Department of Civil Engineering, Kyung Hee University, 1732 Deokyoung-daero, Yongin-si, Gyeonggi-do, Republic of Korea.
Environ Res. 2019 Apr;171:92-100. doi: 10.1016/j.envres.2019.01.019. Epub 2019 Jan 10.
Encapsulating magnetic nanoparticles in a silica shell is a promising approach in many research fields. We recently demonstrated that the magnetic yolk-shell structure of FeO@SiO, which consists of an inner magnetite core and outer silica shell separated by a hollow void space, and its modified counterparts can be used as an effective catalyst for removal of acetaminophen in a heterogeneous Fenton-like reaction. The present study develops this approach further in an effort to design an effective procedure for preparing an optimum yolk-shell structure capable of greater catalytic performance. We investigated the use of a controlled synthesis strategy to fabricate an FeO@SiO yolk-shell structure under varying conditions. Our focus was a single-step process that examines the effects of Stöber solution temperature, tetraethyl orthosilicate (TEOS) and hexadecyltrimethylammonium bromide (CTAB) concentrations, ethanol and water volume ratio, incubation time, and temperature on FeO@SiO textural morphologies. The catalytic performance of the prepared materials was evaluated through oxidative degradation of acetaminophen in a heterogeneous Fenton-like reaction. Field emission transmission electron microscopy observation showed that magnetic yolk-shell structures with appropriate diameter, shell thickness, and hollow void space could be generated through tight control of synthesis conditions. Particle size and hollow void space increased when TEOS concentration increased from 22.10 to 88.50 mM. Hollow void space also increased as incubation time increased from 24 h to 72 h or incubation temperature increased from 50 to 90 °C. However, a yolk-shell structure did not form at a TEOS concentration of 11.10 mM, an incubation time of 3 h, or with an inappropriate ratio of ethyl alcohol and deionized water. Catalytic activity for degradation of acetaminophen increased with increasing hollow void space and thinning silica shell. In addition, the selected appropriate materials exhibited effective catalytic performance over five cycles of regeneration. This study demonstrates the significance of controlling the formation of yolk-shell structures, which enabled us to produce FeO@SiO yolk-shell structures of desired and predictable size, hollow void space volume, and shell thickness for higher catalytic performance in degradation of pharmaceuticals in heterogeneous Fenton-like systems.
将磁性纳米颗粒封装在二氧化硅壳中是许多研究领域中很有前途的方法。我们最近证明，由内磁铁矿核和外二氧化硅壳组成的 FeO@SiO 蛋黄壳结构及其修饰物可以用作非均相类 Fenton 反应中去除扑热息痛的有效催化剂。本研究进一步发展了这种方法，以设计一种能够获得更高催化性能的最佳蛋黄壳结构的有效制备方法。我们研究了在不同条件下使用控制合成策略来制备 FeO@SiO 蛋黄壳结构。我们的重点是一个单步过程，研究了斯托贝溶液温度、正硅酸乙酯（TEOS）和十六烷基三甲基溴化铵（CTAB）浓度、乙醇和水体积比、孵育时间和温度对 FeO@SiO 结构形态的影响。通过在非均相类 Fenton 反应中氧化降解扑热息痛来评估制备材料的催化性能。场发射透射电子显微镜观察表明，通过严格控制合成条件，可以生成具有适当直径、壳厚和中空空隙的磁性蛋黄壳结构。当 TEOS 浓度从 22.10 增加到 88.50mM 时，粒径和中空空隙增大。当孵育时间从 24 小时增加到 72 小时或孵育温度从 50 增加到 90°C 时，中空空隙也增加。然而，当 TEOS 浓度为 11.10mM、孵育时间为 3 小时或乙醇和去离子水的比例不合适时，不会形成蛋黄壳结构。降解扑热息痛的催化活性随着中空空隙的增加和二氧化硅壳的变薄而增加。此外，选择的合适材料在五个循环的再生中表现出有效的催化性能。本研究表明控制蛋黄壳结构形成的重要性，这使我们能够生产具有所需和可预测尺寸、中空空隙体积和壳厚的 FeO@SiO 蛋黄壳结构，从而在非均相类 Fenton 体系中提高药物降解的催化性能。
