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81.
负载型金催化剂用于室温下CO的消除 总被引:4,自引:0,他引:4
从催化活性、抗潮湿、抗硫中毒、稳定性等方面考察了负载型金催化剂对于CO氧化反应的性能。筛选出的2-3催化剂可在-22℃下完全消除CO,并且在催化活性、抗潮湿、抗硫中毒、稳定性等方面具有现行催化剂无法比拟的优点。 相似文献
82.
采用溶胶-凝胶法制备铜锌复合氧化物(Cu/ZnO),并将Cu/ZnO纳米粒子负载到还原氧化石墨烯(RGO)表面制备Cu/ZnO-RGO复合材料.对Cu/ZnO-RGO复合材料进行表征分析及抗菌性能考察,结果表明,Cu/ZnO纳米粒子成功负载在RGO表面,负载前后Cu/ZnO纳米粒子形态不发生改变,复合材料纯度较高.Cu/ZnO-RGO复合材料对大肠杆菌与金黄色葡萄球菌均有着优异的抗菌性能,可以破坏细菌细胞膜,导致细菌内容物流出,延长细菌进入对数生长期所需的时间.当RGO质量分数为15%?Cu/ZnO-RGO复合材料使用量为120μg/mL时,在循环冷却水系统中作用2h即可拥有96.76%的抗菌率. 相似文献
83.
二氧化钛纳米颗粒(TiO2NPs)的广泛应用使其环境释放量不断增加,从而影响到土壤氮的转化过程.然而,目前关于TiO2NPs对湖滨沼泽土壤氮矿化的影响机制尚不明确.因此,本研究以典型沼泽土壤为研究对象,通过室内培养实验研究不同剂量TiO2NPs处理(0 mg·kg-1(CK)、10 mg·kg-1(A10)、100 mg·kg-1(A100)、250 mg·kg-1(A250)、1000 mg·kg-1(A1000))对土壤理化性质、酶活性和氮矿化过程的影响,探讨TiO2NPs输入对土壤氮矿化过程影响的内在机制.结果表明:①不同剂量TiO2NPs处理显著降低了土壤pH和总有机碳(TOC)含量(p<0.05),A100、A250和A1000处理显著降低了硝态氮(NO3--N)含量(p<0.05).②A250和A1000处理显著抑制了过氧化氢酶活性(p<0.05);培养7 d,不同剂量TiO2NPs处理均显著促进了脲酶活性(p<0.05),抑制了脱氢酶活性(p<0.05);随着培养时间延长,TiO2NPs处理对脲酶和脱氢酶活性的抑制作用逐渐减弱,表明TiO2NPs的负面作用会随时间减弱.③不同剂量TiO2NPs处理对氨化速率没有显著影响(p>0.05),A250、A1000处理对硝化和矿化速率有显著抑制作用(p<0.01).④土壤氮矿化速率与土壤pH、总磷(TP)、NO3--N含量呈显著正相关,与脲酶、过氧化氢酶活性呈显著负相关.TiO2NPs主要通过改变沼泽土壤NO3--N含量影响氮矿化过程.本研究可为湖滨湿地保护和TiO2NPs环境风险评估提供理论依据. 相似文献
84.
Ali Movafeghi Alireza Khataee Mahboubeh Abedi Roshanak Tarrahi Mohammadreza Dadpour Fatemeh Vafaei 《环境科学学报(英文版)》2018,30(2):130-138
Plants are essential components of all ecosystems and play a critical role in environmental fate of nanoparticles. However, the toxicological impacts of nanoparticles on plants are not well documented. Titanium dioxide nanoparticles (TiO2-NPs) are produced worldwide in large quantities for a wide range of purposes. In the present study, the uptake of TiO2-NPs by the aquatic plant Spirodela polyrrhiza and the consequent effects on the plant were evaluated. Initially, structural and morphological characteristics of the used TiO2-NPs were determined using XRD, SEM, TEM and BET techniques. As a result, an anatase structure with the average crystalline size of 8nm was confirmed for the synthesized TiO2-NPs. Subsequently, entrance of TiO2-NPS to plant roots was verified by fluorescence microscopic images. Activity of a number of antioxidant enzymes, as well as, changes in growth parameters and photosynthetic pigment contents as physiological indices were assessed to investigate the effects of TiO2-NPs on S. polyrrhiza. The increasing concentration of TiO2-NPs led to the significant decrease in all of the growth parameters and changes in antioxidant enzyme activities. The activity of superoxide dismutase enhanced significantly by the increasing concentration of TiO2-NPs. Enhancement of superoxide dismutase activity could be explained as promoting antioxidant system to scavenging the reactive oxygen species. In contrast, the activity of peroxidase was notably decreased in the treated plants. Reduced peroxidase activity could be attributed to either direct effect of these particles on the molecular structure of the enzyme or plant defense system damage due to reactive oxygen species. 相似文献
85.
To use stabilized nanoparticles(NPs) in water as disinfectants over a very long period, the amount of coating agent(for NP stabilization) needs to be optimized. To this end, silver nanoparticles(Ag-NPs) with two different coating densities of tri-sodium citrate(12.05 and46.17 molecules/nm~2, respectively), yet of very similar particle size(29 and 27 nm, respectively)were synthesized. Both sets of citrate capped NPs were then separately impregnated on plasma treated activated carbon(AC), with similar Ag loading of 0.8 and 0.82 wt.%, respectively. On passing contaminated water(containing 10~4 CFU Escherichia coli/m L of water) through a continuous flow-column packed with Ag/AC, zero cell concentration was achieved in 22 and 39 min, with Ag-NPs(impregnated on AC, named as Ag/AC) having lower and higher coating density, respectively. Therefore, even on ensuring similar Ag-NP size and loading, there is a significant difference in antibacterial performance based on citrate coating density in Ag/AC.This is observed in lower coating density case, due to both:(i) higher Ag~+ ion release from Ag-NP and(ii) stronger binding of individual Ag-NPs on AC. The latter ensures that, Ag-NP does not detach from the AC surface for a long duration. TGA-DSC shows that Ag-NPs with a low coating density bind to AC with 4.55 times higher adsorption energy, compared to Ag/AC with a high coating density, implying stronger binding. Therefore, coating density is an important parameter for achieving higher antibacterial efficacy, translating into a faster decontamination rate in experiments, over a long period of flow-column operation. 相似文献
86.
在胶州湾西北部海区和大沽河河口区选择S站和E站2个研究站位,现场采样带回实验室进行模拟培养,研究纳米银对沉积物反硝化能力、反硝化酶活性及功能基因丰度的影响.将不同剂量(0、135、1 350 mg·L~(-1))的纳米银添加至由表层沉积物和原位底层海水组成的培养体系中培养6 d,测定其在不同时间内NO_3~-和NO_2~-含量、NO_3~-还原酶和NO_2~-还原酶活性、反硝化功能基因narG和nirS相对丰度的变化,探讨纳米银对不同区域沉积物反硝化过程的影响和可能的作用途径.结果表明,纳米银胁迫对2个站位沉积物NO_3~-和NO_2~-的还原能力、NO_3~-和NO_2~-还原酶活性及narG和nirS的基因丰度均具有明显的抑制效应,纳米银浓度越高,抑制程度越强,并会导致NO_2~-累积量的增加;纳米银对NO_2~-还原酶的抑制程度明显大于NO_3~-还原酶,对功能基因nirS的抑制程度明显大于narG;纳米银胁迫对NO_3~-还原过程的影响主要通过对功能基因的抑制作用,而对NO_2~-还原过程的影响主要是通过对还原酶活性的抑制作用;纳米银对胶州湾西北部海域反硝化能力、NO_3~-还原酶和基因丰度的抑制程度大于大沽河河口区. 相似文献
87.
88.
Nitin Shrivastava Devanshu Shrivastava Vipin Shrivastava 《International Journal of Green Energy》2018,15(2):136-143
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. 相似文献
89.
90.