JPH0480337A - Method for extracting palladium - Google Patents

Abstract

PURPOSE:To efficiently and selectively extract palladium with a solvent, at the time of extracting palladium with an organic solvent from a palladium aqueous soln., by adding a chlorine gas to the above palladium aqueous soln. and preferably executing bubbling. CONSTITUTION:Palladium in an aqueous soln. is extracted and separated by using an organic solvent from other metals on the side of the organic solvent. As the above organic solvent, kerosine or the like insoluble in water can be used, and it is preferable to add sulfide thereto as well, by which the extracting efficiency of the palladium can be improved. In the above extracting method, a chlorine gas is added on the side of the palladium aqueous soln., and preferably, bubbling is executed. In this way, the metals other than the palladium are oxidized into an oxidizing state of a high level by the chlorine gas to be added and remains on the side of the aqueous soln., so that the purity of the palladium extracted on the side of the organic solvent increases, and its extracting efficiency can remarkably be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for solvent extraction of palladium from an aqueous hydrochloric acid solution containing palladium.

(Prior Art and its Problems) A solvent extraction method has conventionally been employed to separate palladium in an aqueous solution, and is considered to be a particularly effective means for separating platinum-palladium. Dialkyl sulfides are suitable solvents for the selective extraction of palladium, and although they have excellent selectivity for palladium, they do not improve the solubility of the extracted species in the organic phase, or may cause precipitation of organic matter or generation of a third phase. Alcohol may be added to the organic phase for prevention purposes. However, when alcohol is added to the organic phase, there is a problem in that a large amount of platinum is extracted into the organic phase during the solvent extraction of palladium.

This is because platinum (IV) is reduced from tetravalent to divalent in an aqueous solution, and this platinum (n) is easily extracted into the organic phase. Also, when tin (II) is present in an aqueous solution, this tin (n
) forms a double salt with platinum (IV) and promotes the extraction of platinum into the organic phase, and at present, platinum is mixed in as an impurity during palladium extraction, making it impossible to completely extract and separate palladium.

(Object of the Invention) The present invention was made in view of the above drawbacks, and an object of the present invention is to provide a method for selectively solvent extracting palladium from an aqueous solution containing palladium.

(Means for Solving the Problems) The present invention provides a method for extracting palladium from an aqueous palladium solution using an organic solvent, which comprises adding chlorine gas to the aqueous palladium solution, preferably bubbling the same. It is.

The present invention will be explained in detail below.

In the present invention, when palladium in an aqueous solution is extracted and separated from other metals using an organic solvent, if the oxidation state of the metals mentioned above, such as platinum or tin, is low, that is, platinum (n) or We focused on the fact that in the tin (II) state, as mentioned above, platinum and tin are also extracted into the organic solvent, making it impossible to selectively extract and separate palladium. In order to convert the lower state metals, such as platinum(n) and tin(II), into the corresponding higher oxidation state metals, platinum(IV) and tin(IV), and to separate the palladium from the platinum and tin, organic This palladium extraction method is intended to selectively extract palladium to the organic solvent side while preventing platinum and tin from being extracted to the organic solvent side during extraction with a solvent and water.

Therefore, the present invention is an effective method for extracting and separating palladium from metals that can exist in multiple oxidation states, and these metals include copper and iron in addition to platinum and soot.

The organic solvent used for the present palladium is not particularly limited as long as it is insoluble in water, and commonly used organic solvents such as kerosene, chloroform, and ether can be used.

In the present invention, it is desirable to add sulfide to the organic solvent before extraction, which improves palladium extraction efficiency. The sulfide used has the general formula R-8-
It is represented by R', and the functional groups R and R' may be the same or different. R and R' are selected from those having a carbon atom (preferably 6 to 10 carbon atoms) directly bonded to a sulfur atom and having no active functional group or complex-forming group that acts as an ion exchange group; Although the group is most suitable, it may also be an aryl, aralkyl group, etc., and the alkyl chain may be bonded through an oxygen atom. Preferred sulfides include dialkyl sulfides such as di-n-octyl sulfide, di-n-hexyl sulfide, and decylmethyl sulfide, which are dissolved in an appropriate organic solvent to a concentration of 5 to 30% by volume.

Alcohol may be added to this organic solvent in order to improve the extraction efficiency, and it is desirable that this alcohol is substantially insoluble in water and is retained in the organic solvent phase.

Preferred alcohols include those having 6 to 15 carbon atoms, such as n-hexyl alcohol, 2-ethylhexyl alcohol, n-decyl alcohol, isodecyl alcohol, n-
- Octyl alcohol, etc., and it is preferable that the amount added is such that the concentration when added to the organic solvent is 3 to 95% by volume.

The palladium aqueous solution is preferably a hydrochloric acid acidic aqueous solution, and the palladium concentration is not particularly limited, for example, 0.1.
- Palladium aqueous solutions with a wide concentration range of 100 g/β are targeted. The hydrochloric acid concentration is desirably 0.1N or higher, and particularly desirably 1 to 10N.

In the present invention, chlorine gas is added to the palladium aqueous solution side, preferably by bubbling, to prevent metals other than palladium from being reduced to lower-order oxides. (It is preferable to bubble chlorine gas into the aqueous solution to saturate the aqueous solution.The adding or bubbling step may be carried out before mixing the palladium aqueous solution with the organic solvent. In order to prevent the deterioration of the extractant, it is recommended to remove excess chlorine gas by bubbling with N2 gas or air.

Metal ions that exist in an aqueous palladium solution and can assume multiple oxidation states, such as platinum ions, are in a divalent state, which is a lower oxidation state, and these platinum (n) ions are oxidized to platinum (IV) ions by chlorine gas. It remains in the aqueous solution side and is prevented from being extracted into the organic solvent phase. Furthermore, even if the aqueous solution and the organic solvent are mixed and shaken and the platinum (II) ions have already been extracted into the organic solvent phase, the chlorine gas will be added to the platinum (II) ions in the organic solvent phase during shaking due to bubbling of chlorine gas, etc. ) The platinum (II) ions are oxidized to platinum (IV) ions by contact with the platinum (IV) ions, and the platinum is extracted into the aqueous solution and prevented from being extracted into the organic solvent phase.

(Example) Next, an example of palladium extraction according to the present invention will be described, but this example is not intended to limit the present invention.

Example 1 100 ml of an organic solvent phase in which 20% by volume of di-n-hexyl sulfide and 20% by volume of 2-ethylhexyl alcohol were dissolved in kerosene, 50 g/l of palladium,
100 ml of a hydrochloric acid aqueous solution containing 90 g/A of platinum was bubbled with chlorine gas until it was saturated, and then nitrogen gas was bubbled through it to dissipate excess chlorine gas. The solution was shaken for 1 hour in a separatory funnel to remove palladium as a solvent. When extracted, the palladium concentration in the organic solvent phase was 50 g/A and the platinum concentration was 15 ppm.

Example 2 100 ml of the organic solvent phase of Example 1 and 50 ml of palladium
g / (2. Bubble chlorine gas into 100 ml of a 3N hydrochloric acid aqueous solution containing 90 g/A of platinum and 10 g/l of tin until it is saturated, and then divide 100 ml of the hydrochloric acid aqueous solution by bubbling air to diffuse excess chlorine gas. Liquid funnel medium 1
When the palladium was extracted with a solvent by shaking for hours, the palladium concentration in the organic solvent phase was 50 g/jl' and the platinum concentration was 23 ppm.

Comparative Example 1 Palladium was extracted by shaking 100 ml of the same organic solvent phase as in Example 1 and 100 ml of a 3N hydrochloric acid aqueous solution containing 50 g/l of palladium, 90 g/A of platinum, and 10 g/β of tin in a separatory funnel for 1 hour. However, the palladium concentration in the organic solvent phase was 50 g/l and the platinum concentration was 350 ppm.

Comparative Example 2 100 ml of the same organic solvent phase as in Example 1 and 1 aqueous 3N hydrochloric acid solution containing 50 g/l of palladium and 90 g/l of platinum.
When extracting palladium by shaking 00 ml in a separatory funnel for 1 hour, the palladium concentration in the organic solvent phase was 50 g/
The platinum concentration was 120 ppm.

(Effects of the Invention) The present invention provides a palladium extraction method characterized in that chlorine gas is added when palladium is separated from other metals that can take multiple oxidation states by solvent extraction using an organic solvent. (Claim 1) According to this method, even if metals other than palladium exist in a lower oxidation state where they are easily extracted into the organic solvent phase, they are oxidized to a higher oxidation state by the added chlorine gas and are dissolved in the aqueous solution. Since the palladium remains on the organic solvent phase side, the purity of palladium extracted into the organic solvent phase increases, and the extraction efficiency improves markedly.

Furthermore, when dialkyl sulfide is added to the organic solvent (claim 2), palladium can be extracted and separated from other metals such as platinum more effectively.

It is desirable to bubble the chlorine gas into the palladium aqueous solution to saturate the aqueous solution before mixing the palladium aqueous solution with the organic solvent (Claim 3). By doing so, it becomes possible to sufficiently improve the extraction efficiency.

Claims (3)

[Claims] (1) A method for extracting palladium from an aqueous palladium solution using an organic solvent, the method comprising adding chlorine gas to the aqueous palladium solution. (2) The method according to claim 1, wherein the organic solvent contains sulfide. (3) The method according to claim 1 or 2, wherein the aqueous palladium solution is saturated by bubbling chlorine gas into the aqueous solution before mixing the aqueous solution with the organic solvent.