Capturing CO2 with Upcycled Gloves

Upcycled nitrile and SBS rubbers can become solid polyamine sorbents for CO₂ capture and rubber waste recovery.

Recent estimates from the United Nations Environment Programme indicate that annual global plastic production exceeds 400 million metric tons. As plastic waste accumulates, it could generate massive CO₂ emissions and require significant removal capacity by 2050. Some estimates indicate that the world may need to remove 5–16 gigatons of CO₂ by then.

Therefore, carbon storage technologies such as direct air capture and carbon capture will become increasingly important. Current industrial systems usually rely on aqueous amine solutions or metal-organic frameworks (MOFs). Although these methods can be highly efficient, they still face key technical limitations. These challenges include sorbent evaporation, structural instability, and high energy demand during regeneration.

You can also read: Bio-Based Synthetic Rubbers: A Sustainable Shift in Plastics.

Carbon Capture with Waste Upcycling

Next-generation solid adsorbents may help reduce many of these drawbacks. These materials include amine-grafted or amine-impregnated supported systems. To address these challenges, Danish chemists developed a new approach to upcycle nitrile and styrene-butadiene-styrene rubbers. This work introduces a promising circular route for processing these difficult rubber waste streams.

Building on advances in next-generation sorbents, Professor Troels Skrydstrup and his team at Aarhus University linked carbon capture with waste upcycling. They developed a method to repurpose used and discarded nitrile rubber, including single-use laboratory gloves, into functional solid sorbents.

In their recent paper, Post-Modified Nitrile and Styrene-Butadiene-Styrene Rubbers, the team outlines two synthetic routes. These routes convert nitrile and SBS rubbers into nonporous solid polyamines, which are known for their strong CO₂-binding capacity.

Using ruthenium and nickel catalysis, the researchers convert nitrile groups into amines. As a result, the modified rubbers can capture and release CO₂ through thermal swing adsorption. These materials can also undergo repeated regeneration. Therefore, they offer two potential benefits: efficient carbon capture and circular pathways for rubber waste.

• Upcycling Rubbers into Sorbents

Nitrile rubber is common in laboratories because it offers chemical resistance, flexibility, and waterproof performance. However, this material remains difficult to recycle. The Danish group developed two synthetic pathways to transform rubbers into potential carbon-sequestering solid poly(allylamine) sorbents.

This conversion relies on the nucleophilic reaction between amines and CO₂ gas to form carbonate species. Through this chemistry, waste rubber can become a functional material for CO₂ adsorption.

• Catalytic Hydrogenation of Nitrile Rubber

When researchers start with nitrile rubber, hydrogenation becomes the first reaction step. According to Simon S. Kildahl, a member of the Skrydstrup team, ruthenium-catalyzed hydrogenation activates the dormant nitrogen in nitrile rubber.

This hydrogenation reaction converts nitrile groups into amines. After optimization, the reaction produced approximately 90% polyamine from the acrylonitrile units.

• Catalytic Hydrocyanation of Polybutadiene

The Skrydstrup team also developed another reaction pathway using SBS reactants instead of nitrile rubber. First, they introduced nitrile groups through hydrocyanation using a nickel-based catalyst. Then, they hydrogenated the resulting nitrile-containing rubber using the group’s ruthenium-catalyzed hydrogenation route. This sequence produced solid poly(allylamine).

Upcycling Research

Using the resulting polyamines, the Skrydstrup team investigated the materials’ CO₂ adsorption properties. The researchers tested the procedure on commercial rubbers and products, including nitrile gloves, SBS rubber shoe soles, and vulcanized materials.

They found that upcycled nitrile-butadiene and hydrocyanated SBS rubber showed promise for CO₂ capture. Because poly(allylamine) resembles traditional polyamine CO₂ sorbents, the team expected similar adsorption behavior. However, the group found that adsorption peaked at 90°C. This result indicates that higher temperatures optimize performance.

Although these polyamines remain less efficient than conventional CO₂ MOF sorbents, they may suit higher-temperature applications. MOF sorbents typically operate at ambient temperatures, while these modified rubbers perform better under warmer conditions.

Additional progress is also emerging. For example, the Kumar group at the University of St Andrews published related work in Angewandte Chemie. The paper outlines two chemical approaches for upcycling nitrile rubber into either polyamines or polyols. Both methods rely on ruthenium-catalyzed hydrogenation and chemoselective reactions. These reactions convert the material into either amines or alcohols. Although these methods differ from the Skrydstrup work, both studies highlight the same challenge. Upcycling rubber materials into truly circular solutions remains technically difficult.

Toward Circular Carbon Capture Materials

SBS, nitrile rubber, and other vulcanized materials vary widely in formulation. Therefore, not all of them can be upcycled successfully. Differences in additives, crosslinking, fillers, and processing methods strongly influence whether these materials can be repurposed.

With further research and process improvements, researchers may develop a more robust and economically viable route. These synthetic techniques could also provide alternatives that avoid expensive catalytic systems, high-temperature applications, or MOFs.

Even so, transforming nitrile waste into CO₂ sorbents could provide another circular solution for carbon capture materials. As demand for CO₂ capture grows, upcycled rubber may help address both plastic waste and carbon management challenges.