JPS58135139A - Recovery process for palladium - Google Patents

Abstract

PURPOSE:To separate Pd efficiently even in case an aqueous solution exists together with a poor metal, by bringing the aqueous solution containing Pd into contact with a chelate-forming resin containing an iminodiacetate group, adsorbing Pd on the resin. CONSTITUTION:An aqueous solution dissolving Pd at <=6pH, which may contain a poor solvent such as Al, etc., is passed through a column packed with a chelate-forming resin containing an iminodiacetate group shown by the formula -N(CH2COOX)2(X is H, Na, K, etc.), and Pd is selectively adsorbed on the resin. About 1-3vol. based on 1vol. resin of an aqueous solution of a hydrogen halide (e.g., hydrochloric acid) having a concentration of >=1 equivalent is passed through the column packed with the resin having adsorbed Pd at about 0.5- 3hr<-1> liquid space velocity, and Pd is eluted in the aqueous solution of a hydrogen halide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating palladium in a solution with chelate 8118M, adsorbing the palladium from the aqueous solution, and separating and recovering the palladium.

Palladium is widely used in the petroleum and chemical industries, as a contact material in the electronic industry, as a material for semiconductor electron tube parts, as a surface material for various types of plating, and as accessories.

Since palladium is expensive and scarce in resources, it is extremely important to recover palladium from wastewater or scrap containing palladium.

In catalyst production, the catalyst carrier is impregnated and supported with a noble metal compound such as palladium, and the first step is to collect waste precious metal catalysts, plating waste liquid, parts, and other low-grade scraps.
After dissolving palladium in aqua regia, flll, etc., it is precipitated separately by formation of an insoluble salt or reduction, and impurities and palladium are separated and purified and recovered. Alternatively, a method is known in which palladium is recovered by treating an aqueous solution in which palladium is dissolved with an ion exchange resin to adsorb it, eluting the palladium therefrom, and incinerating the resin that has adsorbed palladium.

Among these, the method of adsorbing palladium with an ion exchange resin is a method that is easy to operate, but conventionally known methods either have a low elution rate or require the use of a specific eluent. The method for recovering palladium was not necessarily satisfactory.

For example, V Donny Φ Satsushiman (5lney 8uss
1man) and others (industrial andEn)
gineeringChem1str7.87 Volume 7 No. 6
(pp. 18-625) attempted to adsorb platinum with an anion exchange resin and then elute it with a 1N ammonium hydroxide solution, but the elution rate remained below 40%, so they decided to recover it by incineration. is recommended.

Furthermore, in JP-A No. 51-9089, as an elution method after adsorbing palladium ions with a resin having a polyethylene polyamine type chelate forming group, hydrochloric acid, caustic soda, etc. have an elution rate as low as 101%, but an aqueous ammonia solution The elution rate is high at 89%, and an ammonia aqueous solution is recommended.

After eluting palladium from the resin by passing an ammonia aqueous solution through it, the resin is washed with water, and the resin is regenerated into an O1 type using hydrochloric acid as a regenerating agent, and then used again to adsorb palladium.

Elution with this aqueous ammonia solution is necessary to ensure that the palladium ions obtained first form a stable complex with ammonia. For example, if the palladium ions are to be reused as a catalyst support solution, it is necessary to convert them into the halide palladium form. Ashi problem t-
I'm leaving it behind. Secondly, since it is necessary to re-process with hydrochloric acid in order to re-adsorb the resin tube, problems remain both in terms of equipment and economics. (9) In the method of recovering precious metals by incinerating the resin, the resin cannot be reused and is economically problematic.

The purpose of the present invention is to eliminate the problems seen in conventional processing methods, and by using a chelating resin with a constant t% of palladium ions, palladium can be selectively removed even when base metals coexist in the aqueous solution. The object of the present invention is to provide a method for efficiently separating palladium from an aqueous solution by adsorption. Still another object is to provide a method that can efficiently elute and recover nine palladium adsorbed onto a resin, and also allow the resin to be adsorbed again without regeneration treatment.

These objects of the present invention can be easily achieved by adsorbing palladium ions onto a chelating resin having iminodiacetic acid groups and then eluting them with an aqueous solution of hydrohalic acid.

That is, the method for separating palladium of the present invention involves contacting an aqueous solution in which palladium is dissolved with a chelate-forming resin having an iminodiacetic acid group, thereby adsorbing palladium onto the resin, and separating palladium from the aqueous solution. I'll go. Further, the resin adsorbing palladium is brought into contact with a hydrogen halide aqueous solution, and palladium is eluted into the aqueous solution.

It is a chelate resin having a so-called iminodiacetic acid group represented by K, etc.).

As such chelate resin, Japanese Patent Publication No. 61-141
! Resins shown in 4G can be used. When this resin is polycondensed with phenols and aldehydes, first, an acidic mixture of phenol, aldehyde, and iminodiacetic acid is added to the tube.
Phenol with iminodiacetic acid base obtained by heating reaction at 90-110'C, introducing iminodiacetic acid into the phenol nucleus, adding phenols and aldehydes or aldehydes, and finally heating and condensing at 90-110'C. It is a type chelate resin. It is also possible to use the resin shown in Japanese Patent Application Laid-open No. 60-101490. During the polycondensation of phenols and aldehydes, this resin first produces N (hydroxybenzyl).
Synthesize iminodiacetonitrile, hydrolyze it to N (hydroxybenzyl)iminodiacetic acid, hydrolyze it during polymerization or polymerization, introduce iminodiacetic acid groups into part or all of the phenol, and use nine phenol groups. This is the resin that was used. Commercially available products include UNISEREFUKU UR-50 (manufactured by Uni+Riki), Amberlite RC-718 (manufactured by Rohm Yuhaas Co., Ltd.), and DOWEX A-1 (manufactured by Dow Chemical Company). Note that these resins have a three-dimensional structure and are naturally water-insoluble. Note that the resin is not limited to the nine resins mentioned above, and any resin having an iminodiacetic acid group may be used.

The aqueous solution in which palladium is dissolved refers to an aqueous solution in which palladium is present as palladium ions.

This aqueous solution may also contain ions of other base metals such as aluminum. Such aqueous solutions include catalyst impregnating and supporting waste liquids and plating waste liquids. Note that a water bath solution in which palladium is dissolved by treating a material containing palladium with aqua regia or the like may be used. These aqueous solutions have a pH of 6 or less, preferably P
It is preferable to be acidic below H4. If the pH is high, palladium will precipitate as hydroxide and will not be adsorbed by the resin.

The method of bringing an aqueous solution containing palladium into contact with a resin is similar to column chromatography, in which the resin is placed in a column and water is added.
ll solution is passed through the solution, or the resin is added to the aqueous solution, stirred and mixed, and then Fj! Methods employed in normal ion exchange unit operations, such as a method of separating a resin and an aqueous solution using a method such as No. 11, can be used.

The method for passing the liquid through the column may be any conventional method without any special brazing, and may be arbitrarily determined as appropriate, such as an upward flow method or a downward flow method.

The palladium is eluted from the resin that has adsorbed palladium using an aqueous hydrogen halide solution such as hydrochloric acid or hydrobromic acid as an eluent.

The concentration of the hydrogen halide and aqueous solution is not particularly limited, but for efficient elution, the higher the concentration is, the higher the concentration is usually 1N or more, preferably 4 to 1ON.

The temperature during elution has no particular effect, but if the eluate precipitates, it is preferable to elute at a temperature that prevents precipitation.

The method of contact between the resin and the eluent for elution is the same as that for adsorption. In the case of the column flow method, the eluent is usually 1 to 8 times the volume of the resin that adsorbs palladium and gold, and is passed through the resin-filled column that adsorbs palladium at a liquid hourly space velocity of about 0.6 to 8 hr-'. The adsorption and elution mechanism of palladium to the iminodiacetic acid group is not yet clear, but it is currently speculated as follows.

It is speculated that adsorption occurs through selective ion exchange with the two carbonyl group cabaladium ions of the iminodiacetic acid group, forming an ionic bond as shown in the following formula. As explained in the examples below, the chelating ionic bond of the lever is stronger for palladium ions than for other base metals, such as NIL□, /+, etc.
It is presumed that it is selectively adsorbed.

As for the elution mechanism, it is thought that when a hydrohalic acid aqueous solution is used, palladium ions form a stable complex compound with halogen ions as shown in the following formula, and are easily eluted. (As is clear from the c4° formula in the figure, the iminodiacetic acid group becomes the Ti type during the elution process, so it can adsorb palladium ions again without any regeneration treatment, adsorption and elution.) However, the amount of palladium adsorbed by l11il oil hardly decreases, so the resin can be used permanently.

On the other hand, palladium eluted from the resin can also be easily recovered as a solid by heating the palladium-containing l# water syneresis solution and evaporating and removing the solvent.

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples, which do not go beyond the gist thereof.

Example 1 As a chelating resin having an iminodiacetic acid group, Amberlite Re-718 (Rohm Haas Co., Ltd.) at resin 8 was used.
Packed in a column with a filter of 0 mjl f inner diameter 101 cl, Pd"+: 860 PPm, AA"":
800 PPmN": 600 PPz 1 A PH2,4 (D palladium chloride hydrochloric acid acidic solution was passed through the liquid nitrogen at a rate of 2.5 hr-'. Liquid passing force s, a 1
(10411/11・1Iij resin>ItC case, the pa concentration in the liquid after treatment was less than IPPm.The amount of liquid passed reached 9.51C1191/l・resin), and the treatment fM at the 9th point The pa'+ concentration in the liquid is 40 PPm
I failed. Furthermore, the amount of liquid passed was 11.14' (189171
The P(1″+ concentration) in the treatment liquid at the 9th point in time when the resin reached 98 PPm. This relationship is shown in the figure.

At this point, raise the liquid passage tube, 240 ml of deionized water with an electrical conductivity of 5.4 or less (Bl/l-resin) t-1, axillary bud reach 5
hr-' to pass the liquid and wash with water. Next, the 4 rules wo fortune wtt
Water #ew4omll<81/l-resin) was passed through at a rate of 1.5 hr-' for 22 minutes, and then 125 m of deionized water was added.
1 (L611/II "4!1111 tM air-related rate of 15 hr-') to elute pa"+. 865 ml of eluent was obtained, and the concentration shown in Table 1.

Calculating the elution rate of palladium from the resin [(amount of palladium eluted/amount of palladium adsorbed on the resin) x 100), the elution rate is 8. 6 at Tf/8.81×100-97%. Ta.

Table 1 Furthermore, in order to examine the regeneration ability and reusability of the chelate resin of this example, after eluting palladium, the same aqueous palladium solution as above was passed through it again to adsorb palladium.

Elute palladium from the adsorbed resin in a similar manner.

This adsorption/elution process was repeated several times for 7 liters. The results are shown in Table 2. In addition, in Table 2, number 1 indicates that virgin resin was used.

Therefore, the number of times 2 corresponds to 1 reuse.

Table 2 Example 2 Chelate-forming resin having iminodiacetic acid group and Cite Unicelec UR-60 (Unitika #) It resin 180 ml
Adsorption and elution were carried out in the same manner as in Example 1 using :. As a result, the eluent shown in Table 8 was obtained, the absorption amount was 8.7F/80ml, and the resin elution rate was 99. Example 8 Using Amberlite IRQ-718 resin, palladium was added in the same manner as in Example 1. After adsorption, elution was carried out in the same manner as in Example 1 using hydrobromic acid (111Br) in ION water as the eluent. The elution rate was 80%.

As detailed above, the palladium recovery method of the present invention is characterized by the use of a chelate-forming fat-resistant resin containing iminodiacetic acid groups, and by treating a palladium-containing aqueous solution with this resin, Palladium can be selectively adsorbed onto the resin even when a base metal is present in the aqueous solution. Moreover, it can be easily eluted by using an aqueous hydrogen halide solution such as hydrochloric acid as an eluent. Furthermore, after elution, palladium can be adsorbed again during aqueous imitation without regeneration treatment. By arbitrarily selecting an aqueous hydrogen halide solution as an eluent, pools-FIOI II, panr, etc.
= l+ HBr f@ solution, pa process l ■ solution, etc., it is possible to prepare compounds with appropriately changed compositions of anion t- that binds to palladium.

[Brief explanation of drawings]

The figure shows the amount of treatment liquid passed through the resin and the palladium l in the treated liquid, which shows the skin absorption ability of palladium according to the first embodiment of the present invention.
FIG. 1 is a diagram showing the relationship with 1IJf. Patent originator Hiroshi Okawa, patent attorney representing Toyota Motor Corporation

Claims (2)

[Claims] (1) By subjecting an aqueous solution in which palladium is dissolved to a chelate-forming resin having an iminodiacetic acid group, palladium is adsorbed onto the resin, and υ palladium is separated from the aqueous solution. Separation method (2) A method for separating palladium according to claim 1, wherein an iminodiacetic acid type chelate-forming resin adsorbing palladium is brought into contact with an aqueous hydrogen halide solution, and palladium is eluted into the aqueous solution.