氨基功能化纳米Fe3O4磁性高分子吸附剂对废水中Cr(VI)的吸附研究

采用分散聚合法通过共聚、开环反应, 对纳米Fe3O4进行表面功能化修饰, 得到富含NH2官能团的纳米磁性高分子复合材料. 通过透射电镜(TEM)、振动样品磁强计(VSM)、热重差热分析(TGA)、X射线衍射(XRD)、红外光谱(IR)等对其进行表征, 着重研究了其作为吸附剂对Cr(VI)的吸附性能. 结果表明: 该吸附剂对Cr(VI)的吸附能在10 min内达到平衡; 废水溶液pH值能显著影响吸附剂对Cr(VI)的吸附效果, pH为2.5时效果最佳. 废水中Cr(VI)的初始浓度、吸附时间、温度等因素对吸附效果均有不同程度的影响. 结合相应pH值下Cr(VI)的形态分布, 探讨了这种新型材料对Cr(VI)的吸附机理. 结果表明: 其吸附机理及吸附容量与废水中Cr(VI)的离子形式有关; 吸附过程以离子交换与静电引力为主. 等温吸附数据符合Langmuir模型, T＝308 K, pH＝2.5, V＝40 mL时, 吸附剂的饱和吸附容量qm＝25.58 mg/g. 吸附为吸热过程, 焓变ΔH＝8.64 kJ/mol.

Adsorption Studies on Cr(VI) in Wastewater by NH2-functionalized Nano-Fe3O4 Magnetic Composites

A novel nano-sized magnetic polymer adsorbent coupled with ethylenediamine has been obtained via co-polymerization and ring-opening reactions, followed by chemical co-precipitation for the preparation of Fe3O4. The adsorbent was characterized by TEM, VSM, TGA, XRD, FTIR, etc. Its application to the adsorption of Cr(VI) from wastewater was also investigated. The results showed that the adsorption capability was affected by pH, the initial concentration of Cr(VI), the adsorption time and temperature. With the distributions of Cr(VI) species in function of pH under corresponding conditions, the adsorption mechanisms of Cr(VI) including both ion exchange and electrostatic gravitation were discussed. The adsorption of Cr(VI) reached equilibrium rapidly within 10 min. The adsorption data were well fitted with the Langmuir isotherm. The maximum sorption capacity of adsorbent to Cr(VI) calculated from the Langmuir isotherm was 25.58 mg/g at 308 K, pH 2.5 with volume of 40 mL. The adsorption was an endothermic process with the enthalpy deviation ΔH at 8.64 kJ/mol.