Institute of Chemistry, São Paulo State University (UNESP), Araraquara, SP, 14800-060, Brazil.
National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), Institute of Chemistry, UNESP, Araraquara, SP, 14800-900, Brazil.
Environ Sci Pollut Res Int. 2021 May;28(19):23767-23777. doi: 10.1007/s11356-020-11238-5. Epub 2020 Oct 30.
The effect of incorporation of different amounts of cerium on iron oxides and different heat treatment temperatures was evaluated for the degradation of cephalexin (CEX) using heterogeneous Fenton and photo-Fenton processes. The materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), specific area (BET), and zeta potential (ZP). The conversion of magnetite to maghemite was observed when a 140 °C thermal treatment was applied. The insertion of cerium resulted in a loss of the uniform spherical shape of the particles. The material containing the lowest amount of cerium (0.5% w/w) presented an increase in the specific area from 91.2 to 171.6 m g relative to the pure iron oxide, while with 2% (w/w) a decrease to 99.2 m g was observed for the materials treated at 70 °C. The same behavior was observed for materials treated at 140 °C, however, with smaller areas. At pH 6.0, a low catalytic activity was observed contrasting to the high consumption of HO, suggesting its catalytic decomposition into water and oxygen. This was confirmed by the very low production of HO• in the degradation system. On the other hand, the high production of HO• was observed at pH 3.5, which was chosen as a working pH. The material treated at 140 °C and containing 1% Ce (w/w) was the highlight, promoting degradation of 0.052 mg of CEX per m area of the catalyst after 150 min using 1.0 mmol L of HO. The CEX intermediates identified indicated hydroxylation as the major route of degradation.
采用非均相芬顿和光芬顿工艺，研究了不同量铈的掺入对氧化铁的影响和不同的热处理温度对头孢氨苄（CEX）降解的影响。采用 X 射线衍射（XRD）、扫描电子显微镜（SEM）、比表面积（BET）和zeta 电位（ZP）对材料进行了表征。当应用 140°C 的热处理时，观察到磁铁矿向磁赤铁矿的转化。铈的插入导致颗粒的均匀球形形状丧失。与纯氧化铁相比，含铈量最低（0.5%w/w）的材料的比表面积从 91.2 增加到 171.6 m/g，而在 70°C 处理的材料中，当铈含量为 2%（w/w）时，比表面积则下降到 99.2 m/g。在 140°C 处理的材料中观察到相同的行为，然而，比表面积较小。在 pH 6.0 下，观察到催化活性低，与 HO 的高消耗形成对比，表明其催化分解为水和氧气。这通过降解系统中 HO•的极低生成得到证实。另一方面，在 pH 3.5 下观察到 HO•的高生成，因此选择 pH 3.5 作为工作 pH。在 140°C 下处理并含有 1%Ce（w/w）的材料是亮点，在 150 分钟内使用 1.0mmol/L 的 HO 后，每平方米催化剂面积可降解 0.052mg 的 CEX。鉴定的 CEX 中间体表明羟基化是主要的降解途径。
