Construction Of Visible Light Photocatalytic System Based On Modified PAN Fiber And Its Research On Degradation Of Organic Matte

Photocatalytic technology has been widely used for dye wastewater treatment owing to its environment-friendly feature and strong oxidation capacity.The most common photocatalytic materials included inorganic semiconductors（TiO₂,Bi OCl）and organic semiconductors（graphite-phase carbon nitride,g-C₃N₄）,but they all suffered from narrow visible light response range,high photogenerated carrier recombination rate and difficulty in recycling.To address the above problems,this paper proposed a strategy to enhance their visible photocatalytic performance by using amidoxiamated polyacrylonitrile fiber（AO-PAN）as the photocatalyst support.A photosensitive photocatalyst（hemin/TiO₂-PAN）was firstly prepared by immobilizing TiO₂and a photosensitizer（hemin）onto the fibrous support through coordination bonds,and then another fibrous photocatalyst（Bi OCl-PAN）was obtained by anchoring Bi OCl onto the surface of AO-PAN via an in situ synthesis method.In addition,the Fe³⁺doped g-C₃N₄ was also loaded onto AO-PAN to synthesize a composite photocatalyst（Fe-g CN-PAN）by implying Fe³⁺as a combination"bridge".The molecular structures and light absorption properties of the as-prepared photocatalysts were characterized by FE-SEM,XPS,FT-IR,XRD,EDAX,DRS and PL.Then their photocatalytic performance was investigated in the oxidative degradation of organic dyes under visible light,and the corresponding reaction mechanism of the photocatalytic systems was also explored.The results showed that TiO₂ and hemin could bind with the amidoxime groups in AO-PAN through coordination bonds,and the obtained hemin/TiO₂-PAN exhibited high photocatalytic activity under visible light,resulting in completely degradation of rhodamine B within 90 min.This fibrous photocatalyst also showed a wide p H range and excellent recycling ability.The growth of highly crystalline Bi OCl was achieved on the surface of AO-PAN via the in situ synthesis method,and the coordination interactions between amidoxime groups and Bi³⁺was observed,which broadened the visible light absorption of the photocatalyst through LMCT effect.This enables Bi OCl-PAN to show high visible light activity with complete degradation of rhodamine B in 90 min,as well as the excellent reusability.In addition,the Fe³⁺doped g-C₃N₄ could be firmly loaded on the AO-PAN through the strong coordination interactions between amidoxime groups and Fe³⁺,which also enhanced its visible light absorption through LMCT effect.The fiber ligand could promote the separation of photogenerated charges in Fe³⁺doped g-C₃N₄,leading to a higher photocatalytic activity of Fe-g CN-PAN than that of the single g-C₃N₄ or Fe³⁺doped g-C₃N₄photocatalyst.Additionally,a photocatalytic/Fenton synergistic catalytic system was explored by adding H₂O₂,which could porduce a large amount of hydroxyl radicals under visible light and in turn lead to a complete degradation of rhodamine B in 70min.The Fe-g CN-PAN/H₂O₂ system exhibited certain universality in the degradation of various dyes and also showed excellent recycling ability.