Abstract：
The present work aimed at decorating halloysite nanotubes (HNT) with magnetic Fe3O4 nanoparticles through different synthetic routes (co-precipitation, hydrothermal, and sol-gel) to test the efficiency of three magnetic composites (HNT/Fe3O4) to remove the antibiotic ofloxacin (OFL) from waters. The chemical-physical features of the obtained materials were characterized through the application of diverse techniques (XRPD, FT-IR spectroscopy, SEM, EDS, and TEM microscopy, thermogravimetric analysis, and magnetization measurements), while ecotoxicity was assessed through a standard test on the freshwater organism Daphnia magna. Independently of the synthesis procedure, the magnetic composites were successfully obtained. The Fe3O4 is nanometric (about 10 nm) and the weight percentage is sample-dependent. It decorates the HNT\'s surface and also forms aggregates linking the nanotubes in Fe3O4-rich samples. Thermodynamic and kinetic experiments showed different adsorption capacities of OFL, ranging from 23 to 45 mg g-1. The kinetic process occurred within a few minutes, independently of the composite. The capability of the three HNT/Fe3O4 in removing the OFL was confirmed under realistic conditions, when OFL was added to tap, river, and effluent waters at µg L-1 concentration. No acute toxicity of the composites was observed on freshwater organisms. Despite the good results obtained for all the composites, the sample by co-precipitation is the most performant as it: (i) is easily magnetically separated from the media after the use; (ii) does not undergo any degradation after three adsorption cycles; (iii) is synthetized through a low-cost procedure. These features make this material an excellent candidate for removal of OFL from water.
摘要：
本工作旨在通过不同的合成路线（共沉淀，热液,和溶胶-凝胶），以测试三种磁性复合材料（HNT/Fe3O4）从水中去除抗生素氧氟沙星（OFL）的效率。通过应用各种技术（XRPD，FT-IR光谱,SEM,EDS,和TEM显微镜，热重分析,和磁化测量)，而生态毒性是通过对淡水生物大型水蚤的标准测试来评估的。独立于合成程序，成功获得了磁性复合材料。Fe3O4是纳米级的(约10nm),重量百分比取决于样品。它装饰HNT的表面，还形成聚集体，连接富含Fe3O4的样品中的纳米管。热力学和动力学实验表明，OFL的吸附能力不同，范围从23到45毫克g-1。动力学过程发生在几分钟内，独立于复合材料。在现实条件下证实了三种HNT/Fe3O4去除OFL的能力，当OFL被添加到水龙头时，河,和废水浓度为µgL-1。在淡水生物中未观察到复合材料的急性毒性。尽管所有复合材料都获得了良好的结果，通过共沉淀的样品是最有效的,因为它:(i)在使用后容易与介质磁性分离;(ii)在三个吸附循环后不经历任何降解;(iii)通过低成本程序合成。这些特征使得该材料成为从水中去除OFL的优异候选物。
