School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China.
School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
J Hazard Mater. 2021 Mar 15;406:124678. doi: 10.1016/j.jhazmat.2020.124678. Epub 2020 Nov 26.
In the work, we employed a hydrothermal method for modification of red mud using colloidal silica and sodium hydroxide under mild conditions, and applied it into adsorbing Pb(II) ions in aqueous solutions. In the modification, zeolite structure was formed. The adsorption experiments found that the adsorption capacity of the modified red mud for Pb(II) ions was significantly improved, almost 10 times as much as that of the original red mud. Both the pseudo-first-order and pseudo-second-order kinetic equation can describe the adsorption process, indicating it a more complicated interaction. Langmuir and Dubinin-Radushkevich models well fit the adsorption isotherm, indicating that the modified red mud mainly removes lead ions from aqueous solution by monolayer physical adsorption. According to the fitting results, the saturated adsorption capacity of Pb (II) by the modified red mud is 551.11 mg/g, confirming its high efficiency adsorption performance. XRD, FTIR, XPS and SEM-EDS all detected the formation of PbCO and Pb(CO)(OH). It was speculated that the adsorption mechanism should be attributed to the joint contribution of ion exchange and precipitation. The excellent performance of the modified red mud on Pb(II) ions adsorption makes it a promising candidate for the treatment of wastewater contaminated by heavy metal ions.
在这项工作中，我们采用水热法，在温和条件下使用胶体二氧化硅和氢氧化钠对赤泥进行改性，并将其应用于吸附水溶液中的 Pb(II) 离子。在改性过程中，形成了沸石结构。吸附实验发现，改性赤泥对 Pb(II) 离子的吸附容量显著提高，几乎是原始赤泥的 10 倍。拟一级和拟二级动力学方程都可以描述吸附过程，表明这是一种更复杂的相互作用。Langmuir 和 Dubinin-Radushkevich 模型很好地拟合了吸附等温线，表明改性赤泥主要通过单层物理吸附从水溶液中去除铅离子。根据拟合结果，改性赤泥对 Pb(II) 的饱和吸附容量为 551.11 mg/g，证实了其高效的吸附性能。XRD、FTIR、XPS 和 SEM-EDS 均检测到 PbCO 和 Pb(CO)(OH) 的形成。推测吸附机理应归因于离子交换和沉淀的共同作用。改性赤泥对 Pb(II) 离子吸附的优异性能使其成为处理重金属离子污染废水的有前途的候选材料。
