Hunan Province Key Laboratory of Coal Resources Clean Utilization and Mine Environment Protection, Hunan University of Science and Technology, Xiangtan, Hunan 411201, China; School of Resource Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201, China.
School of Resource Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201, China.
Sci Total Environ. 2021 May 15;769:145159. doi: 10.1016/j.scitotenv.2021.145159. Epub 2021 Jan 14.
Considering that hyperaccumulators can accumulate high concentrations of iron salt, they can successfully obtain magnetic hydrochar from iron-rich hyperaccumulators. In this study, iron-rich biomass was obtained by irrigating Phytolacca acinosa Roxb. using iron salt. Magnetic nano-FeO hydrochar was prepared from iron-rich Phytolacca acinosa Roxb. via hydrothermal carbonization to remove Cd. The characterization results showed that the synthesized magnetic nanoparticles had an average size of 2.62 ± 0.56 nm and N elements were doped into magnetic nano-FeO hydrochar with abundant oxygenic groups. Cd adsorption on magnetic nano-FeO hydrochar was better fitted using the Langmuir isotherm and the pseudo-second-order kinetic model. The maximum adsorption capacity was 246.6 mg g of Cd. The research confirmed that Cd adsorption was controlled by multiple mechanisms from the jar test, transmission electron microscopy mapping, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. CdCO crystals can be formed after adsorption, indicating that surface precipitation played an important role in Cd adsorption. The abundance of O atoms and the doping of N atoms on the hydrochar surface were conducive to Cd adsorption, indicating that the mechanisms were related to surface complexation and electrostatic attraction. In addition, the significant decrease in Na content after Cd adsorption illustrated that ion exchange had a non-negligible effect on Cd adsorption. This study not only provides a strategy for preparing magnetic nano-FeO hydrochar derived from iron-rich plants but also verifies multiple Cd adsorption mechanisms using magnetic nano-FeO hydrochar.
考虑到超积累体可以积累高浓度的铁盐，它们可以成功地从富铁超积累体中获得磁性水凝胶。在这项研究中，通过用铁盐灌溉商陆（Phytolacca acinosa Roxb.）获得富铁生物质。通过水热碳化从富铁商陆（Phytolacca acinosa Roxb.）中制备磁性纳米-FeO 水凝胶以去除 Cd。表征结果表明，合成的磁性纳米颗粒的平均粒径为 2.62±0.56nm，N 元素被掺杂到具有丰富含氧基团的磁性纳米-FeO 水凝胶中。Cd 在磁性纳米-FeO 水凝胶上的吸附更符合 Langmuir 等温线和拟二级动力学模型。最大吸附容量为 246.6mg·g-1 Cd。研究证实，从瓶试验、透射电子显微镜映射、扫描电子显微镜-能量色散 X 射线光谱、X 射线衍射、傅里叶变换红外光谱和 X 射线光电子能谱来看，Cd 的吸附是由多种机制控制的。吸附后可以形成 CdCO3 晶体，表明表面沉淀在 Cd 吸附中起着重要作用。水凝胶表面 O 原子的丰富和 N 原子的掺杂有利于 Cd 的吸附，表明这些机制与表面络合和静电吸引有关。此外，Cd 吸附后 Na 含量显著降低，表明离子交换对 Cd 吸附有不可忽视的影响。本研究不仅为制备富铁植物衍生磁性纳米-FeO 水凝胶提供了一种策略，还利用磁性纳米-FeO 水凝胶验证了多种 Cd 吸附机制。
