BITS-H Develops Ultra-Microporous Material For CO₂ Capture
The material could have applications in carbon dioxide/nitrogen separation, water adsorption, molecular sieving and selective amine detection: Reports
HYDERABAD: Researchers at BITS Pilani Hyderabad have developed a material with extremely small pores that can selectively capture carbon dioxide and water while detecting certain chemicals based on their size and shape, potentially opening applications in carbon capture, solvent drying and chemical sensing.
The material could have applications in carbon dioxide/nitrogen separation, water adsorption, molecular sieving and selective amine detection.
A statement said the zirconium-based metal-organic framework (MOF), named BITSH-3, has pore openings of about 4 angstroms, or roughly four ten-billionths of a metre. The study was conducted by Govu Radha of the Department of Chemistry under the guidance of Dr Himanshu Aggarwal and has been published in ‘Small’.
The researchers used a bulky, rigid pyrene-based molecule, 1,6-pyrenedicarboxylate (1,6-Pydca), to construct the material. “Unlike the conventional approach of using shorter molecular linkers to make smaller pores, the team found that making the linker wider and bulkier could also restrict the pore opening,” Radha explained.
The resulting structure allowed the material to distinguish between molecules based on their size. In experiments of the temperature at 298-degree Kelvin and pressure of 55 bar, BITSH-3 absorbed up to 205 cm³/g of CO₂, while nitrogen, methane and hydrogen showed negligible uptake, Dr Aggarwal explained.
It also showed a strong preference for water. At 1 bar, it absorbed 112.3 cm³/g of water, while methanol, ethanol and hexane showed negligible uptake, indicating potential for drying solvents by selectively removing water, he added.
The researchers tested the material as a fluorescence-based sensor for amines. Smaller molecules such as ammonia, methylamine, ethylamine and n-butylamine could enter the tiny pores and reduce fluorescence, while larger aromatic amines such as aniline and N-methylaniline produced negligible changes, the statement said.
The material could distinguish even between molecules with similar lengths but different widths. While n-butylamine could enter the pores, wider diethylamine was largely blocked, Radha said.
The calculated detection limits were 0.43 ppm for ammonia, 0.90 ppm for methylamine, 0.76 ppm for ethylamine and 1.29 ppm for n-butylamine. The study attributed the fluorescence reduction to dynamic quenching and electron transfer involving the amine molecules.
BITSH-3 also retained its crystal structure after exposure to acidic and basic conditions, water, boiling water, air and amines. The researchers said the findings demonstrate that the width and shape of molecular building blocks, along with their length, can be used to precisely control pore size.
