Loading...

Novel Sol Gel– and Electrospun– Based Nanostructure Sorbents for Extraction of Drugs and Pollutants

Asgari, Sara | 2019

522 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 51884 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Bagheri, Habib
  7. Abstract:
  8. The main purpose of this dissertation was to synthesize nanostructured adsorbents based on the sol–gel and electrospinning methods and implement them to the trace determination of the desired analytes from different matrices. In the first and second chapters, a summary of the sol–gel and electrospinning methods along with a glance on extraction methods are presented. Then, the implemented projects are presented in the consecutive chapters.In the first work, third chapter, silica nanofibers were successfully produced using electrospinning method. In this process, sol–gel was formed during electrospinning and then, the backbone polymer was removed by heating. To obtain a thin layer of silica nanofibers, the influencing parameters such as backbone polymer types, imprinting time and the components ratio were explored. The data obtained from Fourier transform infrared spectroscopy and thermogravimetric analysis revealed that the polyamide moiety was removed after heating. The extraction efficiency of the electrospun silica nanofiber mat was compared with the same silica precursor sol–gel produced by bulk and electrochemical approaches. The data obtained from the online micro–solid phase extraction–liquid chromatography analysis demonstrated the superiority of the electrospun silica nanofibers. Comparison of MIP and NIP (ratio of 3.3) proved the efficiency and selectivity of the prepared silica nanofibers to the atrazine, template molecule. The limits of detection and quantification of the method under optimized condition were 1.6-1.8 and 5.3-6.0 μg L-1, respectively.In the second research, fourth chapter, a selective 3–D molecularly imprinted interpenetrating polymer (MI–IPN) sorbent was synthesized for microextraction in packed syringe (MEPS) of carbamazepine from urine sample. An interlocked homogeneous polystyrene–silica gel polymer was synthesized by in–situ radical polymerization method. The styrene monomers were incorporated throughout the sol–gel matrix during its formation. Carbamazepine, as the MIP template along with naproxen and dexamethasone were examined to prove the MI–IPN selectivity and efficiency by analyzing urine samples. The existence of two separated interlocked polymeric networks led to the formation of appropriate spaces among the 3–D structure to specifically allocate the desired template for a convenient MIP procedure. The feasibility of the developed method was confirmed by obtaining acceptable analytical data regarding the selective isolation of carbamazepine for urine samples (MIP/NIP ratio of 4.7).In the third work, fifth chapter, a cryogel–based interpenetrating polymer network–solid phase extraction (Cryo–IPN–µSPE) method was developed and optimized for isolation of selected antibiotic residues from food and aqueous samples. The significant variables such as sample volume, desorption solvent volume, sample flow rate, and pH were optimized using a central composite design (CCD) to find optimum conditions. The validated Cryo–IPN–µSPE method, coupled with HPLC–UV, was implemented for determination of selected antibiotics in honey, urine and wastewater samples. The LOD and LOQ values for antibiotics were in the range of 17-50 µg kg-1 and 47-140 µg kg-1 in honey sample,respectively. In the fourth research, sixth chapter, a composite of electrospun polybutylene terephthalate nanofibers (NFs) and porous carbon nanosheets (CNS) was prepared. The entrapment of CNS between NFs lead to more porosity in the composite and made it a suitable medium for extraction purposes. The prepared NFs-NCS was used as thin film microextraction for isolation of selected drugs from a urine sample in a 96–well plate system. The developed method provided the acceptable experimental results for extraction of rupinurole, risperidone and citalopram. The use of NFs-NCS and ultra–performance liquid chromatography–mass spectrometry, provided a very fast, sensitive and selective analytical method for the desired drugs. The obtained LODs in the range of 0.05-0.5 µg L-1 showed the significant efficiency of the prepared nanofibers
  9. Keywords:
  10. Sol-Gel Method ; Electrospun Nanofibers ; Molecularly Imprinted Polymers ; Cryogenic ; Interpenetrating Polymer Network ; High Performance Liquid Chromatography ; Environmental Pollutant ; Antibiotic

 Digital Object List

 Bookmark

No TOC