Environmental Health Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran.
Department of Environmental Health Engineering, School of Health, Jiroft University of Medical Sciences, Jiroft, Iran.
Environ Sci Pollut Res Int. 2020 Jan;27(3):2691-2706. doi: 10.1007/s11356-019-07165-9. Epub 2019 Dec 13.
The aim of this research was to develop a simple and inexpensive process for reduction of Cr(VI) to Cr(III). Zinc oxide nanoparticles were synthesized with an easy co-precipitation procedure, and the addition of Cu doping agent effectively enhanced the Cr(VI) reduction in the presence of ultrasound (US). XRD, FT-IR, FE-SEM, EDX, VSM, and XPS were used to determine the structural specifications of the zinc oxide nanoparticles. Under optimal conditions such as pH 3, initial Cr(VI) content of 20 mg/L, and catalyst dosage of 0.8 g/L, the ultrasonic/Cu-ZnO process showed a higher sonocatalytic activity (96.83%) than ultrasonic/ZnO (67.36%) after 60 min. By increasing pH and Cr(VI) concentration, the removal efficacy of Cr(VI) declined. The experimental data was well described with the first-order kinetic model. When initial Cr(VI) concentration increased from 10 to 50 mg/L, the first-order rate constant declined from 0.2326 to 0.0019 min and electrical energy per order (E) enhanced from 19.81 to 2425.26 kWh/m. Also, the ultrasonic/Cu-ZnO system exhibited considerable sonocatalytic performance in Cr(VI) reduction in the presence of hydrogen peroxide and citric acid, and complete removal was achieved within 60 min. The presence of anions negatively affected Cr(VI) reduction. Complete reduction was attained when ultrasound was applied at a power of 100 W. The catalyst activity was well maintained up to six consecutive cycles. In addition, the removal efficiency was approximately 62 and 65% for field water and real electroplating wastewater samples, respectively.
本研究旨在开发一种简单且廉价的方法，用于将 Cr(VI)还原为 Cr(III)。采用简单的共沉淀法合成氧化锌纳米粒子，添加 Cu 掺杂剂，在超声（US）存在下，有效地增强了 Cr(VI)的还原。采用 XRD、FT-IR、FE-SEM、EDX、VSM 和 XPS 来确定氧化锌纳米粒子的结构规格。在最佳条件下，如 pH 值为 3、初始 Cr(VI)含量为 20mg/L、催化剂用量为 0.8g/L，超声/Cu-ZnO 工艺在 60min 后显示出比超声/ZnO（67.36%）更高的超声催化活性（96.83%）。当 pH 值和 Cr(VI)浓度增加时，Cr(VI)的去除效率下降。实验数据很好地符合一级动力学模型。当初始 Cr(VI)浓度从 10mg/L 增加到 50mg/L 时，一级速率常数从 0.2326 降低到 0.0019min，每阶电能（E）从 19.81 增加到 2425.26kWh/m。此外，超声/Cu-ZnO 体系在过氧化氢和柠檬酸存在下对 Cr(VI)还原具有相当好的超声催化性能，在 60min 内即可实现完全去除。阴离子的存在对 Cr(VI)的还原有负面影响。当超声功率为 100W 时，可实现完全还原。催化剂活性在六次连续循环中得到很好的保持。此外，对于野外水和实际电镀废水样品，去除效率分别约为 62%和 65%。
