Zahra Eshaghi Gorji, a postdoctoral researcher in the Department of Chemistry at the University of Helsinki, is leading new work on a reusable compound designed to capture carbon dioxide directly from ambient air. The research, describes a chemical system that combines high capture efficiency with relatively low energy requirements for carbon release, addressing several limitations of existing direct air capture approaches.
Eshaghi Gorji, Z., Singh, B., Lempinen, A., & Repo, T. (2025). Direct Air Capture: Recyclability and Exceptional CO 2 Uptake Using a Superbase. Environmental Science & Technology, 59(49), 26506–26513. https://doi.org/10.1021/acs.est.5c13908
Direct air capture remains a technical challenge because carbon dioxide is present in the atmosphere at low concentrations and is mixed with much larger amounts of nitrogen, oxygen, and water vapor. Many current capture systems rely on solid sorbents or aqueous solutions that either require high regeneration temperatures or degrade quickly after repeated use. As a result, energy demand and material longevity continue to limit large scale deployment.
Zahra Eshaghi Gorji, from University of Helsinki stated,
“The idea is to bind the compound to compounds such as silica and graphene oxide, which promotes the interaction with carbon dioxide.”
The University of Helsinki team focused on a liquid compound formed from a strong organic base, known as a superbase, combined with an alcohol. In laboratory tests, one gram of the compound absorbed up to 156 milligrams of carbon dioxide from untreated ambient air. Importantly, the compound showed little interaction with other atmospheric gases, indicating a high degree of selectivity for carbon dioxide.
The base used in the system, 1,5,7-triazabicyclo[4.3.0]non-6-ene, or TBN, was previously developed in the research group of Professor Ilkka Kilpeläinen. When paired with benzyl alcohol, the resulting compound forms a reversible chemical bond with carbon dioxide. This reversibility is central to the system’s performance, allowing the captured gas to be released without extreme conditions.
Unlike many existing capture materials that require regeneration temperatures approaching or exceeding 900 degrees Celsius, the Helsinki compound releases carbon dioxide when heated to around 70 degrees Celsius for approximately 30 minutes. The released gas is relatively pure and can be collected for reuse or storage. Lower regeneration temperatures translate directly into reduced energy input, which is a critical factor for the overall efficiency of carbon capture technologies.
Reusability was another key focus of the study. The compound was tested through multiple capture and release cycles to assess long term performance. After 50 cycles, it retained about 75 percent of its original capture capacity, and after 100 cycles, around half. While some degradation was observed, the results compare favorably with many current materials that lose effectiveness much more rapidly.
From a materials and process engineering perspective, the simplicity of the system is notable. The individual components are not considered expensive to produce, and the compound is reported to be non-toxic. These factors could ease challenges related to manufacturing, handling, and regulatory approval if the technology moves beyond the laboratory.
The next phase of the research involves scaling the compound from gram scale experiments toward pilot level testing. For this, the liquid capture agent will likely need to be immobilized onto solid supports such as silica or graphene oxide. Binding the compound to porous materials could increase surface area and improve contact with air, making it more suitable for industrial reactors or modular capture units.
Similar efforts reported elsewhere in the carbon capture field emphasize that no single solution is likely to dominate. Instead, progress is being made through incremental improvements in efficiency, selectivity, and durability. The Helsinki work contributes to this landscape by demonstrating that high capture capacity does not necessarily require high regeneration energy or highly complex materials.
While further testing will be required to understand performance under real world conditions, including humidity, contaminants, and long term cycling, the results point to a potentially practical route for direct air capture. By combining chemical selectivity with low temperature regeneration and reasonable stability, the compound offers a new reference point for designing capture systems that are both efficient and reusable.
For Engineeringness readers, the significance lies less in a single metric and more in the balance achieved across multiple constraints. The study illustrates how careful molecular design can address energy use, material lifetime, and scalability together, which remains one of the central engineering challenges in carbon dioxide removal technologies.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
