改性PTFE纤维金属配合物的制备及其光催化降解性能

使用聚丙烯酸接枝改性聚四氟乙烯(PAA-g-PTFE)纤维分别与Fe³⁺及其与Cu²⁺的混合物反应制备改性PTFE纤维铁和铁铜双金属配合物, 并分别使用傅里变换叶红外(FTIR)光谱和紫外-可见(UV-Vis)漫反射光谱(DRS)对两种配合物的化学结构和光吸收性能进行表征. 然后将两种配合物分别作为非均相光Fenton 反应催化剂应用于典型偶氮染料活性蓝222氧化降解反应中, 考察和比较了二者在不同pH介质中对降解反应的催化作用. 结果表明, 在有或无Cu²⁺的存在条件下, 一个Fe³⁺能够与三个PAA-g-PTFE表面的6个羧基发生反应形成配合物, 并且它们在紫外和可见光区表现出好的光吸收特性. 当两种金属离子共存时Cu²⁺比Fe³⁺更容易与PAA-g-PTFE发生配位反应形成铁铜双金属配合物. 在可见光辐射下PAA-g-PTFE铁配合物对不同pH水溶液中染料降解反应均表现出显著的催化作用, 但是溶液pH的升高不利于配合物催化活性的发挥. 而配合物中铁离子含量提高特别是引入Cu²⁺作为助金属离子能够较大幅度地改善其在高pH范围内的催化活性和重复利用性.

Preparation of Grafted PTFE Fiber Metallic Complexes and Their Photocatalytic Degradation Abilities

Polyacrylic acid grafted polytetrafluoroethylene (PAA-g-PTFE) fibers were coordinated with Fe³⁺ ions and with a mixture of Cu²⁺ and Fe³⁺ ions to prepare PAA-g-PTFE Fe and Cu-Fe bimetallic complexes. The chemical structures and light adsorption properties of the complexes were characterized using Fourier transform infrared (FTIR) spectrometry and UV-Vis diffuse reflection spectroscopy (DRS), respectively. The complexes were used as heterogeneous photo-Fenton catalysts in the oxidative degradation of the azo dye, Reactive Blue 222, in different pH aqueous media. The results indicate that Fe³⁺ coordinates with six carboxyl groups grafted on the surface of PAA-g-PTFE in the presence or absence of Cu²⁺ ion, and improved light adsorption properties are achieved in the UV and visible regions. When both metal ions coexist in solution, the Cu²⁺ ion coordinates more easily with PAA-g-PTFE than Fe³⁺ to produce a PAA-g-PTFE Cu-Fe bimetallic complex. Moreover, PAA-g-PTFE Fe significantly increases the degradation of Reactive Blue 222 in the pH range 3-9 under visible irradiation. However, at high pH conditions (> 7) the catalytic ability is reduced. Increasing the Fe content, and especially incorporating Cu²⁺ ions in the complex, dramatically improves the catalytic reusability at high pH value.