超声辅助纳米铁降解酸性红G的实验研究

通过硼氢化纳还原法制备了铁纳米颗粒,并用十二烷基硫酸钠对其进行保护。所得铁纳米颗粒大小在13nm左右,体心立方相。对比了在机械搅拌和超声辅助条件下纳米铁对酸性红G的降解率,超声条件下纳米铁和微米铁对酸性红G的降解率,以及纳米铁投加量、pH值对酸性红G降解率的影响。结果表明,超声辅助下,pH=6～7时,4min内纳米铁对酸性红G有较高的降解率。机理分析表明超声辅助条件下纳米铁对酸性红G的降解主要是超声分散下纳米铁的还原作用得到提高以及纳米铁氧化产物的絮凝作用。     

Effects of silica nanoparticles on growth and photosynthetic pigment contents of Scenedesmus obliquus

To assess the aquatic ecosystem safety for silica (SiO2) nanoparticles (NPs), the growth inhibition and photosynthetic pigment contents of Scenedesmus obliquus in logarithm growth phase exposed to SiO2 NPs and SiO2 bulk particles (BPs) suspensions were measured. SiO2 NPs with 10-20 nm diameters were found to be toxic. The 20% effective concentration (EC20) values for 72 and 96 hr were 388.1 and 216.5 mg/L, respectively. The contents of chlorophyll decreased significantly under moderate and high concentratio...     

Genotoxicity of ferric oxide nanoparticles in Raphanus sativus: Deciphering the role of signaling factors, oxidative stress and cell death

We have studied the genotoxic and apoptotic potential of ferric oxide nanoparticles(Fe_2O_3-NPs) in Raphanus sativus(radish).Fe_2O_3-NPs retarded the root length and seed germination in radish.Ultrathin sections of treated roots showed subcellular localization of Fe_2O_3-NPs,along with the appearance of damaged mitochondria and excessive vacuolization.Flow cytometric analysis of Fe_2O_3-NPs(1.0 mg/m L) treated groups exhibited 219.5%,161%,120.4% and 161.4% increase in intracellular reactive oxygen species(ROS),mitochondrial membrane potential(ΔΨm),nitric oxide(NO) and Ca2+influx in radish protoplasts.A concentration dependent increase in the antioxidative enzymes glutathione(GSH),catalase(CAT),superoxide dismutase(SOD) and lipid peroxidation(LPO) has been recorded.Comet assay showed a concentration dependent increase in deoxyribonucleic acid(DNA) strand breaks in Fe_2O_3-NPs treated groups.Cell cycle analysis revealed 88.4% of cells in sub-G1 apoptotic phase,suggesting cell death in Fe_2O_3-NPs(2.0 mg/m L) treated group.Taking together,the genotoxicity induced by Fe_2O_3-NPs highlights the importance of environmental risk associated with improper disposal of nanoparticles(NPs) and radish can serve as a good indicator for measuring the phytotoxicity of NPs grown in NP-polluted environment.     

Experimental investigation of performance and emission characteristics of diesel engine using Jatropha biodiesel with alumina nanoparticles

Biodiesels have come up as a very strong alternative for diesel fuel. Biodiesels such as Jatropha Oil Methyl Ester (JOME) are comparable in performance with that of the diesel engine. The thermal efficiency of engines fuelled with biodiesels was found lower than conventional diesel fuel but due to the bio-origin, the emission characteristics are much better. However, biodiesel increases the NOx emissions as these are rich in oxygen, hence nanoparticles are used in this experiment to curb the high temperatures and reduce the NOx formation. The experiment on naturally aspired diesel engine was conducted with four prepared test fuels other than neat diesel and neat biodiesel. The 50 and 150 of alumina nanoparticles were added separately to the pure diesel and pure Jatropha biodiesel to form the nano emulsions using ultrasonicator. The properties of nanoemulsion were evaluated using dynamic light scattering technique using zetasizer. The performance and emission characteristics of multi-cylinder diesel engine with these nanoemulsions were compared with that of neat fuels. The results showed that using nanoparticles with diesel and biodiesel can contribute in a more efficient, economical, and eco-friendly engine operation.     

自组装纳米金修饰玻碳电极检测亚硝酸根

将N-［3-(三甲氧硅基)丙基］-乙二胺与金溶胶通过自组装制备亚硝酸根的电化学传感器.原子力显微镜图(AFM) 显示纳米金自组装在氨基硅烷修饰的玻碳电极表面.由于质子化的氨基硅烷与带负电的亚硝酸根间的相互作用以及纳米金对亚硝酸根具有较好的催化作用,亚硝酸根在该修饰电极上的氧化电位与在玻碳电极上的氧化电位相比负移了140 mV.利用微分脉冲伏安法和微分脉冲安培法研究了亚硝酸根电流响应信号与浓度间的关系.在最优实验条件下,亚硝酸根的氧化峰电流与其浓度在5.0×10^-7～1.0×10^-3 mol·L^-1的浓度范围内呈良好的线性关系, 检测限可达到2.0×10^-7 mol·L^-1(信噪比为3). 用分光光度法及本研究提出的方法对实际样品中亚硝酸根的测定进行了比较,测定结果的差异很小.本研究所提出的测定亚硝酸根的方法具有较高的灵敏度和较好的重现性.     

两种粒径氧化镍纳米颗粒对小球藻(Chlorella vulgaris)的生物毒性

采用藻类生物毒性测试方法(OECD201)研究了两种粒径氧化镍(NiO)纳米颗粒对小球藻(Chlorella vulgaris)的生物毒性.发现纳米颗粒的毒性与其尺度有关,7 nm NiO的毒性大于20 nm NiO,二者72 h EC50分别为18.01和74.64mgNiO/L.利用扫描电子显微镜(SEM)观察了对...     

SiO2纳米颗粒对小球藻(Chlorella pyrenoidosa)生长活性的影响

从Si02纳米颗粒对小球藻(Chlorella pyrenoidosa)生长活性的影响来探讨纳米材料的生物安全性问题.结果表明Si02纳米颗粒降低了小球藻的生物量和蛋白含量,并可以附着在细胞表面和进入细胞内部,造成了细胞的形变和结构损伤,从而抑制了小球藻的正常生长活性.Si02纳米颗粒对小球藻具有一定的毒性效应.     

Ag／ZnO光催化降解甲基对硫磷研究

描述了掺杂体系Ａｇ／ＺｎＯ用于甲基对硫磷水溶液光催化降解,有氧存在下,经ＵＶ照射对甲基对硫磷光降解是有效的,并讨论了影响光降解中甲基硫磷诸因素,初步探讨了光降解机理和动力学,起始降解物为Ｃ２Ｈ６Ｐ＾＋Ｓ和Ｏ２ＮＨ４Ｏ,且是一级反应,半衰期为１．８２ｍｉｎ。     

Preconcentration of cadmium and copper ions on magnetic core–shell nanoparticles for determination by flame atomic absorption

Magnetic core–shell nanoparticles modified by (3-aminopropyl) trimethoxy silane were prepared and used as adsorbent for the extraction and preconcentration of cadmium and copper ions. The ions were desorbed with nitric acid followed by determination with flame atomic absorption spectrometry. The extraction conditions were investigated systematically. The method was applied for the determination of Cd(II) and Cu(II) ions in different water samples. The accuracy was also evaluated through analysis of certified reference material.     

Effect of two TiO2 nanoparticles on the growth of unicellular green algae using the OECD 201 test guideline: influence of the exposure system

This work aimed at assessing the influence of different exposure systems to perform the commonly used OECD 201 freshwater algal growth inhibition test in the context of nanoparticles hazard assessment. Two distinct TiO₂ nanoparticles were considered and three different exposure systems were investigated: Erlenmeyers flasks and 24-well microplates (both using an orbital shake system), and an alternative system using cylindrical vials and magnetic stirring. All three systems are in accordance with the OECD 201 test guideline recommendations. We concluded that the exposure systems applied to achieve the test can substantially affect the ecotoxicological results and the subsequent calculated ECx. The selected systems influenced both the interaction between algal cells and TiO₂ nanoparticles as well as the growth inhibition recorded. Disparities in ecotoxicity relative to the TiO₂ nanoparticles tested were also observed and are finally discussed.