介孔硅酸钙的合成及其对Pb(Ⅱ)的吸附性能

Synthesis of mesoporous calcium silicate and its adsorption properties for Pb(Ⅱ)

以硝酸钙和硅酸钠为原料、十二烷基磺酸钠为模板剂,通过共沉淀法制备了介孔硅酸钙;采用X-射线粉末衍射(XRD)、扫描电镜(SEM)、红外光谱(FT-IR)和孔容与比表面积分析仪(BET)等对其结构和形貌进行了表征;考察了其对含Pb2+模拟重金属废水的吸附及解吸再生性能.结果表明,合成的硅酸钙具有介孔结构,为狭缝孔,孔径介于4-50 nm,比表面积为250.12 m2·g-1;在298 K下,介孔硅酸钙对Pb2+的饱和吸附量为613.42 mg·g-1,远比比表面积为847.47 mg·g-1的活性炭大;吸附反应为吸热反应,吸附等温线符合Langmuir吸附模型;经5次洗脱再生后,介孔硅酸钙对Pb2+的饱和吸附量和去除率仅分别降低37.64 mg·g-1和5.88%,表明其具有较好的吸附/再生性能.

Mesoporous calcium silicate was prepared from calcium nitrate and sodium silicate using sodium dodecyl sulfonate as a template by means of co-precipitation. The calcium silicate synthesized was characterized by the X- ray diffraction （ XRD）, scanning electron microscopy （ SEM）, infrared spectrum （ FT- IR） and Brunauer-emmett-teller （BET）. The adsorption performance of mesoporous calcium silicate synthesized for Pb^2＋, and its desorption regeneration performance was also studied. The results show that, the mesoporous calcium silicate synthesized has mesoporous slit-pore structure, with a specific surface area of 250.12 m^2·g^-1, and 4-50 nm pore size; the adsorption capacities of mesoporous calcium silicate for Pb^2＋ is 613.42 mg·g^-1 at 298 K,which is far greater than that by activated carbon with a specific surface area of 847.47 m^2·g^-1. The adsorption between heavy metal ions and mesoporous calcium silicate synthesized is an endothermic reaction and in line with the theory of Langmuir isothermal adsorption. The adsorption capacity and removal rate for Pb^2＋ have only decreased 37.64 mg·g^-1 and 5.88% after 5 times elution-regeneration, respectively, indicating that the mesoporous calcium silicate synthesized is of excellent adsorption and regeneration performance.