不同含羧酸纤维与铁离子的配位反应动力学及配合物的催化降解性能

摘要

分别使用具有相似羧基含量的海藻纤维、丙烯酸接枝改性聚四氟乙烯纤维和聚丙烯纤维( PAA-g-PP和PAA-g-PTFE)3种含羧酸纤维与Fe3+进行配位反应,研究和比较了反应的动力学特性及影响因素.将3种含羧酸纤维铁配合物分别作为非均相Fenton反应催化剂应用于染料降解反应中,分析和评价了其配位结构和表面性能对催化活性的影响.结果表明,在所涉及的温度和浓度范围内,3种含羧酸纤维与Fe3+的反应均很好地符合Langmuir等温吸附模型和Lagergren准二级动力学方程. Fe3+初始浓度的增加会降低反应速率常数,而反应温度的升高则会增加配合物中Fe3+的配合量.在相同反应条件下,海藻纤维比PAA-g-PP和PAA-g-PTFE更容易与Fe3+发生反应,且反应速率常数和Fe3+配合量按照下列顺序排列：海藻纤维>PAA-g-PP>PAA-g-PTFE.3种含羧酸纤维铁配合物都能够在染料氧化降解反应中作为非均相Fenton催化剂,且紫外光比可见光更能够提高其催化活性.海藻纤维铁配合物比其它2种含羧酸纤维铁配合物具有更好的催化作用,这与三者在配位结构和表面性能之间的显著差异有关.%Three carboxylic fibers including alginate fiber, polyacrylic acid grafted polypropylene and polyte-trafluoroethylene fibers ( PAA-g-PP and PAA-g-PTFE ) with similar carboxyl contents were coordinated with Fe3+, respectively to prepare the different Fe (Ⅲ)-carboxylic fiber complexes. The coordinating kinetics of three carboxylic fibers with Fe3+was compared, and the effecting factors were also examined. And the catalytic performance of three Fe(Ⅲ)-carboxylic fiber complexes was then evaluated as the heterogeneous Fenton cata-lysts in the dye degradation in water. The results indicated that within the observed temperature and concentra-tion range, the coordination of carboxylic fiber with Fe3+showed better agreement with Langmuir isotherm equa-tion and Lagergren second order equation. Increasing Fe3+initial concentration led to a low coordination rate constant. Higher temperature increased the Fe content of the resulting complexes. Alginate fiber reacted more easily with than PAA-g-PP and PAA-g-PTFE at the same conditions. Moreover, their coordination rate con-stants and Fe contents were ranked as follow: alginate fiber >PAA-g-PP >PAA-g-PTFE. Three Fe(Ⅲ)-car-boxylic fiber complexes acted as the heterogeneous Fenton catalysts for dye degradation. UV irradiation could more significantly enhance the catalytic capacity of the complexes than visible irradiation. Fe (Ⅲ)-alginate fiber complex has a higher catalytic performance than the other Fe(Ⅲ)-carboxylic fiber complexes with similar Fe content, which is in relation to the big difference in coordinating structure and surface property between them.