环境激素的光化学降解研究进展

环境激素所带来的危害已成为全球性的焦点问题,也是近年来学术研究的热点问题。本文综述了近年来各种环境激素光化学降解方法,并对各种方法进行了对比,对存在的问题进行了总结。     

叶片状CuO/BiVO4的合成及可见光催化性能研究

以Bi(NO3)3.5H2O和NH4VO3为原料,P123为表面活性剂,辅助水热法在反应液pH值为6,7,9和10时合成了4种CuO/BiVO4复合光催化剂。并采用X-射线衍射(XRD)和扫描电子显微镜(SEM)对样品的晶相和形貌进行了表征。以亚甲基蓝作为降解物,研究了所制备样品的可见光催化活性。结果表明,pH=6时所制备的样品为单斜相BiVO4复合材料,具有叶片状形貌,其光催化活性最强;样品的降解率随着亚甲基蓝溶液的pH值增大而增大,当pH=10时,可见光照射120 min后,样品对初始溶度为20 mg/L的亚甲基蓝溶液的降解率可达95%。     

桑蚕丝光降解机理初探

通过对光降解产物气相色谱分析，对桑蚕丝光降解机理作初步探讨。     

La掺杂TiO2光催化材料制备工艺优化与催化性能

采用溶胶凝胶法制备La掺杂改性纳米TiO_2光催化材料,利用X射线衍射仪与jade软件分析材料的晶相结构与晶格参数,采用三因素正交试验法探索La掺量、热处理温度、热处理时间对材料的光催化性能的影响;并利用SEM对最佳制备工艺条件下的材料进行微观表征。结果表明,在La摩尔掺量为0.5%、热处理温度为550℃、热处理时间为2 h条件下,材料的晶粒大小和畸变程度达到最佳平衡状态;对NO气体的光降解率达到70.26%。La掺杂改性后,材料粒径更加均匀,多分布在18~20 nm区间。     

Gd–La codoped TiO_2 nanoparticles as solar photocatalysts

Gd–La codoped Ti O2 nanoparticles with diameter of 10 nm were successfully synthesized via a sol–gel method. The photocatalytic activity of the Gd–La codoped Ti O2 nanoparticles evaluated by photodegrading methyl orange was significantly enhanced compared to that of undoped or Gd or La mono-doped Ti O2. Ti4+tmay substitute for La3+tand Gd3+tin the lattices of rare earth oxides to create abundant oxygen vacancies and surface defects for electron trapping and dye adsorption, accelerating the separation of photogenerated electron–hole pairs and methyl orange photodegradation. It is believed that the formation of an excitation energy level below the conduction band of Ti O2 from the binding of electrons and oxygen vacancies decreases the excitation energy of Gd–La codoped Ti O2, resulting in versatile solar photocatalysts. The results suggest that Gd–La codoped Ti O2 nanoparticles are promising for future solar photocatalysts.     

Photochemical alteration of biogenic particles in wastewater effluents

Biogenic particles discharged by wastewater treatment plants play important roles in receiving water because of the large specific surface area and good mobility of the particles. In this study, the changes induced in biogenic particles by natural sunlight were investigated to understand the phototransformation of the particles in the receiving waters. The results showed that photoexposure resulted in significant decreases in the sizes of the biogenic particles but that photoexposure did not impact the zeta potentials. In addition, the photodissolution of biogenic particulate organic matter(POM) led to the generation of biogenic dissolved organic matter(DOM). Characterization using excitation–emission matrix(EEM) spectroscopy showed that photoexposure changed both the shapes and the intensities of the EEM spectra of the biogenic POM; the regions of the T1 and T2 peaks were susceptible to photoexposure. Modeling by parallel factor analysis(PARAFAC) decomposed the EEMs of the biogenic POM into four valid components, i.e., terrestrial or microbial humic-like substances, tryptophan-like proteins, tyrosinelike proteins and hydrophobic proteins. The humic-like substances in the biogenic POM from the effluents were subject to lower decreases(17.0 % and 11.6 %).Throughout the entire incubation time, the PARAFAC components in the biogenic DOM were dominated by elimination mechanisms rather than by production through photodissolution of the biogenic POM.     

Pt-induced electrochemical growth of ZnO rods onto reduced graphene oxide for enhanced photodegradation performance

Photodegradation of organic pollutants over semiconductor catalysts is considered to be a viable method for wastewater treatment.Of the different semiconductor photocatalysts,ZnO has been widely used for the photodegradation of organic pollutants.Meanwhile,graphene is being actively investigated as a cocatalyst for such processes.The high carrier transport rate of graphene can favor the transfer of photoexcited electrons,while the increased specific surface area provides adsorption sites for the organic effluent molecules,thereby improving overall photocatalytic activity.Therefore,in this study,Pt–ZnO–reduced graphene oxide(RGO)rods with different RGO contents are synthesize during a novel Pt-induced electrochemical method,where ZnjZnO acts as the anode and PtjH2OjH2acts as the cathode.The photocatalytic degradation activity of the Pt–ZnO–RGO rods is remarkably improved under UV–visible light irradiation,with the optimum loading RGO content of 1 wt%.     

响应面法研究水体中溶解性组分对双酚A光解的复合影响

在紫外光照射条件下,以双酚A(BPA)为模型化合物,采用响应面法(Response Surface Methodology,RSM)研究水环境中代表性可溶组分(腐殖酸(Humic acid,HA)、Fe3+、NO- 3 和Cl-)对BPA光解的复合影响。结果表明,HA、Fe3+是影响BPA光降解的显著因素,其次是NO- 3和Cl-。HA、NO- 3和Cl-对BPA的光解起抑制作用,而Fe3+为促进作用(P < 0.05)。这些代表性可溶性组分共存于水体中时表现出交互作用。作为显著性因素,Fe3+分别与Cl-或HA复合时抑制BPA的光解,HA-Cl-以及HA-NO- 3共存时则表现为促进作用。作为非显著性因素,NO- 3和Fe3+以及NO- 3和Cl-之间显示出拮抗作用。自由基猝灭实验证明,作为最重要的影响因素,HA对BPA光解的影响主要是通过其激发三重态进行的。利用天然水样得到的模型预测值和实验值之间显示较好的一致性,表明该模型可用于估算BPA在所用天然水样中的光解,但也有一定的局限性。     

Cobalt doped ZrO2 decorated multiwalled carbon nanotube: A promising nanocatalyst for photodegradation of indigo carmine and eosin Y dyes

This paper reports the degradation of indigo carmine and eosin Y dyes in water, catalyzed by cobalt and multiwalled carbon nanotube modified zirconium oxide nanocomposite(Co-ZrO_2-MWCNTs) under simulated visible light. The bare ZrO_2,ZrO_2-MWCNTs, Co-ZrO_2 and Co-ZrO_2-MWCNTs with different percentage compositions of cobalt were synthesized by homogeneous co-precipitation method. Characterization of the prepared nanocomposites was carried out using X-Ray powder Diffraction(XRD), Fourier Transformer Infrared(FTIR) Spectroscopy, Transmission Electron Microscopy(TEM), Raman Spectroscopy,(UV–Vis)-Spectroscopy and Energy Dispersive Spectroscopy(EDS) for their structure, formation,morphology, size and elemental analysis. The experimental results indicated that all the cobalt and MWCNTs modified nanocomposites demonstrated higher photocatalytic activities compared to the bare ZrO_2. The most efficient catalyst(0.5% Co-ZrO_2-MWCNTs) with the band gap and Ka values of 5.21 e V and 16.86*10~(-3) min~(-1) respectively exhibited 98% degradation efficiency toward indigo carmine and 87% toward eosin Y in 180 min.     

灭幼脲类杀虫剂在环境中的降解机理研究

综述了灭幼脲类虫在环境中的水解、微生物降解和光解机理。指出：灭幼脲类杀虫剂的水解、微生物降解和光解机理分别为碱催化的新核取代反应、酶催化的水解反应及自由基反应。灭幼脲类虫剂分子中都有一个 基团,其中三个Ｃ－Ｎ键随分子结构中其它基团和外界影响因素的不同有很大的差异,从而决定了灭幼脲类杀虫剂降解产物的多样性。