Preparation of a flexible polyurethane/graphene porous adsorbent for rapid sample collection

Autor: Chia-Hua Cheng, 鄭嘉樺
Rok vydání: 2019
Druh dokumentu: 學位論文 ; thesis
Popis: 107
In this study, the flexible solvent-resist porous polyurethane (PU) foam was first developed and prepared as an sorbent to collect chemical species from aqueous samples for chemical analysis and for potential related purposes. The flexible porous PU material was prepared by combing toluene-2,4- diisocyanate (TDI) as monomer, dimethylformamide (DMF) as solvent, cross-linker, catalyst, water, foam-stabilizer, and amino-modified graphene oxide for the foam formation under temperature-controlled viscosity. FT-IR and element analyzer were applied to observe functional groups in the foam to ensure the reactions occurred and on the surface. The SEM and BET were used to observe the porosity inside the foam and the surface area. TGA was used to test its thermal-stability. The flexible PU foam was examined as the sorbents for the flexible solid-phase extraction (F-SPE) to collect parabens, and the floating stirring sorptive extraction (FSSE) for bisphenol A (BPA) and alkylphenols extraction from aqueous samples. The optimal conditions to collect parabens by the F-SPE was by press/release the flexible PU foam within 1 min in pH 5 sample solution, then desorbed methanol. The extractants were combined and purged to dryness, then re-dissolved with methanol for HPLC-UV analysis. Detection of parabens is linear in 1- 110 ng/mL with determination coefficient 0.9947-0.9986. Detection limits are in 0.1- 0.2 ng/mL and the relative standard deviation (RSD) are in 2.97 - 5.87%. When detecting parabens in swimming-pond water, only methyl paraben was found, the recoveries for parabens were in 81.5 - 104.0%. When the flexible PU foam was applied for FSSE, optimal condition to collect BPA and alkylphenols was stirring the foam in sample solution for 20 min. After desorption with methanol, the extractant was purged to dry, re-dissolved with methanol for HPLC-UV analysis. The detections of BPA and alkylphenols are linear in 0.5-100 ng/mL with determination coefficient 0.9954-0.9988. Detection limits are in 0.04-0.1 ng/mL. When the method was applied to detect BPA and alkylphenols in household wastewater, BPA and nonylphenol were found, and recoveries were in 90.5 - 102.2% with 0.8 - 9.9% RSD. In this study, a flexible solvent-resist PU has been developed and applied successfully for both F-SPE and FSSE, with advantages of easy operation, rapidity, efficiency, sensitivity, in-expensiveness, and eco-friendly. It has highly potential to apply in varied areas for species extraction.
Databáze: Networked Digital Library of Theses & Dissertations
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