Thesis of Ensiye Kazemi

Synthesis of mesoporous silica (KCC-1) and preparation of its electrospun nanocomposites for application in microextraction of environmental pollutants

By: Ensiye Kazemi

Supervisor: Dr.Mahmood Kazemzad, Dr.Ali Aghakhani

Materials and Energy Research Center

February 2015

Abstract: In this thesis, a novel nanofibrous composite of the KCC-1/nylon 6 was prepared by the electrospinning techniques and used for adsorptive microextraction of ibuprofen from aqueous media. Fist fibrous silica nanospheres (KCC-1) were synthesized via a hydrothermal method and new solvent system and characterized successfully. The scanning electron microscopy (SEM) images showed spongy spherical morphology with uniform distribution with an average diameter around 293 nm. Synthesized KCC-1 nanospheres with a high BET specific surface area (576 m2 g-1) and BJH average pore diameter of 3.28 nm considered as a mesoporous material. Then mesoporous silica KCC-1 was modified by functional groups such as Metformin, 1- Methyl imidazole, Sulfonic acid and C8. The composite of the KCC-1/nylon 6 was fabricated by preparation of the dispersion of the nanosilica (10-50% w/w) in a solution of nylon 6 (15% w/v) in formic acid. Upon applying a high voltage the nanocomposite of KCC-1/nylon 6 was obtained. KCC-1 nanospheres were arranged in line along the nylon 6 fibers like a rosary beads. Based on the SEM images, even at higher silica content, a well distributed nanocomposite was obtained. The prepared KCC-1/nylon 6 composite showed 29% higher BET specific surface area than pure nylon 6 nanofibers and makes it a good candidate to be used as a sorbent material for environmental polutant. Finally, the nanocomposite fibers were used for the adsorptive microextraction of ibuprofen from aqueous media by TFME method. The effective parameters on the extraction and desorption including of pH, salt, extraction time and desoption solvent were optimized. The nanocomposite fibers of nylon 6/ KCC-1 modified with sulfonic acid, as the best adsorbent for ibuprofen in acidic environment, showed 20% absolute extraction efficiency for 45 min extraction time. Good dynamic linear range (50-2000 ng mL-1) and detetion limit (20 ng mL-1) and relative standard deviation (11%) was obtaned for the developed method. Real water sample including local tap water and bottled water showed negative result for ibuprofen in the liner range of the deveopled method.

 AWT IMAGEAWT IMAGE

Images from left to right:

1- SEM images and diameter distribution of KCC-1 nanospheres

2- SEM images of KCC-1/nylon6 composite nanofibers based on diferent percent of KCC-1 nanospheres: a 0, b 20, c 33, d 50 %(w/w)

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