硅铝介孔材料的制备及其吸附磷酸盐的性能

Preparation of Mesoporous Aluminumsilicate Materials and Performance of Phosphate Adsorption

为缓解富营养化现象,有效去除水体中的磷酸盐已成为亟待解决的问题之一。采用一步水热合成法,分别以硫酸铝、异丙醇铝为铝源,制备出两种不同铝源的有序介孔硅铝材料,并研究其对磷酸盐的去除性能。采用N_2吸附-脱附、小角X射线衍射、核磁共振光谱(NMR)、透射电子显微镜(TEM)对材料进行表征。研究表明:异丙醇铝是制备硅铝材料的一种较好的铝源,可使铝较好地分散于硅骨架中;当铝以四配位形式进入MCM-41骨架时,材料中的酸性位多,吸附性能强,此时硅铝材料中的铝与磷酸根发生键合作用从而去除磷酸盐;在常温、低浓度含磷水体中(C_0为3 mg/L),以异丙醇铝为铝源的介孔硅铝材料其吸附容量是以硫酸铝为铝源的1.2倍,是纯MCM-41的1.6倍;在常温、高浓度含磷水体中(C_0为30 mg/L),以异丙醇铝为铝源的介孔硅铝材料作为吸附剂,其吸附容量是低浓度水体(C_0为3 mg/L)的20余倍。由以上结果可知,将异丙醇铝为铝源合成的介孔硅铝材料用于治理富营养化的水体有较好的应用前景。

It is of great urgency to remove phosphate from eutrophicated water. Two kinds of Al-containing MCM -41 were introduced, which were prepared by one-pot hydrothermal synthesis method adopting aluminum sulfate and aluminum isopropoxide as aluminum sources respectively. The materials were characterized by N 2 adsorption-desorption, small angle X - ray diffraction, nuclear magnetic resonance （NMR）,transmission electron microscope （ TEM ） and mapping . Results showed that aluminum dispersed better in the framework of MCM -41 by using aluminum isopropoxide as precursor and it was incorporated to the framework by the formation of Si - 0 - Al linkages. When the Al species were incorporated into MCM -41 frameworks in the form of tetrahedral coordination,Al could bond with phosphorus to remove phosphate with enhanced adsorption capacity, due to the increased acidic sites of the materials. When the initial concentration is 3 mg/L,the adsorption capacity of mesoporous Al _MCM _41 using aluminum isopropoxide as precursor was 1.2 times higher than using aluminum sulfate as precursor and 1.6 times than pure MCM - 41. Increasing the initial concentration of phosphorus to 30 mg/L,the adsorption capacity of Al - MCM -41 using aluminum isopropoxide as aluminum source is 20 times higher than the low concentration phosphates. Therefore, mesoporous Al - MCM - 41 using aluminum isopropoxide as precursor are good candidate to remove phosphates.