Thesis (M.Sc.)-Cairo University, 2024.

Bibliography: pages 136-157.

Nanoceramic materials are desirable materials for use in a variety of applications due to their strength, biocompatibility, hydrophilicity, insulating and/or conducting properties, and wear resistance. Nano cordierite
(2MgO: 2Al2O3: 5SiO2), nano mullite (3Al2O3.2SiO2) and nano tetragonal zirconia (t-ZrO2) were synthesized using modified sol-gel and co-precipitation methods. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) combined with Energy Dispersive X-ray Analysis (EDAX) and the Brunauer-Emmett-Teller (BET) surface area technique were used to characterize the phase composition, particle size, microstructure and surface area of the synthesized nano cordierite (2MgO:2Al2O3:5SiO2), nano tetragonal zirconia (t-ZrO2) and nano mullite (3Al2O3.2SiO2). The nano-crystallite size of the synthesized nano-ceramic materials was also calculated using the XRD technique and the Debye-Scherrer equation.
Waste materials like bagasse ash and sawdust ash have recently been recycled and reused in the production of porous ceramics to increase the porosity of samples leading to protecting the environment from their side effects. So, the synthesized nano t-ZrO2 and nano mullite were combined with nano cordierite and bagasse ash, or sawdust ash (as pore-forming agents) as waste materials to prepare nano cordierite- nano mullite – nano
t-ZrO2 macroporous ceramics. Nano t-ZrO2 was added from 0 to 30 wt.% at the expense of nano mullite to nano cordierite (70 wt.%). Bagasse ash or sawdust ash (as pore-forming agents) were added to the mixed compositions in fixed weight percentages of 10%. All prepared samples were sintered at different temperatures (1350, 1375 and 1400 °C). The influence of nano mullite, nano t-ZrO2, pore-forming agents (bagasse ash and sawdust ash) addition, and sintering temperature on the phase composition, densification parameters (BD and AP), cold crushing strength (CCS), microstructure and the pore size distribution of sintered samples were investigated. The XRD results showed a good crystallinity of the prepared macroporous ceramic samples and the main phase compositions were cordierite, mullite, tetragonal zirconia, and monoclinic zirconia except the sample containing 30%
t-ZrO2 showed an additional phase for zircon (zirconium silicate). The trend of BD, CCS, and AP exhibited a significant enhancement in BD, CCS and a decrease in AP with an increase in sintering temperatures as well as an increase in t-ZrO2 weight percentages. The BD ranges from 1.5 to 1.95 and 1.42 to 1.83 g/cm3, CCS ranges from 5.40 to 31.35 and 3.26 to 7.56 MPa and AP ranges from 46 to 51.13% and 50.16% to 55.92% for sintered samples containing bagasse and sawdust ash, respectively. Additionally, the microstructures and pore size distribution of the macroporous samples demonstrated that the average pore size was 12.77 µm and 12.07 µm for the samples containing bagasse and sawdust ash, respectively. The water contact angles assessments approve the hydrophilic and super hydrophilic nature of measured samples which were 41.80 o and 0 o, respectively.
Ion-selective electrodes are preferable to competing electrochemical methods for potentiometric detections regarding operating convenience, speed, and cost. The development of a novel class of carbon-paste electrochemical sensors that exploit synthetic cordierite (2MgO:2Al2O3:5SiO2) nanoparticles as an ionophore is investigated in this thesis. Cordierite nanoparticles were used to accelerate the electron transfer which refers to the extensive surface area, electrical characteristics, porous design, and nanoscale dimension. The modified carbon paste electrode (MCPE) has estimated the function of a selective sensor for strontium ion detection. Stable potentiometric behavior was proved by the electrode and displayed a significant response that was predicted in the concentration range of 1.0×10−6 -1.0×10−2 M (R2 = 0.998). The electrode detection limit and response time were 5.0×10−7 M and 6 s, respectively. As well as the electrode showed selectivity towards the Sr(II) ion in the vicinity of certain cation species and performed without being impacted by variations in pH within that pH range of (3-8). Additionally, the performance of the postulated electrode toward Sr(II) ion determination was detected in some real samples (plant origin) such as legumes (kidney bean), cereals (wheat), leafy vegetables (cabbage), stems (onion), roots (carrot), fruits (tomatoes) and nuts (almond)) with high recoveries and reproducibility through around 72 days. Subsequently, the outcome was assessed against the ICP technique's superior performance

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