Precipitates, washing 288 precipitation metals

A silver-containing solution was basified with sodium hydroxide, and after filtration, ammonia solution was used to wash residual silver from the filter. Hydrazine sulfate was then added to precipitate metallic silver and when the mixture was heated it exploded. This may have been caused by formation of silver nitride and/or hydrazine-silver complexes, both of which are explosively unstable. 

Preparation of Zinc.—To obtain perfectly pure zinc is a task of some difficulty, so much so that the commercial article is never met with in a puro state, hut rather with variable quantities of arsenic, cadmium, tin, lead, manganese, iron, cobalt, and nickel. In order to obtain perfectly pure metal, the purest commercial ziuo should be dissolved in dilute sulphuric acid, filtered from any residue, and the foreign metals thrown down by Immersing plates of zinc in the liquid till no further deposit takes place. After separating the precipitated metals, which may be tin, lead, copper, cadmium, antimony, and a trace of arsenic, the solution is treated with carbonate of soda, and the carbonate of zinc, which Falls after filtration and thorough washing, Is dried, heated to redness to expel carbonic acid, mixed with charcoal or lampblack, and introduced into a crucible as represented in Fig. 23, placed in a furnace,... 

The metals in wash effluents are then extracted by complexation with added resins. A second approach to recovery of metals is to use a flocculant to separate the metals from soil particles following an acid wash. The metals are then concentrated and recovered by sodium hydroxide precipitation. 

Fluorobenzoic acid (13 10 g, 71 mmol) was dissolved in a solution of NaOH (25 g) and H20 (200 mL) the solution was then healed on a bath to ca. 100 C and stirred vigorously during the gradual addition of small portions of Raney Ni alloy (23 g). The mixture was stirred and heated for a further 3 h, then decanted from the precipitated metal, which was washed several times by decantation with warm water. The combined decantates were cooled and acidified with HC1 and the liberated benzoic acid was extracted with Et20. The extract was dried (Na2S04) and the Et20 removed to afford benzoic acid yield 5.2g (60 %) mp 122 C (hexane). 

A solution of appropriate salts can also be reduced in the liquid phase by the addition of an appropriate reducing agent. Sodium borohydride has been used but care must be taken to remove the boron from the catalyst, particularly for the mixed noble metals. This has been accomplished by adding a dilute borohydride solution to the mixed metal salt solution under rapid agitation followed by a thorough washing of the precipitated metal black with warm water.The use of hydrazine, formaldehyde or formic acid is preferred to borohydride since the byproducts of the reduction do not contaminate the catalyst. Another procedure is to use a ternary alloy and to leach out one component as in the preparation of Raney nickel and similar catalysts. 

Precipitate Wash with NH CI solution, dry and ignite spongy platinum. Filtrate Add zinc, filter the precipitated metals, wash with boiling water and add aqua regia. ... 

For precipitation, the synthetic process consists of addition of orthophosphate anions to an aqueous solution of the metallic salt. The precipitated metallic orthophosphate was then recovered by filtration, then washed, dried at 110°C and then calcinated at various temperature. By this method CaHP04, FeP04, Ce(FlP04)2, Zr(HP04)2 were obtained. The dissolution, reprecipitation process consists of preparing a metallic salt suspension of known solubility and in adding to it an aqueous orthophosphate anion solution in order to displace the following equilibrium ... 

According to Hargreaves, finely powdered ore can bo troatofl with hot hydrochloric acid. Lime is used to neutralise tho solution, which is then to be treated with zinc or iron for precipitation of the antimony. The precipitated metal is to be washed succossivoly with antimony chloride solution, hydrochloric acid, and water, and then fused with potash in crucibles. 

Anions that precipitate metal ions can be analyzed with EDTA by indirect titration. For example, sulfate can be analyzed by precipitation with excess Ba at pH 1. The resulting BaS04( ) is filtered, washed, and boiled with excess EDTA at pH 10 to bring Ba back into solution as Ba(EDTA). The excess EDTA is back titrated with Mg. ... 

The bubbles of CO2 that form are trapped in the dough, causing it to rise. Washing soda is used to precipitate metal ions that interfere with the cleansing action of soap. 

Synthetic manganese carbonate is made from a water-soluble Mn (IT) salt, usually the sulfate, by precipitation with an alkafl or ammonium carbonate. The desired degree of product purity determines the quaUty of manganese sulfate and the form of carbonate to be used. For electronic-grade material, where the content of K O and Na20 cannot exceed 0.1% each, the MnSO is specially prepared from manganese metal, and ammonium bicarbonate is used (26) (see Electronic materials). After precipitation, the MnCO is filtered, washed free of excess carbonate, and then, to avoid undesirable oxidation by O2, dried carefljlly at a maximum temperature of 120°C. 

Gibbsite usually contains several tenths of a percent of alkaU metal ions the technical product, precipitated from a sodium aluminate solution, contains up to 0.3% Na20 wliich carmot be washed out even using dilute HQ. Several authors (1,2) suggest that these alkaU ions are an essential component of gibbsite structure. 

The synthetic pigment is produced by one of several related procedures. The best quahty product is made by reaction of an aqueous solution of CdSO or CdCl with a solution of an alkaline metal sulfide or H2S. Zn, Se, or Hg may be added to the CdS to produce shade vatiations. After precipitation, the color is filtered, washed, and calcined in an inert atmosphere at 500—600°C. 

Double Decomposition. In the double decomposition reaction, an inorganic metal salt such as a sulfate, chloride, acetate, or nitrate reacts with the sodium salt of the carboxyUc acid ia a hot aqueous solution. The metal soap precipitate is filtered, washed, dried, and milled. 

The crystallization of wax from lubricating oil fractions makes better oil. This is done by adding a solvent (often a mixture of benzene and methyl ethyl ketone) to the oil at a temperature of about -5 F. The benzene keeps the oil in solution and maintains fluidity at low temperature the methyl ethyl ketone acts to precipitate the wax. Rotary filters deposit the wax crystals on a sp woven cloth stretched over a perforated cylindrical drum. A vacuum in the drum draws the oil through the perforations. The wax crystals are removed from the cloth by metal scrapers and ol vent-washed to remove oil followed by solvent distillation to remove oil for reuse. 

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