Impregnation with copper

Silica (mesoporous) impregnated with copper(ll) Laboratory solutions Ambient 5-6 As(V)... 

Figure 19. Influence of copper as a promoter on the reduction of Ni0/Si02. The NiO/Si02 sample is the same as for the experiments of Fig. 13. Part of the sample was subjected to a second impregnation with copper nitrate (total Cu added 0.4 wt%) calculated on the total NiO + Si02 weight) and calcined at 773 K in air for 5h. The apparent (or conventional) maximum degree of reduction, ama, corresponds to that obtained after 40 min. Reduction in pure hydrogen (lOOkPa) [81].

Hydrogen sulphide, phosphine PH3, and stibine SbH3, give a similar reaction. They may be removed by means of a purified cotton-wool plug impregnated with copper(I) chloride. 

Practically every type of separation that has been done by the column technique can also be carried out by thin-layer chromatography. Several papers and reviews were published on the various aspects of the technique. In addition to the books on chromatography [17,26-301, an overview of ion-exchange application of TLC was presented by Devenyi and Kalasz 311. Recent results on the separation of enantiomers have been reviewed by Mack, Hauck and Herbert (32.33) (enantiomer. separation on an RP-18 plate, impregnated with copper salt and proline derivative as chiral selectors) and Lepri, Coas and Desideri, using a microcrystalline triacetylcellulose stationary phase, or modified beta-cyclodextrins in the mobile phase 134.35). 

Kim et al. [40] made an attempt to oxidize phenol in water solutions using a monolith reactor. Alumina-washcoated cordierite monoliths (62 celLs/cm ) impregnated with copper... 

FIG. 15 Effect of pH on the uptake of arsenic by activated carbon impregnated with metallic copper (1) As(Ill), no metal added (2) As(III). impregnated with copper (.3) As(V), no metal added (4) As(V), impregnated with copper. (Adapted from Ref.. 301.)... 

The XRD diffraction patterns of the zeolites impregnated with copper(II) chloride were identical to that of the parent materials. This shows that no copper chloride clusters had been formed with diameters above 2.5 nm, the minimum detectable size [11]. 

After aqueous impregnation, copper(II) chloride is present as a highly dispersed phase on the surface of zeolites. After a thermal treatment in nitrogen and subsequently in ammonia, the copper appears to be present as isolated ions in the zeolite. Therefore, impregnation is a suitable method to prepare non-acidic copper-zeolites. As copper vaporization is limited with a catalyst not having a cation excess, a zeolite pre-exchanged with ammonium ions and consecutively impregnated with copper seems especially suitable. 

The catalysts were prepared by impregnation with excess solution of the supports and then subsequently dried in a rotary evaporator. The palladium employed was the granular metal dissolved in nitric acid (Productos Quimicos Monterrey) while the copper was its nitrate (Aldrich). All of the catalysts were dried at 120°C for 8 h and subsequently calcined at 500°C in flowing air for a further 8 h. For the bimetallic Pd-Cu catalysts the supports were initially impregnated with copper, dried and calcined then subsequently impregnated with palladium then dried and calcined. The drying and calcination routines between each impregnation were the same as that employed with the monometallic catalysts. The catalysts were characterised by atomic adsorption spectroscopy, TPR, TPD-NH3, TPD-CO, these values have been published elsewhere [5]. 

The Deacon process for the manufacture of chlorine from hydrochloric acid is a scientific method, whereby hydrochloric acid gas and air are passed over hot brick-work impregnated with copper salts. The products are chlorine gas and water, the copper salts acting merely as carriers of oxygen. The only losses are that of the hydrogen of the hydrochloric acid and the oxygen of the air. 

Among non-precious metals, copper-chromium combinations seem to be the most effective catalysts for CO exhaust elimination. For example, monoliths and pellets impregnated with copper-chromite have been reported to have activities near those of precious metal-based auto-emission control catalysts (ref. 1,2). This comparison has also been extended to the oxidation of CO with NO (ref. 3,4), another important auto-emission pollutant. 

A complementary approach is to use reverse phase silica gel impregnated with a chiral selector [55,56]. Chiral plates comprising reverse phase Cjg impregnated with copper A,Ar-dialkyl-a-amino acids, e.g. proline have been used successfully for the separation of a variety of enantiomeric mixtures, e.g. d- and L-dopa. The resolution is based on ligand exchange, the enantiomers to be separated forming chelate complexes with the copper ion of differing stabilities. 

A thirty fold increase in the capacity of carbons for HjS removal was found after their impregnation with copper [121], It was explained by ability of copper to activate oxygen, increase in the rate of radicals formation and thus oxidation of hydrogen sulfide to elemental sulfur. 

The effectiveness of modern masks depends on both physical adsorption and chemical inactivation of the threat agent. For example, in the M17 protective mask the adsorbent, known as ASC Whetlerite charcoal, is charcoal impregnated with copper oxide and salts of silver and chromium.6 The M40 protective mask uses an ASZ impregnated charcoal, which substitutes zinc for the hexavalent chromium (CrVI). The Centers for Disease Control and Prevention and the National Institute for Occupation... 

Contact with wet woods, in particular beech wood [24]. Any wood impregnated with copper preservatives is especially damaging. 

FIGURE 5.11 Amount of hydrogen sulphide adsorbed from its mixture with air on different carbons. (1) activated carbon fiber, ACF (2) oxidized activated carbon fiber OCF, (3) oxidized activated carbon fiber impregnated with copper, (4) oxidized carbon fiber impregnated with iron. (After Svetlana, S., Kartel, N.T., and Tsyba, N.N., Carbon 02, Intern. Conf. on Carbon, Beijung, 2002, Paper PI 68 D. 063. With permission.)... 

Lorenzen et al. studied the adsorptive removal of arsenic using three activated carbons prepared from different source raw materials and observed that all three activated carbons impregnated with copper were capable of ranoving arsenic effectively from aqueous solutions at a slightly acidic pH of 6. They also observed that the adsorption was not related to the surface area of the carbon but was enhanced by the presence of ash in the activated carbon. Sen and De determined the effect of several parameters such as, the time of equilibration, pH, and adsorbent dose on... 

Saxena et al. studied the adsorption of dimethyl methyl phosphonate (DMMP) as a stimulant for Sarin, which is a highly toxic warfare gas agent. The adsorption was carried out on an activated carbon, a whetlerite and activated carbon impregnated with copper hexafluorocacetylacetonate (1) copper trifluoro acetyl-acetonate and a copper oxime. The adsorption isotherms are Type 1 of the BET classification and show maximum adsorption in the case of activated carbon (1). The amount adsorbed was 68.5 weight percent on (1). The adsorption involved both physisorption and chemisorption. TGA and IR studies of DMMP loaded activated carbons, and mass spectric analysis of the decomposition products showed that the decomposition products were methyl methyl phosponic acid and methylphosphonic acid. 

Only a few chiral stationary phases for TLC enantiomeric separation have been developed. The separation principle most frequently used is based on a ligand-exchange mechanism. The appropriate commercially available precoated plates consist of optimized RP-carriers impregnated with copper salts and chiral selectors based on amino acids. Typical applications of this separation mechanism are mainly amino acids and their derivatives (229,230), as well as hydroxy carboxylic acids (231). Figure 10 shows a concrete example of the application to separation of a racemic mixture of phenylalanine. 

A filter paper impregnated with copper sulfate solution gives a dark brown color on exposure to AsHsi SbH, has no effect. ... 

Copper sulfate Impregnation with copper sulfate, now seldom used, is usually revealed by the grass-green color (due to copper tannates). On adding a drop of 1 % solution of potassium ferrocyanide, a brick red to brown-red color appears (copper ferrocyanide). If the color later turns dirty greenish blue, the copper sulfate contained some iron sulfate. 

Metals that are very sensitive to hydrogen sulfide, such as copper and silver, are protected by enclosing them in paper impregnated with copper or zinc compounds. These materials are not corrosion inhibitors in a strict sense since they adsorb gaseous sulfur compounds to prevent reaction with the silver or copper. 

Figure 9.10 shows an example of a non-adjustable steel filling secured to an alnminum structure. Canvas fabric impregnated with copper salts should not be attached to steel or alnminum structures, or used as a rain cover for steel or aluminum equipment. 

Retention (hRfi, hRf2) and Resolution a, R ) Data of Racemic Aromatic Amino Acids on 10 x 10 cm RP-18W F254S HPTLC Plates Impregnated with Copper (II) Complex of L-/V-Decylhistidine under Optimized Elution Conditions [10]... 

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