Photocatalytic Performance Of Metal Complex Loaded PAN Fiber For Degradation Of Organic Dyes

In this study,the amidoximated Polyacrylonitrile(PAN)fibers were selected as the support materials to prepare the novel heterogeneous Fenton catalysts,which used the iron 2,2'-bipyridine complex(FeB)and iron Phthalocyanine(FePc)as the substitute of Fe ions.Several techniques including Fourier transform infrared spectrometer(FTIR),X-ray photoelectron spectroscopy(XPS),and Diffuse reflectance UV-Vis spectra(DRS)were employed to evaluate the molecular structures of these complexes,and the immobilization pathway of FeB/FePc onto the fibrous supports was studied.Subsequently,these complexes were used as heterogeneous Fenton catalysts for the degradation of a commonly used dye,Rhodamine B,and some factors affecting the dye degradation such as the molecular structure,Fe content,visible light irradiation and the pH value of the solution were investigated.Additionally,the Cu2+ ion was chosen as the assisted metal ion to prepare the Cu-FeB/FePc supported bimetallic PAN fibrous catalysts.The molecular structures of which were characterized,and the synergetic effect between Cu and Fe ions on the catalytic performance of bimetallic catalysts was also investigated.The results indicated that FeB molecules were immobilized onto the modified PAN fiber through both ionic bonds with the third comonomers and coordination bonds with the OH in amidoxime groups,while FePc molecules mostly anchored onto the modified PAN fiber though axially coordination bonds with the OH in amidoxime groups.FeB/FePc supported PAN fibrous catalysts exhibited much higher photocatalytic activity than that of PAN fiber supported Fe ion catalyst under otherwise similar conditions.The FeB catalyst should be activated by visible irradiation,while FePc catalyst could effectively catalyze the dye degradation in the dark conditions.Both the FeB/FePc catalysts could catalyze the mineralization of RhB and be easily recycled without any loss of activity.However,the ESR analysis showed that the catalytic process of FeB catalysts performed via a hydroxyl radical pathway,while the FePc catalysts can selectively catalyze the H2O2 decomposition to generate high-valent iron-oxo species.In addition,Cu2+ could coordinate with both OH and NH2 of amidoxime groups in the Cu-FeB/FePc bimetallic PAN fibrous catalysts.When the Cu/Fe molar ratio was approached to 1,the addition of Cu2+ could significantly improve the photocatalytic performance of FeB/FePc catalysts through the interaction between the two metal ions.Furthermore,the Cu/FeB bimetallic catalysts still catalyzed H2O2 decomposition to generate hydroxyl radical,which could oxidize the dye into small compounds.In contrast,the instruction of Cu2+ affected the reaction mechanism of Cu/FePc catalytic process greatly,in which the synergetic effect between Cu and Fe ions would facilitate the cycle of Cu2+/Cu+,changing the H2O2 decomposition pathway and producing both hydroxyl radical and PcFe(?)=O during the catalytic process.