掺氮二氧化钛可见光照射降解微囊藻毒素-LR

采用溶胶凝胶法制备了N掺杂TiO2(N-TiO2)纳米粉体光催化剂,利用X射线光电子能谱(XPS)、X射线衍射(XRD)、紫外可见反射光谱及透射电镜(TEM)分析测定,对光催化剂N/TiO2进行了结构表征.发现N掺杂TiO2相对纯TiO2禁带宽度变窄,可见光区有明显吸收.在可见光照射下,利用纳米N/TiO2作为光催化剂降解微囊藻毒素(Microcystin-LR,MC-LR),通过高效液相色谱仪(HPLC)跟踪检测降解过程MC-LR浓度变化,液质联用仪(LC-MS)检测MC-LR降解中间产物变化.利用电子自旋共振法(ESR)及过氧化物酶催化氧化方法跟踪定性定量测定光催化过程中氧化物种的种类变化.采用总有机碳(TOC)测定仪测定了MC-LR光催化深度氧化矿化效果.结果表明,可见光(λ420nm)照射可有效激发光催化剂N-TiO2活化分子氧降解MC-LR,在反应条件下,光催化反应14h,MC-LR降解率达到100%,20h矿化率达到59%.其光催化反应体系中氧化物种主要为羟基自由基(·OH).质谱检测到13种降解产物,主要反应机理为光催化反应产生·OH进攻MC-LR结构四个易氧化部位,以及一些氨基酸之间的肽键的水解.

Visible light-activated N-doped TiO_2 nanoparticles for the photocatalytic degradation of microcystin-LR

N-Doped nano-crystalline TiO2 powder have been by the sol-gel method.The characteristics of TiO2 were carried out using X-ray photoelectron spectroscopy（XPS） ,transmission electron microscopy（TEM） and UV-visible reflection spectrum.The result showed that the band gap was narrower,and there are obviously absorption in visible light region.Under the visble light（λ420 nm） ,this catalyst has been used to degrade MC-LR.The concentration of MC-LR was detected by high performance liquid chromatography,the structure elucidation of reactionin termediates was accomplished by LC-MS/MS.At last,the mineralization effect was detected by total organic carbon（TOC） tester. Simultaneously,photocatalytic oxidation species was tracked by electron spin resonance（ESR） and Peroxidase method.Fourteen hours later,the degradation rate reached 100%and the mineralized rate of MC-LR was 78%after 20 h.And the major oxidation species in the system was hydroxyl radical（·OH） and H2O2.We found 13 reactionin termediates in the system.Four parts MC-LR are easy to be attacked and oxidized.Some peptide bonds break down too with longer reaction time.