Abstract In the present work we describe a simple and low-cost method for the decolorization of textile dyeing and printing wastewaters, using ZnO as photocatalyst supported on natural Tunisian clay (ZnO/Clay). This composite ZnO/Clay material was synthesized through a sol–gel method. X-ray diffraction (XRD), Nitrogen Physisorption (BET), Infrared Spectroscopy (FTIR), Scanning Electronic Microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HRTEM) linked with Energy Dispersive X-ray (EDX), were performed in order to explain the characteristics of the ZnO/Clay photocatalyst. The XRD patterns, pointing to the presence of ZnO of very small crystal sizes, i.e. highly dispersed on the clay surface. The photocatalytic activity of ZnO/Clay was assayed in the decolorization of a cationic dye (Malachite Green, MG) and anionic dyes (Red Congo, RC) in aqueous solution as models pollutants under UV irradiation. In addition, the effects of different parameters such as pH of the solution, catalyst dosage, concentration of the dyes, irradiation source, as well as the influence of the presence of inorganic ions were investigated. The ZnO/Clay photocatalyst exhibited high photocatalytic activity of MG and CR decolorization under simulated solar compared to UV irradiation. The recyclability of the ZnO/Clay photocatalyst was as well validated.

中文翻译：

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固定在突尼斯天然粘土上的 ZnO 纳米颗粒对阳离子和阴离子染料的光催化脱色

摘要 在目前的工作中，我们描述了一种简单且低成本的纺织印染废水脱色方法，使用 ZnO 作为负载在天然突尼斯粘土 (ZnO/粘土) 上的光催化剂。这种复合 ZnO/粘土材料是通过溶胶-凝胶法合成的。X 射线衍射 (XRD)、氮物理吸附 (BET)、红外光谱 (FTIR)、扫描电子显微镜 (SEM) 和高分辨率透射电子显微镜 (HRTEM) 与能量色散 X 射线 (EDX) 相关联，在为了解释ZnO/Clay光催化剂的特性。XRD 图表明存在非常小的晶体尺寸的 ZnO，即高度分散在粘土表面上。在阳离子染料（孔雀石绿，MG）和阴离子染料（红刚果，RC）在水溶液中作为紫外线照射下的模型污染物。此外，还研究了溶液pH值、催化剂用量、染料浓度、辐照源等不同参数的影响，以及无机离子存在的影响。与紫外线照射相比，ZnO/Clay 光催化剂在模拟太阳光下表现出较高的 MG 和 CR 脱色光催化活性。ZnO/粘土光催化剂的可回收性也得到了验证。与紫外线照射相比，ZnO/Clay 光催化剂在模拟太阳光下表现出较高的 MG 和 CR 脱色光催化活性。ZnO/粘土光催化剂的可回收性也得到了验证。与紫外线照射相比，ZnO/Clay 光催化剂在模拟太阳光下表现出较高的 MG 和 CR 脱色光催化活性。ZnO/粘土光催化剂的可回收性也得到了验证。