Abstract Magnetic nanomaterials have been widely studied as adsorbents in the removal of contaminants from effluents. In this context, lanthanum-doped cobalt ferrites (CoLaxFe2-xO4) were successfully synthesized via sol-gel method at 300 °C. XRD, TEM and BET analyses showed that minute particle size was achieved, with decreases along increasing La3+ content. XRD patterns confirm single cubic spinel CoFe2O4 nanoparticles. The average crystallite size confirmed via TEM images ranges between 5 nm and 12 nm. Surface area increased from 74.3 to 109.3 m2 g−1 with the addition of La3+. Raman spectra indicate a tendency towards inversion of the spinel induced by the addition of the lanthanide. The optical band gap of the samples doped with La showed a progressive decrease from 1.35 to 1.1 eV, which was not expected. Hysteresis loops indicate a transition from hard to soft magnetism. A significant decrease in coercivity from 740 to 158 Oe was observed with increase in La3+ (CoFe2O4 to CoLa0.025Fe1.975O4). Total magnetization (M* defined for maximum available field H = 20 kOe) decayed from 44.6 to 29.0 emu.g−1. These results show that the produced nanoparticles are ideally suited as magnetic adsorbents in separation of pollutants from wastewater.

中文翻译：

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用于环境应用的镧掺杂尖晶石钴铁氧体 (CoFe2O4) 纳米粒子

摘要 磁性纳米材料作为吸附剂在去除废水中的污染物方面得到了广泛的研究。在此背景下，通过溶胶-凝胶法在 300 °C 下成功合成了镧掺杂的钴铁氧体 (CoLaxFe2-xO4)。XRD、TEM 和 BET 分析表明实现了微小的粒径，随着 La3+ 含量的增加而减小。XRD 图案证实了单个立方尖晶石 CoFe2O4 纳米颗粒。通过 TEM 图像确认的平均微晶尺寸范围在 5 nm 和 12 nm 之间。随着 La3+ 的加入，表面积从 74.3 增加到 109.3 m2 g-1。拉曼光谱表明，由于镧系元素的加入，尖晶石有反转的趋势。掺杂 La 的样品的光学带隙显示出从 1.35 到 1.1 eV 的逐渐减小，这是意料之中的。磁滞回线表示从硬磁到软磁的转变。随着 La3+ 的增加（CoFe2O4 到 CoLa0.025Fe1.975O4），观察到矫顽力从 740 Oe 显着降低到 158 Oe。总磁化强度（M* 定义为最大可用场 H = 20 kOe）从 44.6 衰减到 29.0 emu.g-1。这些结果表明，所产生的纳米颗粒非常适合作为磁性吸附剂，用于从废水中分离污染物。