高疏水性磁性高硅沸石的制备及其对有机污染物的吸附性研究

The aim of this study is to solve the problem of aid leached dealuminated zeolites with low crystal structure stability, high surface silanol groups, difficult recovery and hydrophobicity barrier etc. Silica coated magnetic particles are first mixed with the dealuminated zeolite followed with heat treatment in the purpose of improving the crystal structure stability, decreasing the surface silanol groups, loading of the magnetic particles on the surface of the dealuminated zeolites. Silane coupling agents are finally modified on the surface of the as-prepared magnetic high-silica zeolites in the purpose of further decreasing the remained surface silanol groups, increasing the hydrophobic groups and improving the hydrophobicity of the particles. The crystal structure, silicon/aluminum ratio, pore structure, surface silanol groups and surface hydrophobicity of the dealuminated, silica coated magnetic particles loaded, and silane coupling agent modified zeolites, and the occurrence, distribution and bonding state of the magnetic particles and silane coupling agent on the surface of the substrates are analyzed. The mechanisms of acid leaching dealumination and magnetic particles loading on the crystal structure stability of the dealuminated zeolites are clarified. The hydrophobic regulation mechanisms of heat treatment and silane coupling agent modification on the magnetic high-silica zeolites are then revealed. The adsorption mechanisms of the silane coupling agent modified magnetic high-silica zeolites on the organic contaminations are defined. Relationships of the hydrophobicity of the zeolites and the adsorption properties of the zeolites on the organic contaminations are established. The above studies provide theoretical support on preparation and application of the magnetic high-silica zeolites with high hydrophobicity in the organic contaminations disposal.

针对酸浸脱铝后沸石存在的结构稳定性低、表面硅醇基含量高、颗粒难回收和疏水性“壁垒”等问题，本项目拟将脱铝沸石与磁性氧化硅混合并热处理，用以提高脱铝沸石的结构稳定性，降低颗粒表面的硅醇基含量，实现磁性颗粒在脱铝沸石表面的固载；再在得到的磁性高硅沸石表面修饰硅烷偶联剂，用以消除颗粒表面的硅醇基并增加疏水基团，提高颗粒表面的疏水性。通过对酸浸脱铝、磁性氧化硅固载、热处理和偶联剂修饰后沸石的晶体结构、硅铝比、孔结构、表面硅醇基和疏水性等进行表征分析，结合磁性氧化硅和偶联剂在载体表面的赋存、分布及与载体间的结合状态等，阐明酸浸脱铝和磁性氧化硅固载对脱铝沸石结构稳定性的影响机理，揭示热处理和偶联剂修饰对磁性高硅沸石表面的疏水性调控机制，明确偶联剂修饰磁性高硅沸石对有机污染物的吸附机理，确立沸石表面疏水性与其对有机污染物吸附性的关系，为高疏水性磁性高硅沸石的制备及其在有机污染物处理中的应用提供理论支持。

环境污染物的治理是关乎国计民生的重大课题，开发新型高效环境污染处理用吸附剂是当前的研究热点之一。本项目以河北承德围场地区的天然沸石为原料，对其进行酸处理以脱除其结构中的铝元素，通过控制酸处理浓度、处理温度和处理时间定量调控沸石的硅铝比，获得了具有不同硅铝比（5.3-372.7）的沸石，所得沸石具有较高的比表面积和疏水性；对酸处理沸石进行热处理，通过控制热处理温度调控沸石的表面羟基含量，获得了具有较高疏水性的沸石；在磁性四氧化三铁表面包覆氧化硅，通过控制pH值、硅酸钠添加量等获得了具有较佳包覆效果的磁性氧化硅；将磁性氧化硅与酸处理沸石进行混合并热处理获得了具有高比表面积（>167 m2/g）和良好磁性能的磁性沸石；在沸石及磁性沸石表面修饰硅烷偶联剂，通过控制偶联剂的改性量获得了具有不同疏水性的有机修饰（磁性）沸石。采用制备的一系列沸石样品处理苯、甲苯、萘、煤油等有机污染物，发现沸石疏水性的提高有利于其对疏水性污染物的吸附，其中沸石的疏水性与其对煤油的吸附性具有很高的正相关性。通过对所制备材料的结构、表面亲疏水性和吸附性进行表征分析，阐明了酸处理、热处理、磁性氧化硅固载和有机修饰等对沸石结构和表面亲疏水性的影响机理，明确了高硅沸石及有机修饰沸石等对有机污染物的吸附机理，建立了沸石表面亲疏水性与其对有机污染物吸附性的关系。完成了项目的预期目标，截止目前，已发表学术论文6篇，其中SCI论文4篇，EI论文和中文核心论文各1篇；申请国家发明专利4项，其中已授权1项。