Young Researchers and Elite Clube, Marand Branch, Islamic Azad University, Marand, Iran.
Department of Chemistry, Iran University of Science and Technology, Tehran 16846-13114, Iran.
J Hazard Mater. 2015 Apr 9;286:64-74. doi: 10.1016/j.jhazmat.2014.12.038. Epub 2014 Dec 24.
Porous NiO/Nb2O5 nanocomposites with Ni/Nb molar ratio of 0.4, 0.8 and 1.2 have been obtained via the EISA route using P123 copolymer as organic template, and are assigned as NiNb0.4, NiNb0.8 and NiNb1.2, respectively. For comparison, pure Nb2O5 sample assigned as NiNb0.0 was also synthesized by the same method. Structural and textural features of the as prepared samples were investigated by XRD, FTIR, FE-SEM, EDX, UV-vis DRS and BET techniques. The results indicated that the porous p-NiO/n-Nb2O5 junction nanocomposites were formed and coupling of NiO with Nb2O5 resulted a remarkable red shift in the optical response of the nanocomposite samples. The photocatalytic properties of the nanocomposite samples, and also synthesized pure Nb2O5 (NiNb0.0) and commercial Nb2O5 as reference catalysts were evaluated for the first time by simultaneous Cr(VI) reduction and MO decolorization in aqueous suspension under visible light irradiation at pH 2. NiNb0.4 was found to be the most active photocatalyst, which might be attributed to the extended absorption in the visible light region and the effective photogenerated electron-hole separation by the photosynergistic effects of the p-NiO/n-Nb2O5 composite powder. The photocatalytic efficiency of the most active photocatalyst, NiNb0.4, was found to be rather low for either single Cr(VI) solution or single MO solution. However, the photocatalytic reduction of Cr(VI) and photocatalytic decolorization of MO proceed more rapidly for the coexistence system of Cr(VI) and MO than for the single process, showing synergetic effect between the reduction and decolorization reactions. The effects of initial concentration of Cr(VI), MO and the initial pH value on the rate of simultaneous photoreactions over NiNb0.4 sample, were also investigated. The Cr(VI) and MO removal rates were further enhanced by increasing MO and Cr (VI) concentration to an optimal value, respectively, and/or decreasing solution pH.
多孔 NiO/Nb2O5 纳米复合材料，其中 Ni/Nb 的摩尔比为 0.4、0.8 和 1.2，通过 EISA 路线使用 P123 共聚物作为有机模板获得，并分别指定为 NiNb0.4、NiNb0.8 和 NiNb1.2。为了比较，还通过相同的方法合成了纯 Nb2O5 样品，指定为 NiNb0.0。通过 XRD、FTIR、FE-SEM、EDX、UV-vis DRS 和 BET 技术研究了所制备样品的结构和织构特征。结果表明，形成了多孔 p-NiO/n-Nb2O5 结纳米复合材料，并且 NiO 与 Nb2O5 的耦合导致纳米复合材料样品的光学响应发生显著红移。纳米复合材料样品的光催化性能，以及合成的纯 Nb2O5（NiNb0.0）和商业 Nb2O5 作为参考催化剂，首次在 pH 2 下在可见光照射下的水溶液中同时进行 Cr(VI)还原和 MO 脱色，进行了评价。发现 NiNb0.4 是最活跃的光催化剂，这可能归因于可见光区域的扩展吸收和 p-NiO/n-Nb2O5 复合粉末的光协同效应有效光生电子-空穴分离。最活跃的光催化剂 NiNb0.4 的光催化效率对于单独的 Cr(VI)溶液或单独的 MO 溶液都相当低。然而，对于 Cr(VI)和 MO 的共存体系，Cr(VI)的光催化还原和 MO 的光催化脱色比单独的过程进行得更快，显示出还原和脱色反应之间的协同效应。还研究了 NiNb0.4 样品上同时光反应的初始 Cr(VI)浓度、MO 和初始 pH 值的影响。通过增加 MO 和 Cr(VI)浓度至最佳值，以及/或降低溶液 pH，Cr(VI)和 MO 的去除率进一步提高。
