الفهرس 
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Abstract
Thesis title: ”Preparation of Iron-based Materials and Low-dimensional Architectures from Secondary and Pure Resources for Wastewater Treatment and Its Advanced Applications”
The work introduced in this thesis gave detailed protocols of synthesis iron and titanium-based modified nanoarchitectures. Also, the characterization of the as-prepared photocatalysts has included in this work to prove its novel compositions and structures. Finally, the thesis dealt with using the synthesized nanomaterials and their modified composites for wastewater treatment and advanced applications such as formic acid oxidation, nitrophenol reduction, hydrogen production and ammonia borane hydrolysis under solar light irradiation.
The thesis is divided into introduction part and three main chapters including: chapter 1, literature survey, chapter 2, experimental and chapter 3, results and discussion.
Introduction part
This part included a brief account on the problems of water contamination and energy need then photocatalysis as interested solution for these issues. Introduction comprehensively mentioned the various techniques applied for wastewater treatment and hydrogen production using photocatalysis.
Chapter-2: literature survey
This chapter displayed a literature survey on use of photocatalysis technology (reduction and oxidation processes during photochemical
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reactions) for wastewater treatment and hydrogen production on the photocatalysts surface via advanced oxidation processes and photoreduction processes, respectively. Also, it included definition for preparation methods and applications of mixed valent-iron minerals (magnetite and green rusts) and titanate nanomaterials.
Chapter-3: Experimental
This chapter contained itemized parts showing the origin and purity of chemicals used in this work. It displayed the synthesis of nanostructures and their modified composites under study using various methods such as coprecipitation/solvothermal/hydrothermal methods. Photocatalytic applications including formic acid oxidation, 4-nitrophenol reduction, hydrogen production and ammonia borane hydrolysis under solar light irradiation were stated in details.
Chapter-4: Results and discussion
This chapter was divided into four parts as following:
The first part discussed the coprecipitation method for preparation magnetite (Fe3O4) nanoparticles from ferrous sulfate as byproduct prepared by drying sulfate liquor in Egyptian iron and steel company in the region of Tibben, Helwan, Cairo, Egypt and ferric chloride. Nucleation and crystallization of magnetite nanoparticles were investigated. characterization of the as-prepared nano-magnetite has done using different analytical techniques such as XRD, XRF, SEM and TEM. Also, discussed the photocatalytic applications by the prepared magnetite for formic acid oxidation and
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hydrogen production from methanol/water under solar simulator.
The second part spotted on the synthesis of magnetite and modification of magnetite with silver and TiO2 by solvothermal/hydrothermal method then characterization of magnetite (Fe3O4) nanoparticles and their modified composites by various analytical techniques to explore the chemical and physical characteristics. Additionally, the application of these nano-materials for formic acid oxidation and 4-nitrophenol reduction into 4-aminophenol were studied.
The third part included the perpetration of the exceptional stable green rust (GR) then its characterization by different instrumental analyses to prove the GR composition and structure. Additionally, the as-prepared GR was applied for oxidation of formic acid and hydrolysis of ammonia borane into hydrogen under solar light irradiation.
The fourth part included the preparation of novel protonated titanate nanowires (HTO-NWs) from potassium titanium layered oxide (KTLO) that was prepared from TiO2 precursor via solid state method then its modification with with Pt-loaded-TiO2.The characterization of the prepared nanomaterials were explored by XRD, SEM, UV-Vis, TEM and Raman spectroscopy. The photocatalytic application of the obtained structures were studied for formic acid oxidation and hydrogen production from methanol/water under solar simulator.
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The previous four parts can be summarized as following:
Part 1: included the characterization of the dried ferrous sulfate as secondary resource from the Egyptian iron and steel company using XRF. The XRF revealed heptahydrate Fe(II) salt with traces of Si, Al, Co and sodium in the sample. Then preparation of magnetite was proceeded via coprecipitation method depending on both Fe(II) and Fe(III) salts as iron precursor. Magnetite nanoparticles were formed/crystalized at temperature ranged from 50 to 100 °C. The XRD pattern of magnetite appeared with a cubic structure as evidenced by the strong diffraction peaks at 30.2°, 35.5°, 43.2°, 57.1°, 62.8°. The average calculated crystallite size for magnetite is 16.0 nm, in agreement with FE-SEM, EDX and TEM results.
Moreover, detailed formation/nucleation study of coprecipitated magnetite using NaOH and NH4OH as precipitating agents was monitored. This study showed that nucleation of magnetite takes place in a few seconds (about 2 seconds)
The as-prepared magnetite from secondary resource revealed inactivity toward both of formic acid oxidation and hydrogen production from water/methanol under photo-irradiation. This due to non-suitability of its bandgap for charges separation.
Part 2: focused on synthesis of Ag loaded at magnetite-TiO2 nanostructured catalyst by solvothermal method:
XRD aanalysis of magnetite, magnetite-modified with TiO2 and loaded Ag@magnetite-TiO2 revealed the appearance of of
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magnetite and TiO2 phases in Fe3O4-TiO2 nanostructures. The Fe3O4 (311) and anatase (101) diffraction peaks noticed at 35.5 and 25.3, respectively. These all as-assigned peaks match with the reported XRD cards of magnetite (JCPDS NO.8411533) and of anatase-TiO2 (JCPDS NO.841285).
TGA analysis revealed the loss of adsorbed/hydrated water occurred at temperature around 100 °C then less than 5% weight loss was seen at temperature range from 150-700 °C due to oxidation of cored magnetite into hematite.
FE-SEM examined morphology of the formed structures of magnetite microspheres as agglomerates and display the dispersion of silver on Fe3O4/TiO2 nanoparticles with particle size about (20 nm), respectively. As well, N2 adsorption/desorption isotherms of magnetite before and after the modification showed the high surface area and pores size distributions of modified magnetite about 150 m2/g and 9.3 nm. The isotherms was type IV curves, displaying the mesoporous nature of silver loaded- Fe3O4/TiO2.
FT-IR spectra investigated the surface functional groups of the as-prepared nanostructures. The magnetite exhibit characteristic stretching vibration band of Fe-O appeared around 520 cm-1 and the broad band in 3000-3500 indicate the OH groups on the surface of Fe3O4-TiO2 and Ag@Fe3O4-TiO2. UV-Vis and PL analyses tested the optical characteristics of the 1wt% Ag-laoded-Fe3O4 was favorable as it has lower emission intensity and higher charges separation and bandgap about (1.6 eV).
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The Fe3O4-TiO2 photocatalyst without Ag loading was more active than P25-TiO2 (commercial catalyst) for oxidation of formic acid. UV-Vis spectrophotometer was used for monitoring the transformation of p-nitrophenol in water via photo-reduction into p-aminophenol by Ag@Fe3O4-TiO2 photocatalyst under solar light irradaition. The ultrafast reduction efficiency occurred within time less than 4 minutes by using 1% Ag@Fe3O4-TiO2 powder as the best modified magnetite sample due to higher electron-hole pairs separation and formation active interfaced core-shell nanostructures for photo-assisted redox processes.
Part 3: discussed the structural and oxidation stability characterizations of new exceptional stable green rust and its application for formic acid oxidation and hydrolysis of ammonia borane as following:
XRD instrument distinguished GRs with different compositions (i.e., interlayer anions) including a reference carbonate-type GR sample having carbonate anions in the interlayer space ([FeII4FeIII2(OH)12]·[CO3]·4[H2O]), prepared by a co-precipitation method reported in the literature as well as our novel GR synthesized by solvothermal treatment of anhydrous FeCl3 with sodium acetate trihydrate in glycerol at 200 °C for 24h. Our GR powder was stable in air for more than 90 days having basal spacing (d(003) value) of the green product was 7.94 Å, which was slightly larger than that reported for carbonate-type GRs (7.50" ~ "7.87 Å).
57Fe Mössbauer spectroscopy identified Fe(II)- and Fe(III) mixed valent ratio, of the green rust product and it revealed that the
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obtained hyperfine parameters, isomer shift (IS), and quadrupole splitting (QS), are in good agreement with those reported for GRs. The Fe(III)/{Fe(II) + Fe(III)} molar ratio of the green product is calculated as 0.94, which is considerably larger than that (0.25-0.33) reported for conventional GRs. These results indicate that the green product is a GR, and the crystallinity and layer charge density are unusually higher than that of conventional GRs.
The data of FT-IR analysis of the synthesized GR gave absorption band assigned to the carboxylate group, hydroxy group, C−H linked to the hydroxy group, and methyl group, which are characteristic of lactate anions (CH3−CHOH−COO−). The absorption bands due to the ether group were also detected, indicating that a part of lactate anions was oligomerized (the dimer, as an example). Moreover, the absorption band due to carbonate anions was detected at 1372 cm−1. Consequently, the present GR must have lactate anions, in addition to carbonate anions, in the interlayer space.
The XPS of the GR confirmed that C element corresponding lactate and carbonate anions was detected and no presence of Cl−. The data of TG-DTA curves measured in air of the GR, mass loss assignable to the oxidative decomposition of lactate anions (e.g., 330–360 °C and 480–680 °C), in addition to that assignable to CO2 liberation from the carbonate anions (e.g., 360–480 °C), was explored.
The CHN elemental analysis of the GR (C = 14.9 wt%, H = 3.2 wt%, N = trace), determined the molar ratio of lactate anions to
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carbonate anions was roughly estimated as " ~ "3.
The structure and composition determination of the formed GR was done by TBDF calculation. This study concluded that the simulated GR with a chemical formula of [FeII0.33FeIII5.67(OH)12]·3[C3H5O3]·1.33[CO3] and an orthorhombic unit cell of a = 3.276 Å, b = 19.659 Å, c = 23.918 Å and basal spacing of the simulated structure is 7.96 Å. The interlayer space of the GR is almost fully occluded with the lactate and carbonate anions due to the high layer charge density.
SEM, TEM, and AFM measurements of the obtained GR revealed that the present GR was mainly composed of nanoneedle- or nanobelt-like particles with a width of up to 150 nm and a thickness of up to 20 nm. TEM-energy dispersive X-ray (EDX) elemental analysis reveals that C element is entirely and densely distributed on/within each particle. This means the effective interlayer surface coverage of the present GR with lactate and carbonate anions is consistent with the other results.
The discussed exceptional stability of the present GR results from the carbonated-lactate GR as new structure that has low CO2 liberation out of carbonate-type GR composing of oxidation-retarding structural Fe(II) and high interlayer coverage with lactate and carbonate anions. So that our GR was stable at wide range of pH (2" ~ "12).