Synthesis Of Zeolite NaA From Coal Gangue Of Baotou And Its Adsorption For Triphenylmethane Dye

Coal plays an important role in China’s energy supply.Coal gangue is a solid waste discharged from coal mining and processing.The content of SiO~2、Al₂O₃in coal gangue can account for more than 50%of its total chemical composition,so it can be used as a raw material for synthesizing zeolite by domestic and foreign researchers.In addition,synthetic zeolite can be used as adsorbent to treat dye in wastewater in order to make full use of coal resources to treat water environment problems.In this study,the coal gangue in Inner Mongolia as raw material,alkali melting-hydrothermal method successfully synthesized NaA zeolite,XRD,SEM,BJH and other characterization methods,the synthetic products were compared and analyzed to determine the best conditions for synthesizing NaA zeolite,and the best zeolite was used as adsorbent to conduct adsorption experiment on MG,BF dye to explore its adsorption kinetics mechanism and isothermal adsorption mechanism this paper through the above research to draw the following conclusions:（1）The optimized preparation process of NaA zeolite:The Coal gangue in Baotou was ground through 100 mesh sieve and roasted at 600℃ for 2 h.The pre-treated sample was added with appropriate amount of SiO₂solid and mixed evenly with NaOH solid at a mass ratio of 1:1.2,roasted at 800℃ for 2h,after cooling,add a certain concentration of NaOH solution to adjust the ratio of sodium to silicon to n（Na₂O）/n（SiO₂）to 2.0,the ratio of water to sodium to n（Na₂O）/n（H₂O）to 32,place in the reaction kettle,crystallize at80℃ for 16 h,and wash to pH<11 after cooling,drying,NaA zeolite molecular sieves were obtained.The optimized synthesized NaA zeolite was characterized and analyzed by XRD,SEM,FT-IR BJH.The results showed that the zeolite NaA prepared under the best conditions had smooth surface,clear edges and regular shape,and was a microporous material with double four-member ring structure.（2）The optimal conditions for adsorption of MG dye by NaA zeolite are as follows:Add 0.08000 g zeolite NaA to MG dye solution with pH of 7 and initial concentration of 200 mg/L under the optimal conditions,and after place it in a thermostatic oscillator with an oscillation frequency of 250 r/min for150 min and centrifugation,the supernatant was detected by UV-spectrophotometer.The adsorption capacity and removal rate of NaA zeolite were 59.23 mg/g and 94.77%respectively.The optimal conditions for BF dye adsorption were as follows:Add 0.04000 g zeolite NaA to BF dye solution with pH of 9 and initial concentration of 150 mg/L,and after place it in a thermostatic oscillator with an oscillation frequency of 150 r/min for 90min and centrifugation,the supernatant was detected by UV-spectrophotometer.The adsorption capacity and removal rate were 86.65mg/g and 92.43%,respectively.（3）The kinetic experiment results of zeolite NaA adsorption of MG,BF dye showed that Lagergren quasi-second-order kinetic model was more consistent with the adsorption process of MG,BF by zeolite NaA zeolite than that by quasi-first-order kinetic model,and the adsorption reaction process might be closer to chemical adsorption.Adsorption of MG,BF dye by zeolite NaA isothermal adsorption experiment results show that the adsorption process of Malachite green basic fuchsine by zeolite NaA is significantly positively correlated with the Langmuir adsorption isothermal equation,indicating that Langmuir can describe the adsorption process of MG,BF dye by zeolite NaA,and the adsorption process is mainly monolayers.Adsorption of MG,BF dye by zeolite NaA is mainly due to ion exchange between dye cations and zeolite molecular sieves.