Roles of metal, ligand and post synthetic modification on metal organic frameworks to extend their hydrophobicity and applicability toward ultra–trace determination of priority organic pollutants

Autor: Alireza Abbasi, Habib Bagheri, Hasan Javanmardi
Rok vydání: 2020
Předmět:
Zdroj: Analytica Chimica Acta. 1125:231-246
ISSN: 0003-2670
Popis: Implementation of metal organic frameworks (MOFs) in the separation science has attracted many researchers attention. In this study, the role of metal, ligand, the reaction condition and modification on the extraction efficiency of some MOFs was investigated. Among the prevalent reported MOFs, some members of the MIL and MOF–5 families were chosen, and eleven MOF–based sorbents were prepared by changing the metal and ligand type, reaction condition, and/or functionality through post synthetic modification (PSM). MIL–101 and MIL–101–NH2 based structures were initially synthesized based on the chromium and iron salts. Also, three zinc–based structures including MOF–5, [NH2(CH3)2]2 [Zn3(C6H4(CO2)2)4].DMF.H2O and [NH2(CH3)2]2 [Zn3((C6H4)2(CO2)2)4].5DMF were synthesized. The PSM hydrophobic–oriented products of MILs were obtained by their reactions with benzyl alcohol. The resulted MOFs were characterized by FT–IR, PXRD, SEM, BET, BJH, water contact angle and TG analyses. The extraction trends of these nanostructures were studied toward some priority environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs), chlorobenzenes (CBs), and benzene homologs. The extraction procedures were performed via adapting a home–made headspace needle trap extraction (HS–NTE) setup, and determinations were followed by gas chromatography-mass spectrometry (GC–MS). Among all the synthesized nanostructures, the chromium–based PSM product of MIL–101–NH–CH2C6H5 proves its improved extraction capability for most of the model compounds. Eventually, the superior MOF was applied as the extractive phase in a HS–NTE–GC–MS method for isolation and trace determination of PAHs, in tea, coffee, and some other environmental water samples. Under the optimized conditions, the linear dynamic range (LDR) was in the range of 1–1000 ng L−1 (R2 > 0.992) while the limits of detection (LOD) and limits of quantification (LOQ) values were 0.1–0.2 and 0.3–0.7 ng L−1, respectively. Also, the extraction capability of the Cr–based MIL–101–NH–CH2C6H5 was compared with commercial polydimethyl siloxane–divinyl benzene (PDMS–DVB) fiber coating. The intra–and inter–day relative standard deviations for three replicates at the concentration levels of 20 and 500 ng L−1 were in the range of 4–7% and 5–10%, respectively. The needle–to–needle reproducibility was also found to be in the range of 6–10%. Acceptable relative recovery values at the concentration levels of 20 and 500 ng L−1 ranged from 89 to 98%, showing no significant matrix effect.
Databáze: OpenAIRE
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