Anode Copper

Aromatic perfluoroaLkylation can be effected by fluorinated aUphatics via different techniques. One category features copper-assisted coupling of aryl hahdes with perfluoroalkyl iodides (eg, CF I) (111,112) or difluoromethane derivatives such as CF2Br2 (Burton s reagent) (113,114), as well as electrochemical trifluoromethylation using CF Br with a sacrificial copper anode (115). Extmsion of spacer groups attached to the fluoroalkyl moiety, eg,... 

In both the sulfuric and nitric acid processes, the dorn metal must be in shot form prior to treatment to secure a reasonably rapid reaction. A number of steps also may be required in processing the dorne metal to remove miscellaneous impurities, particularly in treating material from copper-anode slime (31). 

Hydrocarbon, typically natural gas, is fed into the reactor to intersect with an electric arc stmck between a graphite cathode and a metal (copper) anode. The arc temperatures are in the vicinity of 20,000 K inducing a net reaction temperature of about 1500°C. Residence time is a few milliseconds before the reaction temperature is drastically reduced by quenching with water. Just under 11 kWh of energy is required per kg of acetylene produced. Low reactor pressure favors acetylene yield and the geometry of the anode tube affects the stabiUty of the arc. The maximum theoretical concentration of acetylene in the cracked gas is 25% (75% hydrogen). The optimum obtained under laboratory conditions was 18.5 vol % with an energy expenditure of 13.5 kWh/kg (4). 

Manufacture and Recovery. Electrolytic copper refinery slimes are the principal source of selenium and its sister element, tellurium, atomic numbers 34 and 52, respectively. Electrolytic copper refinery slimes are those constituents in the copper anode which are not solubilized during the refining process and ultimately accumulate in the bottom of the electrorefining tank. These slimes are periodically recovered and processed for their metal values. Slimes generated by the refining of primary copper, copper produced from ores and concentrates, generally contain from 5—25% selenium and 2—10% tellurium. 

If the cations in solution are condensable as a soHd, such as copper, they can plate out on the cathode of the cell. As the same time, perhaps some hydrogen is also produced at the cathode. The SO can react with a copper anode material by taking it into solution to replace the lost copper ions. Thus the anode is a consumable electrode in the process. 

Copper-plating bath compositions of various types have been used. A typical bath formulation consists of 200 g copper sulfate crystals, 30 mL cone, sulfuric acid, 2 mL phenylsulfonic acid, and 1000 mL distUled water. A pure copper anode may be used a copper anode containing a trace of phosphoms reduces sludge accumulation in the plating bath. 

Copper anodes for use in acid copper plating solutions preferably contain a small amount of phosphoms [7723-14-0] usually 0.03—0.04 wt %, which retards chemical dissolution of the copper and thus the subsequent copper build-up. Typically, acid copper plating solutions increase in copper and require periodic dilution. Additionally, additives for brightening acid copper baths tend to last longer in plating tanks using phosphorized copper anodes. In cyanide copper solutions, phosphorized copper anodes should not be used. 

The electrolytic oxidation of quinoxaline at a copper anode gives pyrazine-2,3-dicarboxylic acid in excellent yield. A similar conversion may be effected with alkaline potassium permanganate, and a list of quinoxaline derivatives which can be oxidized with potassium... 

The Cu+2 ion drifts away into the solution but the electrons remain in the copper rod. They move up through the copper anode, through the wire, and enter the silver cathode. At the surface of this rod, the electrons encounter Ag ions in the solution. The electrons react with Ag+ ions to give neutral silver atoms which remain on the rod as silver metal ... 

Although iodides are more reactive than bromides, 2-(trifluoro-methyl)pyridine was obtained in 95% yield from 2-bromopyridine and CF3Br using an undivided electrochemical cell, DMF, and a sacrificial copper anode. CF3Cu was the reactive intermediate (92CC53). Photochem-... 

A thermal plasma system has been developed for the decomposition of methane. A schematic diagram of the experimental apparatus is shown in Fig. 1. The system consists primarily of D.C. plasma torch, plasma reactor and filter assembly. Plasma was discharged between a tungsten cathode and a copper anode using N2 gas. All the experiments were carried out at atmospheric pressure at 6 kW input electric power and N2 flow rate of 10 to 12 1/min. The feed gas (CH4) flow rates were varied from 3 to 15 1/min depending on the operating conditions, shown in Table. 1. 

Copper can be electro-deposited on to a silvered article the plating bath consists of 10 gm of copper sulphate in 100 gm water. The article is taken from the silvering bath, washed, and put wet in the plating bath—on to a copper cathode so that electrical contact is made to the silver. A copper anode is placed 1-2 cm above the article. The electrodes should be about the same size as the article. The current density should be about 0-05 amp/cm, and in 2-4 minutes a thin copper film should be made. If the current density is too high a granular deposit will be formed which will rub off, and if it is too low a non-uniform deposit will be formed. 

JusysZ. 1994. H/D substitution effect on formaldehyde oxidation rate at a copper anode in alkaline medium studied by differential electrochemical mass spectrometry. J Electroanal Chem 375 257-262. 

Read the entire laboratory activity. Using the above equations to guide you, form a hypothesis about how many copper atoms you expect to lose from the copper anode for each copper atom deposited on the cathode. How many electrons do you expect to pass through the circuit for each copper atom deposited at the cathode Record your hypothesis on page 166. 

These instructions will assume that you are plating a key. Clean the surfaces of the key and copper anode with steel wool. 

Place 30 mL of 3M sodium hydroxide solution in a 100-mL beaker. Immerse the key and copper anode in the solution for a few minutes. Remove with tweezers and rinse with distilled water. CAUTION Avoid skin contact with sodium hydroxide. 

Place the copper anode in the beaker, bending the strip to fit over the edge of the beaker. Secure the copper strip to the beaker using an alligator clip. See Figure A. 

Without switching the power on, connect the power supply and ammeter in a circuit with the plating cell. The copper anode is connected, via the ammeter, to the positive (red) terminal of the power supply. The key acts as the cathode and is connected to the negative (black) terminal. 

Remove the key and copper anode. Rinse with distilled water and blot dry with a clean paper towel. 

The electrolysis of a copper(II) sulfate solution is now considered in two different situations. In the first, a copper cathode and a platinum or carbon anode are used. The second case involves the use of a copper cathode and a copper anode. The solution has Cu2+ (aq) and S04 (aq) ions from the copper(II) sulfate and H+ (aq) and OH (aq) ions from water. Both Cu2+ (aq) and H+ (aq) ions migrate to the copper cathode, and the Cu2+ ions, being lower in the electrochemical series, discharge in preference to the H+ ions ... 

Advantages 1. More impurities can be tolerated in the copper anode since the electrode distances are relatively large. 2. The fabrication of anodes and the operation of the electrolytic cell is relatively simple. 3. More suited for refining copper of varied impurity contents. Advantages 1. Energy losses are comparatively less because of small interelectrode distances and contacts are practically eliminated. 2. The refining cycle is shorter due to higher number of electrodes and the anodic residue is relatively small. 

Refining operations have two principal wastestreams, waste electrolyte and cathode and anode washwater. Spent electrolyte is normally recycled. A bleed stream is treated to reduce copper and impurity concentration. Varying degrees of treatment are necessary because of the differences in the anode copper. Anode impurities, including nickel, arsenic, and traces of antimony and bismuth, may be present in the effluent if the spent electrolyte bleed stream is discharged. Tables 3.14 and 3.15 present classical and toxic pollutant data for raw wastewater in this subcategory. 

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