Coal Gangue Synthetic Zeolite And Its Application In Printing And Dyeing Wastewater

Coal gangue is a kind of solid waste discharged by coal mining. The piled coal gangue can pose great risks to the environment and human health. As the main composition of coal gangue is silicon and aluminum oxide, it can be used as a raw material of synthetic zeolite. Zeolite, a kind of crystalline silicon aluminate hydrate, can be used as an effective adsorbent and ion exchanger. Dye wastewater is hard to degrade due to its high content of organic compounds, its complexity of the components and high chroma. Using gangue to synthesize zeolite molecular sieves, can achieve the purpose of the solid wastes. Using zeolite molecular sieve synthesis by coal gangue adsorbing dyeing wastewater can reach the purpose of using waste treat waste.Our study made attempt to use the coal gangue as raw material to prepare X zeolite with a alkali fusion-hydrothermal synthesis method and focusing on investigating the effect of conditions to sample crystallization. The result shows products can be successfully obtained under optimum condition, namely, calcined at 350℃ for 3h, the ration of liquid to solid is 5:1,6mol/L hydrochloric acid, soaked at 80℃ for 9h, mixed with NaOH at the weight ratio of 1:2.0, alkali-fused at 700℃ for 3 h, aging for 12 h at room temperature and then hydro treat at 105℃ for 18h. E-SEM graph show a complete conversion from coal gangue to octahedral crystal (NaX) with well-distributed size. XRD pattern of the synthetic sample, exhibits high peak intensity and accurate matching peak, point, further conform to the existence of zeolites. The experiment also investigates the influence of acid leaching time on synthesis product. The result shows that sodalite with high crystallinity, single crystal size can be synthesized successfully by coal gangue after acid leaching for 9 hours.Our study also explore the effect of step-change of synthesis temperature, seeded growth method and in-situ method on synthesizing X zeolite by coal gangue. We can find that step-change of synthesis temperature can speed up the crystallization reaction in shorter crystallization time. The seed of X zeolite can inhibit the formation of mixed crystal through induced synthesize target products. And X zeolite can be synthesized by gangue coal through in-situ method without additional silicon and aluminum material.We tentative try to spy out how temperature, contact time, addition of X zeolite and initial solution concentration can affect the adsorption capacity. Adsorption experiment indicates the removal efficiency goes up as the temperature rise. The absorption reached absorption equilibrium after 300 minutes. The removal efficiency goes up when initial solution concentration rises and then keeps constant adsorption capacity. The effect of is addition of X zeolite as same as initial solution concentration. The experimental data were well fitted by the Pseudo-second-order kinetics model and the equilibrium data were better fitted by the Freundlich model and the adsorption rate was controlled by both liquid-film-diffusion and intra-particle-diffusion. In addition, about 94% basic fuchsin at solution can be absorbed by zeolite under the optimum adsorption conditions with adsorbing capacity of 23mg/g.The regeneration of the zeolite adsorbed and saturated by basic fuchsin solution was studied. We can find that 89.91% basic fuchsin at solution can be absorbed by zeolite with twice regeneration.