Abstract

Tetracycline (TC) is one of the most commonly applied antibiotic and due to the risk posed by antibiotic-resistant pathogens, the need for treating these wastewater is beyond question. Photocatalytic degradation of TC in aqueous solution was studied using TiO₂ based on natural zeolite (clinoptilolite, CP) under UV irradiation in a batch reactor. For the first time, in order to propose an accurate model for the photocatalytic degradation of TC under UV light, central composite design based on response surface methodology was employed to assess the individual and interactive effects of several classic parameters on both TC degradation and TOC removal (mineralization). In order to analyze the process, three significant variables pH, catalyst concentration, and tetracycline concentration and tetracycline degradation as the process response were studied. The results of the experiments were fitted to quadratic polynomial models. A maximum degradation of TC of more than 77% was achieved at the optimum conditions (pH 5.9, catalyst concentration of 0.30 g L^–1 and TC concentration of 8 mg L^–1) within 60 of irradiation. The mineralization or oxidation profile, represented as the total organic carbon, was decreased significantly during the optimum conditions, achieving value near 54% after 4 h. The experimental values agreed with the predicted ones, indicating suitability of the model employed and the success of model in optimizing the conditions of photocatalysis. The quadratic model had high R² coefficient (0.980) and high F-value, confirming that the model was valid to predict the experimental results. Moreover, the adjusted R² is very close to the R² value as another evidence for goodness of the model fit. Initial TC concentration and catalyst dosage are the major factors affecting the photocatalytic degradation of TC using TiO₂/CP.

中文翻译：

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响应面法优化基于天然沸石的二氧化钛光催化降解四环素

摘要

四环素（TC）是最常用的抗生素之一，由于抗药性病原体的风险，毫无疑问需要处理这些废水。用TiO ₂研究TC在水溶液中的光催化降解。在间歇反应器中在紫外线照射下以天然沸石（斜发沸石，CP）为基础。为了首次提出一个准确的模型，用于紫外光下TC的光催化降解，基于响应表面方法的中心复合设计被用于评估几个经典参数对TC降解和TOC去除的个体和相互作用影响（矿化）。为了分析该过程，研究了三个重要变量pH，催化剂浓度，四环素浓度和四环素降解作为过程响应。实验结果适合二次多项式模型。在最佳条件（pH 5.9，催化剂浓度为0.30 g L ^–1）下，TC的最大降解超过77％。辐射60内的TC浓度为8 mg L ^–1）。在最佳条件下，矿化或氧化曲线（以总有机碳表示）显着降低，在4小时后达到接近54％的值。实验值与预测值一致，表明所用模型的适用性以及该模型在优化光催化条件方面的成功。二次模型具有较高的R ²系数（0.980）和较高的F值，证实该模型可有效预测实验结果。此外，调整后的R ²非常接近R ²值作为模型拟合优度的另一个证据。TC的初始浓度和催化剂用量是影响TiO ₂ / CP光催化降解TC的主要因素。