Copper-ammonia solution washing

The content of inert gas (Methane, Argon, Helium etc.) in the feed gas depends on the methods of gasification and purification for the feed gas. The copper-ammonia solution washing process is employed to purify the synthesis gas, which is produced by coal as the raw materials, the content of inert gas in the synthesis gas is generally from 0.5% to 1%, more than 1% with the methanation purification process and only a few ml-m with the methanol and liquid nitrogen wash purification process. 

Dissolve 3 g. of copper sulphate pentahydrate and 1 g. of sodium chloride in 12 ml. of hot water, and add a solution of 1 g. of sodium bisulphite in 10 ml. of 5 per cent, sodium hydroxide solution. Shake, cool under the tap, and wash the precipitated wlute cuprous chloride with water by decantation. Dissolve the cuprous chloride in a few ml. of concentrated ammonia solution and dilute with water to 10 ml. 

Benzoin-a-oxime (cupron). Copper(II) ( > 50mg in ammoniacal solution). Add 2 per cent ethanolic solution of the reagent to the boiling solution, filter and wash the precipitate with hot dilute ammonia solution (1 100), then with hot water and finally with warm ethanol. Dry at 105-115 °C and weigh as Cu(C,4H,, 02N) (Section 11.26). 

Filter off the precipitated copper(I) chloride, wash it first with water, and then two or three times with ethanol. See how the salt reacts with hot concentrated hydrochloric acid and a 25% solution of ammonia. Let the hydrochloric acid solution and ammonia solution stand in the air. What do you observe ... 

Filter off the product and wash it with water. Put a small amount of the copper iodide into three test tubes. Pour an ammonia solution into one of them, concentrated hydrochloric acid into the second, and carefully heat the third tube on a gas burner. How can you explain the change in the colour of the copper(I) iodide when it is heated How can the instability of copper(II) iodide be explained ... 

Preparation of a Complex Ammonium Salt of Copper(II). Dissolve 0.5 g of finely triturated copper(II) sulphate pentahydrate in 12.5 ml of a 15% ammonia solution. If the solution is turbid, filter it. Slowly add 7.5 ml of ethanol to the filtrate and let it stand for a few hours in the cold. Filter off the formed crystals, wash them first with a mixture of ethanol and a concentrated ammonia solution (1 1), and then with ethanol and ether. Dry them at room temperature. Into what ions does the product dissociate in the solution Consider the structure of the complex ion from the viewpoint of the valence bond theory. 

In a 2-1. round-bottom flask, equipped with a stirrer, are placed 231 g. (0.5 mole) of the addition compound of /3-naphthalene diazonium chloride and mercuric chloride (p. 55), 700 cc. of acetone (b.p. 55-57°) and 189 g. (3 moles) of copper powder (Note 1). The mixture is quickly cooled to 20° and stirred for one hour. The mixture is treated with 700 cc, of concentrated aqueous ammonia solution (sp. gr. 0.9), mixed well, and allowed to stand overnight. The supernatant liquid is decanted the solid is collected on a Buchner funnel and washed successively with 25-cc. portions of water, acetone, and ether. After airdrying, the crude material is recrystallized from xylene, using decolorizing carbon. The crystals thus obtained are slightly yellow (Note 2) and melt at 241.5-243.50. The yield is 51-55 g. (45-48 per cent of the theoretical amount based on the addition compound used). 

Finally, one of the first continuous ion-exchange plants installed used a weak-acid resin to recover copper from rayon-fibre spinning solutions. In the Bemberg or copper(II) ammonium process,357 the spinning takes place in an addic copper sulfate solution, and the fibre is then washed in ammonia solution. The wash water contains as much as 30% of the copper required for the spinning operation and its recovery is important in economic and environmental terms. The copper is extracted as the cationic amine complex by the weak-acid resin, and is then stripped from the resin with the acidic spinning solution. Zinc is recovered in a similar manner from vicrose rayon-spinning operations. 

Dissolve 15.5g of barium nitrate (AnalaR) and 130 g of copper(n) nitrate trihydrate (AnalaR) in 450 ml of water at 80 °C. Prepare a solution of sodium chromate by dissolving 89 g of recrystallised sodium dichromate dihydrate in 200 ml of water and adding 112.5 ml of concentrated ammonia solution (d0.880). Add the warm solution (80 °C) of nitrates in a thin stream, with stirring, to the sodium chromate solution (at 25 °C). Collect the orange precipitate by suction filtration, wash it with two 50 ml portions of water, drain well and dry at 75-80 °C for 12 hours powder finely. 

A solution of /7-chloroaniline in water (100 ml) and hydrochloric acid (80 ml) is diazotized at 0° by a solution of sodium nitrite (15 g) in water (30 ml). The clear (filtered, if necessary) diazonium solution is added to a cold solution of cinnamic acid (30 g) in acetone (250 ml). Then sodium acetate (44 g), followed by a solution of copper(n) chloride (8.5 g) in water (20 ml), are added. The temperature may rise slowly to 16° when gas evolution has begun. The mixture is stirred at 14-16° for 3 h. By the end of the coupling reaction two layers will have been formed — an upper layer of dark green oil and a lower layer of pale green aqueous acetone. The whole is distilled in steam. The residue is extracted in benzene and washed several times with 3N-ammonia solution and then with water. Distilling off the benzene leaves a crystalline residue of 4-chloro-stilbene which recrystallizes from 2-propanol in shiny leaflets, m.p. 129° (40%). 

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