催化学报 ›› 2017, Vol. 38 ›› Issue (2): 192-198.DOI: 10.1016/S1872-2067(16)62583-4

• 论文 • 上一篇    下一篇

p-n型异质结催化剂Ag2O-BiVO4对微囊藻毒素(MC-RR)的光化学氧化机理研究

吴春红a,b,c,d, 方艳芬a,b,c, Araya Hailu Tirusewb,c, 向淼淼a,b,c, 黄应平b,c, 陈春城b,c   

  1. a 三峡大学生物与制药学院, 湖北宜昌 443002;
    b 三峡地区地质灾害与生态环境湖北省协同创新中心(三峡大学), 湖北宜昌 443002;
    c 三峡库区生态环境教育部工程研究中心(三峡大学), 湖北宜昌 443002;
    d 三峡大学医学院, 湖北宜昌 443002
  • 收稿日期:2016-09-25 修回日期:2016-10-23 出版日期:2017-02-18 发布日期:2017-03-14
  • 通讯作者: Yingping Huang,Tel:+86-717-6397488;Fax:+86-717-6395966;E-mail:huangyp@ctgu.edu.cn;Chuncheng Chen,Tel:+86-717-6397488;Fax:+86-717-6395966;E-mail:ccchen@iccas.ac.cn
  • 基金资助:

    国家自然科学基(21677086,21407092,21377067,21577078);湖北省自然科学基金创新团队项目(2015CFA021).

Photochemical oxidation mechanism of microcystin-RR by p-n heterojunction Ag/Ag2O-BiVO4

Chunhong Wua,b,c,d, Yanfen Fanga,b,c, Araya Hailu Tirusewb,c, Miaomiao Xianga,b,c, Yingping Huangb,c, Chuncheng Chenb,c   

  1. a College of biology and pharmacy, China Three Gorges University, Yichang 443002, Hubei, China;
    b Innovation Center for Geo-Hazards and Eco-Environment in Three Gorges Area, Yichang 443002, Hubei, China;
    c Engineering Research Center of Eco-environment in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang 443002, Hubei, China;
    d Medical College of China Three Gorges University, Yichang 443002, Hubei, China
  • Received:2016-09-25 Revised:2016-10-23 Online:2017-02-18 Published:2017-03-14
  • Contact: 10.1016/S1872-2067(16)62583-4
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21677086, 21407092, 21377067, 21577078) and the Natural Science Foundation for Innovation Group of Hubei Province, China (2015CFA021).

摘要:

微囊藻毒素(MC-RR)是一种具有两个精氨酸结构的微囊藻毒素,它是由蓝藻细菌产生的一种能普遍被检测到的细胞毒素,近来由于其潜在的肝毒性受关注.在可见光(λ≥420 nm)照射条件下,以MC-RR为光催化降解污染物,对BiVO4,Ag-BiVO4,Ag2O-BiVO4和Ag/Ag2O-BiVO4光催化降解性能进行了比较研究.通过HPLC-MS测定了其中间产物,并分析了其可能的降解途径.结果表明,Ag的存在通过构筑p-n异质结光催化剂而提高了Ag/Ag2O-BiVO4的光催化效率.此外,Ag0的存在极大地促进了MC-RR在光催化剂表面上的吸附作用.小鼠的毒理学实验表明,MC-RR经过光催化降解后毒性显着降低.
由于水体富营养化形成的蓝绿藻促进微囊藻毒素的形成,这已成为全球关注的问题.被微囊藻毒素污染的饮用水除了会毒害野生动物,家畜和家禽外,还会损害人类肝脏,这也是肝癌的发病率高的原因.毒理学研究发现,微囊藻毒素通过结合到1A(PP1)和2A(PP2)上强烈地抑制蛋白磷酸酶的活性,从而导致肝细胞的损伤,引发原发性肿瘤.
目前对光催化降解MC-RR的研究主要集中在紫外光催化氧化领域.采用太阳光中的紫外区或者近紫外区,利用传统的TiO2光催化剂对MC-LR的光催化氧化研究;太阳光中只有极少部分(约4%)的紫外光,大部分(约43%)是可见光,因此,如何将光催化剂的吸收光谱拓宽至可见光区域,提高催化剂对可见光的利用率,进一步提高光催化降解MC-RR的能力,具有一定的理论和实际意义.
钒酸铋是一类新型的p型可见光光催化剂,将其与n型半导体Ag2O材料选择性的复合制备出p-n型异质结复合光催化剂能够显著地提高其光催化性能.本文将这种复合光催化剂的应用扩展到广泛检测到的毒素MC-RR的降解中,以实现可见光降解.发现Ag/Ag2O-BiVO4可以在可见光照射下有效光催化降解MC-RR.跟踪其降解中间产物,研究了其可能降解途径,并提出了在异质结催化剂表面上的光催化降解机理.
催化剂表征结果表明,Ag2O和BiVO4形成有效的异质结界面,在降解中发挥重要作用.在该异质结结构中,Ag和Ag2O作为电子受体以增强电荷载流子寿命并提高光催化活性.依据MC-RR氧化产物的结构、化学性质和降解体系中所检测到的产物,推测其可能的机理:Ag-Ag2O-BiVO4可见光光催化降解MC-RR是一个涉及到羟基自由基和超氧自由基的共同氧化作用,同时根据液相质谱对中间产物的鉴定,得到MC-RR两条主要的可能降解途径,其中主要涉及到Adda中不饱和碳碳双键和Mdha中烯键的氧化,以及各氨基酸之间肽键的水解.小鼠急性毒理实验表明,经光催化反应后MC-RR的毒性明显减小.

关键词: 光催化, p-n异质结, 银, 氧化银, 钒酸铋, 微囊藻毒素(MC-RR), 机理

Abstract:

Microcystin-RR (MC-RR), a form of microcystin with two arginine moieties, is a cyanobacterial toxin that has been detected across a wide geographic range. It is a great concern globally because of its potential liver toxicity. Herein, the abilities of BiVO4, Ag-BiVO4, Ag2O-BiVO4 and Ag/Ag2O-BiVO4 to photocatalytically degrade MC-RR under visible-light irradiation (λ≥420 nm) were investigated and compared. The possible degradation pathways were explored through analysis of the reaction intermediates by high-performance liquid chromatography-mass spectrometry. The results showed that the presence of Ag0 enhanced the photocatalytic efficiency of Ag/Ag2O-BiVO4 via a synergetic effect between Ag2O and Ag0 at the p-n heterojunction. Moreover, the presence of Ag0 also greatly promoted the adsorption of MC-RR on the photocatalyst surface. Toxicological experiments on mice showed that the toxicity of MC-RR was significantly reduced after photocatalytic degradation.

Key words: Photochemical, p-n heterojunction, Silver, Silver oxide, Bismuth orthovanadate, Microcystin-RR (MC-RR), Mechanism