Carbon in copper

In copper carbon residues are an indicator for the co-precipitation of organic additives during the electrowinning of the cathodes. These inclusions have to be kept as low as technically possible. Carbon contents near the surface of copper plates or sheets allow to draw conclusions on the rolling process and the auxiliary materials used for it. 

---

Oxidizing fusion has also been used successfully to determine carbon in copper. 

The determination of carbon in copper can be carried out without difficulties provided that the blank value is determined accurately and that the surface of the sample is correctly treated before analysis. 

Copper is thought to be noneatalytic to carbon deposition in all gas atmospheres, and owing to the extremely low solubility of carbon in copper, inert to the metal dusting reaction. Copper-based alloys have recently been reported in the patent literature [13, 14] to be resistant or immune to earburisation, metal dusting and coking. Thus, the addition of copper to niekel, which forms a near perfect solid solution, may be able to suppress or... 

Dissolve 180 g. of commercial ammonium carbonate in 150 ml. of warm water (40-50°) in a 700 ml. flask. Cool to room temperature and add 200 ml. of concentrated ammonia solution (sp. gr. 0 88). Introduce slowly, with swirling of the contents of the flask, a solution of 50 g. of chloroacetic acid (Section 111,125) in 50 ml. of water [CAUTION do not allow chloroacetic acid to come into contact with the skin as unpleasant burns will result]. Close the flask with a solid rubber stopper and fix a thin copper wire to hold the stopper in place do not moisten the portion of the stopper in contact with the glass as this lubrication will cause the stopper to slide out of the flask. Allow the flask to stand for 24-48 hours at room temperature. Transfer the mixture to a distilling flask and distil in a closed apparatus until the volume is reduced to 100-110 ml. A convenient arrangement is to insert a drawn-out capillary tube into the flask, attach a Liebig s condenser, the lower end of which fits into a filter flask (compare Fig.//, 1) and connect the... 

Benedict s solution Is prepared as follows. Dissolve 86-5 g. of crystallised sodium citrate (2Na,C,H(0, l 1H,0) and 50 g. of anhydrous sodium carbonate in about 350 ml. of water. Filter, if necessary. Add a solution of 8-65 g. of crystallised copper Sulphate in 50 ml. of water with constant stirring. Dilute to 500 ml. The resulting solution should be perfectly clear if it is not, pour it through a fluted filter paper. 

The pure acid does not react in the cold with sulfur, selenium, tellurium, carbon, silver, copper, zinc, iron, chromium, or manganese, but slowly dissolves mercury and tin (20). At higher temperatures, lead, mercury, tin, and sulfur react rapidly, eg ... 

Pentafluorobenzene. Pentafluoroben2ene has been prepared by several routes multistage saturation—rearomati2ation process based on fluorination of ben2ene with cobalt trifluoride reductive dechlorination of chloropentafluoroben2ene with 10% pabadium-on-carbon in 82% yield (226,227) and oxidation of penta uorophenylbydra2ine in aqueous copper sulfate at 80°C in 77% yield (228). Its ioni2ation potential is 9.37 V. One measure of toxicity is LD q = 710 mg/kg (oral, mouse) (127). 

In addition to the requirement to conform to steam purity needs, there are concerns that the boiler water not corrode the boiler tubes nor produce deposits, known as scale, on these tubes. Three important components of boiler tube scale are iron oxides, copper oxides, and calcium salts, particularly calcium carbonate [471-34-1]. Calcium carbonate in the feedwater tends to produce a hard, tenacious deposit. Sodium phosphate is often added to the water of recirculating boilers to change the precipitate from calcium carbonate to calcium phosphate (see also Water, industrial water treatment). 

Total carbon in beryUium is determined by combustion of the sample, along with an accelerator mixture of tin, iron, and copper, in a stream of oxygen (15,16). The evolved carbon dioxide is usuaUy measured by infrared absorption spectrometry. BeryUium carbide can be determined without interference from graphitic carbon by dissolution of the sample in a strong base. BeryUium carbide is converted to methane, which can be determined directly by gas chromatography. Alternatively, the evolved methane can be oxidized to carbon dioxide, which is determined gravimetricaUy (16). 

In these processes, a carbon monoxide containing gas is fed to an adsorber bed containing copper, typically dispersed on a high surface area support such as alumina or carbon. The copper is present predominately as Cu", which selectively adsorbs carbon monoxide. The remainder of the gas stream passes through the adsorbent bed. The carbon monoxide is then removed from the adsorbent by lowering the pressure. Figure 6 shows a typical process for a CO-PSA process. Process conditions are typically adsorption pressures of 0.68—204 MPa (6.8—20.4 atm) and temperatures of 313—373 K. Regeneration occurs at reduced pressure or by vacuum. 

Tribasic coppersulfate is usually prepared by reaction of sodium carbonate and copper sulfate. As the temperature of the reaction contents increases so does the size of the resulting particle. For use as a crop fungicide, intermediate (40—60°C) temperatures are used to obtain a fine particle. When lower temperatures are used to precipitate basic copper(II) sulfate, products high in sulfate and water of hydration are obtained. 

Tube-side headers for water sei vice are made in a wide variety of materials carbon steel, copper alloy, cast iron, and lead-hned or plastic-lined or specially painted carbon steel. 

Carbochem - Supplies carbon and other chemical products based in copper, cerium, nickel, and cobalt. http //www.carbochem.com. 

Avoid fitting copper alloy pipes upstream of carbon steel equipment. Salts of carbon from copper-base pipes can dissolve in solution and pose problems to carbon-steel components and vessels downstream. If the use of copper alloy pipes is unavoidable, sacrificial sections of mild steel pipe can... 

Joints in copper components may be a source of trouble. Copper/zinc brazing alloys may dezincify and consequently give rise to leaks . In some waters, soft solders are preferentially attacked unless in a proper capillary joint. Copper/phosphorus, copper/silver/phosphorus, and silver brazing alloys are normally satisfactory jointing materials. Excessive corrosion of copper is sometimes produced by condensates containing dissolved oxygen and carbon dioxide. Rather severe corrosion sometimes occurs on the fire side of fire-back boilers and on electric heater element sheaths under scales deposited from hard waters . 

Solders are anodic to copper, but soldered joints in copper pipes are widely used without trouble for cold supply waters possibly corrosion is restricted by the deposition of cathodic carbonate scales and the formation of insoluble lead compounds. Hot supply waters tend to be more aggressive and, where these are involved, it is wise to tin any copper which has a soldered joint. Electrolytes of high conductivity such as sea-water will also attack soldered joints in copper. 

The effect of pH on the corrosion of zinc has already been mentioned (p. 4.170). In the range of pH values from 5 -5 to 12, zinc is quite stable, and since most natural waters come within this range little difficulty is encountered in respect of pH. The pH does, however, affect the scale-forming properties of hard water (see Section 2.3 for a discussion of the Langelier index). If the pH is below the value at which the water is in equilibrium with calcium carbonate, the calcium carbonate will tend to dissolve rather than form a scale. The same effect is produced in the presence of considerable amounts of carbon dioxide, which also favours the dissolution of calcium carbonate. In addition, it is important to note that small amounts of metallic impurities (particularly copper) in the water can cause quite severe corrosion, and as little as 0-05 p.p.m. of copper in a domestic water system can be a source of considerable trouble with galvanised tanks and pipes. 

Chelants are particularly useful in maintaining very clean, deposit-free waterside conditions and can be employed in both FT and WT boilers. In practice, however, they are relatively indiscriminant in their reactions and under unsuitable conditions may seriously corrode carbon steel, copper, and copper alloy boiler components. Chelants also may react with any available oxygen under BW conditions and temperatures. 

Erythorbates are safe products and there are no harmful breakdown products, although when early formulations utilized ammonia as a PH buffer (and neutralizer for part of the carbon dioxide), copper corrosion problems resulted. However, erythorbates are not steam-volatile,and consequently there is no post-boiler oxygen scavenging potential available. Thus, in the event of complete breakdown of the product at high pressure, oxygen-induced, ammonia corrosion of copper may continue unchecked. 

Figure 22. Practical 2000-A anode. Features include 108 channels and/or grooves, YBD carbon impregnated with epoxy, electrolytic nickel plate on carbon, electrolytic copper plate on nickel, copper wool packing, and central copper conductor. The anode is 20 cm in diameter and 120 cm long. (Reproduced with permission from paper 933 presented at the May 1997 meeting of The Electrochemical Society in Montreal.)...

---