盐（卤）水中微量碘的脱除技术研究

发布时间：2018-04-04 05:27

本文选题：盐(卤)水　切入点：碘　出处：《北京化工大学》2015年硕士论文

【摘要】：烧碱与我们日常生活和生产都有着密不可分的联系,在印染、纺织、冶金等行业中应用广泛。在工业制备烧碱的工艺中,主要采用的是离子膜烧碱法。其原理是原料盐水在利用离子交换膜分隔开的阳极室和阴极室中进行电解,根据离子交换膜所具有的选择透过性,制得所需的烧碱。离子交换膜的使用寿命直接影响到工业生产烧碱的品质、产率和成本。其中,影响离子交换膜使用寿命的主要因素为在原料盐水中是否含有杂质。例如：Ca2+、Sr2+、Ba2+、Al3+、Hg2+、Mg2+、 Ni2+、Fe2+、Al3+、I-、SO42-等离子会影响电槽的电压电流等等。其中金属阳离子可以通过沉淀法及螯合树脂法除去,硫酸根离子可以通过脱硝除去。相较于这些离子,碘离子较难脱除。若盐水中存在碘负离子,当其进入到在阳极液中就会被氧化成碘酸根或高碘酸根的形式。高碘酸根与钙离子、镁离子、钠离子等阳离子生成不溶的沉淀,易聚集在离子交换膜上,严重影响了离子交换膜的使用寿命。因此,对于盐水中碘的脱除至关重要。本课题就离子膜烧碱中的脱氯淡盐水、脱硝盐水、精盐水和卤水进行脱除碘的研究。其中,卤水中的碘以还原态(I-)的形式存在,盐水中存在碘离子,并含有一种或多种其他形式的碘,成分较为复杂。分别对卤水和盐水进行除碘实验设计,并进行结果分析,研究得到的具体结论如下：1、本实验所讨论的脱硝盐水、脱氯淡盐水和精盐水中均含有碘离子,同时可能有微量IO3-、I2、I3-、I2Cl-、Cl2I-等其他形式的碘存在,成分较为复杂。2、改进文献报导中利用加入亚硫酸钠作为还原剂来去除盐水中碘的方法,先加入过量亚硫酸钠,再加入氧化剂,利用吸附剂对于碘单质进行吸附的方法,来去除盐水中的碘。优化氧化剂的加入量,这种方法对脱氯淡盐水脱碘率为29.41%,对脱硝盐水的脱碘率为27.20%,对精盐水的脱碘率为30.13%。3、利用蒙脱土的吸附性与铜盐沉淀法,将蒙脱土进行铜盐改性,用于盐水除碘。优化反应条件,在pH=5.0～6.0条件下,50 mL盐水中加入2.00 g铜盐改性蒙脱土,反应40 min,对脱硝盐水、脱氯淡盐水和精盐水中碘的吸附率分别25.37%、27.10%和24.90%。4、卤水除碘的最优条件为：在pH为2.0的酸性条件下,加入0.40mL氧化剂对100 mL卤水进行氧化反应40 min,将处理后的卤水以6.0 mL/min的流速通过吸附柱,对碘单质进行吸附。可以成功地除去卤水中大部分的碘,脱碘率达到80.00%以上,碘含量低于0.40 ppm,基本达到碘含量标准。5、本课题所研究的脱氯淡盐水、脱硝盐水和精盐水中成分较为复杂,含有很多与碘同族的氯元素。并且,碘的存在形式也较为复杂,可能会相互影响反应进行程度。这些原因均对盐水除碘的效果产生了影响。
[Abstract]:Caustic soda is closely related to our daily life and production. It is widely used in printing, dyeing, textile, metallurgy and other industries.In the industrial preparation of caustic soda, the ionic membrane caustic soda method is mainly used.The principle is that raw brine is electrolyzed in anodic and cathode chambers separated by ion exchange membrane, and the caustic soda is prepared according to the selective permeability of ion exchange membrane.The service life of ion exchange membrane directly affects the quality, yield and cost of caustic soda in industrial production.The main factor influencing the service life of ion exchange membrane is the impurity in raw brine.For example, the effect of Ni2 / Fe _ 2 / Al _ 3 / Al _ 3 / so _ 42- plasma on the voltage and current of the cell is observed.Metal cations can be removed by precipitation and chelating resin, and sulfate ions can be removed by denitrification.Compared with these ions, iodine ions are more difficult to remove.If iodide anion is present in brine, it will be oxidized to the form of iodate or periodate when it enters the anodic solution.The insoluble precipitation of periodate with calcium, magnesium, sodium ions and other cations is easy to accumulate on the ion exchange membrane, which seriously affects the service life of the ion exchange membrane.Therefore, it is very important for the removal of iodine in brine.In this paper, iodide removal from ionic membrane caustic soda by dechlorination, denitrification, refined salt water and brine was studied.Among them, the iodine in brine exists in the form of reduced iodide, and in brine there is iodine ion and one or more other forms of iodine, so the composition is more complex.The experimental design of deiodization of brine and brine was carried out, and the results were analyzed. The specific conclusions of the study were as follows: 1. The iodine ions were found in denitrification brine, dechlorinated light brine and refined brine discussed in this experiment.At the same time, there may be some other forms of iodine, such as small amounts of iodide, such as IO _ 3-I _ 2H _ 2H _ 2C _ 2Cl _ 2I- and so on. The composition of iodide is more complicated. 2. The method of using sodium sulfite as reducing agent to remove iodine in brine is improved by adding excessive sodium sulfite first and then adding oxidant.Iodine was removed from brine by adsorbent adsorbent.By optimizing the amount of oxidant, the deciodization rate of dechlorinated light brine is 29.41, the deiodination rate of denitrification salt water is 27.20 and the deiodination rate of refined salt water is 30.13. 3. Montmorillonite is modified with copper salt by the method of adsorption of montmorillonite and precipitation of copper salt.Used for iodine removal in brine.The optimum reaction conditions were as follows: adding 2.00g copper salt to modified montmorillonite in 50 mL brine under pH=5.0~6.0 condition, reacting for 40 min, then treating denitrification salt water.The adsorption rates of iodine in dechlorinated light brine and refined salt water were 25.377.10% and 24.90%, respectively. The optimum conditions for iodine removal in brine were as follows: at pH 2.0 acid,Adding 0.40mL oxidant to oxidize 100ml brine for 40 mins, the treated brine was adsorbed by adsorption column at the flow rate of 6.0 mL/min.Most of the iodine in the brine can be removed successfully. The deiodization rate is over 80.00%, the iodine content is less than 0.40 ppm, and basically reaches the standard of iodine content .5.The composition of dechlorinated light brine, denitrification salt water and refined salt water studied in this paper is more complex.There are many chlorine elements of the same family as iodine.Moreover, the existence of iodine is complex and may affect the degree of reaction.All of these factors have an effect on the iodine removal in brine.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028

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