磁性纳米材料的光催化产氢性能研究

发布时间：2018-01-29 19:28

  本文关键词： 铁氧体/LDH复合材料 光催化 产氢 电镀废水 酸洗废液　出处：《上海大学》2015年硕士论文　论文类型：学位论文

【摘要】：本研究在课题组前期工作的基础上,通过溶胶凝胶法成功制备了三种尖晶石型铁氧体Cu Fe2O4、Ni Fe2O4和Zn Fe2O4;选择光催化性能最优的Cu Fe2O4作为磁性前驱体,采用微波水热法将其负载在层状双金属氢氧化物上制备新型铁氧体/LDH磁性复合材料(Cu Fe2O4/Zn2Cr-LDH);并以电镀废水和酸洗废液作为原材料,通过两步微波水热法制备废物基铁氧体和废物基磁性复合材料(CFL),同时净化重金属废水中的金属离子。在模拟可见光照射的条件下,测试了此类材料的光催化裂解水产氢性能,并研究了不同因素对其产氢性能的影响以及废物基磁性复合材料的最优合成条件。研究工作得到了以下主要结论:(1)通过溶胶凝胶法制备的Cu Fe2O4具有粒径小、分散性好、结构边缘平滑清晰可见、磁性强的优点,其粒径为20 nm左右、饱和磁化强度为18.16 emu/g。光催化产氢实验表明:Cu Fe2O4具有优秀的可见光响应性能,在6h内的总产氢量为791.9μmol·g-1,并表现出良好的光催化稳定性。最适宜的催化剂投加量为0.8 g/L,最适宜的牺牲剂为乙醇,牺牲剂投加量为溶液体积分数的10%。(2)通过溶胶凝胶-微波水热法联用制备磁性复合材料Cu Fe2O4/Zn2Cr-LDH,其饱和磁化强度为8.47 emu/g,在6h内的总产氢量为1567.7μmol·g-1,几乎是纯Cu Fe2O4或Zn2Cr-LDH的一倍以上。在复合材料的内部存在电子由铁氧体向LDH部分迁移的现象,有助于可见光激发的空穴和电子对分离,提高其光催化性能。单因素试验表明磁性复合材料光催化裂解水产氢的最优反应条件为:合成p H值为7、Cu Fe2O4负载量为0.20 g、Cu Fe2O4/Zn2Cr-LDH投加量为1.0 g/L、牺牲剂投加量为溶液体积分数的10%。该磁性复合材料至少可以重复利用三次并保持较稳定的结构和光催化性能。(3)通过微波水热法制备废物基铁氧体可有效净化重金属废水,碱性环境有助于铁氧体晶格结构的形成。实验表明在p H=7~10、合成时间t=15~40 min、合成温度T=100~180 oC的范围内,通过两步微波水热法合成废物基CFL对废水中的重金属去除率可达到90%以上。废物基CFL光催化产氢性能略优于废物基Cu Fe2O4,在4h内的总产氢量为343.9μmol·g-1。受到重金属废水中复杂成分的影响,废物基CFL的光催化性能与纯药剂合成材料存在明显差距。在连续光照后废物基CFL的结构仍然保持完整、重金属离子的释放量低,说明其作为光催化剂的稳定性能较好。通过单因素试验研究不同合成条件对材料光催化性能的影响,并根据响应曲面法模拟CFL的最优合成条件。
[Abstract]:Based on the previous work of our research group, three kinds of spinel ferrite Cu Fe 2O 4 Ni Fe2O4 and Zn Fe 2O 4 have been successfully prepared by sol-gel method. Cu Fe2O4, which has the best photocatalytic activity, is chosen as the magnetic precursor. A new type of ferrite / LDH magnetic composite, CuFe2O4 / Zn2Cr-LDHN, was prepared by microwave hydrothermal method on layered bimetallic hydroxides. Waste ferrite and waste magnetic composite (CFL) were prepared by two-step microwave hydrothermal method using electroplating wastewater and pickling waste liquid as raw materials. At the same time, the metal ions in heavy metal wastewater were purified. Under the condition of simulated visible light irradiation, the photocatalytic cracking of aquatic hydrogen was tested. The effects of different factors on the hydrogen production properties and the optimum synthesis conditions of the waste based magnetic composites were studied. The main conclusions are as follows: 1). The Cu Fe2O4 prepared by sol-gel method has small particle size. It has the advantages of good dispersion, smooth structure edge and strong magnetic properties, and its particle size is about 20 nm. The saturation magnetization is 18.16 emu / g. The photocatalytic hydrogen production experiments show that the Fe2O4 has excellent visible light response. The total hydrogen production was 791.9 渭 mol 路g -1 in 6 h, and showed good photocatalytic stability. The optimum dosage of catalyst was 0.8 g / L, and the most suitable sacrificial agent was ethanol. A magnetic composite Cu Fe2O4/Zn2Cr-LDH was prepared by sol-gel microwave-hydrothermal method in which the dosage of sacrificial agent was 10% of the volume fraction of the solution. The saturation magnetization is 8.47 emu / g, and the total hydrogen production is 1 567.7 渭 mol 路g ~ (-1) in 6 h. The electron migration from ferrite to LDH is observed in the composite material, which is almost twice as large as that of pure Cu Fe2O4 or Zn2Cr-LDH. The single factor experiment showed that the optimum reaction conditions for the photocatalytic cracking of aquatic hydrogen with magnetic composites were as follows: the pH value was 7. The loading amount of Cu Fe2O4 is 0.20 g / L Cu Fe2O4/Zn2Cr-LDH is 1.0 g / L. The dosage of the sacrificial agent is 10 parts of the volume fraction of the solution. The magnetic composite can be reused at least three times and maintain a stable structure and photocatalytic performance. Waste ferrite prepared by microwave hydrothermal method can effectively purify heavy metal wastewater. The alkaline environment contributes to the formation of the lattice structure of ferrite. The experimental results show that the synthesis time is 1540 min, the synthesis time is 1540 min, and the synthesis temperature is 100 鈩，

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