摘要
根据宣城沸石化学成分、可交换阳离子组成和热处理晶体结构演化,判断宣城沸石为富钙斜发沸石,具有低热稳定性的特点。通过正交实验研究了沸石CEC测定的最佳条件,并在此条件下对不同温度焙烧后沸石CEC进行了测定。结果表明,焙烧温度小于400℃时,沸石CEC变化很小;250℃时CEC稍微升高,达到最大值,这是由于焙烧导致体积密度降低、计算基准差异造成的;在250～400℃之间,焙烧样品CEC缓慢降低;焙烧温度大于400℃,沸石CEC迅速降低。热分析和X射线衍射分析结果证实,沸石晶体结构发生变化的起点在250℃,结构发生突变的温度为400℃。在高温焙烧中沸石CEC迅速降低是沸石晶体结构破坏所致。富钙沸石作为离子交换剂使用时,热加工温度不能超过400℃。
According to chemical composition, exchangeable cation and thermal behaviors of crystal structure, Xuancheng zeolite should belong to calcium-rich clinoptilolite with low thermal stability. Optimal test conditions were determined by orthogonal experi- ments, and then CEC values were measured under such conditions. The results show that when the roasting temperature is lower than 400 ℃, only an indistinctive change in CEC value of the clinoptilolite occurs, whereas at 250 ℃, the CEC value slightly rises and reaches its maximum. This is ascribed to the calculation basis discrepancy caused by the decrease of volume density. Between 250 ℃ and 400 ℃, the CEC value of Xuancheng zeolite decreases slowly. When the baking temperature exceeds 400 ℃, the CEC value drops sharply. Thermal and X-ray diffraction analysis has proved that there exists a starting point of 250 ℃ in structure destroy and an abrupt change at 400 ℃, which causes rapid decrease in CEC value at a high temperature. It is thus concluded that when calciumrich clinoptilolite is used as an ion exchange reagent, the processing temperature should not exceed 400 ℃.
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2007年第6期511-514,共4页
Acta Petrologica et Mineralogica
基金
安徽省科技攻关资助项目(07020303062)
关键词
富钙斜发沸石
晶体结构
焙烧
热结构演化
阳离子交换容量
calcium-rich clinoptilolite
crystal structure
roasting
thermal structure evolution
cation exchange capacity
