SK89294A3 - Prolongation method of electrolyte durability by elimination of organic impurities - Google Patents

Description

A method of extending the life of an electrolyte by eliminating organic impurities

Technical field

The invention relates to a process for extending the life of an electrolyte, in particular process solutions in galvanic and semiconductor applications, where chemical, autocatalytic and galvanic working solutions are preferably used in the coating of metals, non-conductive substrates and conductive plates by eliminating organic impurities.

BACKGROUND OF THE INVENTION

Electropolyte solutions containing heavy metals are used in the production of galvanic metal coatings and metal foils, to which selected organic compounds can be added to achieve specific surface properties such as gloss, ductility, tensile strength and the like. These organic substances undergo chemical changes during the deposition process, so that impurities are produced which lead to process malfunctions in the loss-free production process or in the completely reversible electrolyte conduit. The enrichment of the electrolyte solution with organic impurities can also occur by fouling the impurities.

Known solutions for the removal of organic impurities consist of adsorption on activated carbon and oxidation with hydrogen peroxide or potassium permanganate, as is evident, for example, from DD 280 560. However, in this way not all components of these organic impurities are removed from the active bath.

The disadvantages of using activated carbon are also large heavy metal losses and also adsorbent losses of up to 20% during regeneration. Due to the heavy metal content, the spent activated carbon is a special hardly recoverable waste.

In many cases, the use of oxidizing agents even promotes enrichment of impurities.

Another variant of the process of eliminating the orcyanic impurities from the electrolyte solution for the galvanic plant is based on the formation of an internal circulation of substances and includes the steps of precipitating heavy metals in the irrigation water in the form of hydroxides, sedimentation of heavy metal hydroxide sludge, dewatering by filtration. electrolyte solution to a galvanic production bath or electrolytic production, cathodic deposition of heavy metals and recovery in electrolytic production, anodic deposition of sulfuric acid to dissolve the sludge. Organic impurities remain in the filtrate after precipitation of heavy metals and separation of the sludge, so that enrichment in the electrolytic electrolyte can be prevented. This procedure is described in Galvanotechnik 71, 1980, 7, p. 712 to 720.

Another variant of the process is also based on the formation of internal ions at the circulation of the substances and involves a combination with an exchange of electrolytic deposition. In the irrigation water containing the electrolyte, the separation of organic materials and heavy metals is achieved by ion exchange. The organic materials remain in the elution water and are thus separated from the electrolyte solution, while the heavy metal ion exchange eluate is either recycled to the electrolyte solution or processed by electrolytic deposition to the metal. (Acta Hydrochim et Hydrobiol. 12 (1984) 2, 183.202). All the mentioned regeneration variants have the disadvantage that they lead to much higher substance loss and do not represent a solution to the problem in terms of pollutant minimization techniques.

SUMMARY OF THE INVENTION

It is an object of the present invention to minimize waste electrolyte solutions to eliminate organic impurities to extend their lifetime and to treat water and waste. The removal of impurities must be carried out with a regenerable adsorption polymer, while organic diluents are excluded as regenerating agents for the polymers used.

The object of the present invention is to provide a process for extending the life of an electrolyte solution by eliminating organic impurities with a regenerable adsorption polymer. After the adsorption elimination of impurities, the electrolyte solution must be unrestrictedly usable. A decisive prerequisite for the use of the process is the complete regeneration of the adsorption polymers with an aqueous solution.

This object is solved by the teachings of the claims. Surprisingly, it has been found that the oxidative treatment of the adsorption polymer, for example with a dilute hydrogen peroxide solution, alters the adsorption structure so that the complete regeneration of the adsorption polymer reliably only in one regeneration step with an alcoholic solution such as dilute sodium hydroxide. The treatment can also occur in one step by contact with an alkaline aqueous solution of the oxidizing agent. In addition to the hydrogen peroxide solution, water-dilutable persulfate or persulfate can be used as the oxidizing agent.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

The nickel electrolyte highly contaminated with organic impurities with a nickel concentration of 95.9 g / l and a carbon concentration of 25.5 g / l, which had no functionality due to the high concentration of organic substances, was regenerated by means of an adsorption polymer. The adsorption regeneration of the galvanic nickel electrolyte is carried out by an adsorption polymer, in this case ethyl vinylbenzene-divinylbenzene copolymer, without polar groups, by a column process with an effluent flow rate of about 2.5 m / h. The inner diameter of the columns was about 3 cm, the height of the adsorption polymer layer was about 70 cm.

The undiluted electrolyte and the electrolyte diluted with water at a ratio of 1: 5 were tested. The adsorption column was loaded only when the total volume capacity was filled. The total volumetric capacity is the amount of adsorption polymer for all organic substances, i.e. the sum of the organic substance introduced, formed or contaminated by the foreign organic substance, expressed as organically bound carbon in grams per liter of adsorbent. The determination of the total volumetric capacity is performed by evaluating the penetration curve, provided that the load on the adsorption column remains the same, i.e. the introduced organic bound carbon is identical to the withdrawn organically bound carbon.

The following results were achieved:

the total bulk capacity of the undiluted electrolyte regeneration was about 63 g / l adsorber, the total bulk capacity of the 1: 5 water diluted electrolyte regeneration was 37 g / l adsorber.

electrolyte regeneration reduced the bound carbon content from 25.5 g / l to 10.4 g / l.

The electrolyte regeneration is followed by the correction of the inserted organic substance according to the company's recipe. Subsequent verification in the Hull chamber shows that the electrolyte was reusable indefinitely.

Example 2

The 0.9 cm internal diameter column, 16 cm adsorption polymer height, filled with an adsorption polymer of ethylvinylbenzenedivinylbenzene copolymer without polar groups, was loaded with a dysfunctional galvanic nickel electrolyte with a nickel concentration of 78.1 g / l and an organically bound carbon concentration of 4.8 g / l. first Loading takes place at the outlet with a flow rate of approx

2,5m / h until the total volume capacity is reached.

Regeneration of the introduced adsorption polymers occurs in the same columns according to the following regeneration scheme:

1. Countercurrent washing of the column with water until there is no evidence of nickel in the washing water. The washing speed is 3 m / h.

2. Treatment of an adsorption polymer with five feed volumes in about 2.5% hydrogen peroxide solution at outlet and in a circular run, with a flow rate of about 1.7 m / h, for a maximum of 1 h.

3. Wash with water unless hydrogen peroxide is detectable in the wash water.

4. Treatment of the adsorption polymer with five volumes of its charge with about 6% sodium hydroxide in effluent and in a circular run, with a flow rate of about 1.7 m / h, for a maximum of 1 h.

5. Wash with water until the wash water is non-alkaline. The adsorption polymer is then recharged. The total volumetric capacity remained constant during the five cycles tested and was about 16 g of carbon per liter of adsorber.

Claims (4)

PATENT CLAIMS Method for extending the life of organic impurity electrolytes, characterized in that the electrolyte containing organic impurities is brought into contact with the regenerable adsorbent polymer by elimination of the solution, and optionally optionally rinsing the adsorbent polymer with water, further treating the adsorbent polymer with an aqueous oxidizing agent solution and thereafter optionally, the adsorption polymer is rinsed with water, the adsorption polymer is treated with an aqueous alkaline solution, and optionally the adsorption polymer is washed with water. The method of extending organic impurities, an electrolyte containing organic impurities, introduces an alkaline polymer with a regenerable adsorption polymer. Second The electrolytes are characterized in that they are rinsed into the adsorbent polymer and rinsed with water, the aqueous solution of the oxidizing agent is then treated with a contact solution or an adsorbent, and optionally the adsorbent polymer is rinsed with water. Method according to claims 1 and 2, characterized in that the regenerate containing organic substances is treated with a redox process, for example UV radiation and an oxidizing agent. The process according to claims 1 and 2, characterized in that the alkaline aqueous solution is sodium hydroxide or potassium hydroxide at a concentration of 2 to 10%.