الفهرس 
Chapter (1) IntroductionOnly 14 pages are availabe for public view
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Abstract
In recent years, the interest in mesoporous silica materials has grown due to their exceptional composition. These materials possess properties that make them highly useful and adaptable in various applications, including adsorption, catalysis, and drug delivery. The most notable features of mesoporous silica include: high surface area and pore volume, adjustable and uniform pore sizes between 2 and 50 nm, regular and uniform channels, and an order structure. To make these materials suitable for practical use, they must be functionalized to meet specific requirements.
In this thesis, two hydrothermal methods (autoclave and co-precipitation) were used to produce pure, ordered mesoporous MCM-41 (Mobil Composition of Matter No. 41) with good textural properties and a well-ordered pore structure. The effects of different types and concentrations of surfactants were investigated using three different surfactants: cetyl trimethyl ammonium bromide (CTAB), hexa decyl pyridinium chloride (pyridinium), and tetra decyl trimethyl ammonium bromide (myristyl) as templates at different molar concentration ratios (0.06, 0.12, 0.25, and 0.415 M) of the surfactant to the silica source. Additionally, a comparison between two different silica sources, TEOS and sodium silicate, as low-cost material was also investigated. The synthesized mesoporous MCM-41 were analyzed and characterized using standard equipments such as X-ray diffraction (XRD), nitrogen adsorption/desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy to establish structure-property relationships by determining the structure, morphology, and surface properties. It was found that the highest quality and highly ordered pure MCM-41 structure was formed using either CTAB or myristyl at concentrations of 0.25 M and 0.12 M, with the 0.25 M concentration producing a higher degree of ordered pure MCM-41 structure than the 0.12 M concentration. On the other hand, MCM-41 formed using pyridinium surfactant had a low degree of ordered structure but had a larger pore diameter and pore volume. In regards to the comparison between the different silica sources, all analyses confirmed the successful synthesis of highly ordered pure mesoporous MCM-41 prepared using sodium silicate or TEOS, especially that prepared using sodium silicate.
The incorporation of mesoporous MCM-41 with two different concentrations of indium (Si/In = 95 and Si/In = 90) was achieved through a hydrothermal-assisted method in order to improve the chemical and physical properties of MCM-41 and enhance its ion-exchange capacity by generating a large number of active sites. The structural, textural and morphological characteristics of the materials were evaluated using XRD, N2 adsorption-desorption, SEM-EDX, TEM, diffuse reflectance (DR) UV-vis spectroscopy and FTIR. The results showed that indium entered the skeleton of the MCM-41 molecular sieve to form In-MCM-41 composites. Additionally, the indium incorporation increased the oxidizing ability and the ion-exchange capacity through the generation of a large number of active sites, thus enhancing the adsorption activity. Furthermore, surface modification of In-MCM-41 (Si/In = 95) was accomplished using different concentration percentages (1, 3 and 5%) of cobalt through post-grafting method. The prepared materials were characterized and it was found that the cobalt modified the surface and enhanced the optical properties of In-MCM-41.
In parallel to successful synthesis of aforementioned mesoporous powders, films of pure polystyrene, pure MCM-41 and In-MCM-41/polystyrene were prepared by casting method. The prepared films were characterized using several techniques as XRD, TEM and FTIR. The electrical properties including dielectric measurements were also studied using Hioki LCR technique. The results revealed that the dielectric properties of the prepared films make them suitable for use in advanced electric power systems and electronic devices.
The abilities of the prepared highly ordered pure MCM-41 and hybrid MCM-41 powders were evalauted for removal of hazardous materials (such as dyes and pharmaceutical drugs) from water. The potential of highly ordered pure MCM-41 prepared using CTAB surfactant (MC0.25 sample) and In-MCM-41 samples for adsorption of Basic yellow 28 (BY28) and methylene blue (MB) dyes was investigated. The adsorption experiments revealed that the prepared samples were evaluated as effective adsorbents for BY28 and MB dyes removal from aqueous solutions with good recovery and recyclability.
The potential of the prepared highly ordered pure MCM-41 using myristyl surfactant (MM0.25 sample) for adsorption of tetracycline (TC) drug was investigated. The adsorption experiments revealed that MM0.25 sample could be used as effective adsorbent for the removal of TC drug from aqueous solutions.
The photocatalytic activity of cobalt modified In-MCM-41 (IMC1, IMC3 and IMC5 samples) was assessed for BY28 dye and TC drug degradation under sunlight irradiation. The photocatalytic experiments revealed that the prepared samples could be considered as promising photocatalysts for organic pollutants degradation.