Synthesis Of A Zeolite From Coal Gangue Of Wuhai And Its Adsorption For Fluoride And Arsenic In Waste Water

The safety of drinking water is one of the most important issues in China.In some areas of China,the groundwater was polluted by fluorine and arsenic seriously.The life safety of nearby residents were threaten.Compared with different kinds of methods,it was found that the adsorption method could effectively reduce the fluorine and arsenic contents in the water.It was also without caused secondary pollution.In this study,A zeolite（LTA）was synthesized from Coal Gangue in wuhai,Inner Mongolia.A zeolite was used for adsorption experiment to simulate the fluorine waste water and arsenic waste water.The optimum conditions for the synthesis of A Zeolite from Coal Gangue were studied,and the characterization of A zeolite was also analyzed.Adsorption simulation of arsenic and fluorine waste water by A zeolite and explored the impact of various factors on the adsorption test.The dates of experiments were used to fitted the experimental data of adsorption kinetics model and adsorption isotherm,the adsorption mechanism was discussed,the main conclusions were as follows:（1）The preparation process of zeolite A was as follows:The coal gangue was crushed and passed through the 100 mesh screen.Coal gangue was calcined under 900℃for 2 hours.The ratio of Na₂O and SiO₂ was adjusted to 1.5.The ratio of SiO₂ and Al₂O₃ was adjusted to 2.The mixture was placed under a magnetic stirrer and aged for 1 hour under 50℃.The the clear liquid that lies above a sediment was poured into a reaction kettle and placed into a drying oven.Product was crystallized for 7 hours under 100℃and washed to neutral.It was dried finally.（2）The results of XRD and SEM showed that the A zeolite was synthesized in this condition with high crystallinity.It was a cubic crystal with clear structure,complete and clear edges.BET analysis showed that zeolite with larger specific surface area,which was 5.499 m²/g.Its pore diameter was between 0.4 and 0.8 nm,which belonged to the microporous material.（3）The optimum adsorption conditions for A zeolite to simulate fluorine contained waste water were as follows:0.1 g A zeolite was added to simulate the waste water contained fluorine,which initial concentration was 10 mg/g and pH was 5.51.The oscillation frequency was adjusted to 160 r/min and oscillated for 60 minutes at room temperature.The removal rates and adsorption capacity were 94.85%and 4.74 mg/g respectively.（4）The optimum adsorption conditions for A zeolite to simulate arsenic containing waste water were as follows:0.2 g A zeolite was added to simulate the waste water contained arsenic,which initial concentration of waste water was 35 mg/g and pH was 5.The oscillation frequency was adjusted to 180r/min and oscillated for 120 minutes at room temperature.The removal rate and adsorption capacity were 88.96%and 7.78 mg/g respectively.（5）A zeolite with a fast adsorption rate for simulated waste water containing fluoride and arsenic.Its adsorption reaction was balanced in 60minutes and 120 minutes respectively.The adsorption process could be fitted with quasi-second-order kinetic equation,and it was highly significant.The correlation coefficients were 0.9999 and 0.9994.It had indicated that the adsorption behavior of A zeolite to the simulated fluorine and arsenic waste water could be described by the second order kinetic equation.The adsorption process was mainly chemical adsorption.Weber and Morris particle internal diffusion model was fitted and indicated that the adsorption of A zeolite to simulated fluorine and arsenic waste water was the result of the interaction between the particle diffusion and surface adsorption.（6）The isothermal experimental data was simulated by Langmuir and Freundlich model.The results were as follows:The adsorption behavior of A zeolite to simulated fluorine and arsenic waste water could be better described by Langmuir model than Freundlich model.The correlation coefficients were0.9994 and 0.9876 respectively.The main adsorption behavior was the chemical adsorption of monolayer.R_L in Langmuir model and 1/n in Freundlich model were used to describe the degree of difficulty of reaction.The R_Lvalues were in the range of 0.0075⁰.0399 and 0.0001⁰.0008.The1/n values were 0.8102 and 0.6403 respectively.It had shown that the adsorption behavior of A zeolite to the simulated fluorine and arsenic wastewater was easy to be carried out.D-R model was simulated that showed the adsorption behavior were the chemical adsorption and physical adsorption.（7）After adsorption saturation,the zeolite could be recycled for at least three times.The regeneration rates were all above 80%.The regeneration rate was 98%at first time.