Abstract

Developing titanium dioxide (TiO₂) samples able to absorb and effectively utilize both ultraviolet radiation and visible light will lead to considerable reduction in costs of photocatalytic purification of natural and waste waters. Using the sol–gel method, we synthesized nanoscale titanium dioxide samples doped with nitrogen or co-doped with nitrogen and iron ions, with the samples having a narrower band gap of 2.59–2.99 eV. The synthesized N-TiO₂ and (Fe,N)-TiO₂ samples and the standard titanium dioxide Degussa P-25 are compared in terms of their activities in photocatalytic oxidation of aqueous salicylic acid solutions (0.2 mmol/L, pH 4) by dissolved oxygen or hydrogen peroxide upon irradiation with light from a SVD-120 lamp (λ > 200 nm) or a metal-halide GE CMH70 lamp (λ > 360 nm). The relative photocatalytic activity of doped TiO₂ samples in oxidation of aqueous salicylic acid solutions depends on their iron content (0–1% Fe), the type of oxidant used, and the irradiation conditions. In photocatalytic oxidation with oxygen, samples N-TiO₂ (λ > 200 nm) and (Fe,N)-TiO₂ (1.0% Fe) (λ > 360 nm) exhibit the highest degree of mineralization of salicylic acid among the doped TiO₂ samples, while (Fe,N)-TiO₂ (0.5% Fe) is the most effective in degradation of salicylic acid by hydrogen peroxide. Using hydrogen peroxide raises the degree of photocatalytic mineralization of salicylic acid in the presence of any of the synthesized samples under both types of irradiation conditions, compared to its oxidation by dissolved oxygen. In addition, the use of H₂O₂ levels off the differences in the activity between synthesized TiO₂ samples with different doping level of iron that are observed in the O₂/TiO₂/UV photocatalytic system upon irradiation with UV–visible light (λ > 200 nm), while the extent of salicylic acid degradation in the presence of most active synthesized catalysts is considerably closer to that achieved with the standard photocatalyst.

中文翻译：

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掺杂(N,Fe)二氧化钛在不同辐照条件下光催化降解水中水杨酸

摘要

开发能够吸收和有效利用紫外线辐射和可见光的二氧化钛 (TiO ₂ ) 样品将大大降低天然水和废水的光催化净化成本。使用溶胶-凝胶方法，我们合成了掺杂氮或共掺杂氮和铁离子的纳米级二氧化钛样品，样品的带隙较窄，为 2.59-2.99 eV。合成的N-TiO ₂和(Fe,N)-TiO ₂比较样品和标准二氧化钛 Degussa P-25 在 SVD-120 灯照射下溶解氧或过氧化氢对水杨酸水溶液 (0.2 mmol/L, pH 4) 进行光催化氧化的活性(λ > 200 nm) 或金属卤化物 GE CMH70 灯 (λ > 360 nm)。掺杂 TiO ₂样品在水杨酸水溶液氧化中的相对光催化活性取决于它们的铁含量（0-1% Fe）、所用氧化剂的类型和辐照条件。在氧的光催化氧化中，样品 N-TiO ₂ (λ > 200 nm) 和 (Fe,N)-TiO ₂ (1.0% Fe) (λ > 360 nm) 在掺杂的 TiO 中表现出最高程度的水杨酸矿化₂样品，而 (Fe,N)-TiO ₂ (0.5% Fe) 在过氧化氢降解水杨酸方面最有效。与通过溶解氧的氧化相比，在两种类型的辐照条件下，在任何合成样品存在的情况下，使用过氧化氢提高了水杨酸的光催化矿化程度。此外，H ₂ O ₂的使用平衡了在 O ₂ /TiO ₂中观察到的具有不同铁掺杂水平的合成 TiO ₂样品之间的活性差异。/UV 光催化系统在紫外-可见光（λ > 200 nm）照射下，而在大多数活性合成催化剂存在下水杨酸的降解程度与标准光催化剂所达到的程度相近。