Synthesis Of Waste Fly Ash Based Magnetic Zeolite A And Its Adsorption Properties

The rapid development of modern industry has caused increasingly serious problems of environmental pollution.Organic dye has aroused widespread concern because it’s difficult to decompose and its toxicity and other properties could do great harm on the organisms.At the same time,the emissions and post-processing of coal fly ash have caused serious environmental problems.So using cheap waste fly ash based magnetic zeolite A and using it to adsorb organic dye in the industrial waste water,which have a great significance.Zeolite A has a unique porous skeleton structure and large specific surface area as well as high temperature resistance and acid alkali-resistance property,which give it excellent physicochemical properties.However,because zeolite A particle is nano size,the separation of the particles from a complex system for recycling remains a major obstacle after the adsorption process.Magnetic carrier technology grants the material with strong magnetism evenly dispersed over the surface of the weakly or non-magnetic matrix to increase the magnetic susceptibility,realizing the purpose of separating the matrix from the system under the action of external magnetic field and providing a reliable theoretical basis to solve these problems.In this investigation,fly ash was used as the raw material.Magnetic zeolite A was synthesized by the method of alkali fusion followed by hydrothermal treatment.Waste ash based magnetic zeolite A was researched in aspects of synthesis method,methylene blue adsorption and regeneration capability.The following conclusions are obtained.Through repeated experiments,the conditions for the synthesis of magnetic zeolite A are as followed:silica alumina ratio is 1,calcination temperature is 600℃,calcination time is 2 hours,liquid solid ratio is 6,alkali ash ratio is 1.2,crystallization temperature is 100℃,and crystallization time is 4 hours.After that the magnetic zeolite A synthesized on the optimal condition was analyzed by XRD、SEM、FTIR and VSM.Test results show that the magnetic zeolite A has a good thermal stability and the introduction of Fe3O4 particles doesn’t destroy the structure of zeolite A.Though the test of vibrating sample magnetometer,the highest saturation magnetization of Fe3O4 and magnetic zeolite A are 80emu/g and 15.8emu/g,respectively.The methylene blue adsorption property of the synthesized product was tested by UV-Vis spectrophotometer and the results show that when the concentration of methylene blue is 30 mg/L,pH of the solution is 8.0,the mass of adsorbent is 0.3g/L,at room temperature with adsorbing 50min,the adsorption capacity is 95.34mg/g,and the removal efficiency is up to 95.34%.The effect of the electrolyte solution concentration on the adsorption effect is not significant.The pseudo-first-order kinetic equation can describe the adsorption behavior of magnetic zeolite A to methylene blue,which is endothermic.Raising temperature properly will help accelerate the adsorption rate and shorten the time equilibrium to reach.The maximum adsorption capacity of magnetic zeolite A is 1047.75mg/g by Langmuir isothermal adsorption equation and the adsorption form is monomolecular layer adsorption.The parameter n of Freundlich equation is larger than 1,thus the removal of methylene blue by the magnetic zeolite A is easier than zeolite A.After regeneration experiments,it concludes that zeolite A and magnetic zeolite A can be separated by solid-liquid separation under the same conditions.At the same,zeolite A and magnetic zeolite A need 108min and 0.5min for solid-liquid separation,respectively.It demonstrates that the magnetic zeolite A can achieve rapid solid-liquid separation.Besides,the adsorption effect of desorbed magnetic zeolite A to methylene blue is better under acidic condition than alkaline condition,indicating that the micro structure of magnetic zeolite A is not destroyed during the desorption process,and the adsorption performance is maintained.When the concentration of HCl solution is 0.4mol/L,the desorption rate is 93.42%and the regeneration rate is 91.83%,which suggests that the proper concentration of HCl solution could promote the regeneration of magnetic zeolite A,and magnetic zeolite A has a great cycle performance.