New method could lower both emissions and building construction costs
Structural materials like steel or cement come at a high cost both in dollars and carbon dioxide emissions; building construction and use accounts for an estimated 40% of emissions. Developing sustainable alternatives to existing materials could help mitigate climate change and reduce carbon dioxide emissions.
Working to address both issues at once, materials scientist Muhammad Rahman and collaborators found a way to incorporate molecules of a carbon dioxide-trapping crystalline porous material into wood, according to a study published in Cell Reports Physical Science.1
To achieve the feat, the network of cellulose fibers that gives wood its strength is first cleared out through a process known as delignification.2
Next, the delignified wood is soaked in a solution containing microparticles of a metal-organic framework, or MOF, known as Calgary framework 20 (CALF-20). MOFs are high-surface-area sorbent materials used for their ability to adsorb carbon dioxide molecules into their pores. “The MOF particles easily fit into the cellulose channels and get attached to them through favorable surface interactions,” said Soumyabrata Roy, a Rice research scientist and lead author on the study.3
- 1. “Wood is a sustainable, renewable structural material that we already use extensively,” Rahman said. “Our engineered wood did exhibit greater strength than normal, untreated wood.”
- 2. “Wood is made up of three essential components: cellulose, hemicellulose and lignin,” Rahman said. “Lignin is what gives wood its color, so when you take lignin out, the wood becomes colorless. Removing the lignin is a fairly simple process that involves a two-step chemical treatment using environmentally benign substances. After removing the lignin, we use bleach or hydrogen peroxide to remove the hemicellulose.”
- 3. MOFs are among several nascent carbon capture technologies developed to address anthropogenic climate change. “Right now, there is no biodegradable, sustainable substrate for deploying carbon dioxide-sorbent materials,” Rahman said. “Our MOF-enhanced wood is an adaptable support platform for deploying sorbent in different carbon dioxide applications.”
Soumyabrata Roy, Firuz Alam Philip, Eliezer Fernando Oliveira, Gurwinder Singh, Stalin Joseph, Ram Manohar Yadav, Aparna Adumbumkulath, Sakib Hassan, Ali Khater, Xiaowei Wu, Praveen Bollini, Ajayan Vinu, George Shimizu, Pulickel M. Ajayan, Md Golam Kibria, Muhammad M. Rahman. Functional wood for carbon dioxide capture. Cell Reports Physical Science, 2023; 4 (2): 101269 DOI: 10.1016/j.xcrp.2023.101269
With increasing global climate change, integrated concepts to innovate sustainable structures that can multiaxially address CO2 mitigation are crucial. Here, we fabricate a functional wood structure with enhanced mechanical performance via a top-down approach incorporating a high-performance metal-organic framework (MOF), Calgary framework 20 (CALF-20). The functional wood with 10% (w/w) CALF-20 can capture CO2 with an overall gravimetric capacity of 0.45 mmol/g at 1 bar and 303 K that scales linearly with the MOF loading. Interestingly, the functional wood surpasses the calculated normalized adsorption capacity of CALF-20 stemming from the mesoporous wood framework, pore geometry modulation in CALF-20, and favorable CO2 uptake interactions. Density functional theory (DFT) calculations elucidate strong interactions between CALF-20 and the cellulose backbone and an understanding of how such interactions can favorably modulate the pore geometry and CO2 physisorption energies. Thus, our work opens an avenue for developing sustainable composites that can be utilized in CO2 capture and structural applications.
