Adsorption of a PFAS Utilizing MOF-808: Development of an Undergraduate Laboratory Experiment in a Capstone Course

Abstract

A two-component undergraduate laboratory experience has been developed by students in a senior level capstone course. The first component is a 3 h laboratory experience dedicated to the rapid synthesis of a metal−organic framework (MOF-808) in aqueous solution using readily available reagents and equipment. During the second component, MOF-808 was characterized via a suite of instruments: powder X-ray diffraction (PXRD), thermal gravimetric analysis (TGA), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In addition, quantitative 19 F{ 1 H} NMR spectroscopy was utilized to quantify the amount of perfluorobutanesulfonate (PFBS), one example of a poly-or perfluoroalkyl substance (aka PFAS), adsorbed from solution. The two 3 h laboratory experiences were subsequently deployed in a foundation level inorganic chemistry course. This two-component, multi-instrument lab experience provides students an opportunity to synthesize a modern porous solid and utilize it in an emerging application of MOF science.

Synergistic Effect of Ion Doping and Type-II Heterojunction Construction and Ciprofloxacin Degradation by MIL-68(In,Bi)-NH2@BiOBr under Visible Light

“…In addition, the broad peak located at 3340 cm −1 and the peak at 1610 cm −1 are due to the stretching and bending vibrations of the hydrogen− oxygen bonds of the adsorbed water on the surface. 29 300MIBN@BOB has the basic characteristic peak of MIL-68(In)-NH 2 and BiOBr, which proves that the material is successfully composite. 31 In addition, the pore size of the resulting composite 300MIBN@BOB was investigated by using N 2 adsorption curves (Figure S1a).…”

“…FT-IR was used to study the functional group compositions of 300MIBN@BOB, MIL-68­(In)-NH 2 , and BiOBr. As shown in Figure b, the absorption peaks of MIL-68­(In)-NH 2 at 1558, 1381, and 1255 cm –1 belong to the symmetric, asymmetric tensile vibration of the carboxyl bond and the tensile vibration of the C–N bond . After binding with BiOBr, the intensity of peaks during the above area is reduced, but the position remains unchanged, indicating that the structure of MIL-68­(In)-NH 2 is not disrupted.…”

“…As shown in Figure 1b, the absorption peaks of MIL-68(In)-NH 2 at 1558, 1381, and 1255 cm −1 belong to the symmetric, asymmetric tensile vibration of the carboxyl bond and the tensile vibration of the C−N bond. 29 After binding with BiOBr, the intensity of peaks during the above area is reduced, but the position remains unchanged, indicating that the structure of MIL-68(In)-NH 2 is not disrupted. The peak at 765 cm −1 in MIL-68(In)-NH 2 represents the tensile vibration of the In−O bond.…”

Implementation of High School Level Laboratory Experiments Demonstrating Nanoscale Porosity in Metal–Organic Frameworks

“…Many of the MOF-based experiments published for educational purposes are designed for upper-level undergraduate courses 21,23,[26][27][28][29][30] and necessitate the use of hazardous reagents and specialized equipment. Hence, these experiments may be inaccessible to high school and lowerlevel undergraduate laboratories, especially those located in institutions that do not focus heavily on scientific research (such as liberal arts or community colleges).…”

“…21-24, 26-29, 31, 33, 35, 38 Furthermore, standard characterization of MOFs requires expensive instruments that are unavailable in most high school and undergraduate classrooms. Previously published articles have recommended characterization using powder Xray diffraction (PXRD), 21-22, 24, 26-30, 32-35, 38-39 gas sorption analysis, 21-22, 27-28, 33 Fourier-transform infrared spectroscopy (FTIR), 29-30, 32-35, 38-39 Raman spectroscopy, 33 nuclear magnetic resonance spectroscopy, 21,[30][31]35 thermogravimetric analysis, 21-22, 26-30, 32-35, 39 differential scanning calorimetry, 22 and gas chromatography-mass spectrometry; 35 all of these instruments cost tens or hundreds of thousands of US dollars (excepting some inexpensive, low resolution FTIR instruments). As has recently been recognized, [24][25] exploring and understanding the properties of MOFs by high school and undergraduate students at under-and moderately-resourced institutions must be accomplished by avenues that do not require the use of such expensive equipment.…”