电催化合成重铬酸钠过程中氯离子的变化规律

Variation of chloride ions in preparation on sodium dichromate by electrosynthesis method

利用电催化合成技术从铬酸钠制备重铬酸钠,研究了阳极溶液中氯离子的变化规律和脱除效果,并对氯离子的脱除原理进行了分析。结果表明,电催化合成重铬酸钠技术能够有效脱除原料溶液中的氯离子。氯离子集中在电催化反应后期(钠铬物质的量比<1.2,阳极电解液p H<4.8)发生氧化反应,以氯气形式自溶液中逸出。当反应时间>5.4 h时,阳极电解液中氯离子含量已经极低。其析出原理可能是电催化合成反应后期,阳极电解液不断增大的酸度提高了H2O/O2反应的过电位,导致氯离子在阳极优先失去电子,被氧化成氯气集中析出。

Study on the variation of chloride ions in preparation on sodium dichromate by electrosynthesis method,as well as the principle of oxidation of chloride. The results show that the electro-catalytic synthe-sis technology can effectively remove chloride from sodium dichromate solution. The oxidation reaction of chloride which is changed to chlorine occurs in the last stage of electrosynthesis process （ the molar ratio of Na and Cr is below 1. 2,the pH of anolyte is below 4. 8）. When the reaction time〉5. 4 h,the chloride ions content from anolyte already very low. The reason may be the increasing acidity of anolyte increases the overvoltage of H2 O/O2 reaction in the final stage of electrochemical reactions. Chloride ions which are preferentially lost electrons in the anode are oxidized to chlorine and come out of solution.