Deposits oxalate surface

The commonest staining trouble is iron stain —the blue-black stain caused by the interaction of soluble iron corrosion products and the natural tannins in wood. Hardwoods are generally more susceptible than softwoods. Steel wool should not be used for smoothing wood surfaces. Iron stains, if not too severe, can be removed with oxalic acid. Heavy contamination with soluble iron corrosion products usually results in migration and conversion to rust deposits in the wood. 

Post-precipitation involves the deposition of a sparingly soluble impurity of similar properties to the precipitate on the surface of that precipitate after it has been formed. It is particularly a problem where similar materials are being separated on the basis of their different rates of precipitation, e.g. calcium and magnesium oxalates or zinc and mercury sulphides. Copreci-... 

It forms numerous salts, some of which are listed in Ref 4, p 466 L. It has been used for determination of about 40 metals and several anions (Ref 2) also used for decontamination of radioactive surfaces and removal of insol deposits of Ca Mg soaps (Ref 4). Its application in volumetric titrations is discussed in Ref 3. Accdg to Alrose Chem Co, PO Box 1294, Providence, RI, EDTA dissolves Ca oxalate and serves as a sequestrene. The term sequestration may be used for any instance in which an ion is prevented from exhibiting its usual props due to close combination with an added material (Ref 4, p 1013 L) ... 

Objects of iron are often nickel-plated, or covered with a thin film of nickel, a white, hard metal which preserves its lustre in air, for it is not easily oxidisable. This is done by making the object to be coated with nickel the kathode and a bar of nickel the anode the liquid is a solution of oxalate of nickel and potassium. Iron objects are first coated with copper before nickelling. Silver and gold are best deposited from their double cyanides with potassium these salts are used because the deposit is harder and more uniform than if a halide be used. In thus coating objects, it is of importance that the current density, i.e. the ratio of the current to the area of the surface of the object to be coated, should be considered if this be too high, the metal will be deposited in a loose, flocculent condition. 

The inorganic mineral oxalate (e.g. whewellite CaC204 H20) sometimes deposits on top of or underneath rock varnish. Because this mineral contains datable carbon, the radiocarbon age can provide a minimum age for the underlying or overlying varnish. The most reliable research on radiocarbon dating of oxalates in rock surface contexts has been conducted in west Texas (Rowe, 2000 Russ et al., 2000)... 

Fujishima and coworkers reported a method to electrochemically deposit IrOx NPs at BDD electrodes [87]. The deposition process was based on preparation of a solution containing hydrolysis products of IrCl63 and oxalate, followed by anodic electrodeposition of IrO% from this solution onto an anodically pretreated BDD electrode. They showed that for conditions under which only limited deposition was allowed to occur it was possible to deposit about 30 nm diameter IrO% N Ps that were relatively homogeneously distributed across the surface. They examined these deposits for hydrogen-peroxide oxidation and observed significant oxidative current at potentials as low as + 0.35 V at pH 7. 

Anodic porous alumina is conventionally grown on aluminum foils, as indicated in Fig. 2. Similar self-assembled growth is achieved on Si by depositing an A1 thin film on the front side of a silicon wafer and forming an ohmic contact on the back side that is used as anode. The electrochemical solutions currently used are oxalic or sulfuric acid aqueous solutions. Details for the fabrication of thin alumina templates on Si with adjustable pore size and density are given elsewhere [8]. Electrochemical oxidation of A1 starts from the A1 surface and continues down to the Al/Si interface, following an anodization current density/time curve as shown in Fig. 3. 

A Basicity of Alkali Metal Ion-doped Oxides.- In order to increase a surface basicity, different species with donor properties may be deposited. The majority of these are the alkali metal salts or salts of the alkaline earth metals. The deposition of hydroxides carbonates, nitrates, oxalates and other organic salts of L,i, Na, K, Rb, Cs, Mg, Ca, Sr, Ba on different supports has been known for years. They are said to increase the basic properties of the surface. The mechanism of the creation of these new basic centres is not clear, because the acid-base properties of a support, on which the salt has been introduced, do not change monotonically with the quantity of introduced metal ions. It is possible, that the interaction of surface groups with the metal ions leads to several reactions,... 

Figure 16.11 Three electropolymerization procedures used for the deposition ofPPy films on iron (0.9 C cm corresponding to about 1.5-2 pm thickness) (a) electropolymerization at constant current (ImA cm ) of a 0.05 M oxalic acid + 0.05 M pyrrole solution (galstat) (b) one-step and two-step procedures (see text for explanation). (Reprinted with permission from Electrochimica Acta, Influence of the surface pre-treatment prior to the film synthesis on the corrosion protection of iron with polypyrrole films by T. Van Schaftinghen, C. Deslouis, A. Hubin and H. Terryn, 51, 8-9, 1695-1703. Copyright (2006) Elsevier Ltd)...

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