Preparation of consolidated zeolite body using mechanochemical phenomena and its application to removal of heavy metals

以水玻璃（硅酸钾或硅酸钠溶液）和氢氧化铝为原料合成无机固结体。研究了固结体向块状沸石体转变的可能性。研究了氢氧化铝对形成沸石相的力学化学效应。对合成的块状沸石的去除率进行了评价。对于含钾沸石体系，将前驱体在高于140℃的温度下热处理，合成F沸石。地层温度与钾的含量有关。钾的加入显著降低了沸石的形成温度。以原料中K:Al:Si=1:1:1的成分为例，需要热处理温度高于140℃才能形成沸石相。当K:Al:Si=1.5:1:1和K:Al:Si=2:1:1时，温度分别下降到80℃和60℃。合成的不同化学成分的沸石均为f型沸石，过量添加钾使固结沸石的耐水性变差，沸石在水中破碎。而对于以钠为主要成分的沸石体系，则可以合成整体式沸石A （Na:Al:Si=1:1:1）作为固结体。未经机械化学处理的氢氧化铝作为起始材料，其晶相很大程度上取决于颗粒大小。对于较大的颗粒，合成faujasite型沸石，较小的颗粒促进形成A型沸石。机械化学处理对A型沸石的形成温度有较大影响。机械化学处理对A型沸石的形成温度有较大影响，使60℃的热处理温度足以形成体积较大的A型沸石。F型沸石和A型沸石对Pb、Cd等重金属均表现出较好的去除特性。

Inorganic consolidated bodies were synthesized from water-glass (potassium or sodium silicate solution) and aluminum hydroxide. The possibility of transition of the consolidated body to bulky zeolite body was investigated. Mechanochemical effect of aluminum hydroxide on formation zeolite phase was also investigated. The removal capability of the synthesized bulky zeolite was estimated.For system of zeolite composed of potassium, zeolite F was synthesized when the precursor was heat-treated at a temperature higher than 140℃. The formation temperature was dependent on the amount of potassium. Addition of potassium remarkably decreased the formation temperature zeolite. For composition of K:Al:Si=1:1:1 in starting materials, for example, heat-treatment temperature higher than 140℃ was required to form zeolite phase. For composition of K:Al:Si=1.5:1:1 and K:Al:Si=2:1:1, on the contrary, the temperature decreased to 80℃ and 60℃, respectively. All of synthesized zeolites with different chemical composition were identified as type F. Excessive addition of potassium deteriorated the water resistance of the consolidated zeolite and the zeolite broke down in water.For system of zeolite composed of sodium, on the contrary, monolithic zeolite A (Na:Al:Si=1:1:1) could be synthesized as a consolidated body. Crystalline phase was greatly dependent on particle size of aluminum hydroxide as a starting material without mechanochemical treatment. For larger particle, faujasite type zeolite was synthesized and smaller particle promoted to form A type zeolite. In addition, mechanochemical treatment was very effective to synthesize monolithic zeolite A. The mechanochemical treatment had much effect on formation temperature of zeolite A. Aluminum hydroxide powder treated mechanically made the heat-treatment temperature of 60℃ enough to form bulky zeolite A.Both of zeolites, type F and type A, exhibited good characteristic of removal for heavy metals such as Pb and Cd.