水杨酸功能化杂化材料的制备及其在盐湖老卤吸附法提硼中的应用研究

Boric acid is an importance resource in chemical industry. Annually more than 90 thousand tons of boron were discharged from potash brine in Qinghai province. As the concentration of boron in potash brine is as low as less than 1g/L, adsorption process using a boron-selective resin is a promising technique for boron recovery from aqueous solutions, however, the widely used N-methylglucamine-based chelate resin can only show acceptable adsorption uptake in the alkaline solutions with pH around 10. The fact that inferior performance of the chelate resin in acidic solution restricts its application for boron recovery from potash brine. Organic-inorganic hybrid materials are of type of sorbents with their structures, compositions and properties adjustable. This project utilizes the discovery in salicylic acid’s interaction with boric acid in acidic solutions to propose the present research on the preparation of hybrid boron-selective adsorbent. In order to prepare boron adsorbent with high-density functional groups, we devise some novel silane monomers containing moiety of salicylic acid. The objective of this proposal is to explore the regulation method of controlled pore structure and properties of the adsorbents prepared by sol-gel reaction and to demonstrate the intrinsic relationship between the performance of the adsorbent and the density of salicylic acid as well as corresponding variations in the structure of salicylic acid derivatives. Thus it is possible for us to obtain a technique for preparing high-performance boron adsorbents-based on the moiety of salicylic acid. If we succeed, it is probable for the invented boron adsorbent to fill a gap in a practical application such as boron recovery from brine where we fail to use traditional N-methylglucamine-based chelate resin.

硼酸是一种重要的化工资源，青海盐湖地区每年随提钾老卤排放的总量多达9万吨，资源浪费严重。由于老卤中硼含量低，吸附法是一种较为可行的提硼技术，但现有基于N-甲基葡萄糖胺的硼选择性螯合树脂在碱性条件（pH~10）才能发挥较好的吸附性能，而对弱酸性水溶液中硼的吸附量普遍较低，制约了该类树脂在盐湖卤水提硼的应用。本项目利用杂化材料具有结构、组成、性质可调的特点，针对水杨酸阴离子在弱酸溶液与硼酸中性分子发生螯合的特性，设计合成新型含水杨酸衍生物功能基的硅源单体，采用溶胶-凝胶法工艺并通过提高硅烷单体比例实现大容量硼吸附剂的制备，研究材料制备过程微观结构、组成与性能的演变规律，建立吸附剂水杨酸功能基结构-密度-吸附/传质/机械性能的内在联系，掌握高性能水杨酸功能基硼吸附剂可控制备关键参数。本项目可望发展一种新型硼吸附材料，弥补现有硼特效螯合树脂的不足，为盐湖卤水等弱酸环境中提硼应用奠定基础。

本项目针对盐湖老卤高盐体系中硼酸的脱除及回收利用问题，开展了高性能硼螯合吸附材料的制备研究，探索了不同表面功能配基的硼吸附剂的制备方法及其吸附性能，研究内容及所取得的结果如下：1）研究了水杨酸（SA）、4-羟基水杨酸（DHBA）、邻苯二酚（CT）、苦杏仁酸（MA）、没食子酸（GA）等芳香型功能单体与苯酚、甲醛的酚醛缩聚反应，采用反相悬浮聚合工艺制备了一系列硼螯合树脂并对其结构进行表征，分别测试了它们的硼酸吸附性能，其中水杨酸螯合树脂的硼吸附容量最大，饱和吸附量达0.56 mmol/g。2）研究了键合型多羟基硼螯合树脂的制备及其硼酸吸附性能。分别以氨基水杨酸（ASA）、3-氨基-1,2-丙二醇（3-APD）和2-氨基-1,3-丙二醇（2-APD）、葡甲胺（NMDG）为功能单体，对氯球骨架进行接枝修饰制备得到硼螯合树脂；其中，葡甲胺键合树脂的硼酸吸附性能最佳，饱和吸附量达1.61 mmol/g。3）硼螯合吸附材料的工业应用可行性研究。考察了盐湖老卤中各种离子对树脂吸附材料硼酸吸附性能的影响，包括钠离子、镁离子、钾离子和钙离子等阳离子对吸附容量的影响，同时还考察了树脂的再生方法及再生循环使用性能。经过三年的研究，在AIChE J、Sep. Purf. Tech.等期刊上发表SCI收录论文4篇（包括1篇Chemistry - A European Journal期刊内封论文）及EI收录论文2篇，申请发明专利3项（其中2项已获得授权）；项目完成人参加国内外学术会议12次，培养研究生5名和本科生2名。