Chemical reduction method

Preparation of nickel powders from nickel salt by ultrasonic chemical reduction method... 

Suhtnicion nickel powders luive been synthesized successfully from aqueous NiCh at various tempmatuTKi and times with ethanol-water solvent by using the conventional and ultrasonic chemical reduction method. The reductive condition was prepared by flie dissolution of hydrazine hydrate into basic solution. The samples synthesized in various conditions weae claractsiz by the m ins of an X-ray diffractometry (XRD), a scanning electron microscopy (SEM), a thermo-gravimetry (TG) and an X-ray photoelectron spectroscopy (XPS). It was found that the samples obtained by the ultrasonic method were more smoothly spherical in shape, smaller in size and narrower in particle size distribution, compared to the conventional one. 

The major synthetic steps for the preparation of Au colloids by the chemical reduction method are presented in Figure 5. 

Recently, Chaudhari compared the activity of dispersed nanosized metal particles prepared by chemical or radiolytic reduction and stabilized by various polymers (PVP, PVA or poly(methylvinyl ether)) with the one of conventional supported metal catalysts in the partial hydrogenation of 2-butyne-l,4-diol. Several transition metals (e.g., Pd, Pt, Rh, Ru, Ni) were prepared according to conventional methods and subsequently investigated [89]. In general, the catalysts prepared by chemical reduction methods were more active than those prepared by radiolysis, and in all cases aqueous colloids showed a higher catalytic activity (up to 40-fold) in comparison with corresponding conventional catalysts. The best results were obtained with cubic Pd nanosized particles obtained by chemical reduction (Table 9.13). 

Some other chemical reduction methods that may be applied for laboratory generation of small quantities of potassium from its salts at high temperatures require a suitable reducing agent such as carbon, calcium, or calcium... 

To speed up this latter step, higher current densities In the electrolysis step or other selective chemical reduction methods should be applicable. 

Originally, the reduction of carbon disulfide was carried out electrochemically, but this procedure is not practical for preparative amounts of material.8 In 1979, a chemical reduction method was discovered by Steimecke.9 The present procedure is based on that 1979 report, but sodium is substituted for potassium (which presents an explosive hazard).10 Practical improvements have allowed the development of a one-pot procedure that is easily scaled up to provide 70-80 g of material. 

Kan-Sen Chou and Chiang-Yuh Ren, Synthesis of nanosized silver particles by chemical reduction method. Materials Chemistry and Physics 64 (2000) pp. 241-246. 

Recently, a chemical reduction method was developed for the isolation of Gd-EMFs directly from raw soot [75]. Reduction of the raw soot with an Al-Ni alloy in toluene-THF gave rise to a solution of Gd Cg2 and Cd2 Cgo anions, whereas empty fullerenes remained in the soot. The anions of Gd Cg2 and Gd2 Cgo react with aqueous NaOH to form water-soluble Gd-metallofullerols, which are potential MRI contrast agents. It is particularly interesting that pure Gd2 Cgo was isolated directly from the raw soot merely by tuning the ratio of toluene to THE... 

Nitroso, azoxy and azo groups are also reduced under the conditions used to effect the hydrogenation of nitro compounds. Nitroso compounds form the amine with about the same ease as is observed with the corresponding nitro compound. a-Nitroso-chlorides are hydrogenated to oximes over platinum if the reaction is stopped when the color disappears (Eqn. 19.30). No other catalyst is effective for this reaction, which is also superior to all chemical reduction methods. The use of other catalysts, as well as further hydrogenation over platinum, results in amine formation. ... 

Cao J, Sun J-Z, Hong J, Li H-Y, Chen H-Z, Wang M (2004) Carbon nanotube/CdS core-shell nanowires prepared by a simple room-temperature chemical reduction method. Adv Mater 16 84... 

Certain microorganisms, such as Escherichia coli and Staphylococcus albus strains will reduce dehydroascorbic acid. This reduction has been used for the estimation of ascorbic acid after its oxidation in extracts by ascorbic acid oxidase (S27) and also in the chemical reduction methods as a way of reducing dehydroascorbic acid to ascorbic acid. The reduction is not specific for L-ascorbic acid, but interfering compounds are unlikely in natural products. The use of this reducing action of bacteria has been improved by Mapson and Ingram (M8). 

Pt/Al-B catalyst was made by reducing by gaseous hydrogen (4% in Ar) at 300°C a catalyst precursor that was obtained by incipiently wetting Al-B by chloroplatinic acid solution. The bimetallic Pt-Ru catalysts were prepared on Al-B by co-impregnation of the metal salts followed by the chemical reduction (method-1) at the same temperatures that were used for the monometallic catalysts, as described briefly above. 

Focusing attention on fee other two (chemical) reduction methods, it is observed from rows 1 and 2 of Table 2 that reduction method 1 generates more active as well as more C=0 bond hydrogenation selective catalyst, as conqtared wife method 2. In case of Al-A-based catalysts a similar effect of fee reduction method was found on fee activity (see rows 1 and 4 in Table 1) of fee catalysts. 

How is aluminum metal produced by electrolysis Why can t simpler chemical reduction methods be used ... 

Benzoyl peroxide can be analyzed by HPLC, polarography, and chemical reduction methods. In the latter method, excess sodinm... 

The interface between two immiscible electrolyte solutions offers the means to combine two-phase catalysis, colloid catalysts, and electrocatalysis. In the study of Lahtinen et al. [158] citrate-stabilized palladium and gold colloids were prepared by a traditional chemical reduction method. The voltammetric response of a system with an aqueous colloid and an electron donor in the organic phase revealed an irreversible voltammetric wave as the potential was swept positive. The response was detected only in the presence of both the colloid and the electron-donor DCMFc. The response was concluded to result from heterogeneous charging of the colloid with electrons from DCMFc. 

Guzman, M.G., Dille, J., Godet, S., 2009. Synthesis of silver nanoparticies by chemical reduction method and their antibacterial activity. Int. J. Chem. Biomol. Eng. 2, 104—111. 

Also, there are several other chemical methods utilized in the preparation of nanoparticles, including the chemical reduction method, irradiation method, electrochemical method, pyrolysis (Figure 15.1) which are described briefly below. 

Because GO is a poor conductor, the electrical conductivity of ECP-GO can he increased hy the reduction of GO to RGO in the composite film. Despite of the large variety of available chemical reduction methods for GO, the electrochemical reduction is a quick, clean, practical, and safe method for the reduction of GO to RGO [78]. For the electro-chemical reduction of GO in ECP-GO composites, they are exposed to sufficiently negative potentials resulting in irreversible reduction of GO to RGO [79], whereas the ECP can be brought back to the electrically conducting state by appl5dng a positive potential to the film. 

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