改性PAN纤维与铁离子的配位结构及其对染料降解的催化作用

Coordination Structure between Modified PAN Fiber and Fe(Ⅲ) Ion and Its Catalytic Function on Degradation of Azo Dyes

在室温条件下应用偕胺肟改性聚丙烯腈纤维(AO-PAN)与FeCl3反应制备了聚丙烯腈纤维铁配合物(Fe-AO-PAN),并分别使用X射线光电子能谱(XPS)、傅立叶红外光谱(FTIR)、动态热机械分析(DTMA)和电导法对Fe-AO-PAN进行了表征以确定其组成结构.然后将Fe-AO-PAN作为非均相Fenton催化剂应用于两种常用偶氮染料C.I.活性红195(RR195)和C.I.酸性黑234(AB234)的光催化氧化降解反应中,考察了其对降解反应的催化作用.结果表明,Fe-AO-PAN中的Fe3+能够与AO-PAN表面三个偕胺肟(AO)链节单元的三个氨基氮原子和三个羟基氧原子进行配位反应,配位数为6.在Fe-AO-PAN和辐射光存在下,两种染料的氧化降解反应速度显著加快,染料结构中的偶氮键和芳香环结构都遭到破坏.PAN纤维腈基转化率的提高不仅能够明显增加Fe-AO-PAN表面结构中Fe3+含量,而且可显著促进其对染料氧化降解反应的催化作用.

The coordination process and structure between amidoxime modified polyacrylonitrile （AO-PAN） fiber and FeCl3 in aqueous solution were studied by using X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared spectrometer （FTIR）, dynamic thermal mechanical analyzer （DTMA）, and electrical conductivity method, respectively. The coordination Fe-AO-PAN fiber was obtained, and then used as a heterogeneous Fenton catalyst for the oxidative degradation of two azo dyes including C.I. Reactive Red 195（RR 195） and C.I. Acid Black 234（AB 234） in the presence of H2O2. The catalytic function of Fe-AO-PAN on dye degradation was investigated with respect to decoloration percentage in this work. The results indicated that the Fe3＋ ion of Fe-AO-PAN was coordinated with three amino nitrogen atoms and three hydroxyl oxygen atoms of three amidoxime units on the surface of AO-PAN by covalent bond, and the coordination number was six. Moreover, the oxidative degradation of two azo dyes in water was significantly accelerated in the presence of Fe-AO-PAN under light irradiation, and the azo linkages and aromatic ring of azo dye molecules were decomposed. Increasing the degree of conversion from nitrile group to amidoxime group on the surface of PAN fiber caused not only higher Fe3＋ content of Fe-AO-PAN, but also its stronger catalytic performance on dye degradation in aqueous solution.