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C. Liu et al, reported the formation of three dimensional mesoporous calcium oxide nanoparticles prepared by hydrothermal method. They used different surfactant like CTAB, P123 and PEG to fabricate new morphological structures of nanoparticles. Characterization techniques, such as SEM, TEM, TGA, FTIR, XRD and N2 adsorption-desorption were used. The addition of surfactants fairly effected morphology, size and pore size of particles. Factors like high temperature and long hydrothermal also contributed to small particle size. The carbon dioxide adsorption capacity of CaO nanoparticles was also determined .
O. B. Koper et al, (1997) studied the high chemical reactivities of calcium oxide and magnesium oxide nanoparticles to destroy toxins and hazardous chemicals. The ultrafine particles were produced by sol-gel method. A rational was allowed to develop by different characterisation techniques to explain high chemical reactivities of calcium oxide .
S. ganam et al, (2010) discussed the effect of nature of surfactant on the structural and chemical properties of nanoparticles. Very small sized nanoparticles were achieved by using different surfactants. Various morphologies of SNO2 nanoparticles depending upon surfactant were observed in scanning electron micrographs. The smallest particle was synthesised by using sodium dodecyl sulfate as surfactant .
M. A. Farrukh et al, (2012) investigated the effects of parameters of reaction during tin oxide synthesis via hydrothermal method. The parameters such as surfactant, reducing agent, and calcinations temperature were changed during synthesis reaction. Their effects were studied by TEM, SEM, EDX, XRD, FTIR and BET method .
H. Yazid et al, (2011) reported the formation of gold nanoparticles supported on Al2O3 by deposition precipitation method. The effect of pH on the formation of doped nanoparticles was studied by several pH adjustments i.e. above and below isoelectric point. The catalytic property of as synthesised nanoparticles was studied by reducing p-nitrophenol. The catalytic reaction was monitored by UV-VIS spectrophotometer. Characterization gold doped aluminium oxide nanoparticles were carried out by using SEM, EDX, TEM, XRD, atomic absorption spectroscopy and UV-VIS spectrophotometer .
O. Koper et al, (1993) reported that ultrafine particles of CaO synthesised by hydrothermal process, can destructively adsorb alkyl halides (carbon tetrachloride), even the intermediate product phosgene was also degraded when high concentration of calcium oxide was used. The resultant products of this reaction were calcium chloride, CaCO3, water and carbon monoxide gas. It was observed during kinetic studies that high surface area of nanoparticles was the reason of complete degradation .
O. Koper et al, (1994) studied the catalytic activity of nanoscale and commercial scale CaO by destructively adsorbing CCl4. Three types CaO nanoparticles were compared; commercially synthesized; CaO nanoparticles prepared by conventional method; and autoclave method. GC-MS was used to study degradation products of reaction. Autoclave synthesised NP-CaO were best formed because their catalytic activity was fairly higher than others .
K. Tanka et al, (1996) studied the photocatalytic degradation of trinitrophenol by TiO2 nanoparticles. The rate of degradation rise with increase in -NO2 group on phenol. The resultant products were polyhydroxylated moieties which suggested the mechanism of degradation. The -NO2 group and hydrogen was substituted to the nitrophenol molecule by hydroxyl group. Other aromatic compounds, like acetic and formic acid were also formed. The NO3Ì… and NH4+ were formed final degradation products .
M. H. Priya et al, (2005) studied the photocatalytic degradation of nitrobenzenes and their chlorinated substituents, under UV irradiation by using TiO2 nanoparticles as photocatalyst. The degradation reaction followed first order kinetics. Degradation rate was greatest for chloro nitrobenzenes. The mono-substituted nitrobenzenes more rapidly degrade than that of di-substituted nitrobenzenes .
M. Ksibi et al, (2003) investigated the photocatalytic degradability of substituted phenols present in was water, under UV irradiated TiO2. The degradation reaction of nitrophenols and hydroxy phenols followed pseudo first order kinetics. The photodegradability of nitrophenols was more sensitive towards pH than that of hydroxyl phenols as it tend to increase in acidic solution .
A. Odaka et al, (2008) reported calcium doped Al2O3 nanoparticles synthesized via sol-gel method. 0.10 mol% Calcium was doped on 5 mass% of Al2O3 seeding and calcined at 900 -C. These nanoparticles were used to fabricate highly dense alumina ceramics with finer grains. The particle size ranges between 0.66µm to 1.39µm. calcium chloride and polyhydoxoaluminum were used as precursors .
Z. Tang et al. (2008) reported the synthesis of calcium oxide by thermal decomposition at low temperatures. A sol-gel solution was prepared by using calcium nitrate as precursor and sodium hydroxide as precipitating agent in ethylene glycol medium. Characteristics of calcium oxide nanoparticles were studied by using different analytical techniques such as SEM, TEM, XRD and TGA. The last mentioned technique provided the fact that as-synthesized calcium hydroxide decomposed into calcium oxide at relatively low calcinations temperature 500oC in 1.5 hr .
R. Koirala et al, reported the flame spray pyrolysis (single nozzle flame) synthesis of calcium oxide doped with different metals (Hf, Al, La, W, Y). Ca12Al14O33 formation was revealed by x ray diffraction (XRD). There was no metal oxide peak for aluminium, tungsten and hafnium which suggested that the metals are incorporated in crystal lattice of calcium oxide. The molar ratio for Al/Ca was 3:10. It also showed great endurance towards sintering. The uptake ability of CO2 increased which ascribed to more aluminium atoms than Ca atoms in Ca12Al14O33 .