Purpose

This study aimed to test the activity of Mn ferrite, hematin-Mn ferrite and colloidal maghemite in decomposition of Orange II (O-II) and Alizarin Red S (ARS) in model aqueous solutions.

Methods

Color removal was explored at room temperature using magnetic stirring with and without a magnetic bar, taking advantage of the solids’ magnetism. Decomposition of H₂O₂ was also studied separately and as radicals provider in dye decomposition. Catalyst/dye solution was fixed at 10 mg/4 mL. pH and dye concentration were variable. Absorbance was measured during 120 min by UV-Vis. Reuse of catalysts was also performed.

Results

Azo dyes such as O-II are more resistant to oxidative removal using hydrogen peroxide than anthraquinone-like ARS. CITMD5 reduced ARS absorbance up to 71.9% when dye was less than 250 mg/L. HEM-Mn-MAG completely decolorized a 62.5 mg/L O-II solution at pH 11 while CITMD5 reached half of that conversion under the same conditions. The highest color removal in O-II/ARS mixtures was obtained with HEM-Mn-MAG, 40% absorbance reduction in 2 h. Mn-MAG is not active to remove O-II in presence of hydrogen peroxide in the 3–9 pH range at rt.

Conclusions

The high activity of Mn-MAG in hydrogen peroxide decomposition may be assigned to the combination of Mn⁺²/Mn⁺³ and Fe⁺²/Fe⁺³, because the MnO_x is active in the decomposition of hydrogen peroxide. Mn-MAG can be reused, preserving high activity in this reaction. Mn-based magnetic nanoparticles should be considered as inexpensive materials to treat textile wastewaters.

中文翻译：

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用于去除偶氮和蒽醌染料的低成本纳米颗粒氧化催化剂

目的

本研究旨在测试锰铁氧体、血红素锰铁氧体和胶体磁赤铁矿在模型水溶液中分解橙色 II (O-II) 和茜素红 S (ARS) 的活性。

方法

利用固体的磁性，在有和没有磁棒的情况下使用磁力搅拌在室温下探索颜色去除。H ₂ O ₂的分解也被单独研究并作为染料分解中的自由基提供者。催化剂/染料溶液固定在 10 mg/4 mL。pH 值和染料浓度是可变的。在 120 分钟内通过 UV-Vis 测量吸光度。还进行了催化剂的再利用。

结果

偶氮染料如 O-II 比蒽醌类 ARS 更能抵抗使用过氧化氢的氧化去除。当染料低于 250 mg/L 时，CITMD5 将 ARS 吸光度降低至 71.9%。HEM-Mn-MAG 在 pH 11 下完全脱色了 62.5 mg/L O-II 溶液，而 CITMD5 在相同条件下达到了该转化率的一半。使用 HEM-Mn-MAG 获得了 O-II/ARS 混合物中最高的颜色去除，2 小时内吸光度降低了 40%。Mn-MAG 在 rt 在 3-9 pH 范围内没有去除 O-II 的活性。

结论

Mn-MAG 在过氧化氢分解中的高活性可归因于Mn ⁺² /Mn ⁺³和Fe ⁺² /Fe ⁺³的组合，因为MnO _x在过氧化氢的分解中具有活性。Mn-MAG 可以重复使用，在该反应中保持高活性。锰基磁性纳米粒子应被视为处理纺织废水的廉价材料。