Using renewable and abundant phytochemicals for material synthesis should be a fundamental part of minimizing the use of petroleum-sourced molecular building blocks. We have applied this to the synthesis of robust metal-organic frameworks (MOFs) using ellagic acid—a molecule isolated from tree bark, fruit peels, and other waste materials from the food industry. Ellagic acid is a rigid and phenol-bearing molecule that is found as a building unit in the class of biomolecules known as tannins—the second largest natural source of aromatic molecules, second only to lignin.<br/><br/>Rigid organic molecules are a central part of constructing MOFs, yet most materials are made using molecules containing carboxylic acid groups, despite the possible advantages of using molecules containing other functionalities. In particular, phenolic molecules have been previously suggested, and notably proven, as a way of constructing chemically robust materials. However, previous examples of phenol-based MOFs are made exclusively from synthetic ligands. As such, the utilization of ellagic acid as a building block in MOF synthesis combines the renewable sourcing of plant-based ligands with the chemical robustness of phenolate-based MOFs. So far, we have synthesized two ellagate MOFs and investigated their properties as well as potential applications, focusing on the capture of environmental pollutants. Both materials were characterized using state-of-the-art electron crystallography techniques and exhibit excellent chemical stability, as expected when using a phenolate linker.<br/><br/>The acquired materials were investigated for environmental applications as adsorbents of pollutants. In particular, one of the materials was used to capture emerging organic contaminants (EOCs), such as pharmaceuticals and personal care products, from aqueous systems. As a proof-of-concept, real effluent water from a water treatment plant was used and treated with the MOF; showing that a range of small-molecule contaminants not removed using conventional water treatment technology were sequestered with high removal efficiencies (below limit of detection) when using the plant-based MOF as an adsorbent.

Plant-based and robust metal-organic frameworks for the capture of environmental pollutants

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.