Citrate method

To prepare a high surface area amorphous phosphate precursor AIPO4, the citrate method was used [6]. To reach an Al/P ratio fixed at 1, 0.667 mole of A1(N03)3-9H20 (Merck) and 0.667 mole of (NH4)H2P04 (Merck) were dissolved... 

Therefore, by using the sol technique different 1 % Au/ C catalysts have been prepared using the same supporting material (activated carbon) but var5nng the preparation method with the aim of changing the particle size. PVA/ NaBH4, THPC/NaOH and citrate methods were used (Table 3) obtaining sol of different mean size in the order citrate > PVA > TMPC. 

Over the past 20 years, our laboratory has played a major role in the development of liposomal systems optimized for the delivery of conventional drugs, almost all of which are encapsulated by pH-gradient techniques. Our initial studies led to the development of several liposomal drug delivery systems in which uptake was driven by the citrate method of generating pH gradients (15,21-23,27,54—58). This was followed by the development of new... 

The TPR profiles of five Co-based perovskites prepared by reactive grinding with ZnO as additive for different milling times are shown in Figure 4(a-e), Figure 4f represents a LaCoOs perovskite prepared by the citrate method (referenee sample). 

Figure 4. TPR profiles of perovskites [24] a) LaCo03 washed after miling 1 hour with ZnO. b) LaCoOj washed after miling 2 hour with ZnO, c) LaCo03 washed after miling 3 hour with ZnO, d) LaCo03 washed after miling 5 hour with ZnO, e) LaCo03 washed after miling 10 hour with ZnO, f) LaCo03 synthesized by the citrate method.

The methods of analysis for phosphate solubility are not absolute, but empirical that is, they are based on practical experience. For example, the neutral ammonium citrate method is favoured in the USA because it has received over 100 years of study and experimentation, and provides an index correlating the laboratory results with the fertilizing value of water-insoluble phosphates under the conditions prevailing in the principal farming regions of the country. The particular solvent is therefore not an attempt to accurately reproduce the properties of the soil solution in the immediate vicinity of the... 

Colloidal gold- This can be prepared by the citrate method ( citrate gold ) (see also Chapter 29) using gold chloride and sodium citrate. H(AuCL ). 2% stock solution in water, stable for 1-2 yr at 4°C Dilute to 0 01% in water just before use. Sodium citrate 1% in water, freshly prepared All solutions are made up in double-distilled water of highest purity. Glassware has to be extremely clean (see Note 1). 

Teraoka et al. [41, 42] have applied the amorphous citrate process to prepare unsupported (or neat) and supported perovskites of the type LaMn, LaCo, LaMnCu, LaCoFe, LaCaCo, LaCaMn, LaSrMn, LaSrCo, LaSrCoCu, and LaSrCoFe. The use of the citrate method for preparing atomically homogeneous oxides on supports has been a very important extension of the citrate method over the years. Nitrates of constituent metals of the required perovskite were dissolved in water and mixed with an aqueous solution of citric acid (molar ratio of citric acid to total metals 1 1). Water was evaporated from the mixed solution... 

Markovich et al. employed citrate method to prepare LaMnOs sample with different particle sizes (20, 25, 30 nm), and investigated the size effects on magnetic properties (Markovich et al., 2007, 2008a,b). All NPs exhibited a paramagnetic to ferromagnetic transition at a Curie temperature above 200 K. It was foimd that the relative volume of the ferromagnetic phase increases for larger particle size. 

Kurumada, M., Ito, A., and Fujie, Y, Preparation of La2-xSrxGaQ gMgQ jOj.j electrolyte for solid oxide fuel cell by citrate method using industrial raw materials, J. Ceram. Soc. Jpn., Ill, 200-204 (2003). 

Slot and Geuze (1) improved the sodium citrate method for reducing gold salt by the addition of tannic acid to the reaction. The reaction rate, and hence the aze of the gold, could be controlled by the amount of tannic acid added, and monodisperse gold sols, ranging in size from 3 to 17 nm could be produced. 

This study focused on the deactivation of the Mn/Ce catalysts during reaction. The catalytic oxidation of phenol in aqueous solution to carbon dioxide, water and other side-products was selected as the test reaction. Catalysts were prepared from amorphous precursors using the citrate method and controlling the calcination temperature. Activity performance as a function of the time on stream was studied by simultaneously analyzing the conversion of phenol, the total organic carbon content of the catiyst, the cations eluted and the elemental composition of both cerium and manganese. Experimental conditions were widely varied. Fresh and used catalysts were also analyzed by BET surface area, X-Ray Diffraction and X-Ray Photoelectron Spectroscopy. 

Citrate method The preparation procedure consisted in the dissolution of the metal salts, namely Mn(N03)2 4H20 and Ce(N03)3 6H20, in distilled water, the complexation of the metallic cations with citric acid and the rapid concentration of the liquid by evaporation under vacuum. The viscous liquid was dried at 80°C and the amorphous precursor obtained was decomposed in air prior to calcination. Owing to the complexing property of the citrate anion, this procedure leads to the formation of finely dispersed two-phase systems or favours the formation of mixed oxide phases upon calcination, when these exist. Samples were calcined for 5 hours at 200, 300,400 or 500°C. 

By controlling the ratio of Ba/Ti in the citrate method mentioned above, Ba2"n04, BaTiOs and BaTi50i 1 were obtained as a single phase in each composition. The three mixed oxides and Ti02 were combined with nickel at the ratio of 1/0.3 by the citrate method and tested for the CH4 oxidation. 

Thin films of transition metal molybdates, with general formula MM0O4 where M = Co, Ni Cu and Fe, were prepared by the citrate method and deposited by spin-coating on a Si (100) substrate. All characterization data indicated that Co, Ni, and Cu-systems behaved as expected and pure phases P-C0M0O4, a-NIMo04 and a-CuMo04, respectively, were obtained without any... 

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