Mitsubishi Gas Chemical Company, Inc.

Takamitsu Tsuruga

Shoichiro Kajiwara

Ken-ichi Kimizuka

Naoki Kogure

Kenichi Kimizuka

An electrolytic production of sodium persulfate in a decreased number of steps with low unit power cost is described. Sodium persulfate is caused to crystallize by the reaction between an anode product and sodium hydroxide. The resulting sodium persulfate slurry is separated into a mother liquor and sodium persulfate crystals which are recovered and dried to obtain product sodium persulfate. In the process of the invention, ammonia liberated in the reaction-type crystallization of sodium persulfate is recovered into a cathode product, which is then neutralized by sodium hydroxide and/or ammonia. The neutralized solution is combined with sodium sulfate recovered from the mother liquor after recovering the sodium persulfate crystals and reused as a part of the starting material for an anolyte feed solution.

Process for producing sodium persulfate

There are disclosed (1) a process for producing ammonium persulfate which comprises electrolyzing, as the starting raw material for an anode, an aqueous solution containing ammonium sulfate wherein ammonium ions are present in an amount of at least one equivalent based on sulfate ions; (2) a process for producing sodium persulfate which comprises the step (A) of electrolyzing an aqueous solution containing ammonium sulfate at an anode, the step (B) of producing sodium persulfate, the step (C) of crystallizing and separating the sodium persulfate and the step (D) of recycling the liquid produced at a cathode together with ammonia for use as the starting raw material for an anode in the step (A); and (3) a process for producing potassium persulfate which comprises the step (A&prime;) of electrolyzing an aqueous solution containing ammonium sulfate at an anode; and the step (B&prime;) of producing potassium persulfate. The above processes are capable of effectively producing respective persulfates in an industrially advantageous manner.

Process for producing persulfate

There is disclosed a process for producing sodium persulfate which comprises the step (1) of electrolyzing, at an anode, a solution containing ammonium sulfate, and the step (2) of producing sodium persulfate from the resultant liquid produced at the anode and sodium hydroxide and, as desired, the step of removing sodium sulfate, and further as desired, the step (3) of performing crystallization on the reaction liquid as produced in the step (2). According to the above process, it is made possible to efficiently produce sodium persulfate having a markedly high purity substantially free from nitrogen components at a high yield at a high current efficiency in electrolysis.

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Kanagawa-ken, Japan

Takamitsu Tsuruga