电纺La2O3-CeO2纳米纤维的除氟性能

Defluoridation performance of electrospun La2O3-CeO2 nanofibers

  • 摘要: 纳米双金属氧化物作为除氟剂具有广泛的应用前景。以六水合硝酸铈和六水合硝酸镧为原料,聚丙烯腈(PAN)为模板,通过静电纺丝技术与煅烧相结合制备La2O3-CeO2纳米纤维,利用TEM、SEM-EDS、BET、FTIR和XRD对La2O3-CeO2纳米纤维的形貌和结构进行表征。探究了La2O3-CeO2纳米纤维对氟离子吸附性能,研究了pH、吸附质(F)初始浓度、吸附时间、La2O3-CeO2纳米纤维投加量和共存阴离子等对除氟效率的影响。研究结果表明,La2O3-CeO2纳米纤维的比表面积为31.04 m2·g−1。pH为3时,La2O3-CeO2纳米纤维的除氟性能最佳。La2O3-CeO2的吸附效率随着F初始浓度的增大而上升。准二级动力学和Langmuir等温线模型(R2>0.99)能够很好描述La2O3-CeO2纳米纤维的除氟过程,最大吸附量可达111.98 mg·g−1。热力学研究结果表明,La2O3-CeO2纳米纤维的除氟过程是自发的(ΔG0<0)、熵增(ΔS0=56.63 J·mol−1·K−1)和吸热(ΔH0=9.90 kJ·mol−1)的反应。

     

    Abstract: Nano bimetallic oxides have broad application prospects as fluoride removal agents. La2O3-CeO2 nanofibers were fabricated via electrospinning-calcination method using Ce(NO3)3·6H2O and La(NO3)3·6H2O as raw materials and polyacrylonitrile (PAN) as template. TEM, SEM-EDS, BET, FTIR and XRD were employed to verify the morphology and structure of La2O3-CeO2 nanofibers. The defluoridation properties of La2O3-CeO2 nanofibers were discussed under batch mode, and the effects of adsorbate (F) initial concentration, pH, contact time, La2O3-CeO2 nanofibers dose and coexisting anions on the defluoridation were explored. The results illustrate that the specific surface area of La2O3-CeO2 adsorbent is 31.04 m2·g−1. The La2O3-CeO2 nanofibers exhibit the best defluoridation performance at pH of 3, and the adsorption capacity of La2O3-CeO2 nanofibers climbs up with rise of the initial concentration of F. The pseudo-second-order kinetic and Langmuir isotherm model (R2>0.99) simulate the defluoridation process of La2O3-CeO2 nanofibers better, and the maximum uptake of F by La2O3-CeO2 nanofibers is 111.98 mg·g−1 at 45℃. Thermodynamic studies suggest that the defluoridation process of La2O3-CeO2 nanofibers is a spontaneous (ΔG0<0), entropy increase (ΔS0=56.63 J·mol−1·K−1) and endothermic (ΔH0=9.90 kJ·mol−1) process.

     

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