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Electrospinning of Core-shell Nanofibers for Extraction and Determination of Pesticide Residues from Aquatic Media

Rezvani, Omid | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46847 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Bagheri, Habib
  7. Abstract:
  8. Porosity and high surface area is a profound concept for creating advance materials. Nanofibers are an important class of nano materials which would be used as novel sorbents because of their high surface to volume ratio as a result of long lengths and nano-to-micro-scale diameters. Electrospining is a simple method for producing fine nanofibers from different meterials such as, polymers, composites and ceramics to prepare highly efficient sorbents. Moreover, electrospining has been developed for fabricating nanofibers with core-shell structures. These structures in compared with conventional fibers have gained higher attentions due to their high aspect ratios and flexiblity in surface properties and specific mechanical function (hardness and tensional strength). In this project an attempt is made to fabricate appropriate nano-based sorbents by core-shell electrospining. This approach should lead to the production of nanofibers with high porosity and high aspect ratio, capable of extracting low levels of pesticides. Hence, core-shell nanofibers of polyvinylpyrrolidone-Polybutylene Terephthalate/polypyrrole was fabricated and directly was coated on an aluminum foil. Afterwards by removal of central fibers using immersion of nanofibers in double distilled water and under sonication, hollow nanofibers (nanotube) was obtained. Finally, fabricated hollow nanofibers was used as sorbent for extracting of triazines using micro-solid phase extraction. Also, the effect of different parameters affecting the extraction and desorption processes such as, concentration of polymeric solutions, salt addition, sample pH, extraction and desorption time, type of desorption solvent, number of desorption steps and desorption volume was investigated and finally, the optimum amount of each parameter was achieved. Linear dynamic range of proposed method was in the range of 0.3-500 ng mL-1. Detection limits were in the range of 0.05-0.09 ng mL-1. The relative standard deviation (RSD%) for three extractions at the concentration of 1 ng mL-1 was in the range of 4-8%. The modified nanofibers was used for analysis of real samples such as, north paddy water and north well water and also wheat sample. The relative recoveries for these samples was obtained in the range of 94-97% for water samples and 82-84% for wheat sample
  9. Keywords:
  10. Micro-Solid Phase Extraction ; Polypyrrole ; Polyvinylpyrolidon ; Triazins ; Gas Chromatography/Mass Spectrometry (GC/MS) ; Core-Shell Nanostructure ; Electrospinning ; Hollow Nanofiber

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