Synthesis, Characterization, and Evaluation of Metal-Organic Frameworks for Water Decontamination: An Integrated Experiment

An integrated laboratory experience using metal-organic frameworks (MOFs), a nanoporous and crystalline extended solid material composed of metal cations and organic linkers, was developed and adopted for upper-division, major-level chemistry and biochemistry students. In this laboratory, students were guided through the facile solvothermal synthesis of four MOFs: UiO-66, UiO-66-NH2, ZIF-8, and ZIF-67. Characterization, specifically powder X-ray diffraction (PXRD), and energy-dispersive X-ray spectroscopy (EDXS) were used to evaluate the crystallinity, morphology, and composition of the MOFs, respectively. Students then investigated the effects of measurement conditions (MOF dosage, MOF surface charge, and charge density of dye counterions) on the removal of dyes from aqueous solutions using the synthesized MOFs. Through the utilization of Fourier-transform infrared spectroscopy (FT-IR) and UV-vis spectroscopy, students confirmed the binding of dyes and quantified the amounts of dye removed from solution. Students found that all four porous and crystalline MOFs removed acid orange 7 and malachite green from water, but ZIF-67 exhibited the highest adsorption capacity of 30 mg of acid orange 7 per gram of ZIF-67 at a dosage of 5 mg. This laboratory experience allows students to apply and connect concepts found in general, organic, inorganic, and physical chemistry while simultaneously getting introduced to various instrumentation and lab techniques within a growing field in materials chemistry. Exposure to this field can help stimulate student interest, expose them to sustainability problems and potential solutions, and implement strategies to help solve these challenges.