Synthesis, characterization and antibacterial effect of TiO2-based nanocomposites for water treatment application

Зохиогч:  А.Амаржаргал

Хамтран зохиогч:

Үйл явц: Бичиж хэвлүүлсэн

Бүтээлийн товч тайлбар:

Due to a global lack of access to potable water, a problem particularly affecting people in developing countries and the poor, improvement on existing water purification methods are necessary to provide more cost effective, accessible and efficient methods of water purification. Many scientist and technology developers working in the field of water treatment claim that nanotechnology is a major part of the solution for restoring the worid’s clean water resources. Nanotechnology includes the many techniques used to create structures at a size scale below 100 nm, including those used for fabrication of various nanomaterials. Specifically, when this concept is associated with environmental science and engineering to synthesize nanostructured functional materials which are used for environmental remediation, the technology is known with the term “environmental nanotechnology”.

This thesis is devoted to the development, synthesis, properties, and applications of nanocomposite materials for water treatment application. In particular, the first part of this work is focused on the preparation and characterization of novel silver-titanium dioxide (Ag-TiO2) nanocomposite particles by simple one pot refluxing technique, and it was tested against Escherichia coliform (E. coli), and the photoactive property was tested against methylene blue (MB) under ultraviolet (UV) and visible light irradiation.

Also, I have investigated the effect of annealing temperature on the physiochemical properties of TiO2 microrods in situ decorated with Ag nanoparticles (NPs) as a function of material parameters. In order to investigate the morphology, phase composition, crystalline structure, chemical state (valence), molecular structure and thermal stability of samples before and after annealing in air at different temperatures, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectra and thermogravimetric analysis (TGA) were performed. It was found that the annealing temperature influences the size of Ag NPs, which could influence its antibacterial effect.

For application purpose, Ag-TiO2 nanospheres were immobilized on PU (polyurethane) nanofibers to make new type of functional water filtration media. Due to immersion of electrospun mats in hot ethylene glycol solution which contained nanocomposites, spheres can bind to the nanofibers tightly and it was demonstrated by morphological and spectroscopic analysis. As consequence of the antibacterial and photocatalytic properties of the immobilized nanospheres, the PU composite nanofibers with high surface area could present new or additional functionalities than their single-organic counterpart.

In another work, we investigated the synergistic effect of fluidized tourmaline NPs with oscillating electric fields to the inactivation of E. coli in batch suspension. Different amounts of tourmaline NPs (5 to 100 mg) were dispersed in bacterial suspension (50 ml) and oscillating radio frequency (RF) electric field was applied at 3 V (equivalent of 1.5 V/cm electric field strength) and at varying frequencies (100 kHz and 1 MHz). The results showed high inactivation efficiency when combining fluidized tourmaline NPs and oscillating electric fields as compared to individual treatments of electric fields or tourmaline NPs only. The results showed 2.5 to 5-log reduction of viable E. coli concentration depending on the tourmaline concentration, electric field frequency and solution temperature. The present method shows a lot of promise as a novel disinfection technique for water treatment applications.

Similarly, tourmaline (TM) is hydrophilic in nature, while PU is hydrophobic. By incorporating TM into PU, we expected that the nanofibrous composite mat would have enhanced wettability due to the presence of TM at the surface of PU nanofibers and it was confirmed by our next study. The incorporation and homogeneous dispersion of 3 wt% TM in PU exhibited an increase in tensile strength and modulus of 75 and 87%, respectively from the neat PU. All TM/PU composite mats showed improved hydrophilicity compared to neat PU, and superhydrophilic surface with a contact angle of 130 was obtained at 5 wt% TM content. Furthermore, Bacterial tests showed high zone inhibition for both E. coli (Gram-negative) and Enterococci (Gram-positive) using the composite mats with increasing efficiency as with the increase in content of TM. The present TM/PU composite mat, which has improved mechanical properties, superhydrophilic surface, and good antibacterial properties, may be a potential candidate as an antibacterial material, in the field of health-protection textile and water filtration.

 

 

Хэвлүүлсэн газар: Chonbuk National University

Хэвлүүлсэн огноо: 2012/08/22

Хуудасний тоо: 262

Түлхүүр үг: #PU nanofibers #TiO2 microrods #inactivation #electric field #Ag NPs #Ethylene glycole #UV-radiation #nanocomposites #phase transition #antibacterial #titanium glycolate precursor #Electrospinning #antifouling #Tourmaline #hydrophilicity


Бүтээл нэмсэн:А.Амаржаргал

Монгол Улсын Шинжлэх Ухаан Технологийн Их Сургууль © 2019