煤系高岭土磁性吸附材料的制备及对Pb(Ⅱ)吸附研究

Preparation of Coal-based Kaolinite Magnetic Adsorption Materials and their Adsorptions on Pb(Ⅱ)

为开发煤矸石的资源化利用技术,以煤系高岭土为原料,通过共沉淀法制备了一系列磁性煤系高岭土/Fe_(3)O_(4)吸附材料,考察了其对水中Pb(Ⅱ)的吸附性能,并通过XRD、SEM、BET等手段对吸附材料的物理化学性质进行了分析研究。结果表明:在高岭土与FeSO_(4)·7H_(2)O的质量比为1∶1,Fe(Ⅲ)与Fe(Ⅱ)的摩尔比为2∶1时,制备的吸附材料C-F-1对Pb(Ⅱ)的吸附效果最佳。当吸附温度为25℃、吸附剂量为3g/L、Pb(Ⅱ)初始浓度为700mg/L、初始pH为6、吸附时间为90min时,最大吸附容量为201.69mg/g。表征结果显示,C-F-1形状近似球形,粒径在10~20μm、30 nm左右的Fe_(3)O_(4)颗粒负载在煤系高岭土的片层上,表面粗糙且疏松,比表面积约是煤系高岭土的2.3倍,Zeta电位值为负值,且其电位绝对值均高于煤系高岭土和Fe_(3)O_(4)。此外,吸附热力学和动力学分析结果表明,C-F-1对Pb(Ⅱ)的吸附符合准二级动力学模型,以化学吸附为主;吸附等温线符合Langmuir模型,为单分子层吸附;C-F-1对Pb(Ⅱ)的吸附是吸热自发的过程。以煤系高岭土为原料制备的C-F-1具有取材廉价易得,吸附性能好、易于分离回收等优点,具有潜在的工业应用价值。

In order to develop the resource utilization technology of coal gangue,taking coal-based kaolinite as raw material,a series of coal-based kaolinite/Fe_(3)O_(4) magnetic composite materials were prepared through coprecipitation method,and their adsorptions on Pb(Ⅱ)were surveyed.By XRD,SEM,BET and other methods,the chemical and physical properties of adsorption materials were analyzed.The results show that the prepared C-F-1adsorption material has the best adsorption effect on Pb(Ⅱ)when the mass ratio of coal-based kaolinite to FeSO_(4)·7H_(2)O is 1∶1and the mole ratio of Fe(Ⅲ)to Fe(Ⅱ)is 2∶1.When the adsorption temperature is 25℃,the adsorption dose is 3g/L,the initial concentration of Pb(Ⅱ)is 700mg/L,the initial pH value is 6,and the adsorption time is 90 min,the maximum adsorption capacity is 201.69 mg/g.The characterization results show that C-F-1is approximately spherical in shape,the Fe_(3)O_(4) particles with diameters of 10~20μm and about 30nm are loaded on the lamellar of coal-based kaolinite,the surface is rough and loose,and the specific surface area is 2.3times that of the coal-based kaolinite.The Zeta potential value is negative,and its absolute potential value is higher than that of coal-based kaolinite and Fe_(3)O_(4).In addition,the thermodynamic and kinetic results of adsorption show that the adsorption of C-F-1on Pb(Ⅱ)conforms to the quasi-second-order kinetic model,and the chemical adsorption is the main method.The adsorption isotherm conforms to Langmuir model and is monolayer adsorption.The adsorption of C-F-1on Pb(Ⅱ)is endothermic and spontaneous.C-F-1prepared from coal-based kaolinite has the advantages of cheap materials,good adsorption performance,easy separation and recovery,and has potential industrial application value.