Abstract In this study, CoFe2O4/ZrO2 nanocomposite was synthesized by hydrothermal method for photoreduction of hexavalent chromium. ZrO2 nanoparticles were modified by CoFe2O4 nanoparticles to increase the photocatalytic activity of the nanocomposite. The prepared nanocomposite was then characterized by Scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, X- ray diffraction (XRD), Dynamic light scattering (DLS),Vibrating sample magnetometer (VSM) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). In the second part of the research, the effect of pH (2–8), irradiation time, photocatalyst dosage (0.005–0.03 g) and chromium solution concentration (10–50 mg/L) on the photocatalytic reduction of hexavalent chromium under visible light were investigated. Increase in irridation time and photocatalyst dosage had a positive impact on photocatalytic reduction. Additionally, photocatalytic reduction of hexavalent chromium in alkalic environment was less than that of the acidic environment. A maximum photoreduction efficiency up to 83 % was obtained at optimum condition, i.e. pH = 2, 0.02 g photocatalyst, 10 ppm chromium solution. Finally, kinetic studies using pseudo-first order model (simplified Langmuir-Hinshelwood equation) suggested that the implemented model was suitable for describing the experimental data.

中文翻译：

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磁分离CoFe2O4/ZrO2纳米复合材料在可见光下光催化还原六价铬

摘要 本研究采用水热法合成六价铬光还原CoFe2O4/ZrO2纳米复合材料。用 CoFe2O4 纳米粒子修饰 ZrO2 纳米粒子以提高纳米复合材料的光催化活性。然后通过扫描电子显微镜 (FESEM)、傅里叶变换红外 (FTIR) 光谱、X 射线衍射 (XRD)、动态光散射 (DLS)、振动样品磁强计 (VSM) 和紫外-可见漫反射光谱对制备的纳米复合材料进行表征(UV-vis DRS)。在第二部分研究中，pH（2-8）、辐照时间、光催化剂用量（0.005-0.03 g）和铬溶液浓度（10-50 mg/L）对可见光下六价铬光催化还原的影响光进行了调查。增加辐照时间和光催化剂用量对光催化还原有积极影响。此外，碱性环境中六价铬的光催化还原小于酸性环境。在最佳条件下获得了高达 83% 的最大光还原效率，即 pH = 2、0.02 g 光催化剂、10 ppm 铬溶液。最后，使用伪一级模型（简化的 Langmuir-Hinshelwood 方程）的动力学研究表明实施的模型适合描述实验数据。10 ppm 铬溶液。最后，使用伪一级模型（简化的 Langmuir-Hinshelwood 方程）的动力学研究表明实施的模型适合描述实验数据。10 ppm 铬溶液。最后，使用伪一级模型（简化的 Langmuir-Hinshelwood 方程）的动力学研究表明实施的模型适合描述实验数据。