Alkyl-Linked Porphyrin Porous Polymers for Gas Capture and Precious Metal Adsorption

Area of Science:

• Materials Science
• Chemistry
• Environmental Science

Background:

• Porous polymers are crucial for industrial applications like gas adsorption and metal recovery.
• Maintaining porosity while incorporating reactive functionalities in polymers presents a significant challenge.
• Covalently bonded porous organic polymers (COPs) offer a potential solution due to their stability and tunable properties.

Purpose of the Study:

• To synthesize and characterize novel, inexpensive, and highly porous covalent organic polymers (COPs) with porphyrin functionalities.
• To evaluate the adsorption capacities of these COPs for key gases (CO2, H2, CH4).
• To investigate the efficacy of these COPs in selectively recovering precious metals (Au, Pt, Pd, Ag) from various sources, including electronic waste.

Main Methods:

• Friedel-Crafts reaction using chlorinated solvents as linkers to synthesize three COPs: COP-210, COP-211, and COP-212.
• Gas adsorption experiments to determine adsorption capacities for CO2, H2, and CH4.
• Precious metal recovery experiments, including analysis of adsorption mechanisms (reduction, chelation) and selectivity.
• Testing COP-212 for gold recovery from actual electronic waste.

Main Results:

• The synthesized COPs (COP-210, COP-211, COP-212) exhibit high porosity and porphyrin functionalities.
• Competitive adsorption capacities were observed for CO2, H2, and CH4.
• COPs demonstrated high selectivity for precious metals, particularly gold, platinum, palladium, and silver.
• Gold adsorption capacities ranged from 0.901-1.250 g/g with fast kinetics at low pH.
• COP-212 successfully recovered 95.6% of gold from electronic waste.

Conclusions:

• Inexpensive and scalable porous porphyrin polymers are viable materials for gas capture and separation.
• These COPs show significant potential for efficient and selective precious metal recovery, especially gold, from electronic waste.
• The developed materials offer a promising route for sustainable resource management and environmental remediation.