Amalgam extraction

Sodium amalgam extraction can thus be used to remove the whole of the samarium, europium, or ytterbium from mixtures with the other lanthanons. If the initial concentration of any of these is large, the efficiency of the reaction may exceed 75%. Low efficiencies characterize the removal of traces of these elements. Efficiency is enhanced by keeping the acetate solution as nearly free from sodium ion as possible and withdrawing much of the sodium amalgam before it can react. The extraction is an equilibrium process. 

The crude lutetium acetate solution remaining was extracted with five successive portions of sodium amalgam, each consisting of 0.25 g. of sodium in 7 ml. of mercury. Sodium ion was eliminated through precipitation of the hydroxide and reconversion to acetate. Three more series of similar sodium amalgam extractions were made. Lutetium material recovered from the final aqueous solution was spectroscopically free from ytterbium. 

Mercury has been known for many centuries, perhaps because its extraction is easy it has an almost unique appearance, it readily displaces gold from its ores and it forms amalgams with many other metals—all properties which caused the alchemists to regard it as one of the fundamental substances. 

Y-Phenylbutyric acid. Prepare amalgamated zinc from 120 g. of zinc wool contained in a 1-litre rovmd-bottomed flask (Section 111,50, IS), decant the liquid as completely as possible, and add in the following order 75 ml. of water, 180 ml. of concentrated hydrochloric acid, 100 ml. of pure toluene (1) and 50 g. of p benzoylpropionic acid. Fit the flask with a reflux condenser connected to a gas absorption device (Fig. II, 8, l,c), and boil the reaction mixture vigorously for 30 hours add three or four 50 ml. portions of concentrated hydrochloric acid at approximately six hour intervals during the refluxing period in order to maintain the concentration of the acid. Allow to cool to room temperature and separate the two layers. Dilute the aqueous portion with about 200 ml. of water and extract with three 75 ml. portions of ether. Combine the toluene layer with the ether extracts, wash with water, and dry over anhydrous magnesium or calcium sulphate. Remove the solvents by distillation under diminished pressure on a water bath (compare Fig. II, 37, 1), transfer the residue to a Claisen flask, and distil imder reduced pressure (Fig. II, 19, 1). Collect the y-phenylbutyric acid at 178-181°/19 mm. this solidifies on coohng to a colourless sohd (40 g.) and melts at 47-48°. 

The discovery of aqua regia by the Arab alchemist Jabir Ibn Hayyan (ad 720—813) provided a new extraction technology. Amalgamation of silver in ores with mercury was extensively used during the late fifteenth century by the Spaniards in Mexico and BoLvia. In 1861 the complex ores of the Comstock Lode, Nevada, were ground together with mercury, salt, copper sulfate, and sulfuric acid, and then steam-heated to recover the silver. 

The use of mercury for extracting precious metals by amalgamation has a long history and was extensively used by Spain in the sixteenth century when her fleet carried mercury from Almaden to Mexico and returned with silver. However, environmental concerns have resulted in falling demand and excess production capacity. It is still used in the extraction of gold and in the Castner-Kellner process for manufacturing chlorine and NaOH (p. 72), and a further major use is in the manufacture of batteries. It is also used in street lamps and AC rectifiers, while its small-scale use in thermometers, barometers and gauges of different kinds, are familiar in many laboratories. 

This value does not express the actual result since side and/or parallel reactions (e.g., H+ or 02 reduction) are not considered, but it does demonstrate the completeness of the cementation process and the effectiveness of this liquid-liquid extraction. During this extraction no external current flows through the phase boundary Hg (amalgam)/solution thereby establishing a potentiometric condition. The question of the potential difference at the phase boundary can be answered by constructing the experimentally accessible current-voltage curves for the reactions ... 

Fig. 3. Evans-diagram for the cementation of Cu2+ and Pb2 with zinc amalgam of different zinc content. If the zinc concentration in the mercury employed for this special extraction technique is low, the anodic zinc-dissolution current density may be diffusion controlled and below the limiting cathodic current density for the copper reduction. The resulting mixed potential will lie near the halfwave potential for the reaction Cu2+ + 2e j Cu°(Hg) and only Cu2 ions are cemented into the mercury.

Silver was formerly extracted by cyanide solution of Ag2S, the resulting Ag(CN)2 being treated with zinc to afford the metal roasted ores could also be extracted with mercury to give silver amalgam. Presently much silver is extracted by workup of the anode slime from the preparation of non-ferrous metals (Pb, Cu) pure silver is obtained by electrolysis of AgN03. 

The use of mercury for extracting silver and gold from their ores has been known for many centuries. Gold and silver form amalgams with liquid mercury, which is then distilled away to leave the pure precious metal. The... 

Intact biological membranes are far more complex systems than even the lipid extracts (see Fig. 6). In hardly any case do the lipid components exceed 50% of the dry weight, as membranes intrinsically contain numerous proteins and various glycoconjugates. This diversity is most pronounced in the plasma membrane (irrespective of the genera) which is effectively amalgamated with the non-lipidic... 

In many applications, such as the analysis of mercury in open ocean seawater, where the mercury concentrations can be as small as 10 ng/1 [468,472-476], a preconcentration stage is generally necessary. A preliminary concentration step may separate mercury from interfering substances, and the lowered detection limits attained are most desirable when sample quantity is limited. Concentration of mercury prior to measurement has been commonly achieved either by amalgamation on a noble-metal metal [460,467, 469,472], or by dithizone extraction [462,472,475] or extraction with sodium diethyldithiocarbamate [475]. Preconcentration and separation of mercury has also been accomplished using a cold trap at the temperature of liquid nitrogen. 

Half of the participants preconcentrated mercury from the seawater prior to determination, eleven by amalgamation on gold, one by amalgamation on silver, two by collection into oxidising solutions, one by organic extraction, and one by ion exchange chromatography. 

Yamamoto et al. [60] determined picogram quantities of methyl mercury and total mercury in seawater by gold amalgamation and atomic absorption spectrometry. Methyl mercury was extracted with benzene and concentrated by a succession of three partitions between benzene and cysteine solution. Total mercury was extracted by wet combustion of the sample with sulfuric acid and potassium permanganate. The proportion of methyl mercury to total mercury in the coastal seawater sampled was around 1%. 

Boss A development of the Washoe process for extracting silver from sulfide ores, invented in 1861. The chloride solution from the Washoe process was passed continuously through a series of amalgamation pans and settlers. 

Cazo [Spanish, a copper vessel] An ancient process for extracting silver from sulfide ores. The ore was boiled in a copper pot with salt and water addition of mercury gave silver amalgam. The copper served as the reducing agent. Described in 1640 by A. A. Barba who claimed that it had been operated since 1590. Around 1800 it developed into the Fondon process, in which the raw materials were ground together. 

Washoe A process for extracting silver from sulfide ores. The ore is heated with aqueous sodium chloride in an iron pot. The chloride dissolves the silver and the iron reduces it addition of mercury gives silver amalgam ... 

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