表面改性的二氧化钛纳米管对全氟辛酸催化降解研究

Study on the Catalytic Degradation of Surface Modified TiO_2 Nanotubes for Perfluorooctanoic Acid

研究制备了Ag纳米颗粒和分子印迹聚合物(MIP)改性的TiO_2纳米管催化材料,通过场发射扫描电子显微镜、X射线衍射、X射线光电子能谱和傅立叶变换红外光谱手段对表面改性的TiO_2进行表征。研究催化材料对水溶液中的新型污染物全氟辛酸(PFOA)的光催化分解作用。试验结果表明,经过8 h的反应后Ag纳米颗粒和分子印迹聚合物(MIP)改性的TiO_2纳米管(MIP-Ag/TiO_2NTs)对PFOA的降解效率达到91%;与催化材料相比,MIP-Ag/TiO_2NTs对PFOA的吸附-降解具有更高活性,其对PFOA降解伪一级动力学速率常数为0.005 5 min^(-1)。MIP-Ag/TiO_2NTs的对PFOA高效降解作用归因于Ag纳米颗粒对电子的捕获,以及分子印迹聚合物形成的足迹点。对FPOA降解产物进行了鉴定,表明短链全氟化合物(PFCs)为其主要降解产物,据此给出了PFOA的降解机理和途径。

Photocatalytic decomposition of an emerging pollutant perfluorooctanoic acid(PFOA)in aqueous solution by Ag nanoparticles and molecularly imprinted polymers modified TiO2 nanotubes were investigated.The modified TiO2 were characterized by field-emission scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy.PFOA decomposition by the MIP-Ag/TiO2 NTs reached 91%after 8 h reaction.Compared with other prepared photocatalyst,MIP-Ag/TiO2 NTs exhibited higher activities for PFOA decomposition.The rate constant of pseudo-first-order kinetics for MIP-Ag/TiO2 NTs was 0.005 5 min-1,which were much higher than that of other TiO2 materials.The great performance of MIP-Ag/TiO2 NTs were attributed to electron traps of Ag nanoparticles,and the footprint cavities formed by molecularly imprinted polymer.Shorter-chain PFCs were identified as main degradation products,and the PFOA degradation mechanismand pathway were proposed.