合成条件对粉煤灰合成沸石过程中沸石生成和品质的影响

系统研究了由粉煤灰合成沸石过程中温度、反应时间、液固比和NaOH浓度等合成条件对沸石生成及其阳离子交换容量(CEC,CationExchangeCapacity)的影响.结果表明,温度主要影响沸石矿物的结晶度;液固比主要影响沸石种类;NaOH浓度和反应时间对两者均产生明显影响.合成产物的CEC随温度、液固比、反应时间呈快速增加,并在分别达到110℃、2.5和16h时趋于一最大值.NaOH浓度越高,合成产物CEC也越高,至2mol·L^-1时达到最大,之后显著下降.考虑到合成成本,最佳合成条件初步归纳为:温度110-120℃,反应时间8-16h,液固比2.5,NaOH浓度2mol·L^-1.

Effects of Synthesis Conditions on the Formation and Quality of Zeolite During the Hydrothermal Zeolitization Processes of Fly Ash

The formation and cation exchange capacity (CEC) of zeolite synthesized after alkaline activation of a Chinese fly ash, as a function of temperature, liquid/solid ratio, NaOH concentration and reaction time in closed systems were investigated. Temperature affected mainly the crystallinity of zeolite formed, liquid/solid ratio affected mainly the type of zeolite, and while NaOH concentration and reaction time influenced both of them. The CEC value of synthesized products increased greatly as a function of temperature, liquid/solid ratio and reaction time until the temperature of 110℃, the ratio of 2.5, and the time of 16h were reached, and then approached to a constant value. The CEC value of synthesized zeolite increased initially with the increase in NaOH concentration, reached its maximum value at a concentration of 2mol·L^-1, and then decreased sharply above the concentration. The results show that from the economic point of view, the optimal conditions are as follows: a temperature of 110～120℃, a reaction time of 8～16h, a liquid/solid ratio of 2.5, and a NaOH concentration of 2mol·L^-1.