Potassium hydroxide chemical activation with

Platiimin is the most important of the palladium and platinum metals. It is grayish-white in color, and is very ductile. It can be welded at a red heat, and melted in an oxyhydrogen flame. Because of its very small chemical activity it is used in electrical apparatus and in making crucibles and other apparatus for use in the laboratory. Platinum is attacked by chlorine and dissolves in aqua regia. It also interacts with fused alkalis, such as potassium hydroxide, but not with alkali carbonates. 

Chemical.—Its solutions are acid in reaction, and probably contain the true arsenious acid, HjAsOa. They arc neutralized by bases, with formation of arsenites. Solutions of sodium or potassium hydroxid dissolve it, with formation of the corresponding arsenite. It is readily reduced, with separation of As, when heated with hydrogen, carbon, or potassium cyanid, and at lower temperatures by more active reducing agents. Oxidizing agents, such as HlfOj, the hydrates of chlorin, chromic acid, convert it into arsenic pentoxid or arsenic acid. Its solution, acidulated with HCl and boiled in presence of copper, deposits on the metal a gray film, composed of an alloy of Cu and As. 

Other physical properties, such as air permeability, interfiber pore size and porosity, were also studied. Activated carbon nanofibers were produced from eleetrospun PAN by chemical activation with potassium hydroxide (KOH) as the activating agent. They were characterized by morphology, Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller... 

FIGURE 12.5 Carbon monolith synthesis using resorcinol-crotonaldehyde polymer as carbon precursor. The polymerization took place in the pores of the large silica monoliths. Silver nanoparticles could also be dispersed in the silica template and transferred to the final templated carbon materials. The carbons retained the monolithic shape of the silica template and resisted chemical activation with potassium hydroxide (KOH). After activation, carbons exhibited microporous-mesoporous structures. (From Jaroniec, M. et al., Chemistry of Materials, 20, 1069, 2008. With permission.)... 

In acidic electrolytes only lead, because it forms passive layers on the active surfaces, has proven sufficiently chemically stable to produce durable storage batteries. In contrast, in alkaline medium there are several substances basically suitable as electrode materials nickel hydroxide, silver oxide, and manganese dioxide as positive active materials may be combined with zinc, cadmium, iron, or metal hydrides. In each case potassium hydroxide is the electrolyte, at a concentration — depending on battery systems and application — in the range of 1.15 - 1,45 gem"3. Several elec-... 

Sodium hydroxide (NaOFI), also called lye, soda lye, or caustic soda to distinguish it from potassium hydroxide (potash lye), is another important base. Flistorically, lye was obtained from the ashes of wood and used to make soap. Lye, however, is an extremely caustic chemical. It can cause serious chemical burns if it comes into contact with the skin and permanent blindness if it gets into the eyes. People had to be very careful while making the soap. They also had to make sure they got the mixture of lye and animal fat (lard) correct to keep from hurting themselves and their families. Because of its caustic (corrosive) nature, sodium hydroxide is also used as the active ingredient in oven and drain cleaners. 

Novel Manufacturing Processes. Different chemical activation processes have been used to produce carbons with enhanced adsorption characteristics. Activated carbons of exceptionally high surface area (>3000 m2/g) have been produced by the chemical activation of carbonaceous materials with potassium hydroxide (28,29). Activated carbons are also produced commercially in the form of cloths (30), fibers (31), and foams (32) generally by chemical activation of the precursor with a Lewis acid such as aluminum chloride, ferric chloride, or zinc chloride. 

For this reaction the amine (Aldrich Chemical Company, Inc.) from a freshly opened bottle is dried by distillation from active powdered calcium hydride. Addition over 1 min or less is required to avoid excessive foaming which has been observed when slow or dropwlse addition is used. Older samples of amine which contain water should be pre-dried overnight with potassium hydroxide. 

A unique active carbon having very high surface areas over 2500 m / gm, and extraordinary adsorptive capacities was developed in our laboratories. (1) This paper will describe its development, manufacture, properties, and uses. Until recently, samples of this carbon, which were provided worldwide for research and evaluation, were identified as Amoco Grades PX-21, 22, 23, and 24 in the powdered form and Amoco GX-31 and 32 in granular form. The carbon is made (Figure 1) by a direct chemical activation route in which petroleum coke or other carbonaceous sources are reacted with excess potassium hydroxide, KOH, at 400° to 500°C to an intermediate product that is subsequently pyrolyzed at 800°-900°C to active carbon and potassium salts. The salts are removed by water washing. 

An exceptional active carbon has been developed with a high effective surface area and high adsorptive capacity. It is prepared by a controlled chemical activation route using potassium hydroxide and a carbonaceous source, usually petroleum coke, to give a consistent quality product. It has been tested in a gamut of conventional and new uses with performance ratios averaging 2 to 4 times better than other grades of active carbon. Because of its unique structure and properties, it is likely that many new uses will be developed as it now becomes commercially available. 

During catalytic dehydrocondensation of 1,7-dihydrideorganocyclohexasiloxane with 1,4-bis(hyd-roxydimethylsilyl)benzene in the presence of potassium hydroxide, the reaction order, rate constants and activation energy were determined. Catalytic dehydrocondensation is the second order reaction. Some physical and chemical parameters of low-molecular copolymers are shown in Table 16. 

A novel method of chemical activation for producing some of the most active adsorbents so far developed was disclosed by AMOCO (Standard Oil Company) scientists in 1978 (Wennerberg and O Grady, 1978). These superactive carbons were prepared by the high-temperature heat treatment of petroleum coke or coal mixed with excess amounts of potassium hydroxide. After removal of the remaining KOH and other soluble material, the products were reported to have BET areas of over 2300 m2 g 1. 

Activated carbon modified chemically with potassium hydroxide via low temperature wet impregnation method for NOx adsorption was used. The present study examined adsorption and desorption behaviors and the accompanied surface chemistry. In particular, typical desorption behavior was examined after NOx was adsorbed at 100°C while the temperature was increased up to 600°C. This study found that the presence of a relatively larger amount of adsorbent delays surface oxidation. NOx has become oxidized while inducing three types of physical and chemical bonds on the surface of BHAC. The results concerning the surface properties after adsorption and desorption were analyzed using various instruments. Potassium existed on the surface without consumption as K-IAC was adsorbed by potassium oxide after desorption. 

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