煤燃烧是全球最主要的人为汞排放源，燃煤电厂含汞脱硫废水大量排放对人类健康和生态环境造成严重威胁，亟需开发高效、经济的脱硫废水汞离子脱除技术。对燃煤副产物飞灰进行活化后提取铝硅矿物，并利用飞灰中的铁质矿物制备了磁性沸石汞吸附剂，解决吸附剂吸附汞后难以从废水中分离，造成汞二次释放问题。采用BET、XRD、TEM等表征手段对合成的磁性沸石进行表征分析，系统研究了固液比、溶液初始pH、振荡时间等参数对磁性沸石汞离子吸附性能的影响，对磁性沸石吸附汞离子过程进行动力学研究，结果表明合成的磁性沸石为球形核壳结构，磁核被沸石均匀包裹，磁性沸石的比表面积为4.46 m2/g，最可几孔径为18.25 nm，属于介孔范围，磁性沸石表现出磁化滞后，其矫顽力约10 000 A/m，可通过外加磁场从脱硫废水中分离。试验最佳吸附条件为固液比5 g/L、最佳初始pH为5、振荡时间90 min，在此条件下Hg2+脱除率达92%。动力学研究结果表明，准一级动力学模型能较准确描述Hg2+吸附量随时间的变化，拟合的平衡吸附容量为23.24 mg/g，优于商业活性炭汞吸附剂。磁性沸石对脱硫废水中汞离子具有良好的脱除性能，为燃煤飞灰的精细化利用提供了新的思路。

Coal combustion is one of the most significant anthropogenetic mercury emission sources. The massive discharge of mercury-containing desulfurization wastewater from coal-fired power plants poses a serious threat to human health and the ecological environment. It is urgent to develop efficient and economical mercury ion removal technology from desulfurization wastewater. The magnetic zeolite mercury adsorbent was prepared by extracting aluminum silicon minerals from fly ash, a byproduct of coal combustion. The magnetic zeolite mercury adsorbent was prepared by using the iron minerals in fly ash, in order to solve the problem that the adsorbent was difficult to separate from the waste water after mercury adsorption, resulting in the secondary release of mercury. The synthesized magnetic zeolite was characterized and analyzed by BET, XRD, TEM and other characterization methods. The effects of parameters such as solid-liquid ratio, initial pH of solution, and oscillation time on the adsorption  of magnetic zeolite for mercury ions were systematically studied. The kinetics of adsorption of mercury ions on magnetic zeolites was studied. The results show that the synthesized magnetic zeolite has a spherical core-shell structure, and the magnetic core is evenly wrapped by the zeolite. The specific surface area of the magnetic zeolite is 4.46 m2/g, the most probable pore size is 18.25 nm, which belongs to the mesoporous range. The magnetic zeolite exhibits magnetization hysteresis, its coercivity is about 10 000 A/m, and it can be separated from desulfurization wastewater by external magnetic field. The optimum adsorption con ditions are as follows: the solid-liquid ratio is 5 g/L, the optimum initial pH is 5, and the shaking time is 90 min. Under these conditions, the removal rate of Hg2+ reaches 92%. The kinetic study results show that the pseudo-first-order kinetic model can more accurately describe the variation of Hg2+ adsorption capacity with time, and the fitted equilibrium adsorption capacity is 23.24 mg/g, which is better than that of commercial activated carbon mercury adsorbents. Magnetic zeolite has good removal  for mercury ions in desulfurization wastewater, which provides a new idea for the refined utilization of coal-fired fly ash.

0 引言

1 试验

   1.1 样品制备及表征

   1.2 Hg2+吸附性能测试

2 结果与讨论

   2.1 样品表征

   2.2 吸附条件对磁性沸石吸附Hg2+的影响

   2.3 磁性沸石对Hg2+的吸附动力学研究

3 结论