[Preparation and application of magnetic covalent organic framework： open experimental teaching practice of...

Organic synthesis experiments are often deficient and involve relatively independent experimental instrumental-analysis methods that lack integration. Accordingly， an open-instrument-analysis experiment was designed to address these shortcomings； this experiment combines organic synthesis with instrumental analysis to deliver an innovative undergraduate experiment that includes material preparation and characterization， investigating the adsorption performance of hydroxylated polychlorinated biphenyl， and exploring detection methods. First， Fe₃O₄ was treated with tetraethyl orthosilicate， after which 3-aminopropyltrimethoxysilane was introduced to prepare amino-modified Fe₃O₄. Trimesoyl chloride and p-phenylenediamine are then added as monomers to synthesize a magnetic covalent organic framework （MCOF）. The surface groups and thermal stability of the MCOF were then characterized using Fourier-transform infrared spectroscopy and thermogravimetric analysis， after which the MCOF was used to determine hydroxylated polychlorinated biphenyl in Liaohe River water samples using liquid chromatography. During this experiment， students master separation and detection methods for hydroxylated polychlorinated biphenyl， while also learning about its levels in the Liaohe River. Students will recognize the important role that instrumental analysis plays in environmental monitoring by analyzing and discussing the experimental results； they will also improve their abilities to comprehensively apply basic inorganic chemistry， organic chemistry， and instrumental-analysis knowledge， while also improving their abilities to operate， analyze， and solve problems. Implementing this open experiment will help to improve the use of laboratory equipment and fully utilize existing laboratory resources.