自支撑粉煤灰基多孔吸附材料的制备与NH~+4-N吸附效果

Preparation of Self-supporting Fly Ash-based Porous Absorbent Material and Its NH+4-N Adsorption

本研究以粉煤灰为前驱体,偏硅酸钠为激发剂,借助化学发泡原理制备了富含类沸石相的粉煤灰基多孔地质聚合物;再以多孔地质聚合物为基本骨架,经水热处理将基体骨架中的类沸石相原位转化为沸石,得到自支撑粉煤灰基多孔吸附材料。基于正交试验,研究了水热温度、水热时间及碱液浓度对所制备多孔吸附材料矿物组成、抗压强度的影响;以NH_(4)^(+)-N吸附容量为考核指标,结合矿物组成与BET比表面积变化规律,得出了多孔吸附材料的最佳制备条件。研究表明,当水热温度为180℃、水热时间为24 h、碱液浓度为1.5 mol/L时,制备的自支撑粉煤灰基多孔吸附材料富含NaP型沸石、BET比表面积为50.871 m^(2)/g、抗压强度为0.6 MPa。多孔吸附材料对氨氮的吸附动力学数据符合准二级方程,表现出以化学吸附为主,快速高效的特点。

Firstly,porous geopolymer with zeolite-like phase was prepared by chemical foaming method with fly ash as precursor and sodium metasilicate as activator.Then the porous geopolymer was used as the basic skeleton,and the zeolite-like phase in the basic skeleton was converted into zeolite to obtain a selfsupporting fly ash-based porous adsorbent material.Based on the orthogonal experiment,the influences of hydrothermal temperature,hydrothermal time and alkali concentration on the mineral composition and compressive strength of the porous absorbent materials were studied;the NH_(4)^(+)-N adsorption capacity was used as an evaluation index,combined with the mineral composition and BET specific surface area changes law,and the optimal preparation conditions of porous absorbent materials are obtained.The results show that when the hydrothermal temperature is 180℃,the hydrothermal time is 24 h,and the alkali concentration is 1.5 mol/L,the prepared self-supported fly ash-based porous absorbent material is rich in zeolite NaP,BET specific surface area is 50.871 m^(2)/g,and the compressive strength is 0.6 MPa.The adsorption kinetics data of the porous adsorbent material for ammonia nitrogen conforms to the quasi-second-order equation,showing the characteristics of fast and efficient chemical adsorption.