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Cyclic application method of hexavalent chromium in metal passivation solution based on photocatalysis

A technology of metal passivation and application method, which is applied in chemical instruments and methods, metal material coating process, physical/chemical process catalyst, etc., can solve the problems of complex process and high cost, achieve simple process and solve environmental pollution. , Improve the effect of corrosion resistance

Pending Publication Date: 2022-03-04
SHANGHAI UNIV OF ENG SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the recovery rate and purity of chromium are improved by using this method to process the recovered chromium, the process is complicated and expensive.

Method used

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  • Cyclic application method of hexavalent chromium in metal passivation solution based on photocatalysis
  • Cyclic application method of hexavalent chromium in metal passivation solution based on photocatalysis
  • Cyclic application method of hexavalent chromium in metal passivation solution based on photocatalysis

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Effect test

Embodiment 1

[0086] In this embodiment, based on the photocatalytic reduction of heavy metal chromium, and without concentration, it is applied to the cerium-based metal passivation solution to improve the protective performance of the passivation film. The specific preparation method and use method include the following steps;

[0087] (1) First, under the stirring of a glass rod, dissolve 20mg of potassium dichromate and 0.5g of disodium edetate dihydrate in some deionized water, stir evenly until dissolved, and then pour it into a 500ml volumetric flask Constant volume, let stand for a while. Then, the prepared hexavalent chromium solution is subjected to light treatment, and the hexavalent chromium ions in the solution are degraded by photocatalysis, and after the degradation is completed, the degraded supernatant is taken.

[0088] (2) pH value adjustment of the hexavalent chromium treatment solution before degradation: adjust the pH to 2 with a concentration of 65% concentrated nitr...

Embodiment 2

[0099] In this embodiment, based on the photocatalytic reduction of heavy metal chromium, and without concentration, it is applied to the cerium-based metal passivation solution to improve the protective performance of the passivation film. The difference from Example 1 is that the cerium source is adjusted, and Ce(NO 3 ) 3 .6H 2 O adjusted to CeCl 3 .6H 2 O, and the acid ligand hydrochloric acid was adjusted to citric acid, the passivation temperature was adjusted to 55°C, and the soaking time was increased to 10min. Specific steps are as follows:

[0100] (1) First, under the stirring of a glass rod, dissolve 20mg of potassium dichromate and 0.5g of disodium edetate dihydrate in some deionized water, stir evenly until dissolved, and then pour it into a 500ml volumetric flask Constant volume, let stand for a while. Then, the prepared hexavalent chromium solution is subjected to light treatment, and the hexavalent chromium ions in the solution are degraded by photocataly...

Embodiment 3

[0112] In this embodiment, based on the photocatalytic reduction of heavy metal chromium, and without concentration, it is applied to the cerium-based metal passivation solution to improve the protective performance of the passivation film. The difference from Example 2 is that the amount of potassium dichromate and the acid ligand in the cerium-based passivation component are adjusted, the amount of potassium dichromate is increased to 80mg / L, and the photocatalyst is replaced by SnO 2 , the acid ligand hydrochloric acid was adjusted to boric acid, the pH value of the chromium-cerium-based passivation solution was adjusted to 3.5, and the passivation time was adjusted to 5 minutes. Specific steps are as follows:

[0113] (1) First, under the stirring of a glass rod, dissolve 40 mg of potassium dichromate and 1 g of disodium edetate dihydrate in some deionized water, stir evenly until dissolved, and then pour it into a 500 ml volumetric flask to set Let it sit for a while. T...

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Abstract

The invention relates to a cyclic application method of hexavalent chromium in a metal passivation solution based on photocatalysis, which comprises the following steps: S1, reducing hexavalent chromium in a non-concentrated chromium waste liquid into trivalent chromium by utilizing photocatalytic degradation under the conditions of a photocatalyst and illumination; s2, a cerium-based passivation component is prepared, the photocatalytic reduction chromium waste liquid in the S1 is added, and a cerium-chromium composite passivation solution is obtained; and S3, the metal base material is placed in the cerium-chromium composite passivation solution to be passivated. Compared with the prior art, the method has the advantages that the chromium waste liquid subjected to photocatalytic degradation is reused, so that the problem of environmental pollution caused by hexavalent chromium is solved, and the waste chromium is recycled; according to a cerium-chromium composite passivation film obtained based on the cerium-chromium composite passivation solution, due to excellent adhesion and high stability of the composition surface, the protection performance on a coating is greatly improved, and the corrosion resistance of the coating is improved; and the process is simple, the raw materials are easy to obtain, the cost is low, the prepared composite passivation solution is high in stability, and the obtained passivation film is good in corrosion resistance effect.

Description

technical field [0001] The invention relates to the technical field of heavy metal treatment and metal surface protection, in particular to a photocatalytic-based recycling method of hexavalent chromium in a metal passivation solution. Background technique [0002] The development of industrial society has caused serious water pollution, and heavy metal pollution in water poses a huge threat to human health and ecosystems. Hexavalent chromium (Cr(VI)) is one of the common heavy metals in water pollution. It is an ingestion and inhalation poison. Inhalation can cause cancer and has a persistent danger to the environment. Cr(VI) is non-biodegradable. , and is also easily adsorbed on the surface of inorganic substances. With the development of electronics and automobile fields, more and more metal surface treatments are being processed, and hexavalent chromium compound metal surface passivation occupies a large proportion in the industry. However, hexavalent chromium has seri...

Claims

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Application Information

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IPC IPC(8): C23C22/30C02F1/70B01J23/18B01J21/06B01J21/02B01J23/14B01J27/24
CPCC23C22/30C02F1/705B01J23/18B01J21/063B01J21/02B01J23/14B01J27/24C02F2103/16
Inventor 方青杨靖霞
Owner SHANGHAI UNIV OF ENG SCI