Determination of the mechanism of photoinduced toxicity of selected metal oxide nanoparticles (ZnO, CuO, Co3O4 and TiO2) to E. coli bacteria

Cytotoxicity of selected metal oxide nanoparticles(MNPs)(ZnO,CuO,Co 3 O 4 and TiO 2)was investigated in Escherichia coli both under light and dark conditions.Cytotoxicity experiments were conducted with spread plate counting and the LC 50 values were calculated.We determined the mechanism of toxicity via measurements of oxidative stress,reduced glutathione,lipid peroxidation,and metal ions.The overall ranking of the LC 50 values was in the order of ZnO < CuO < Co 3 O 4 < TiO 2 under dark condition and ZnO < CuO < TiO 2 < Co 3 O 4 under light condition.ZnO MNPs were the most toxic among the tested nanoparticles.Our results indicate depletion of reduced glutathione level and elevation of malondialdehyde level correlated with the increase in oxidative stress.Released metal ions were found to have partial effect on the toxicity of MNPs to E.coli.In summary,the dynamic interactions of multiple mechanisms lead to the toxicity of the tested MNPs to E.coli.     

硬脂酸改性磁铁矿对石油污水的处理研究

研究硬脂酸改性磁铁矿对石油污水中油类物质的吸附,通过改变温度、超声振荡时间和磁铁矿与硬脂酸的质量比等因素,在最佳的改性条件下制得改性磁铁矿。将改性后的磁铁矿应用于石油污水处理,改变震荡时间,用红外分光测油仪得出吸附结果。结果表明:当改性温度为35℃、改性时间为35min、硬脂酸与磁铁矿质量比为3.5%时磁铁矿改性效果最佳,当吸附时间为8min时,对石油炼化污水中油类物质的吸附效果最好,吸附量为216.65mg/g。     

单层硅烷负载磁铁矿纳米颗粒的制备及除磷性能

研究了N-氨乙基-γ-氨丙基三甲氧基硅烷在水溶液中以单层形式负载于磁铁矿纳米颗粒表面的方法,并研究了单分子层硅烷负载磁铁矿纳米颗粒吸附剂(monolayer of silane on magnetite nanoparticles,MSMNPs)的除磷性能.结果表明,在低浓度下(平衡浓度小于300 mg·L~(-1))硅烷在磁铁矿纳米颗粒表面产生单层吸附,而反应温度90℃以上或离子强度0.1 mol·L~(-1)NaCl以上可以使单层硅烷在磁铁矿纳米颗粒表面的覆盖度达到~100%.FTIR和XPS图谱显示负载的硅烷以化学键的形式与磁铁矿纳米颗粒表面相结合.单层硅烷负载不引起磁性强度的明显变化.MSMNPs对磷的吸附等温线更符合Langmuir模型,拟合得到的最大吸附量为7.59 mg·g~(-1).由于磷吸附位位于MSMNPs的最外面,磷的吸附及脱附均很快,30 min内达到90%以上,1 h内达到平衡.因此,MSMNPs是一种易分离因而可反复使用,并且可快速吸附与脱附污染物的新型吸附剂.     

Applications of magnetic nanoparticles in surface-enhanced Raman scattering (SERS) detection of environmental pollutants

Environmental pollution, a major problem worldwide, poses considerable threat to human health and ecological environment. Efficient and reliable detection technologies, which focus on the appearance of emerging environmental and trace pollutants, are urgently needed. Surface-enhanced Raman scattering(SERS) has become an attractive analytical tool for sensing trace targets in environmental field because of its inherent molecular fingerprint specificity and high sensitivity. In this review, we focused on the recent developments in the integration of magnetic nanoparticles(MNPs) with SERS for facilitating sensitive detection of environmental pollutants. An overview and classification of different types of MNPs for SERS detection were initially provided, enabling us to categorize the huge amount of literature that was available in the interdisciplinary research field of MNPs based SERS technology. Then, the basic working principles and applications of MNPs in SERS detection were presented. Subsequently, the detection technologies integrating MNPs with SERS that eventually were used for the detection of various environmental pollutions were reviewed. Finally, the advantages of MNP-basedSERS detection technology for environmental pollutants were concluded, and the current challenges and future outlook of this technology in practical applications were highlighted. The application of the MNPsbasedSERS techniques for environmental analysis will be significantly advanced with the great progresses of the nanotechnologies, optics, and materials.     

Synthesis, characterization and application of Lagerstroemia speciosa embedded magnetic nanoparticle for Cr(VI) adsorption from aqueous solution

Lagerstroemia speciosa bark (LB) embedded magnetic nanoparticles were prepared by co-precipitation of Fe²⁺ and Fe³⁺ salt solution with ammonia and LB for Cr(VI) removal from aqueous solution. The native LB, magnetic nanoparticle (MNP), L. speciosa embedded magnetic nanoparticle (MNPLB) and Cr(VI) adsorbed MNPLB particles were characterized by SEM–EDX, TEM, BET-surface area, FT-IR, XRD and TGA methods. TEM analysis confirmed nearly spherical shape of MNP with an average diameter of 8.76 nm and the surface modification did not result in the phase change of MNP as established by XRD analysis, while led to the formation of secondary particles of MNPLB with diameter of 18.54 nm. Characterization results revealed covalent binding between the hydroxyl group of MNP and carboxyl group of LB particles and further confirmed its physico-chemical nature favorable for Cr(VI) adsorption. The Cr(VI) adsorption on to MNPLB particle as an adsorbent was tested under different contact time, initial Cr(VI) concentration, adsorbent dose, initial pH, temperature and agitation speed. The results of the equilibrium and kinetics of adsorption were well described by Langmuir isotherm and pseudo-second-order model, respectively. The thermodynamic parameters suggest spontaneous and endothermic nature of Cr(VI) adsorption onto MNPLB. The maximum adsorption capacity for MNPLB was calculated to be 434.78 mg/g and these particles even after Cr(VI) adsorption were collected effortlessly from the aqueous solution by a magnet. The desorption of Cr(VI)-adsorbed MNPLB was found to be more than 93.72% with spent MNPLB depicting eleven successive adsorption–desorption cycles.     

Estimating the relevance of engineered carbonaceous nanoparticle facilitated transport of hydrophobic organic contaminants in porous media

Naturally occurring nanoparticles (NP) enhance the transport of hydrophobic organic contaminants (HOCs) in porous media. In addition, the debate on the environmental impact of engineered nanoparticles (ENP) has become increasingly important. HOC bind strongly to carbonaceous ENP. Thus, carbonaceous ENP may also act as carriers for contaminant transport and might be important when compared to existing transport processes. ENP bound transport is strongly linked to the sorption behavior, and other carbonaceous ENP-specific properties. In our analysis the HOC-ENP sorption mechanism, as well as ENP size and ENP residence time, was of major importance. Our results show that depending on ENP size, sorption kinetics and residence time in the system, the ENP bound transport can be estimated either as (1) negligible, (2) enhancing contaminant transport, or (3) should be assessed by reactive transport modeling. One major challenge to this field is the current lack of data for HOC-ENP desorption kinetics.     

纳米铜及三氯生对污泥硝化作用的影响

金属纳米颗粒 (NPs) 与药品及个人护理品 (PPCPs) 的广泛使用,使其不可避免地释放至污水中,进入污水处理系统对污水生物处理产生潜在危害。由于硝化菌极易受到有毒有害物质的影响,选取纳米铜(CuNPs) 和三氯生 (TCS) 作为目标污染物,研究其对污泥硝化过程中COD去除、硝化效果、污泥理化性质等方面的影响。结果表明,目标污染物的暴露初期对硝化效果产生不同程度的抑制,TCS、CuNPs及二者复合暴露时硝化效率分别下降8.7%、34%和31.7%,但随着暴露时间的增加,硝化效率逐渐恢复至正常水平。然而尽管硝化反应结束后对NH+4-N的去除率无明显差异,但CuNPs及二者同时暴露时对硝化速率及污泥的同化作用有显著抑制,而单独的TCS无明显影响。进一步研究发现CuNPs及二者复合暴露时对污泥的表面结构有一定的破损影响,且污泥的沉淀性能变差。     

金纳米颗粒的掺杂蛋白介孔硅原位合成及其对p-硝基苯酚的催化

基于介孔硅材料,在其表面掺杂牛血清白蛋白,构建了一种可实现贵金属纳米材料原位制备的蛋白掺杂介孔材料MCM-BSA。通过紫外、红外、吸脱附、透射电镜等表征手段,表明掺杂后的材料兼有蛋白和介孔硅2种特性。以MCM-BSA为载体,即可原位还原氯金酸制备金纳米粒,获得负载金纳米粒的复合材料GNPs@MCM-BSA。以对硝基苯酚的催化还原为模型反应,考察了掺杂蛋白介孔硅负载的金纳米粒的催化性能,发现其具有很好的对硝基苯酚催化能力。更为重要的是,该复合材料可回收循环利用6次以上,对硝基苯酚的转化率都接近100%,表明掺杂蛋白介孔硅是一类性能优异的新型纳米晶载体,可应用于环境污染物的催化还原。     

Ag@SiO2核壳粒子SERS快速检测辛基酚

以Ag@SiO2核壳粒子为基底,利用表面增强拉曼光谱（SERS）技术实现酚类内分泌干扰物的快速检测。采用柠檬酸钠还原硝酸银制得银纳米粒子,以正硅酸乙酯为硅源,在银纳米颗粒表面包裹不同厚度的SiO2得到Ag@SiO2核壳粒子。通过透射电镜、紫外光谱、X射线衍射等表征手段对Ag@SiO2核壳粒子进行了表征和分析。以辛基酚为探针研究Ag@SiO2粒子表面增强拉曼效应与SiO2厚度、核壳粒子浓度的关系及辛基酚的检测限,并以此法检测实际环境样品中辛基酚的含量。结果表明,辛基酚的表面增强拉曼效应随着Ag@SiO2壳厚的增加而减弱,随着辛基酚浓度的增大而增强,且在1 390 cm-1处的峰强信息与浓度有着良好的线性关系,辛基酚最低检测限浓度为1 μg·L-1,可以实现辛基酚的SERS检测。     

聚乙烯亚胺/Fe3O4杂化磁性纳米吸附剂去除甲基橙

采用戊二醛共价交联法制备出了聚乙烯亚胺/Fe3O4杂化磁性纳米吸附剂(PEI-Fe3O4)。通过TEM、XRD、FT-IR、VSM和TGA等手段表征了材料的结构和性质。以甲基橙(MO)为吸附质,系统考察了pH值、吸附时间和染料初始浓度等因素对吸附材料性能的影响。结果表明,MO在PEI-Fe3O4上的吸附具有强烈的pH依赖性,pH为3时吸附量最大;吸附平衡仅需20 min,吸附过程符合准二级动力学模型;等温吸附过程更符合Langmuir模型,MO的最大吸附量为242.4 mg/g。重复实验表明,吸附剂经过15次吸附/解吸附循环后仍可维持最初的吸附性能,显示出良好的机械和化学稳定性。因此,该杂化吸附剂在染料废水中MO的去除方面具有良好的应用前景。