Synthesis of two-organic complexes and characterization of their adsorption behaviour of ten polycyclic aromatic hydrocarbons

Abstract

Metal-organic frameworks (MOFs) are concerned mainly due to the unusual properties for diverse analytical applications, such as high surface area, good thermal stability, inpore functionally and outer-surface modification. Two metal-organic complexes were prepared by two methods of hydrothermal synthesis and room temperature synthesis, separately. The compositions, structures, thermal stability and adsorption properties of the two complexes were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) method, which indicated that the two complexes have not only good thermal stability but also good adsorption for polycyclic aromatic hydrocarbons (PAHs). PAHs enter into environment leading to pollution by industrial and agricultural production and life, rooting in the incomplete combustion or pyrolysis of organism. PAHs are strongly carcinogenic and mutagenic. Some PAHs are considered as endocrine disruptors, and maybe have biological effects on human health. Regulations have thus been formulated for monitoring and controlling PAHs by the United States Environmental Protection Agency (U.S. EPA) and other government agencies. Adsorption kinetic of PAHs on the two complexes could be well described by the pseudo-second order kinetic model, and the adsorption behaviors of the two complexes on PAHs are in accord with Langmuir model. In addition, the adsorption capacities increase with the increasing adsorbent dosage. It is proved by the FT-IR data that pi-pi interactions between the PAHs and the framework terephthalic acid molecules. Ten PAHs were adsorbed well on the two complexes which have good adsorptive selectivity. By further optimizing of the two complex materials, it is promising to use them as chromatographic stationary phases.