Methyl orange degradation enhanced by hydrogen spillover onto platinum nanocatalyst surface

Following a thermal reduction method, platinum nanoparticles were synthesized and stabilized by polyvinylpyrrolidone. The colloidal platinum nanoparticles were stable for more than 3 months. The micrograph analysis unveiled that the colloidal platinum nanoparticles were well dispersed with an average size of 2.53 nm. The sol–gel‐based inverse micelle strategy was applied to synthesize mesoporous iron oxide material. The colloidal platinum nanoparticles were deposited on mesoporous iron oxide through the capillary inclusion method. The small‐angle X‐ray scattering analysis indicated that the dimension of platinum nanoparticles deposited on mesoporous iron oxide (Pt‐Fe₂O₃) was 2.64 nm. X‐ray photoelectron spectroscopy (XPS) data showed that the binding energy on Pt‐Fe₂O₃ surface decreased owing to mesoporous support–nanoparticle interaction. Both colloidal and deposited platinum nanocatalysts improved the degradation of methyl orange under reduction conditions. The activation energy on the deposited platinum nanocatalyst interface (2.66 kJ mol^?1) was significantly lowered compared with the one on the colloidal platinum nanocatalyst interface (40.63 ± 0.53 kJ mol^?1).     

聚乙烯吡咯烷酮对油中酚类物质的吸附性能

煤焦油中酚类物质的有效分离,可实现其高附加值利用。针对酚类物质的分离,本研究采用聚乙烯吡咯烷酮(PVP)为吸附剂,研究了其对模型油中邻甲酚、间甲酚、对甲酚、1-萘酚和2-萘酚等的吸附性能。研究发现,PVP对酚类物质具有较大的吸附容量,其中对间甲酚、对甲酚、1-萘酚和2-萘酚的最大吸附量均可达1000 mg/g以上。同时发现,PVP上的Lewis碱性位点(C=O和C-N)可与酚羟基之间形成氢键作用,该作用的强度受酚类物质空间位阻影响。PVP具有一定的吸附选择性,在苯并呋喃或喹啉存在下,依然能够有效吸附2-萘酚。此外,使用过的PVP可再生并重复利用,同时实现酚的回收。可见,PVP是一种可用于分离煤焦油中酚类物质的优良吸附剂。     

Zn2+@Polyvinylpyrrolidone and Urushiol Preparation of Nanofibrous Membranes and Their Synergistic Effect

In this study, lacquer is gathered from a lacquer tree and rotary evaporation is used to remove impurities to obtain urushiol. Next, 10 mL of anhydrous ethanol serves as the solvent for blending polyvinylpyrrolidone (PVP) at a specified content (0.7 g and 0.2–0.7 g urushiol) to form an electrospinning solution. Electrospinning is carried out with a voltage of 18 kV to prepare PVP/urushiol nanofibrous membranes. At a ratio of 7/4, the PVP/urushiol nanofibrous membranes are not eroded in 98% sulfuric acid and these membranes also demonstrate a 50–60% antibacterial effect against Staphylococcus aureus and Escherichia coli. Moreover, the antibacterial effect can be boosted to 98% with the incorporation of zinc ions. The results indicate that anhydrous ethanol can remove the sensitization of urushiol from PVP/urushiol membranes. Furthermore, animal test results indicate that when rats are in contact with PVP/urushiol anhydrous ethanol for 48 h, their skins are free from dark brown skin allergy. The presence of PVP eliminates the sensitization of urushiol, and the nanofibrous membranes demonstrate low toxicity. Hence, urushiol is the only natural material that enables PVP to withstand 98% sulfuric acid as well as acquire hydrolyzability, thereby qualify PVP as a medical material.     

Isoflavonoid-Antibiotic Thin Films Fabricated by MAPLE with Improved Resistance to Microbial Colonization

Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative) bacteria represent major infectious threats in the hospital environment due to their wide distribution, opportunistic behavior, and increasing antibiotic resistance. This study reports on the deposition of polyvinylpyrrolidone/antibiotic/isoflavonoid thin films by the matrix-assisted pulsed laser evaporation (MAPLE) method as anti-adhesion barrier coatings, on biomedical surfaces for improved resistance to microbial colonization. The thin films were characterized by Fourier transform infrared spectroscopy, infrared microscopy, and scanning electron microscopy. In vitro biological assay tests were performed to evaluate the influence of the thin films on the development of biofilms formed by Gram-positive and Gram-negative bacterial strains. In vitro biocompatibility tests were assessed on human endothelial cells examined for up to five days of incubation, via qualitative and quantitative methods. The results of this study revealed that the laser-fabricated coatings are biocompatible and resistant to microbial colonization and biofilm formation, making them successful candidates for biomedical devices and contact surfaces that would otherwise be amenable to contact transmission.     

Molecularly engineered graphene surfaces for sensing applications: A review

Graphene is scientifically and commercially important because of its unique molecular structure which is monoatomic in thickness, rigorously two-dimensional and highly conjugated. Consequently, graphene exhibits exceptional electrical, optical, thermal and mechanical properties. Herein, we critically discuss the surface modification of graphene, the specific advantages that graphene-based materials can provide over other materials in sensor research and their related chemical and electrochemical properties. Furthermore, we describe the latest developments in the use of these materials for sensing technology, including chemical sensors and biosensors and their applications in security, environmental safety and diseases detection and diagnosis.     

Evaluation of the separation performance of polyvinylpyrrolidone as a virtual stationary phase for chromatographic NMR

Polyvinylpyrrolidone (PVP) was used as a virtual stationary phase to separate p‐xylene, benzyl alcohol, and p‐methylphenol by the chromatographic NMR technique. The effects of concentration and weight‐average molecular weight (Mw) of PVP, solvent viscosity, solvent polarity, and sample temperature on the resolution of these components were investigated. It was found that both higher PVP concentration and higher PVP Mw caused the increase of diffusion resolution for the three components. Moreover, the diffusion resolution did not change at viscosity‐higher solvents. Moreover, the three components showed different resolution at different solvents. As temperature increased, the diffusion resolution between p‐xylene and benzyl alcohol gradually increased, and the one between p‐xylene and p‐methylphenol slightly increased from 278 to 298 K and then decreased above 298 K. It was also found that the polarity of the analytes played an important role for the separation by affecting the diffusion coefficient. Copyright © 2014 John Wiley & Sons, Ltd.     

表面活性剂对LiNi0.80Co0.15Al0.05O2的结构和性能影响

在共沉淀过程中添加表面活性剂聚乙二醇(PEG)或聚乙烯吡咯烷酮(PVP)分别合成类球形Ni_(0.80)Co_(0.15)Al_(0.05)(OH)_2前驱体,再与氢氧化锂(LiOH·H_2O)氧化煅烧得到LiNi_(0.80)Co_(0.15)Al_(0.05)O_2(NCA)三元正极材料。利用X射线衍射(XRD)、扫描电镜(SEM)、透射电子显微镜(TEM)、循环伏安(CV)、交流阻抗(EIS)和充放电循环测试等对材料的结构、形貌、电化学性能等进行表征。结果表明:PEG和PVP的添加不影响材料中Ni、Co和Al元素的比例,能够促进一次晶粒长大和提高振实密度,能够促进正极材料层状结构发育进而提高正极材料的电化学性能。添加PEG、添加PVP和未添加表面活性剂合成正极材料的振实密度分别为2.07、1.86和1.40 g·cm~(-3),在0.2C充放电过程中首次放电比容量分别为210.8、188.9和173.0 mAh·g~(-1),以0.2C充电1C放电循环100次后电池容量保持率分别为78.8%、93.2%和82.7%,添加PEG和PVP的NCA材料表现出良好的电化学性能。     

纳米银催化氧化偶联硫醇制二硫化物

采用多元醇为溶剂和还原剂制备了聚乙烯吡咯烷酮(PVP)保护的纳米银,并将其用于催化正十二烷基硫醇氧化偶联反应.质谱、红外光谱、拉曼光谱和核磁共振氢谱表征结果表明所得产物为二硫化物.考察了反应时间、反应温度、催化剂和水的用量等对正十二烷基硫醇氧化偶联反应的影响,从而得出优化的反应条件:0.157mmolPVP保护的纳米银,20μl水,100℃下反应3h.此外,进一步将PVP保护的纳米银用于正丁硫醇和正辛硫醇的氧化偶联反应,也得到了相应的二硫化物.     

以SDS-PVP项链状软团簇为模板简易一锅法合成Cu2O中空亚微球

在SDS-PVP水溶液中采用N2H4•H2O还原CuSO4, 在pH (10±0.5), (40±1.0) ℃条件下反应55 min得到橙色Cu2O溶胶, 离心分离产物经XRD鉴定为Cu2O立方晶系晶体; SEM和TEM表明该法获得的晶体为形状规整、粒径分布窄的Cu2O中空亚微球, 并证实系由大量10 nm量级的原级Cu2O纳米晶粒组装而成. 根据实验事实推断, SDS-PVP项链状软团簇提供了“双重软模板”功能, 借助独特的“模板诱导两级组装”作用一锅法合成了Cu2O中空亚微球. Cu2O中空亚微球生长的可能途径为: 首先, 项链状软团簇中的SDS束缚胶束作为第一重软模板, 诱导一级组装10 nm量级的原级Cu2O纳米晶粒; 然后, 软团簇中立体桥联SDS束缚胶束的PVP链节作为第二重软模板, 诱导一定空间范围内的原级Cu2O纳米晶粒长大并进一步聚集/二级组装, 经一锅法合成得到次级Cu2O中空亚微球. 实验结果证明该一锅法温和、简便、快捷, Cu2O中空亚微球的粒径分布窄.     

Analysis of the Interactions of Polyvinylpyrrolidone with Conventional Anionic and Dimeric Anionic Surfactant

Classical physical method has been applied in the present study of interaction between water soluble polymer with anionic dimeric and conventional anionic surfactants. Micellization activity of carboxylate-based anionic dimeric (CAD) as well as sodium dodecyl sulfate (SDS) surfactants in the presence of nonionic polymer, that is, polyvinylpyrrolidone (PVP), has been studied through conductometric and surface tensiometric measurements. From these methods the critical aggregation concentrations (CACs), critical micelle concentrations (CMCs), and the effective degree of counterion binding (β) were determined. For the evaluation of behavior of CAD toward the PVP various thermodynamic properties viz. standard Gibbs energy of micellization, standard enthalpy, and entropy of micellization of CAD/PVP mixed system have also been estimated and discussed. The results exhibit that anionic dimeric surfactant interacts strongly with PVP as compared to conventional surfactant.