【作者】 何勇；

【导师】 郑杰；

【作者基本信息】 重庆大学 ， 食品科学， 2013， 硕士

【摘要】 碘是人体必需的微量元素，但并不是摄入碘越多越好,摄入量过多，还会对身体有害。一些地区水源中含碘浓度较高，这就需要降低其中碘浓度才能被食用。除碘技术在食品和其他行业中都有很大应用前景。目前工业上主要采用离子膜电解技术制碱，采用的原料有工业盐、卤水加盐、全卤水；但随着时间的推移，因离子膜烧碱生产的特殊性，盐水一直在循环利用，没有外排，某些离子在现有的一次盐水和二次盐水工艺无法处理，形成了离子的富集，对电流效率和离子膜寿命造成了严重的影响，特别是碘离子，因原盐、卤水中含碘，在电解时，碘将以Na₃H₂IO₆、Ba₃H₄（IO₆）₂形式存在，分子量极大，将会堵塞离子膜通道，阻碍钠离子通过，降低电流效率，使离子膜寿命缩短。而离子膜价格昂贵，如频繁更换离子膜，对工厂的利益是极为不利的。因此，去除盐水中的碘是最直接和经济有效的措施。本论文在综述盐水中碘的去除方法及研究现状的基础上，主要采用过氧化氢氧化-粉末活性炭（PAC）联合去除盐水中的碘离子。其主要内容如下：①盐水中碘离子转化为碘单质最佳条件的探究，本实验中考察了不同氧化剂、H₂O₂与I-的物质的量之比、反应温度、pH值及反应时间对I-转化率的影响，结果表明: H₂O₂反应后生成水和氧气相对其它还原剂体系绿色环保无二次污染，适宜用作碘回收时的氧化剂，当H₂O₂与I-的物质的量之比为1，反应温度为40℃，pH为2，反应时间为40min的条件下，碘离子完全转化为碘单质。②活性炭吸附盐水中碘的最佳条件的探究，本实验中考察了吸附时间、温度、搅拌速率、粉末活性炭的量、共存氯离子对碘吸附率的影响，吸附平衡等温线的测定及验证实验。其结果表明：粉末活性炭对碘的吸附为物理吸附过程，等温吸附符合Freundlich方程，粉末活性炭的量为1.5g/L，温度为50℃，转速为100r/min吸附2h的条件下，吸附率为93.4%，共存氯离子对吸附效果影响不明显。表明此法对碘有较好的去除效果。③几种不同方法去除盐水中碘离子的比较，本实验中通过比较阴离子树脂交换法、不同吸附剂吸附法，以及纳滤膜法对盐水中碘的去除效果，结果表明：吸附法效果优于离子交换法，离子交换法效果优于纳滤膜法，结合实验操作过程和成本考虑，粉末活性炭的去除效果是几种方法中更为合适的。进一步确定过氧化氢氧化与粉末活性炭吸附技术的联用，其中过氧化氢做氧化剂清洁无污染不引入新的杂质，活性炭吸附过程操作简单，为工业盐水中碘的去除和回收提供可能的途径。④活性炭洗脱再生，本实验中主要是通过化学方法对活性炭进行再生，研究了包括洗脱剂浓度、洗脱时间、温度和搅拌速率等再生条件对再生效果的影响，实验结果表明：实验选用0.05mol/L的氢氧化钠为洗脱剂，在温度为30℃，搅拌速率为80r/min的情况下，已吸附碘的粉末活性炭洗脱120min可达到较好的再生洗脱效果。更多还原

【Abstract】 Iodine is essential trace elements to human, but excess intake of iodine will beharmful to the body. Some areas with high iodine concentration in water, it will need toreduce the iodine concentration can be edible. The iodine-removing technology has verybig application prospect in food and other industry areas.Membrane cell technology is used in all new chlor-alkali plants. This is due to thefact that the expenditure concerning capital investment, operating costs and energyconsumption, is lower than that of diaphragm and membrane technology. What is more,this is the most environmental friendly technology, yet this technology requires a highpurity brine. One of the most important parameters to be monitored is the concentrationof iodide ion. In the electrolysis cell, iodide is oxidized to iodate, which precipitates inthe ion-exchange membrane and decreases the membrane’s useful lifetime. So thepresence of iodide in brine is the direct reason leading to the damage of ion-exchangemembrane. However, the ion-exchange membrane is quite expensive, the productioncosts will increase greatly if the ion-exchange membrane is changed frequently inchlor-alkali industry. Accordingly, removing iodide from brine is the most effective andeconomical method. In this study, the technique of H₂O₂oxidation coupled withpowdered activated carbon （PAC） to remove iodine from low concentrationiodide-contained chlor-alkali brine was studied. The main contents include thefollowing:①In the process of oxidation of iodide, the optimum condition of iodideconversion was studied, some factors such as different oxidants, the molar ratio ofhydrogen peroxide （H₂O₂） to I-, reaction temperature, pH value and the reaction time oniodide conversion were studied, and the results showed that: in the reaction of H₂O₂, theproducts are water and oxygen, which showed H₂O₂is an suitable oxidant for iodideoxidation, comparing to other oxidants there is no secondary pollution in the reactionsystem.When the molar ratio of hydrogen peroxide （H₂O₂） to I-was1:1, reactiontemperature was40℃, pHwas2, and the reaction time was40min, the conversionefficiency reached to the maximum.②In the process of the adsorption of iodine, the adsorption time, temperature,stirring speed, the amount of powder activated carbon and the influence of coexistenceion were investigated. The results indicated that the optimum conditions for iodine removal were as follows: at a pH range of2⁵the amount of PAC was1.5g/L, theadsorption time was120min, the adsorption efficiency was93.4%and the equilibriumadsorption isotherms can be described by the Freundlich isotherm model, which showedthat PAC can be used as an effective adsorbent for iodine removal from brine andprovides some theoretical basis for the removal of iodide from chlor-alkali brine.③Several different methods to remove iodine ion were in the comparison: in thisexperiment ion resin exchange method, different adsorbent adsorption method, andnanofiltration membrane method to remove iodine in alkali salt water were compared,and the results showed that the adsorption effect of activated carbon was better than thatof ion exchange method, the effect of ion exchange method was better than that ofnanofiltration membrane method. Take the experimental operation process and cost intoconsiderations, powder activated carbon is more appropriate. Further, in this technologycombined the oxidant hydrogen peroxide with powder activated carbon, hydrogenperoxide is pollution-free and will not introduce new impurities, the operation is simple,which provids a possible way for iodine removal and recovery in industrial salt water.④Regeneration of activated carbon: in this experiment activated carbon wasregenerated mainly through chemical method, the effects of elution agent concentration,elution time, temperature and stirring rate and other regenerative conditions wereinvestigated, the experimental results showed that: the powered activated carbon withiodine was eluted in elution agent sodium hydroxide （0.05mol/L）, stirred at the speedof80r/min at30℃for120min can achieve better regeneration elution effect.更多还原