Photocatalytic Performance and Reaction Pathway of TiO2 Composite Materials on Ammonia and Nitrogen Degradation in Water
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摘要: 通过溶胶凝胶法制备了以活性炭负载(TiO2/AC)、吐温80、Cu2+和Fe3+掺杂的四种纳米TiO2颗粒复合材料,采用X-射线衍射分析和全波长UV-VIS扫描对样品进行表征。在紫外灯照射下,以氨氮溶液为光催化降解材料测定各种改性TiO2样品的光催化活性,并探讨了光催化氨氮的降解途径。分析表明,掺杂Fe3+或Cu2+的TiO2均为锐钛矿相,可以使TiO2平均粒径减小,Cu2+掺杂TiO2的吸光波长发生了显著红移现象,而Fe3+掺杂TiO2后此现象不明显。对氨氮光催化作用比较,其性能依次是TiO2/AC>Fe3+/吐温/TiO2和Cu2+/吐温/TiO2> Fe3+/TiO2和Cu2+/TiO2。同时掺杂Cu2+和Fe3+,对二氧化钛光催化效率具有协同效应。TiO2光催化氧化氨氮的反应途径与生物氧化基本相似,最终生成氮气。Abstract: The nano-TiO2 composite photocatalysts,i.e.activated carbon supported TiO2(TiO2/AC),Tween-80,Cu2+and Fe3+doped TiO2,were separately prepared by sol-gel method,and the samples were characterized by X-ray powder diffraction(XRD) and ultraviolet-visible spectrometer(UV-VIS).The photocatalytic performances of the modified TiO2 materials were tested in ammonia and nitrogen solution under the irradiation of ultraviolet lamp,and the photocatalytic degradation pathways of the ammonia and nitrogen were also discussed.The results show that TiO2 doped by Cu2+ or Fe3+ is mainly composed of anatase phase,with the average particle size of TiO2 decreased.Obvious redshift of the absorption spectrum occurs for Cu2+ doped TiO2,while it is unconspicuous for Fe3+ doped TiO2.The order of photocatalytic degradation efficiency for ammonia and nitrogen by the materials(from high to low) is TiO2/AC>Fe3+/Tween-80/TiO2 & Cu2+/Tween-80/TiO2>Fe3+/TiO2 & Cu2+/TiO2.Simultaneous doping of Cu2+ and Fe3+ can play a.synergistic effect on photocatalytic efficiency of TiO2.The reaction pathways for photocatalytic oxidation of ammonia and nitrogen by the modified TiO2 are basically similar to those of bio-oxidation process,with N2 as the terminal product.
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Key words:
- modified TiO2 /
- photocatalysis /
- sewage /
- ammonia & nitrogen /
- degradation rate
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