الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Nanotechnology (NT) is an enabling technology that can help address key needs relating to energy, environment, health and agriculture in less
developed countries (LDCs). Among the developing countries, the key environmental issues are water & sanitation, land degradation, air pollution, climate change. The energy issues cover energy access, clean & advanced energy system and energy efficiency. International R&D efforts over the past five years applicable to the environmental sector include water purification, pollutants sequestration for improved analysis of microcontaminants, wastewater treatment especially to remove recalcitrant compounds, process improvement in liquid-liquid separation, desalination, better electrode sensors etc. In the energy sector, research will impact hydrogen production and storage, fuel cells, CO2 separation, air enrichment, processes like aromatics cracking in refineries biorefineries. Nanotechnology is expected to provide opportunities to developing countries to address many of their developmental needs. This thesis described different methods for preparation of nanoparticles of calcium carbonate and silica using simplified techniques. Calcium carbonate nanoparticles (CaCO3 NPs) have been prepared using both physical and controlled chemical reactions. CaCO3NPs were prepared by fractionation from large one using Developed Hydraulic Classifier system based on sorting particles by specific gravity. Different factors affecting the fractionation process were studied such as effect of water volume (L), effect of terminal (settling) velocity in different stages, effect of CaCO3 feed concentration, g/L, effect of flow rate (L/h) of the fluid on particles classifications. The CaCO3NPs obtained were characterized using SEM and showed that particles with size range 25 to 33nm can be fractionated using the developed Classifier system. CaCO3NPs were synthesized from CaCl2 and Na2CO3 by a new simple method using a newly designed apparatus which is described in this thesis. Different factors affecting the CaCO3NPs size were studied such as the effect of Ca2+ and CO3- concentration, PEG weight dissolved in Ca2+ solution, flow rate, temperature, media type, PEG weight dissolved on the receiving media, CO2 3- concentration, stirrer speed, media volume and additive dissolved within Ca2+ solution. The CaCO3NPs obtained by controlled chemical reaction, are characterized by TGA, XRD, IR, EDX and SEM and showed that the particles were spherical with size range 19-30 nm and the type of crystal was calcite. Silica nanoparticles (SiO2NPs) were prepared by two different methods: the top to down method using the wet mechanical attrition and the controlled chemical reaction technique. Preparation of SiO2 nanoparticles by wet mechanical attrition from white and yellow sand was investigated. The factors affecting the
obtained SiO2 particle size were studied such as milling period, water volume and initial sand particle size. The particles obtained were characterized by SEM, XRD, EDS and IR. The results showed high homogeneity of spherical particles produced with range particle size 22- 33nm, where using 8 hr milling. A simple controlled chemical reaction for synthesis of spherical silica nanoparticles was investigated. The SiO2 nanoparticles were characterized us SEM, XRD, EDS and IR. The synthesized SiO2NPs powder was organically modified by CYANEX 921. The prepared CaCO3NPs and SiO2NPs were potentially used in some environmental applications.