Fernandes Ricardo J C, Cardoso Beatriz D, Rodrigues Ana Rita O, Pires Ana, Pereira André M, Araújo João P, Pereira Luciana, Coutinho Paulo J G
Physics Centre of Minho and Porto Universities (CF-UM-UP), University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
LaPMET-Associate Laboratory, 4169-007 Porto, Portugal.
Materials (Basel). 2024 Jun 27;17(13):3158. doi: 10.3390/ma17133158.
Water pollution is a major environmental challenge. Due to the inefficiency of conventional wastewater treatment plants in degrading many organic complex compounds, these recalcitrant pollutants end up in rivers, lakes, oceans and other bodies of water, affecting the environment and human health. Semiconductor photocatalysis is considered an efficient complement to conventional methods, and the use of various nanomaterials for this purpose has been widely explored, with a particular focus on improving their activity under visible light. This work focuses on developing magnetic and photoactive zinc/magnesium mixed ferrites (ZnMgFeO) by sol-gel and solvothermal synthesis methods, which are two of the most important and efficient methods used for the synthesis of ferrite nanoparticles. The nanoparticles (NPs) synthesized by the sol-gel method exhibited an average size of 14.7 nm, while those synthesized by the solvothermal method had an average size of 17.4 nm. Both types possessed a predominantly cubic structure and demonstrated superparamagnetic behavior, reaching a magnetization saturation value of 60.2 emu g. Due to the high recombination rate of electrons/holes, which is an intrinsic feature of ferrites, surface functionalization with silver was carried out to enhance charge separation. The results demonstrated a strong influence of adsorption and of the deposition of silver. Several optimization steps were performed during synthesis, allowing us to create efficient catalysts, as proved by the almost full removal of the dye malachite green attaining 95.0% (at a rate constant of 0.091 min) and 87.6% (at a rate constant of 0.017 min) using NPs obtained by the sol-gel and solvothermal methods, respectively. Adsorption in the dark accounted for 89.2% of the dye removal for nanoparticles prepared by sol-gel and 82.8% for the ones obtained by the solvothermal method. These results make mixed zinc/magnesium ferrites highly promising for potential industrial application in effluent photoremediation using visible light.
水污染是一项重大的环境挑战。由于传统污水处理厂在降解许多有机复杂化合物方面效率低下，这些难降解污染物最终进入河流、湖泊、海洋和其他水体，影响环境和人类健康。半导体光催化被认为是传统方法的有效补充，为此人们广泛探索了各种纳米材料的应用，尤其注重提高它们在可见光下的活性。这项工作聚焦于通过溶胶 - 凝胶法和溶剂热合成法来制备磁性和光活性锌/镁混合铁氧体（ZnMgFeO），这是用于合成铁氧体纳米颗粒的两种最重要且高效的方法。通过溶胶 - 凝胶法合成的纳米颗粒（NPs）平均尺寸为14.7纳米，而通过溶剂热法合成的纳米颗粒平均尺寸为17.4纳米。这两种类型的纳米颗粒都主要具有立方结构，并表现出超顺磁性行为，达到的磁化饱和值为60.2 emu/g。由于电子/空穴的高复合率是铁氧体的固有特性，因此进行了银的表面功能化处理以增强电荷分离。结果表明吸附和银的沉积有很大影响。在合成过程中进行了几个优化步骤，从而能够制备出高效催化剂，这一点通过使用溶胶 - 凝胶法和溶剂热法获得的纳米颗粒分别几乎完全去除孔雀石绿染料得到了证明，去除率分别达到95.0%（速率常数为0.091 min⁻¹）和87.6%（速率常数为0.017 min⁻¹）。对于溶胶 - 凝胶法制备的纳米颗粒，黑暗中的吸附占染料去除量的89.2%，对于溶剂热法获得的纳米颗粒，这一比例为82.8%。这些结果使得锌/镁混合铁氧体在利用可见光进行废水光修复的潜在工业应用中极具前景。
