Method for preparing sodium dichromate dehydrate by ionic membrane electrolysis method

A technology of ionic membrane electrolysis and sodium dichromate, applied in the direction of chromate/dichromate, electrolysis process, electrolysis components, etc., can solve problems such as hindering the development of chromate enterprises and adverse to the overall development of the national economy, and achieve crystallization. Good appearance, low cost, and the effect of reducing the amount of distilled water

Active Publication Date: 2009-07-15
QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This situation not only hinders the development of chromium salt enterprises, but also is not conducive to the overall development of the national economy. There is an urgent need to develop new production technologies to produce high-quality chromium salt products to meet market demand.

Method used

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  • Method for preparing sodium dichromate dehydrate by ionic membrane electrolysis method
  • Method for preparing sodium dichromate dehydrate by ionic membrane electrolysis method

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Experimental program
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Effect test

Embodiment 1

[0031] ①The first stage of electrolysis: In the one-membrane two-chamber electrolyzer device, the sodium chromate alkaline solution with a mass concentration of 20.40% is passed into the anode chamber, and the sodium hydroxide solution with a mass concentration of 18.40% is passed into the cathode chamber. Voltage DC power supply control current 12.00±0.01A (current density 2400A / m 2 ), and electrolyze for 50 minutes at a reaction temperature of 45.0°C. The anode chamber obtains 21.70% (by mass content of sodium dichromate dihydrate) sodium chromate neutral solution, and the cathode chamber obtains 19.86% (by mass content of sodium hydroxide) sodium hydroxide solution. Oxygen produced in the anode chamber and hydrogen produced in the cathode chamber are recovered through gas collecting devices respectively.

[0032] ②The second stage of electrolysis: the anolyte obtained in the first stage of electrolysis is filtered to remove impurities such as aluminum and silicon, and then...

Embodiment 2

[0035] 1. The first stage of electrolysis: the sodium chromate alkaline solution with a mass concentration of 28.41% (in terms of the mass content of sodium dichromate dihydrate) is passed into the anode chamber, and the sodium chromate alkaline solution with a mass concentration of 16.20% (in terms of the mass content of sodium hydroxide) is passed into the anode chamber. The sodium hydroxide solution is passed into the cathode chamber, and the current is controlled by a regulated DC power supply to 6.00±0.01A (current density 1200A / m 2 ), electrolyzed for 139min at a reaction temperature of 60°C. The anode chamber obtains 30.28% (in terms of the mass content of sodium dichromate dihydrate) sodium chromate neutral solution, and the cathode chamber obtains a sodium hydroxide solution with a mass concentration of 18.46% (in terms of the mass content of sodium hydroxide). Oxygen produced in the anode chamber and hydrogen produced in the cathode chamber are recovered through gas ...

Embodiment 3

[0039] ①The first stage of electrolysis: the sodium chromate alkaline solution with a mass concentration of 35.75% (in terms of the mass content of sodium dichromate dihydrate) is passed into the anode chamber, and the mass concentration is 9.04% (in terms of the mass content of sodium hydroxide) The sodium hydroxide solution is passed into the cathode chamber, and the current is controlled by a regulated DC power supply to 15.00±0.01A (the current density is 3000A / m 2 ), electrolyze for 70 minutes at a reaction temperature of 75°C. A sodium chromate neutral solution with a concentration of 37.87% (in terms of the mass content of sodium dichromate dihydrate) is obtained in the anode compartment, and a sodium hydroxide solution with a mass concentration of 12.82% (in terms of the mass content of sodium hydroxide) is obtained in the cathode compartment. Oxygen produced in the anode chamber and hydrogen produced in the cathode chamber are recovered through gas collecting devices ...

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Abstract

The invention provides a method for preparing sodium bichromate dihydrate (Na2Cr2O7.2H2O) by using an ion-membrane electrolytic method. The method is as follows: a one-membrane two-room electrolytic cell assembly is formed by using a cation-exchange membrane, a negative electrode and a positive electrode; sodium chromate alkali solution is introduced into an anode chamber. Dilute sodium hydroxide solution is introduced into a cathode chamber; after direct current is connected, negative ions and positive ions respectively move to the anode chamber and the cathode chamber under the action of an electric field; the positive ions enters into the cathode chamber by a positive ion membrane, thus obtaining alkali liquor in the cathode chamber; sodium acid chromate solution is obtained in the anode chamber; simultaneously, the negative electrode and the positive respectively output hydrogen and oxygen; sodium bichromate dihydrate products are dissolved out by evaporating and cooling off the sodium acid chromate solution. The Sodium bichromate dihydrate products prepared by the method has high purity; the utilization rate of the raw materials is close to 100%; byproduct sodium hydroxide has high economic value; no waste materials containing chromium are recycled or discharged in the production process; therefore, the method is safe and environment friendly.

Description

technical field [0001] The invention belongs to the technical field of inorganic salt materials, and relates to a preparation method of sodium dichromate, in particular to a method for preparing sodium dichromate dihydrate by ion membrane electrolysis. Background technique [0002] Chromium salt is one of the main varieties of inorganic salts, which is widely used in the national economy and social life. It is mainly used in electroplating, leather tanning, printing and dyeing, medicine, pigments, catalysts, oxidants, matches and metal corrosion inhibition. At present, the domestic production of chromium salts is increasing year by year, but some chromium salts still need to be imported to meet the domestic market demand. [0003] Yet domestic production method of sodium dichromate is mainly sulfuric acid method, and there are many deficiencies in this production technology, mainly shows as: the utilization rate of main metal chromium is low, only 75%; Every ton of sodium di...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25B1/00C25B1/14C01G37/14
Inventor 冯海涛董亚萍陈美达郑竹林王小欢孟庆芬
Owner QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI
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