Formation, colloid, alkaline

Palladium catalysts have been prepared by fusion of palladium chloride in sodium nitrate to give palladium oxide by reduction of palladium salts by alkaline formaldehyde or sodium formate, by hydrazine and by the reduction of palladium salts with hydrogen.The metal has been prepared in the form of palladium black, and in colloidal form in water containing a protective material, as well as upon supports. The supports commonly used are asbestos, barium carbonate, ... 

Sulphates, silicates, carbonates, colloids and certain organic compounds act as inhibitors if evenly distributed, and sodium silicate has been used as such in certain media. Nitrates tend to promote corrosion, especially in acid soil waters, due to cathodic de-polarisation and to the formation of soluble nitrates. Alkaline soils can cause serious corrosion with the formation of alkali plumbites which decompose to give (red) lead monoxide. Organic acids and carbon dioxide from rotting vegetable matter or manure also have a strong corrosive action. This is probably the explanation of phenol corrosion , which is not caused by phenol, but thought to be caused by decomposition of jute or hessian in applied protective layers. ... 

This is only the beginning of a process which ultimately results in the formation of solid state hydroxides or oxides. Actually, the solution species present in neutral or alkaline solutions of transition-metal ions are relatively poorly characterized. The formation of numerous hydroxy- and oxy-bridged polynuclear species makes their investigation very difficult. However, it is clear that there is a near-continuous transition from mononuclear solution species, through polynuclear solution species to colloidal and solid state materials. By the way, the first example of a purely inorganic compound to exhibit chirality was the olated species 9.11. 

The formation of colloidal sulfur occurring in the aqueous, either alkaline or acidic, solutions comprises a serious drawback for the deposits quality. Saloniemi et al. [206] attempted to circumvent this problem and to avoid also the use of a lead substrate needed in the case of anodic formation, by devising a cyclic electrochemical technique including alternate cathodic and anodic reactions. Their method was based on fast cycling of the substrate (TO/glass) potential in an alkaline (pH 8.5) solution of sodium sulfide, Pb(II), and EDTA, between two values with a symmetric triangle wave shape. At cathodic potentials, Pb(EDTA)2 reduced to Pb, and at anodic potentials Pb reoxidized and reacted with sulfide instead of EDTA or hydroxide ions. Films electrodeposited in the optimized potential region were stoichiometric and with a random polycrystalline RS structure. The authors noticed that cyclic deposition also occurs from an acidic solution, but the problem of colloidal sulfur formation remains. 

A strategy to solve this problem is to separate the core formation process from the reduction of metal ions in the cores as shown in Scheme 1, and use solvent (EG) and simple ions (OH , etc.) as the stabilizers [11]. In the first step of this process, metal salts hydrolyzed in the alkaline solution of EG to give rise to metal hydroxide or oxide colloids, which were then reduced by EG at elevated temperature to produce colloidal metal nanoclusters in the... 

The alkaline EG S5mthesis method is a very effective technology for the chemical preparation of unprotected metal and alloy nanoclusters stabilized by EG and simple ions. This method is characterized by two steps involving the formation of metal hydroxide or oxide colloidal particles and the reduction of them by EG in a basic condition. The strategy of separating the core formation from reduction processes provides a valid route to overcome the obstacle in producing stable unprotected metal nanoclusters in colloidal solutions with high metal concentrations. Noble metal and alloy nanoclusters such as Pt, Rh, Ru, Os, Pt/Rh and Pt/Ru nanoclusters with small particle... 

Cadmium oxide, CdO, is a semiconductor with a band gap of 2.3 eV. Irradiation of CdO powder suspended in alkaline solution resulted in the formation of 0 when an electron acceptor such as ferricyanide was present in the solution. When RuOj was deposited onto the surface of the CdO particles the yield of decreased relative to naked CdO. In this respect CdO differs from Ti02 where RUO2 is mandatory if O2 evolution is to be observed Colloidal CdO has not been known until recently. It can... 

In the study of effects of ultrasound on the aqueous reactions of nickel, we found some interesting results, for example, the colloidal formation of Ni-DMG complex and degassing of NH3 during different experiments. When 25 ml of 0.001 M NiSC>4 solution was complexed with 5 ml of 1% dimethyl glyoxime (DMG) in faintly alkaline ammonia medium and sonicated for 30 minutes and compared with another set of 25 ml of complexed solution which was stirred mechanically, a colloidal solution of Ni-DMG complex was formed in sonicated condition. Particles of Ni-DMG complex did not settle even after keeping 3 1 h because of their smaller size, in sonicated solution, whereas in the unsonicated condition large particles of Ni-DMG complex settled down immediately. 

The formation of palladium oxide colloidal particles from an acidic palladium nitrate solution can be achieved by addition of an alkaline solution. The different steps, describing the chemistry involved in such a process are ... 

Most frequently, binding protein is added to the incubation mixtures as either serum or purified serum albumin. With human serum albumin, at equilibrium, the acceptor substrate will largely be protein-bound, when the bilirubin albumin molecular ratio is smaller than one (the dissociation constant of the first binding site of purified human serum albumin is approximately 7 X 10 M with 2 X 10 M for two additional binding sites) (J2). The first binding site of albumin, measured with rat serum, has a dissociation constant of about 5 X 10" M (M8). The unbound fraction will normally not exceed the very low solubility of the pigment. Addition of albumin to an alkaline solution of bilirubin, or its addition immediately after neutralization, prevents colloid formation, if the bilirubin albumin molecular ratio is smaller than one (B25). However, colloidal bilirubin, once formed, cannot be redissolved by the addition of albumin (B26). 

Some authors have used carrier-free enzymatic incubation mixtures at pH 8.0-8.3 (J5, P3, W12). In general, the final concentrations used (incubation at 37°C) were 5-10-fold higher than the solubility of bilirubin at 25°C (B25). Although solubility data at 37°C are not available, it is likely that in most instances the solubility was exceeded. It is not known whether, and to what extent, bilirubin is solubilized in an aspecific way, e.g., by dissolution in lipid membrane regions. Formation of colloidal bilirubin is possible (B25). Aging of the initial, supersaturated (B25) bilirubinate solution is expected to depend (B26) on the procedure of initial solubilization, the time elapsed between lowering the alkaline... 

Unilamellar vesicles have been used as a reactor for the synthesis of nanos-meter-scale magnetic particles (13,14). By adding alkaline solution to vesicles containing intravesicular solutions of Fe2+ and Fe3+, the Fe /Fe resulted in the formation of membrane-bound discrete particles of different ion oxide particles. These results together with the particle formation in microemulsion are not only of interest in colloid chemistry but also have significance in mineralization in biosystems, such as magnetotactic bacteria, where particles are formed within enclosed organic compartments. 

Clay minerals and clay colloids are the products of the advanced weathering of primary silicates. They are comprised mainly of silica and alumina, often with appreciable amounts of alkali and alkaline earth metals and iron. Most also have varying amounts of water bound to their surfaces and can take on a variety of different chemical and physical properties depending on the amount of water adsorbed. They have the ability to exchange or bind cations and anions and are capable of complex formation with a wide variety of organic molecules. 

The mixture is loaded out of the reactor into tank 16 to distil tetraethyllead. The tank should already be filled with ground sulfure and ferric iron chloride. Iron chloride reduces the alkalinity of the dross and improves its consistency due to the formation of the colloid solution of iron hydroxide ground sulfure is uniformly distributed through the dross, also improving its consistency and preventing clotting of lead particles. 

In our process we make use of a 10% solution of hydrochloroplatinic acid for preparation of our colloidal metal, and precipitate the activated metal in aU aqueous solution of gum arabic by reduction with hydrogen gas without first introducing any colloidal metal to promote the reduction of the platinum chloride solution. Skita used in many cases a promoter to stimulate the formation of colloidal metal (Impfmethode). This was prepared by reducing platinum solution with formaldehyde in alkaline solution. 

Fig. 52. Coagulation of mixed colloidal solutions of iron and silica. Environment A—slightly acid B—slightly alkaline. Concentration of recent waters indicated at right. / = total precipitation of iron and silica with formation of banded sediments // = same, with formation of mixed sediments /// = total precipitation of iron and partial of silica / F= total precipitation of iron, silica in solution V = incomplete precipitation of iron, silica in solution VI— no precipitation observed.

Formation of intrinsic colloids in natural waters can be excluded for radioisotopes of elements of groups 0, I and VII, and the probability that they may be formed is small for radioisotopes of elements of other groups as long as the concentration of the elements is low. In general, formation of carrier colloids by interaction of radionuclides with colloids already present in natural waters is most probable. Thus, clay particles have a high affinity for heavy alkali and alkaline-earth ions, which are bound by ion exchange. This leads to the formation of carrier colloids with Cs, Ra and °Sr. Formation of radiocolloids with hydrolysing species has already been discussed (section 13.4). 

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