粉煤灰基成型吸附剂的制备及其对亚甲基蓝的吸附性能

PREPARATION OF COAL FLY ASH BASED FORMING ADSORBENT AND ITS ADSORPTIVE PROPERTIES FOR METHYLENE BLUE

为了增加粉煤灰的反应活性,将原料粉煤灰(raw fly ash,RFA)进行超细球磨得到超细粉煤灰(ultra-fine fly ash,UFA),将超细粉煤灰与NaOH溶液反应后挤出成型烘干,得到超细粉煤灰基成型吸附剂(ultra-fine forming fly ash-based adsorbent,UFFA),通过X射线衍射和扫描电子显微镜对其进行表征。研究了RFA,UFA和UFFA对亚甲基蓝(methylene blue,MB)的吸附性能。结果表明:UFFA的吸附性能最好,其次为UFA,RFA最差。UFFA对MB的吸附过程符合二级吸附动力学模型,UFFA对MB的吸附过程由颗粒内扩散过程控制。热力学研究表明:UFFA对MB的吸附符合Freundlich吸附等温式;UFFA对MB吸附热力学参数ΔG小于0,表明吸附过程是自发进行的;ΔH为-13.84kJ/mol,表明吸附是放热过程。

In order to increase the reaction activity of fly ash,the raw fly ash（RFA） was ball milled and ultra-fine fly ash（UFA） was obtained.The UFA was reacted with NaOH solution,after reaction the mixture was extruded and dried,the ultra-fine forming fly ash-based adsorbent（UFFA） was gained.The three adsorbents were characterized using X-ray diffraction and scanning electron microscope.The adsorptive capacities of RFA,UFA and UFFA for methylene blue（MB） were studied.The results show that the capacity of UFFA is superior to the others.The kinetics of MB on three adsorbents fitted second order kinetic model and the adsorption processes on UFFA are controlled by intra-particle diffusion.The MB adsorption equilibrium on UFFA can be described in terms of Freundlich isotherm.The adsorption thermodynamic parameters free energy（ΔG） of MB is negative and enthalpy（ΔH） is-13.84 kJ/mol which indicates the adsorption process is spontaneous and exothermic.