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以化学试剂为原料,在传统水热合成法的基础上,采用超声波法外加助剂(柠檬酸),通过改变柠檬酸的用量、晶化时间和晶化温度设计三水平三因素正交试验合成4A分子筛,采用XRD、SEM、FI-IR及钙离子交换性等方法进行分析表征,并探讨了制备4A分子筛的最优条件。结果表明,4A分子筛制备的最优条件为:晶化温度70℃,柠檬酸/Al_2O_3=0.75(摩尔比),晶化时间4h。4A分子筛对钙离子交换的Langmuir吸附等温方程为q=0.00012x/(1+0.024x)。钙交换能力达到310.71mg CaCO_3/g,钙离子交换的最佳吸附时间为1h,最佳吸附温度为35℃。
Based on the traditional hydrothermal synthesis method, the chemical reagent was used as the raw material, the three-level three-factor orthogonal experiment was designed and synthesized by changing the amount of citric acid, crystallization time and crystallization temperature by using ultrasonic method plus auxiliary (citric acid) 4A molecular sieves were synthesized and characterized by XRD, SEM, FI-IR and calcium ion exchange. The optimum conditions for preparing 4A molecular sieves were also discussed. The results showed that the optimum conditions for the preparation of 4A zeolite were as follows: crystallization temperature 70 ℃, citric acid / Al_2O_3 = 0.75 (molar ratio), crystallization time 4h. The Langmuir adsorption isotherm equation of 4A molecular sieve for calcium ion exchange is q = 0.00012x / (1 + 0.024x). The calcium exchange capacity reached 310.71 mg CaCO 3 / g, the optimum adsorption time of calcium ion exchange was 1 h, and the optimum adsorption temperature was 35 ℃.