Cl2) is a vital industrial chemical but poses environmental and safety challenges.
• Efficient methods for chlorine capture and recycling are crucial for sustainable chemical processes.

Purpose of the Study:

• To develop novel cryogels for selective and reversible adsorption of elemental chlorine.
• To investigate the adsorption mechanism and capacity of these cryogels.
• To demonstrate the potential for chlorine recycling from gas mixtures.

Main Methods:

• Synthesis of hyperbranched polyethyleneimine (hPEI) cryogels via crosslinking with glutaraldehyde at subzero temperatures.
• Characterization of cryogel structure and composition using freeze-drying and Raman spectroscopy.
• Evaluation of chlorine adsorption-desorption cycles and selectivity using gas mixtures.

Main Results:

• hPEI cryogels exhibit high chlorine adsorption capacities (0.22-0.26 g Cl2/g cryogel) over multiple cycles.
• Adsorption mechanism involves reversible halogen bonding forming trichloride species.
• Selective chlorine adsorption from gas mixtures was demonstrated, with 63-72% release achieved within 16 hours.

Conclusions:

• hPEI cryogels are effective materials for selective and reversible chlorine capture.
• The developed cryogels show promise for industrial applications, particularly in chlorine recycling from tail gas streams.
• This technology offers a sustainable approach to managing chlorine in chemical processes.