超声时间对纳米结构化赤铁矿吸附Eu(Ⅲ)的影响及作用机制

Effect of ultrasonic time on adsorption of Eu(Ⅲ) by nano structured hematite and its mechanism

本文在空气气氛中热处理菱铁矿制备纳米结构化赤铁矿,研究了超声时间对制备的纳米结构化赤铁矿物化性质的影响,考察了反应时间、pH、离子强度、初始浓度对纳米结构化赤铁矿吸附Eu(Ⅲ)的影响.系列表征表明,热处理菱铁矿可形成纳米结构化赤铁矿,超声进一步降低了赤铁矿的粒径和结晶度,增大了比表面积.与纳米结构化赤铁矿相比,超声1 h得到的赤铁矿(PCH-3)具有最大的比表面积(29.37 m^2/g).批实验结果表明, T=288 K,pH 5.5时PCH-3对Eu(Ⅲ)的吸附具有最大的速率常数(K_2=3.49 g/(mg min))和容量(4.88 mg/g). X射线光电子能谱(XPS)分析证实,含氧官能团(特别是羟基)是纳米结构化赤铁矿富集Eu(Ⅲ)的主要吸附位点.而且适当的超声处理可显著提高纳米结构化赤铁矿表面反应性.该研究对矿物纳米结构化材料吸附重金属离子提供了重要的理论依据.

In this paper, the nanostructured hematite was prepared by heat treatment of siderite in air atmosphere. The influence of ultrasonic time on the physicochemical properties of nano structured hematite was studied. The effects of reaction time, pH, ionic strength and initial concentration on the adsorption of Eu（Ⅲ） hematite with different ultrasonic time were investigated. The series of characterization showed that nanostructured hematite can be formed by heating siderite. The size and crystallinity of nanoscale hematite were further reduced by ultrasound, resulting in increasement of the specific surface area. Compared with the nanostructured hematite without ultrasound, nanostructured hematite（PCH-3） after ultrasound for 1 h obtained the biggest specific surface area（29.37m2/g）. Batch experiments results indicated that PCH-3 had the maximum rate constant（K2=3.49g/（mg min）） and the maximum adsorption capacity（4.88mg/g） for Eu（Ⅲ） adsorption at T=288K, pH 5.5. X-ray photoelectron spectroscopy（XPS） analysis confirmed that oxygen-containing functional groups（especially hydroxyl groups） were the main adsorption sites of Eu（Ⅲ） enriched by nano structured hematite. The results showed that proper ultrasound treatment can significantly improve the surface reactivity of the nano structured. This work is of great theoretical value for the adsorption of heavy metal ions by nanostructured mineral materials.