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Three-Dimensional Polyamide Nanofibrous Scaffolds for Needle Trap Microextraction of Chlorobenzenes from Water Samples and Comparing them with Two-Dimensional Nanofibres

Manshaei, Faranak | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50003 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Bagheri, Habib
  7. Abstract:
  8. In the past decades, electrospinning has been widely used for the production of micro/nanofibers. In spite of the simplicity and effectivity of the conventional electrospinning for fabricating nanofibers, compact structure and small pores of the nanofibers hinder the efficient penetration of analytes during the extraction process. In order to overcome this issue, an applicable strategy called wet electrospinnig has been employed to enlarge the pore size of the electrospun scaffolds. By applying this technique, a collector was placed at the bottom of a solvent bath and highly porous foam from polyamide nanofibers was produced immediately after freeze-drying (3D electrospinning). Implementation of conventional electrospinning led to the formation of a dense layer of two-dimensional (2D) structures. The porosity, morphology, and thermal stability of 3D scaffolds have been characterized using various characterization methods including, Fourier transform infrared spectroscopy, scanning electron microscope (SEM) and thermogravimetric analysis. From SEM images of the 2D mats, it is demonstrative that nanofibers are closely packed, while in the 3D ones, they are freely packed, leading to more accessible sites in the extraction process. Eventually to ensure the comparative capability and efficiency of the abovementioned 3D scaffolds over 2D ones, both nanofibers types were synthesized using an appropriate polyamide solution and utilized as sorbent in headspace–needle trap devices (HS-NTD). The influencing parameters on this study including the type of solvent bath, the polyamide solution concentration, desorption time and temperature, sample flow rate, stirring rate, extraction time and temperature and ionic strength were optimized. Subsequently, the enrichment of the chlorobenzenes (CBs), as model compounds, have been investigated from the headspace of some aquatic samples including, Zayandeh Rood river, Oman sea and Inlet Treatment Plant followed by gas chromatography-mass spectrometry (GC-MS) measurement. At the optimum conditions, the calibration curves of analytes were studied in the range of 0.2-10 µg L-1 for chlorobenzene, 0.02-1 µg L-1 for 1,2-dichlorobenzene and 1,4-dichlorobenzene and 0.004-1 µg L-1 for 1,2,4- trichlorobenzene and 1,2,3,4-tetrachlorobenzene that correlation coefficients (R2) were obtained in the range of 0.9917-0.9992. The relative standard deviation were 3-8% for 200 ng L-1 chlorobenzenes spiked in double distilled water. The limit of detection and quantification were between 0.0008 and 0.003 µg L-1, 0.003 and 0.01 µg L-1 respectively
  9. Keywords:
  10. Chlorobenzene ; Wet Electrospining ; Polyamides ; Nanofibrous Scaffold ; Three Dimensional Scaffolds ; Needle Trap Device ; Needle Trap Extraction

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