Ligand-less in situ surfactant-based solid phase extraction for preconcentration of silver from natural water samples prior to its determination by atomic absorption spectroscopy

A simple and rapid ligand-less in situ surfactant-based solid phase extraction method for preconcentration of silver from water samples is developed. In this method, a cationic surfactant containing a proper alkyl group (n-dodecyltrimethylammonium bromide) is dissolved in the aqueous sample and then a proper ion-pairing agent (ClO₄^?) is added. Due to the interaction between surfactant and ion-pairing agent, solid particles are formed and used for adsorption of silver carbonate. After centrifugation, the sediment is dissolved in 2.0 mL 1 M HNO₃ in ethanol and then aspirated directly into the flame atomic absorption spectrometer. Variables affecting the extraction efficiencies such as pH, concentrations of surfactant and CO₃^2?, ion pair concentration, and extraction time, are optimized. Under such conditions, the calibration curve is linear from 3 to 700 μg L^?1. Detection limit is 1.1 μg L^?1 with an enrichment factor of 37. The relative standard deviation for eight replicate measurements of 100 μg L^?1 is 2.1%. The method has been applied for the determination of silver in water samples.     

Manufactured silver and gold nanoparticles-induced apoptosis by caspase-pathway in human cell lines

Abstract

Metallic nanoparticles have emerged as an important class of nanomaterials for a wide range of industrial and medical applications. Because of the intensive commercial applications, risk assessment of these nanoparticles is of great importance. In the present study, the human hepatoma and leukemia cells were used to characterize the apoptotic effects of silver nanoparticles (4.7 and 42?nm) and gold nanoparticles (30?nm). Apoptotic cells were identified by chromatin condensation and flow cytometry analysis, using Annexin V/PI, TUNEL and caspase activation assays. Flow cytometry analysis showed that the three metallic nanoparticles induced apoptotic cell death in a concentration and time dependent-manner. Moreover, the three nanoparticles induced activation of caspase-3 and -7 in hepatoma and leukemia cells. Apoptotic effects were stronger after exposure of both cell lines with 4.7?nm silver nanoparticles than those obtained with 42?nm silver and 30?nm gold nanoparticles. In conclusion, silver (4.7 and 42?nm) and gold (30?nm) nanoparticles induced apoptosis in hepatoma and leukemia cells via the caspase dependent pathway. The smaller silver nanoparticles (4.7?nm) had a greater ability to induce apoptosis in both cell lines.     

Genotoxic effects of Ag2S and CdS nanoparticles in blue mussel (Mytilus edulis) haemocytes

The use of functionalised metal sulphide nanoparticles (NPs) for nanoremediation and biomedical application is rapidly increasing, which could lead to significant inputs into the marine environment. The potential impact of some NPs on marine organisms is still poorly understood. In the present paper the genotoxic potential of Ag₂S and CdS NPs on Mytilus edulis haemocytes was assessed. MPEG-SH (thiol-terminated methyl polyethylene glycol), was used as capping agent to avoid NPs agglomeration. TEM analysis showed that the Ag₂S NPs size was 13±7 nm, whereas CdS quantum dots had an average diameter of 4±1 nm. DNA integrity was evaluated by Comet assay following exposure to increasing concentration series (0.01–10 mg/L). Both silver and cadmium NPs showed genotoxic effects at the highest dose. MPEG-SH was also found to exert a weak genotoxic activity, suggesting that at least part of the genotoxic potential of functionalised NPs on mussel cells might be attributable to the capping agent. These results confirm the genotoxic potential of Ag₂S NPs for mussel cells and demonstrated, for the first time, that CdS NPs is genotoxic in a marine organism.     

纳米银在水环境中的环境行为和毒性效应研究进展

纳米材料的环境行为和生态效应是目前国内外研究的热点,其中纳米银颗粒(Ag NPs)是使用量最高的纳米材料。本文主要总结了Ag NPs在水环境中的赋存、Ag NPs的环境行为、Ag NPs对不同种类微生物的毒性效应以及影响Ag NPs毒性效应的因素,最后对Ag NPs在河口区的研究进行了展望。     

铝片包裹氯化银置换法回收银

将含银废液中的Ag+转化为Ag Cl,再用铝片包裹Ag Cl固体,在Na2CO3溶液中采用置换法回收银。考察了各反应条件对Ag Cl还原为银的转化率的影响。实验结果表明,适宜的反应条件为:Na2CO3溶液质量分数20%,反应温度40℃,反应时间20 h,不搅拌静置反应。在此适宜的反应条件下,Ag Cl还原为银的转化率为95.32%。     

络合-电沉积法制备TiO_2纳米管负载Ag光催化剂

采用柠檬酸钠作为络合剂,通过络合-电沉积法制备了TiO2纳米管负载Ag光催化剂(Ag/TiO2NTs),通过FE-SEM和XRD等手段对Ag/TiO2NTs进行了表征。以偶氮染料甲基橙(MO)为目标降解物,考察了不同制备条件对Ag/TiO2NTs光催化性能的影响。表征结果显示,柠檬酸钠可以有效调控Ag+的电化学还原过程,实现Ag纳米颗粒在TiO2纳米管表面的均匀负载。实验结果表明:以在n(柠檬酸钠)∶n(Ag NO3)=1、电流密度为0.4 m A/cm2、煅烧温度为500℃的条件下制得的Ag/TiO2NTs作为光催化剂(Ag负载量为1.97%(x)),处理初始质量浓度为20 mg/L、初始溶液p H为9的MO溶液,光催化反应120 min后MO去除率为86.53%;经过6次的重复使用,Ag/TiO2NTs催化剂光催化降解MO的去除率基本稳定在80%以上。     

用硝酸银消除高浓度氯离子对COD测定的干扰及测定废液中银的回收

分析了氯离子的干扰机理,提出了用硝酸银代替硫酸汞消除氯离子干扰测定高氯离子水样COD的分析方法,同时对COD废液的处理及废液中银的回收利用进行了研究。实验结果表明,该法具有较好的准确性和重复性,其相对误差均在国家规定的允许范围内;COD废液中的银经分离后,用Zn—H2SO4体系还原回收,银回收率为94．8％,回收的银粉纯度为99．6％,且可实现COD废液中银的循环使用。     

银纳米颗粒对黄菖蒲早期生长和生理特征的影响

N-AgNPs（银纳米颗粒）暴露对湿地植物的生长发育有重要影响,而N-AgNPs对大型湿地植物黄菖蒲（Iris pseudacorus）的影响尚不清楚.选取湿地植物黄菖蒲为受试物种,采用室内土培法分析柠檬酸钠包覆的N-AgNPs对黄菖蒲早期生长和生理特征的影响.结果表明:①不同ρ（N-AgNPs）〔分别为0、5、10、15、20 mg/L,依次记为N0（对照）、N5、N10、N15、N20〕处理和作用时间均会影响黄菖蒲生长和生物量积累.培养初期（0~14 d）,N5、N10处理会抑制黄菖蒲生长,而N15、N20处理会促进黄菖蒲生长;培养后期（14~35 d）,不同ρ（N-AgNPs）处理均抑制黄菖蒲生长.整个培养期内（0~35 d）,N5、N10处理均抑制黄菖蒲地上、地下生物量积累,而N20处理会促进黄菖蒲地上、地下生物量积累.②不同ρ（N-AgNPs）处理均降低了黄菖蒲叶绿素含量,提高了PSⅡ（光系统Ⅱ）反应中心的光能转换效率,降低了光氧化损伤的发生率;N5、N10、N15处理下黄菖蒲叶片PSⅡ功能反应中心的开放度降低、光合电子传递速率（ETR）变慢;N5和N20处理下黄菖蒲叶片光合电子传递活性（qP）增大,而N10和N15处理下光合电子传递活性降低.③各ρ（N-AgNPs）处理均显著降低了黄菖蒲叶片中的丙二醛含量,膜脂过氧化作用减弱;同时,增加了黄菖蒲叶片中w（脯氨酸）,对黄菖蒲产生较强的胁迫.研究显示,随着培养浓度的增加,ρ（N-AgNPs）对黄菖蒲生物量累积的影响由抑制作用变为促进作用;各ρ（N-AgNPs）处理均会降低黄菖蒲的叶绿素含量、增加w（脯氨酸）,对黄菖蒲的生长产生胁迫.      

银纳米颗粒对水葱早期生长和生理特征的影响

选取挺水植物水葱(Scirpus tabernaemontani)为受试物种,研究柠檬酸钠-银纳米颗粒(N-AgNPs)对水葱早期生长和生理特性的影响.结果表明:N-AgNPs显著促进了水葱叶片的生长,与N-0 mg·L~(-1)(对照组)相比,N-5 mg·L~(-1)、N~(-1)0 mg·L~(-1)、N~(-1)5 mg·L~(-1)、N-20 mg·L~(-1)处理组水葱叶片的生长速率分别增加20.7%、37.6%、42.9%、47.7%,生物量分别增加77.3%、158.2%、95.5%、127%,叶片中叶绿素含量分别增加23.3%、67.7%、85.2%、80.5%.N-AgNPs浓度与水葱的生长速率、生物量、叶绿素的含量呈正相关关系.另一方面,N-AgNPs浓度增大提高了光系统Ⅱ(PSⅡ)反应中心的光能转换效率(F_v/F_m),且N-AgNPs浓度与F_v/F_m呈显著正相关关系.N-5 mg·L~(-1)处理组水葱叶片PSⅡ功能反应中心开放度(ΔFv/Fm)最大,光合电子传递速率(ETR)最快,光合电子传递活性(qP)最大.然而,随着N-AgNPs浓度增大,水葱叶片PSⅡ功能反应中心开放度减小,光合电子传递速率逐渐变慢,光合电子传递活性逐渐降低.另外,N-AgNPs浓度增加降低了水葱叶片中的丙二醛含量,膜脂过氧化作用减弱;N-AgNPs浓度增加降低了水葱叶片中脯氨酸含量,水葱自我调节能力减弱.     

废定影液的处理和再生利用

采用Na2S—SO2法处理废定影液,以硫化钠沉淀定影液中的银,用二氧化硫对废定影液进行再生处理,结果表明：银的回收率达到了95％,再生的废定影液,亚硫酸钠补充率达到了100％。硫代硫酸钠补充率约为50％,每1L再生定影液需再投加126gNa2S2O3·5H2O;废定影液处理经济收益约128万元／a。