Method for producing peroxodisulfates in aqueous solution

A technology of peroxodisulfuric acid and sulfate, applied in chemical instruments and methods, peroxide/peroxyhydrate/peroxyacid/superoxide/ozonide, electrolysis process, etc., can solve the problem of yield reduction, Increased current loss and other issues, to achieve high current yield, low reduction loss, and cost savings

Active Publication Date: 2010-02-24
DEGUSSA INITIATORS GMBH & CO KG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If an attempt is made to increase the production capacity by a larger number of bipolar individual cells up to an industrially relevant range, this configuration leads to a reduction in yield due to current losses in the input and output wires, which vary with the total voltage greatly increased

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026]An undivided bipolar cell of construction similar to DE G 200 05681.6 contained 9 bipolar silicon electrodes coated on one side with about 3 μm boron-doped diamond (average about 3000 ppm boron). A niobium electrode coated with diamond on one side and having a current input lead was used as the edge anode. The edge cathodes with current input leads consist of Hastelloy. The size of the bipolar electrode is 100×33mm (33cm 2 ). The average spacing of bipolar electrodes about 1 mm thick was adjusted to about 2 mm by spacers. The electrolysis current was adjusted to a constant value of 16.5A, corresponding to 0.5A / cm 2 anodic and cathodic current densities. The total current capacity of the electrolyzer is thus 10 x 16.5 = 165A. A 21 aqueous solution containing 300 g / l sodium sulfate and 200 g / l sulfuric acid was used as electrolyte. It is pumped at a rate of about 600 l / h from the circulation vessel in a circulation loop through the heat exchanger and through the elec...

Embodiment 2

[0031] The dependence of the current yield on the final concentration of sodium peroxodisulfate (NaPS) achieved was determined by means of the undivided electrolysis cell from Example 1 under the same electrolysis conditions (current density, temperature, batch operation, electrolyte composition). The following results are obtained:

[0032] NaPS final concentration in g / l 25 50 75 100 125 150

[0033] Current yield generated by NaPS in % 84 77 64 50 40 34

[0034] At the most favorable cell voltage of about 4.2 V established after a longer operating time, for a final concentration of 50 g / l, for a final concentration of 100 g / l of NaPS, the specific electrical energy consumption was 1.23 kWh / kg, despite the drop in current yield At 50%, it's still 1.89kWh / kg.

Embodiment 3

[0036] The same undivided electrolyzer as in Examples 1 and 2 was fitted with PVC gauze lying flat on the cathodes and edge cathodes of the bipolar electrode plates; this gauze was pressed onto the surface through plastic spacers. Electrolysis was performed again under the same electrolysis conditions as in Example 2. The following current yields were obtained, based on the final NaPS concentration achieved.

[0037] Final concentration of NaPS in g / l 50 75 100 125 150 175 200

[0038] Current yield generated by NaPS in % 84 77 73 68 61 54 49

[0039] Even in the concentration range of 100-200 g / l, relatively favorable current yields were obtained which were on average about 20% higher compared to shielding without a cathode surface. However, due to the additional resistance of the gauze screen, the cell voltage was about 0.8V higher. However, a very favorable specific electrical energy consumption of about 1.85 kWh / kg is still obtained at a NaPS final concentration of eg 1...

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Abstract

The invention describes a method for producing or regenerating persulfuric acid and the salts thereof by electrolysis of an aqueous solution containing sulfuric acid and / or metal sulfates on diamond-coated electrodes without using promoters. According to the inventive method, bipolar silicon electrodes are used which are diamond-coated on one side and whose uncoated silicon back is used as the cathode.

Description

technical field [0001] The present invention relates to a process for the preparation or regeneration of peroxodisulfuric acid and its salts by electrolysis of aqueous solutions comprising sulfuric acid and / or metal sulfates. As used herein, the term "metal sulfate" includes sulfates of alkali metals and alkaline earth metals or ammonium sulfate in addition to sulfates of metals such as zinc, nickel or iron. For example, alkali metal sulfates or alkaline earth metal sulfates, preferably alkali metal sulfates or ammonium sulfate, can be used as metal sulfates. It is also possible to use various metal sulfates, for example mixtures of magnesium sulfate, zinc sulfate or nickel sulfate or iron sulfate, preferably in the regeneration of etching and pickling solutions. Background technique [0002] It is known from the prior art that diamond-coated electrodes consisting of a valve metal, preferably niobium, or of a ceramic material, preferably silicon, can be used for the prepara...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C25B1/28C25B9/20C25B9/06C25B11/04C01B15/00C25B9/17
CPCC25B1/285C25B9/203C25B11/0447C25B11/0421C25B9/063C25B1/22C25B1/30C25B1/29C25B11/036C25B9/75C25B11/059C25B11/051C25B11/075C25B9/73C25B9/17
Inventor W·斯尔勒H-J·克拉莫H-J·弗斯特
Owner DEGUSSA INITIATORS GMBH & CO KG
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