Method for producing sodium dichromate through cationic membrane electrolysis

Abstract

The invention discloses a method for producing sodium dichromate through cationic membrane electrolysis. The method comprises the following steps: mixing a 20-40% industrial sodium chromate solution and a 23-50% sodium dichromate solution to obtain a mixed feed liquid with a volume ratio of sodium dichromate to chromate being equal to (1.5:1)-(5:1); introducing the mixed feed liquid into an anode chamber and introducing a sodium hydroxide solution with mass concentration of 27-30% into a cathode chamber; switching on direct currents, wherein the current density is controlled to be 2-4kA / m<2>, the electrolysis temperature is 70-90 DEG C, the pressure difference between the cathode chamber and the anode chamber is 200-500mmH2O, the anode feed temperature is 50-85 DEG C, and the cathode feed temperature is 55-90 DEG C; and after electrolysis, obtaining sodium dichromate and oxygen gas in the anode chamber, and obtaining sodium hydroxide and hydrogen gas in the cathode chamber.

Description

Technical field [0001] The invention relates to a method for producing sodium dichromate, in particular to a method for producing sodium dichromate by a continuous cationic membrane electrolysis method. Background technique [0002] Chromium salt is one of the main varieties of inorganic salt, which is widely used in national economy and social life. It is mainly used in electroplating, tanning, printing and dyeing, medicine, pigments, catalysts, oxidants, matches and metal corrosion inhibition. At present, the domestic production of chromium salt is increasing year by year, but some chromium salt still needs to be imported to meet the domestic market demand. [0003] The domestic production method of sodium dichromate is mainly the sulfuric acid method. This production technology has many shortcomings, mainly as follows: the utilization rate of the main metal chromium is only 75%; every ton of sodium dichromate product needs to discharge toxic chromium Slag 2.5-3.0 tons, chromium...

AI Technical Summary

Problems solved by technology

[0007] The technical research on the synthesis of sodium dichromate by ion membrane electrolysis started earlier at home and abroad, but the progress is slow

From the 1980s to the 1990s, there was a research boom. Bayer AG in Germany and Chromium Chemicals in the U.S. etc. conducted more research on this technology, but there is no technology for industrial grade and continuous preparation of sodium dichromate in large quantities. to report

Domestic research on the preparation of sodium dichromate by electrosynthesis started at the end of the 20th century. There are few research units, and the work in this area is basically in the laboratory stage. Industrial-grade, continuous preparation of sodium dichromate by ion membrane electrolysis has not yet been found.

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