Comparison Study Of Adsorption Of Methylene Blue And Acid Red G By Nano Mesoporous Materials SBA-15 And MCFs

SBA-15 and MCFs molecular sieves were prepared by hydrothermal synthesis method.The surface,pore structure and other properties of SBA-15 and MCFs were characterized by chemical analysis,low temperature N₂ adsorption-desorption isotherm,X-ray diffraction?XRD?,transmission electron microscopy?TEM?,scanning electron microscopy?SEM?and Fourier transform infrared?FT-IR?spectroscopy.Methylene blue and acid red G dye solution was adsorbed by the synthetic SBA-15 and MCFs,the optimum adsorption conditions and the maximum adsorption capacities of methylene blue and acid red G by SBA-15 and MCFs were obtained by experiments,and the maximum adsorption capacity of methylene blue on SBA-15 is 223 mg/g,the maximum adsorption capacity of acid red G on SBA-15 is 3.532 mg/g,the maximum adsorption capacity of methylene blue on MCFs is 215.5 mg/g,the maximum adsorption capacity of acid red G on MCFs is 3.053 mg/g.The kinetics of the adsorption of methylene blue and acid red G by SBA-15 and MCFs are in accordance with the quasi-second-order kinetic equations.The results were analyzed by Langmuir and Freundlich adsorption isotherm model,and the adsorptions of methylene blue and acid red G on SBA-15 and MCFs are in accord with the Freundlich adsorption isotherm model.The Gibbs free energy changes during the process of adsorption 00<?G can judge that the adsorption process is spontaneous.The enthalpy change in the adsorption process 00H<? indicated that the adsorption process is an exothermic reaction.The negative value of entropy change indicated that the adsorption process is a process of entropy reduction.Through a series of methods powder chemical analysis,XRD,SEM,TEM,FT-IR,low temperature N₂ adsorption-desorption the adsorption of the composite materials were characterized.The characterization results show that the composite materials after adsorption still retained the skeleton structure of the mesoporous materials,but the order of the composites was decreased.After adsorption,the average pore size,total pore volume and specific surface area of the composite materials are lower than those of the mesoporous materials,indicating that after adsorption the pores of the mesoporous materials are partly filled and blocked.This indicates that the dye molecules were contained in the mesoporous channels.The average each hole of mesoporous material SBA-15 could adsorb 6.67×10²⁰ methylene blue molecules by comparing the variation of the mesopore volume before and after adsorption,average each hole of mesoporous material MCFs adsorbed 2.56×10²¹ methylene blue molecules.