离子交换法脱除双氰胺结晶母液中钙离子的研究

发布时间：2018-05-11 20:47

  本文选题：双氰胺 + 离子交换　； 参考：《宁夏大学》2017年硕士论文

【摘要】：双氰胺是一种重要的精细化工材料,普遍应用于制药、电子、纺织、印刷等行业。由于生产过程中脱钙的不彻底导致后续双氰胺结晶母液中含有Ca(OH)2、CaCO3等含钙化合物,如以Ca2+计,含量约1500mg·kg-1。杂质的存在严重影响了双氰胺的纯度及品质。本文通过在原有生产工艺基础上,在结晶工段前引入离子交换法进行精脱钙,通过系统研究离子交换-结晶耦合工艺获得较优工艺条件,使双氰胺产品中Ca2+含量达到医药级双氰胺产品的要求。首先,通过比较D001、001×4、001×7、001×8四种型号的树脂对双氰胺结晶母液中钙离子的吸附量,发现在相同的实验条件下,001×7型树脂对钙离子的吸附量最大,单位体积吸附量达到68.15mg,并考虑经济性,本文选用001×7型树脂,并对双氰胺结晶母液中的Ca2+进行静态和动态交换实验。静态实验结果表明:在反应时间80min、温度45-50℃、树脂用量为40mL(空隙率0.42,下同)、搅拌速率250r·min-1的最佳工艺条件下处理200mL双氰胺结晶母液,Ca2+脱除率达到98.12%,交换后双氰胺结晶母液中钙离子含量为27.17mg·kg-1。动态实验装置采用高600mm、内径为40mm的玻璃柱。采用100mL树脂处理500mL双氰胺母液,母液流速为5mL·min-1,树脂床层高径比为5.3:1,交换柱内树脂床层交换温度为45-50℃,在此条件下脱钙率达到了97.32%,母液中钙离子含量低至38.71mg·kg-1,同时获得该过程的贯穿函数,并对动态过程的行为进行模拟进而揭示了动态离子交换的特征。在已有的分形多孔介质理论基础上,结合动态离子交换过程,通过实验数据拟合得出了离子交换过程树脂分形表面谱维数的计算方程为线性关系(相关性系数为0.992),利用方程的斜率求得该交换过程的分形表面谱维数为ds=2.21,并且得到了数学模型。通过分析理想表面与分形表面动力学方程中1/Ct与t关系,得出理想表面为线性关系,分形表面为幂函数关系。最后,通过前期单因素实验结果,采用响应曲面法优化结晶工艺,得到最佳工艺条件为:降温速率0.3℃·min-1,搅拌速率300r·min-1,晶种粒度60目,养晶时间30min,在该最佳工艺条件下Ca2+脱除率达到97.86%,双氰胺结晶产品中的钙含量为32.29mg·kg-1。达到了医药级双氰胺产品对Ca2+含量的要求。本文研究成果为工业生产高品质双氰胺提供基础。
[Abstract]:Dicyandiamide is an important fine chemical material, widely used in pharmaceutical, electronics, textile, printing and other industries. Because of the incomplete decalcification in the process of production, the subsequent dicyandiamide crystallization mother liquor contains calcium compounds such as CaOHHf2CaCO3, such as Ca2, the content of which is about 1500mg kg ~ (-1). The purity and quality of dicyandiamide were seriously affected by the presence of impurities. In this paper, on the basis of the original production process, the ion exchange method was introduced before the crystallization section for fine decalcification, and the better process conditions were obtained by systematically studying the ion exchange-crystallization coupling process. The content of Ca2 in dicyandiamide product is up to the requirement of pharmaceutical grade dicyandiamide product. First of all, by comparing the adsorption amount of calcium ions in dicyandiamide crystal mother liquor by D001001 脳 4001 脳 7001 脳 8 resin, it is found that the adsorption amount of calcium ion on D001001 脳 4001 脳 7001 脳 8 resin is the largest under the same experimental conditions, and the adsorption capacity per unit volume is 68.15mg. The static and dynamic exchange experiments of Ca2 in dicyandiamide crystal mother liquor were carried out by using 001 脳 7 resin. The static experiment results show that the reaction time is 80 min and the temperature is 45-50 鈩，

本文编号：1875533