In the race against climate change, a groundbreaking discovery is emerging from one of Earth’s most ubiquitous yet underestimated materials: clay. Researchers from Purdue University, in collaboration with Sandia National Laboratories, have unveiled a novel approach to capturing atmospheric carbon dioxide (CO₂) using clay minerals, potentially transforming how we tackle global warming. This innovative research not only pioneers a new chapter in carbon capture technology but also earned the team a notable 2024 R&D 100 Award, signaling its potential impact on environmental science and engineering.
At the heart of this advancement lies an abundant group of clay minerals known as smectites, celebrated for their high surface areas and nanoscale internal structures. The team, led by Purdue agronomy professor Cliff Johnston, focused specifically on saponite, a variety of smectite renowned for its extensive internal pore network. Rather than applying extreme temperatures or pressures—as has typically been done in earlier studies designed to enhance carbon absorption—the researchers innovatively explored humidity’s role. They observed that saponite exhibited remarkable affinity toward carbon dioxide at ambient conditions with low humidity, revealing a previously unrecognized synergy between water vapor and CO₂ in adsorption processes.
Clay minerals present a unique duality in their internal surfaces: polar and nonpolar regions coexist within their intricate pore landscapes. Johnston’s decades-long research has elucidated that CO₂ molecules preferentially bind to the nonpolar zones, while water vapor tends to associate with polar sites. This molecular partitioning opens avenues for finely tuning clay’s compositional and ionic characteristics to maximize CO₂ uptake—offering a strategic lever for designing cost-effective and environmentally sustainable sorbents.
The implications of this study extend far beyond academic curiosity. Conventional direct air capture technologies often rely on sophisticated materials such as metal-organic frameworks, zeolites, or amine-based sorbents, which demand high energy input and costly manufacturing processes. In stark contrast, smectite clays are not only readily available worldwide but are also inherently low-cost and environmentally benign. Their natural abundance, coupled with their nanoscale structural features, presents an attractive platform for scalable carbon sequestration solutions—potentially democratizing access to green technology in both developed and developing regions.
This research also breaks new ground by for the first time reporting simultaneous absorption of CO₂ and water vapor by a natural clay mineral at realistic atmospheric concentrations of carbon dioxide. Prior explorations mostly concentrated on isolated gas interactions under elevated conditions or used synthetic proxies that mimic natural systems. By maintaining ambient conditions, the Purdue-Sandia collaboration brings us closer to real-world applicability, bridging laboratory insights with practical environmental engineering.
Professor Johnston’s team has long been a leader in studying clay’s interaction with pollutants. Their extensive work on smectites revealed their ability to sorb toxic organic compounds such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, which underscores the diverse environmental remediation potentials of clays. This legacy unites seamlessly with the present discovery, positioning clay minerals as multi-functional materials capable of detoxifying both chemical pollutants and greenhouse gases. Their research paradigm exemplifies how foundational science can lead to revolutionary environmental technologies.
One particularly striking aspect of smectites is their extraordinary surface area; a mere tablespoon of clay unfolds into a surface as vast as an American football field. This immense surface is fragmented into a labyrinthine network of pores, providing countless binding sites for molecules. Manipulating the charge density and ionic composition of these internal surfaces enables precise control over adsorptive behavior—a key insight that could unlock tailored sorbents for diverse greenhouse gases beyond CO₂.
Global interest in carbon capture has surged in parallel with accelerating climate crises, spurring the development of facilities like Climeworks’ Orca plant in Iceland, which uses advanced solid amine sorbents. Although these approaches have advanced the field considerably, their expense and complexity limit widespread adoption. The Purdue team’s revelation about clay minerals repositions Earth’s humble soils and sediments as promising frontline materials in carbon management technology—a prospect that could reshape environmental policy and industrial practice alike.
Methodologically, the team leveraged a sophisticated combination of spectroscopic techniques and gravimetric analysis. This allowed them to probe at the molecular scale how CO₂ and H₂O molecules concurrently interact within the saponite pores, elucidating the thermodynamic and kinetic parameters underlying their co-adsorption behavior. The integrity of measurements at ambient CO₂ concentrations enhances the study’s relevance, providing data that can directly inform design of next-generation direct air capture systems.
Beyond potential atmospheric carbon sequestration, this discovery may catalyze innovations such as integrating clay-based sorbents into emission-cutting factory filters or geologic storage solutions that immobilize CO₂ underground for centuries. Given the strategic partnership between Purdue University and Sandia National Laboratories, the research benefits from combined expertise in geochemistry, materials science, and engineering, exemplifying a multidisciplinary approach needed for addressing planetary-scale challenges.
In conclusion, the utilization of naturally abundant clay minerals for simultaneous absorption of carbon dioxide and water vapor at ambient conditions marks a significant leap forward in environmental chemistry and carbon capture technologies. As climate change continues to threaten ecosystems and economies worldwide, this science-backed, scalable, and cost-effective strategy could propel us closer to sustainable carbon management. Future research and development efforts inspired by this study promise to unlock even greater potential from Earth’s most common nanomaterials, guiding us toward a cleaner, more resilient planetary future.
Subject of Research: Carbon dioxide capture from ambient air using smectite clay minerals.
Article Title: The Journal of Physical Chemistry C
News Publication Date: 9-Apr-2025
Web References:
- https://pubs.acs.org/doi/full/10.1021/acs.jpcc.5c01210
- https://www.eaps.purdue.edu/people/profile/clays.html
- https://climeworks.com/plant-orca
References:
Johnston, C.; et al. “Simultaneous Absorption of Carbon Dioxide and Water Vapor by Smectite Clay Minerals at Ambient CO₂ Concentrations.” The Journal of Physical Chemistry C, 2025.
Image Credits: Purdue University
Keywords: Carbon capture, Clays, Chemistry, Soil chemistry, Soil carbon, Soils, Soil science, Carbon sinks
