| K6Nb10.8O30对微囊藻毒素的光催化降解研究 |
| Photocatalytic Degradation of Microcystin-LR by K6Nb10.8O30 |
| 投稿时间：2014-11-27 修订日期：2015-12-02 |
| DOI：10.15928/j.1674-3075.2015.05.002 |
| 中文关键词:光催化 微囊藻毒素 降解 K6Nb10.8O30 |
| 英文关键词:photocatalysis microcystin degradation K6Nb10.8O30 |
| 基金项目:国家自然科学基金项目（51209147） |
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| 中文摘要: |
| 通过合成含铌类复合氧化物光催化剂，开展其光催化降解藻毒素试验，研究其光催化降解微囊藻毒素的降解效率和机理，为去除水体中微囊藻毒素提供高效环保的水处理技术。采用溶胶凝胶法制备了铌酸盐光催化剂K6Nb10.8O30，利用X射线衍射、扫面电镜、紫外可见漫反射光谱等对光催化剂进行了结构表征，该化合物结构是属于四方相钨青铜结构，空间群为P4/mbm（127），晶粒呈长方柱性，直径约为150nm，长度约400～600nm，吸收能带为2.92eV；在紫外光（UVA）辐照条件下，考察了催化剂对微囊藻毒素（MC-LR）的光催化降解效果，利用高效液相色谱测定水体中微囊藻毒素浓度。结果表明，光催化剂K6Nb10.8O30能够有效的降解藻毒素，降解过程受到pH值、藻毒素的初始浓度、催化剂投加量和光照的影响；在光辐射强度为556μW/cm2、pH4.24、催化剂投加量为0.375g/L的试验条件下，初始浓度3mg/L的藻毒素在180min之内降解率达到93%；对催化剂反应前后的红外光谱分析表明，藻毒素的降解最终不是被催化剂吸附，而是被光催化降解；动力学研究表明，微囊藻毒素的光催化剂降解反应符合一级反应动力学规律，随着微囊藻毒素初始浓度的增大，反应速率常数逐步降低，半衰期也逐渐变长。 |
| 英文摘要: |
| Microcystins, produced during cyanobacteria blooms in eutrophic freshwater, possess high hepatotoxicity, can damage the nervous system and pose a significant health hazard to humans through drinking water. Microcystins have a cyclic heptapeptide structure that makes them highly stable and not easily decomposed by traditional treatment processes. As a result, many significant studies have carried out to find efficient methods for degrading microcystins. Fenton oxidation and photocatalytic oxidation are recognized as the most promising advanced technologies for removal of microcystins at high efficiency, without producing toxic by-products, and have attracted much attention. MC-LR is one of the MCs more frequently observed and is listed in the Sanitary Standard for Drinking Water (2001) and Environmental Quality Standards for Surface Water (GB3838-2002) in China. In this study, photocatalytic degradation of microcystin-LR was investigated using a new photocatalyst (K6Nb10.8O30) under low intensity UVA irradiation. The effects of K6Nb10.8O30 dosage, initial concentration of MC-LR and pH on the degradation efficiency of MC-LR were investigated and the photocatalytic properties and mechanism of the new photocatalyst were revealed by kinetic analysis. Furthermore, the experiments were conducted under UVA irradiation only or using photocatalyst (K6Nb10.8O30) only as controls with each experiment carried out in triplicate. K6Nb10.8O30 was synthesized using niobium pentoxide（Nb2O5）by the sol-gel method and characterized by X-ray diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy. Results indicate that K6Nb10.8O30 assumes a tetragonal tungsten bronze structure with space group P4/mbm (127). The particles display a tetragonal columnar shape of diameter 50–150 nm and length 250–400 nm. The band gap of K6Nb10.8O30 powders was estimated to be 2.92 eV. The concentration of MC-LR was detected by high performance liquid chromatography (HPLC) and results show that MC-LR was easily removed by the photocatalyst. The degradation efficiency was influenced by pH, initial concentration, UV irradiation and catalyst dosage. Under the conditions of pH = 4.24, UV radiation = 556μW/cm2 and catalyst dose = 0.375g/L K6Nb10.8O30, the degradation rate of MC-LR (3mg/L) reached 93% in 180 min. The FT-IR spectrum of K6Nb10.8O30 before and after the degradation revealed that the decrease of MC-LR concentration was caused by photocatalytic decomposition, not adsorption. Kinetic analysis shows that the degradation reaction of MC-LR follows first order kinetics. With an increase in the initial concentration of MC-LR, the apparent reaction rate constant gradually decreased and the half-life period gradually increased. The study provides a novel approach for an effective water treatment technology to remove MC contamination. |
| 邹曦,张高科,胡艳君,潘晓洁,万成炎,邹怡,张曼.2015.K6Nb10.8O30对微囊藻毒素的光催化降解研究[J].水生态学杂志,36(5):8-14. |
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