Application Of Novel Metal-Organic Frameworks And Their Composites In The Sample Pre-treatment Technology

Polycyclic aromatic hydrocarbons (PAHs) are a kind of persistent organic pollutants. They may lead to DNA damage and exhibit carcinogenic, teratogenic, mutagenic impact on human beings. It is urgent and vital to develop efficient, selective and sensitive techniques for PAHs detection. However, PAHs of low concentration levels in water and multiple other substances in the complex samples greatly challenges their effective detection in environmental aqueous solutions. Thereby, sample pre-concentration in real water with efficient techniques becomes rather necessary for PAHs sensitive analysis. As a critical step in analytical testing, sample pre-treatment technology continues to evolve and expects to achieve the purification and enrichment of complex environmental samples through the development of new adsorbents. Metal-organic frameworks (MOFs) are a class of novel porous materials with high porosity, ultrahigh surface area, adjustable internal functionality and excellent thermal and solvent stability, exhibiting great advantages in the field of sample pre-treatment technology. In this paper, novel MOFs and their composite materials are developed and applied as adsorbents for sample pre-treatment. The main contents are summarized as follows:1. Novel cellulose/zeolitic imidazolate frameworks-8 composite microspheres have been successfully designed and fabricated. Macroporous/mesoporous cellulose microspheres were prepared successfully by sol-gel transition method, and effect of process parameters on the structure and morphology of microspheres were investigated. Then, the composite microspheres with hierarchical structure were fabricated through zeolitic imidazolate frameworks-8 in-situ hydrothermal growth on cellulose microspheres. The composite microspheres as-prepared were characterized with multiple techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface areas test.2. The novel cellulose/zeolitic imidazolate frameworks-8 composite microspheres were applied as SPE sorbent for environmental polycyclic aromatic hydrocarbons efficient extraction and sensitive analysis with HPLC. Main factors affecting extraction efficiency were thoroughly investigated, such as sorbent amount, sample volume, extraction time, desorption conditions, organic modifier volume and ionic strength. Our method for PAHs analysis exhibited high sensitivity and accuracy, good linearity in a wide concentration range with R2 ranging from 0.9988 to 0.9999. And satisfactory recoveries have been achieved with good precision (RSDs<9.8%).3. ZIF-7?UiO-66 and HKUST-1 coated fiber was prepared by a versatile strategy based on the use of multifunctional mussel-inspired polydopamine. The MOFs coating were characterized with multiple techniques such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). After the comparison in the same experimental conditions, UiO-66 exhibited better extraction efficiency for most analytes and was selected as SPME coating for PAHs analysis in environmental water samples. Under optimum extraction conditions, such as elution solvent, elution time, extraction time and salt concentration, UiO-66 coated fiber has been successfully developed for environmental PAHs analysis.