The photo-catalytic degradation of a textile azo-dye as Methyl Orange was studied in an innovative unit constituted by a channel over which a layer of titanium dioxide (TiO₂) catalyst in anatase form was deposited and activated by UVB irradiation. The degradation kinetics were followed after variation of the chemical, physical, and hydraulic/hydrodynamic parameters of the system. For this purpose, the influence of the TiO₂ dosage (g/cm³), dye concentration (mg/L), pH of the solution, flow-rate (L/s), hydraulic load (cm), and irradiation power (W) were evaluated on the degradation rates. It was observed that the maximum dosage of TiO₂ was 0.79 g/cm³ while for higher dosage a reduction of homogeneity of the cement conglomerate occurred. The Langmuir–Hinshelwood (LH) kinetic model was followed up to a dye concentration around 1 mg/L. It was observed that with the increase of the flow rate, an increase of the degradation kinetics was obtained, while the further increase of the flow-rate associated with the modification of the hydraulic load determined a decrease of the kinetic rates. The results also evidenced an increase of the kinetic rates with the increase of the UVB intensity. A final comparison with other dyes such as Methyl Red and Methylene Blue was carried out in consideration of the pH of the solution, which sensibly affected the removal efficiencies.

中文翻译：

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TiO2在不同化学，物理和水力条件下的中试装置中甲基橙的光降解作用

在一个创新的单元中研究了一种纺织品偶氮染料，如甲基橙的光催化降解，该单元由一个通道组成，在该通道上沉积了一层锐钛矿形式的二氧化钛（TiO ₂）催化剂并通过UVB辐射活化。在改变系统的化学，物理和水力/流体动力学参数之后，追踪降解动力学。为此，TiO ₂剂量（g / cm ³），染料浓度（mg / L），溶液的pH，流速（L / s），水力负荷（cm）和照射功率（ W）评估了降解速率。观察到TiO ₂的最大剂量为0.79 g / cm ³而对于更高的用量，水泥团块的均质性降低了。随后对Langmuir-Hinshelwood（LH）动力学模型进行了跟踪，直至染料浓度约为1 mg / L。观察到，随着流量的增加，降解动力学得到增加，而与液压负荷的改变相关的流量的进一步增加决定了动力学速率的降低。结果还证明，随着UVB强度的增加，动力学速率也增加。考虑到溶液的pH值，与其他染料（如甲基红和亚甲基蓝）进行了最终比较，这会明显影响去除效率。