Abstract Highly photoactive nanocomposites Sep-TiO2 with various ratios of Ti/Sep were prepared by a novel microwave-hydrothermal method and were compared for their photocatalytic activity. The catalyst with the Ti/Sep ratio of 40 mmol/g showed the highest photodegradation activity on account of its relatively intact sepiolite structure and more anatase active sites. The effects of operational conditions, including photocatalyst amount, initial dye concentration and pH on photocatalytic degradation performance were analyzed and optimized, which demonstrated low and negligible photodegradation efficiency in the presence of sepiolite only and in the absence of photocatalyst, respectively. The photocatalytic degradation kinetics under different reaction conditions was elucidated by modeling. The results showed that the photocatalytic degradation of Orange G could be described by the modified Langmuir-Hinshelwood model. The photocatalytic degradation process fits into first-order kinetics for most of the operational parameters, while follows zero-order kinetics for the condition of high dye concentration. The apparent rate constants kapp for each degradation reaction were calculated by fitting the model to experimental data and the highest value was obtained at catalyst dosage 0.8 g/L, initial dye concentration 10 mg/L and pH = 3. Moreover, the recycling experiments confirmed the stability of the catalyst.

中文翻译：

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使用海泡石-TiO 2 纳米复合材料光催化降解Orange G：理化参数和动力学研究的优化

摘要 采用新型微波-水热法制备了具有不同Ti/Sep 比的高光活性纳米复合材料Sep-TiO2，并比较了它们的光催化活性。由于其相对完整的海泡石结构和更多的锐钛矿活性位点，Ti/Sep比为40 mmol/g的催化剂表现出最高的光降解活性。分析和优化了操作条件，包括光催化剂用量、初始染料浓度和 pH 值对光催化降解性能的影响，分别表明在仅存在海泡石和不存在光催化剂的情况下光降解效率低且可忽略不计。通过建模阐明了不同反应条件下的光催化降解动力学。结果表明，Orange G 的光催化降解可以用改进的 Langmuir-Hinshelwood 模型来描述。对于大多数操作参数，光催化降解过程符合一级动力学，而在高染料浓度条件下遵循零级动力学。通过将模型与实验数据拟合来计算每个降解反应的表观速率常数 kapp，在催化剂剂量 0.8 g/L、初始染料浓度 10 mg/L 和 pH = 3 时获得最高值。 此外，回收实验证实催化剂的稳定性。而在高染料浓度条件下遵循零级动力学。通过将模型与实验数据拟合来计算每个降解反应的表观速率常数 kapp，在催化剂剂量 0.8 g/L、初始染料浓度 10 mg/L 和 pH = 3 时获得最高值。 此外，回收实验证实催化剂的稳定性。而在高染料浓度条件下遵循零级动力学。通过将模型与实验数据拟合来计算每个降解反应的表观速率常数 kapp，在催化剂剂量 0.8 g/L、初始染料浓度 10 mg/L 和 pH = 3 时获得最高值。 此外，回收实验证实催化剂的稳定性。