吸附法去除电解用氯化钠中微量碘离子

摘要

In the manufacturing process of ion-exchange membrane caustic soda, trace iodide ions in the brine are oxidized during the electrolysis process into iodate ions or periodate ions which react with sodium ions, barium ion, calcium ion and magnesium ion in the brine to form precipitates, causing the membrane congested, the service life of the membrane shortened, electrolytic current efficiency reduced, and the voltage raised. Therefore, organic amine adsorbent for iodide was prepared by sol-gel method to study the dynamic adsorption removal performance and adsorption column recycling performance of trace iodine ions in sodium chloride solution. The results showed that the content of iodine ion in salt water was dropped to below 0.2mg/L after the adsorption column treatment, and the performance of the for the brine was between 3.0L/g to 3.6L/g when the quantity ratio of iodide ion and hydrogen ion was 1:2, the material liquid velocity was 6.4mL/(g?min), iodine ion content was 10mg/L, Na2CO3 elution content was 0.01mol/L, and cycle index was five times. Furthermore, the influence of the coexisting ions in the salt water on the iodide removal performance was investigated. The results showed that coexisting Br–, SO42–, Mg2+, and Fe2+ caused handle brine volume of the adsorption column decreased. Therefore, the removal treatment of iodide from brine should be conducted after calcium, magnesium, and iron removal treatments to ensure the iodine adsorption column efficiency.%在离子膜法制碱过程中,盐水中的碘离子会在电解过程中被氧化成碘酸根或高碘酸根,与盐水中的钠离子、钡离子、钙离子、镁离子等形成碘酸盐沉淀或高碘酸盐沉淀,造成膜堵塞、膜使用寿命缩短、电解电流效率降低、电压升高等问题.本文采用溶胶凝胶法制备了有机胺类碘离子吸附剂,研究了动态吸附氯化钠中微量碘离子的去除性能和吸附柱循环再生性能,结果表明:吸附柱可将盐水中碘离子含量降至0.2mg/L以下,碘离子与氢离子物质的量比为1:2、料液流速为6.4mL/(g?min)、碘离子含量为10mg/L时,采用0.01mol/L的Na2CO3洗脱再生循环5次,吸附剂处理盐水体积约在3.0～3.6L/g之间.同时,考察了盐水中共存离子对除碘性能的影响,结果表明:盐水中共存离子Br–、SO42–、Mg2+、Fe2+会使吸附柱可处理盐水体积降低,为保证吸附柱除碘效率,盐水除碘步骤应在精制除钙镁、除铁之后.