氢氧化镁改性硅藻土处理含镉废水的研究

Effictiveness of cadmium-contained wastewater treated by Mg(OH)_2 modified diatomite

采用Mg(OH)_2对天然硅藻土进行改性,并应用于处理含Cd^(2+)废水。以等温吸附模型、吸附动力学模型与吸附热力学模型来剖析,结果证明吸附过程同时包含自发的、吸热的熵增加物理吸附,以及符合伪二阶动力学模型的化学吸附。采用扫描电子显微镜(SEM)、红外光谱(IR)、X射线衍射(XRD)、N_2等温吸脱附曲线等分析手段进行表征,结果表明,改性材料具有粒径小、晶型好、结晶度高、分布比较均匀、孔道结构良好的特点。实验探索出p H值、底物浓度、吸附剂的投加量、温度以及吸附时间等主要参数对处理效果的影响,最佳条件下改性硅藻土对Cd^(2+)的去除率(90.2%)为原土的7.6倍。

Diatomite was modified by magnesium hydroxide and applied to adsorb cadmium ions(Cd 2+)in the sewage.The models of isotherm adsorption,dynamic adsorption and thermodynamics absorption were utilized.The adsorption is a large complex process,which not only contains a spontaneous and endothermic physical process with increased entropy,but also the chemical adsorption consistent with the pseudo-second-order kinetic model.Characterized respectively by scanning electron microscopy(SEM),infrared spectroscopy(IR),X-ray diffraction(XRD)and N 2 adsorption-desorption isothermal curve,the modified material displayed good crystal structure with nano-order-scale size,high crystallinity,relatively uniform dispersion and good structural channels.The effects of the main parameters such as pH,substrate concentration,dosage,temperature and adsorption time were investigated,and the Cd 2+removal rate of modified diatomite(reached at 90.2%under optimum conditions)is 7.6 times larger than that of raw diatomite.