稻壳基A型沸石的表征及其对NH_3-N的吸/脱附动力学研究

以稻壳的煅烧灰分为原料,采用水热合成法制得稻壳沸石,运用SEM、XRD和FTIR表征了稻壳沸石的结构特性,并通过静态平衡吸附实验研究了稻壳沸石对NH3-N的吸附特性。结果表明:实验条件下可获得结晶度高、晶型较好的A型单晶沸石,降低晶化温度有利于A型沸石的生成。初始浓度为25,50,100 mg/L时稻壳沸石的最大吸附量分别为3.36,5.16,8.39 mg/g,吸附过程遵循伪二级吸附动力学模型。碱当量MNa OH/AN对NH3-N从稻壳沸石上的脱附影响较大,MNaOH/AN为0.85、8.47和42.4时伪二级模型拟合的饱和脱附值分别为7.46,16.21,19.96 mg/g,与实测值基本接近,NH3-N从稻壳沸石上的脱附主要受化学作用控制,过程遵循伪二级脱附动力学模型。

CHARACTERIZATION OF RICE HULL BASE A-TYPE ZEOLITE AND ITS ADSORPTION/DESORPTION DYNAMICS OF NH3-N

Rice hull zeolite was prepared via hydrothermal synthesis method using calcined ash contents of rice hull as raw materials.SEM,XRD and FTIR were used to characterize the structural characteristics of rick hull zeolite.Adsorption characteristics of rice hull zeolite on NH3-N were studied through static equilibrium adsorption experiment.Results indicated that maximum adsorbing capacities of rice hull zeolite were respectively 3.36,5.16,8.39 mg/g when initial concentrations were 25,50,100 mg/L,which indicated that adsorption process followed pseudo-second-order adsorption kinetics model.Alkali equivalent weight had great desorption effect on NH3-N from rice hull zeolite,saturated desorption values fitted by the pseudo-second-order model were respectively 7.46,16.21,19.96 mg/g when MNaOH/AN was 0.85,8.47 and 42.4,respectively,which were basically approximate to measured values,adsorption of NH3-N from rice hull zeolite was mainly controlled by chemical action,and the process followed the pseudo-second-order adsorption kinetics model.