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Development and Testing of a Novel MOF-based Composite for MEMS Sensing Applications

El Taher, Bassam Jihad
A Master of Science thesis in Biomedical Engineering by Bassam Jihad El Taher entitled, “Development and Testing of a Novel MOF-based Composite for MEMS Sensing Applications”, submitted in November 2020. Thesis advisor is Dr. Mehdi Ghommem and thesis co-advisor is Dr. Rana Sabouni. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Mercury is one of the most hazardous environmental pollutants due to its immediate health implications on humans. With the potential of pollution of water due to industrial activities, a need for assessment of mercury levels in waters is needed. Metal organic frameworks (MOFs) have emerged as a new class of crystalline porous materials with potential deployment for chemical detection thanks to their outstanding features. This thesis presents the synthesis of a novel MOF namely NH2-Cd-BDC that was successfully developed and investigated toward mercury detection in a competitive aqueous medium in presence of other metal ions. NH2-Cd-BDC is composed of Cadmium ions (Cd²⁺) as the metal cluster and 2-aminoterephthalic acid (NH2-H2BDC) as the organic linker. The luminescent property of the MOF provides a cost-effective and nondestructive method for testing the detection ability of the MOF using fluoro-spectroscopy. The experiments showed that the developed MOF has a limit of detection (LOD) of 0.58 μM and demonstrated the superiority of mercury detection in comparison to other metal ions including Na⁺, K⁺, Ca²⁺, Crᵌ⁺, Cd²⁺, Cu²⁺, Pbᵌ⁺ and Feᵌ⁺. Several characterization tests of the novel developed MOF were executed including XRD, FTIR, TGA, FE-SEM and SEM to inspect its crystalline structure and thermal stability. The experimental study revealed that the MOF has a crystalline sea-shell shape, providing a large pore size for the mercury to be trapped in. To investigate how the NH2-Cd-BDC synthesized stands against other reported MOFs in the literature, three other MOFs, namely NH2-MIL53(Al), NH2-MIL88(Fe) and NH2-UiO-66(Zr), were prepared using microwave-assisted synthesis procedure and their capability to absorb mercury was investigated. All three MOFs comprise the same organic linker (NH2-H2BDC) but different metal clusters, Alᵌ⁺, Zr²⁺+ and Feᵌ⁺. All the three MOFs are characterized using XRD, FTIR, FE-SEM and TGA. Similar to the novel MOF, the performance of the other three MOFs was assessed by experimenting their capability to detect mercury in presence of aforementioned metals ions. The LOD values were found equal to 0.51 μM, 1.03 μM and 1.94 μM for NH2-MIL53(Al), NH2-MIL88(Fe) and NH2-UiO-66(Zr), respectively. This indicates the suitability of the NH2-Cd-BDC MOF for mercury sensing applications.
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