静电层层自组装制备聚苯乙烯微球(核)/MCM-41纳米粒子(壳)阶层结构复合微粒

采用聚苯乙烯磺酸钠(PSS)和聚二烯丙基二甲基氯化铵(PDDA)两种聚电解质, 通过静电层层自组装成功地将MCM-41介孔二氧化硅纳米粒子包覆到聚苯乙烯(PS)微球表面. 实验结果表明, 当以尺寸为1.4 μm的PS微球为核时, 包覆了两个聚电解质双层(PDDA/PSS)2的PS(PDDA/PSS)2(PDDA/MCM-41)复合结构微粒与包覆了一个聚电解质双层(PDDA/PSS)的PS(PDDA/PSS)(PDDA/MCM-41)复合结构微粒相比, 复合结构微粒之间的交联程度降低, 但是MCM-41纳米粒子在聚苯乙烯微球表面的包覆都比较松散, 且产物中存在大量杂质. 而当以尺寸为5 μm的聚苯乙烯微球为核时, MCM-41纳米粒子紧密地包覆在聚苯乙烯微球表面, 复合结构微粒之间只有少量桥连物, 且产物中杂质很少.     

Preparation of diatomite–TiO<Subscript>2</Subscript> composite for photodegradation of bisphenol-A in water

To enhance the photodegradation performance of pure titanium dioxide (TiO₂), diatomite was used as a porous carrier to immobilize TiO₂ powders using calcination method. The photodegradation of bisphenol-A (BPA; 4,4′-isopropylidenediphenol), which has been listed as one of endocrine disrupting chemicals, was carried out in a batch suspension reactor using pure TiO₂ powders and diatomite–TiO₂ composites, respectively. Under the controlled conditions, the photocatalytic efficiencies of the BPA degradation by the diatomite–TiO₂ composites can be found to be higher than those by pure TiO₂ powders. This result should be attributable to the accessibility of the BPA molecules to the surface of TiO₂ particle in the modified photocatalysts, showing that the enrichment of the organic solute enhanced the rate of photodegradation on the diatomite–TiO₂ composite. However, the photodegradation efficiency was not dependent on the pore properties of these TiO₂ photocatalysts. The experimental results further indicated that the photodegradation kinetics for the destruction of BPA in water followed the first-order model well. The apparent first-order reaction constants (k _obs), thus obtained from the fittings of the model, were in line with the destruction-removal efficiencies of BPA in all the photocatalytic experiments.     

聚(丙烯酸-co-丙烯酰胺)/蒙脱土/腐殖酸钠复合物对Pb2+的吸附性能

用制备的聚(丙烯酸-co-丙烯酰胺)/蒙脱土/腐殖酸钠复合吸附剂,研究了溶液pH值、吸附时间和Pb2+溶液初始浓度等因素对重金属Pb2+的吸附性能,探讨了复合吸附剂对Pb2+的吸附机理。结果表明,在pH值为6.0、吸附时间2 h、Pb2+溶液初始浓度0.01 mol/L和吸附剂用量0.10 g的条件下,复合吸附剂对Pb2+的吸附量达到364.05 mg/g,平衡所需的时间为15 min。与蒙脱土相比,复合吸附剂具有更高的吸附容量和更快的吸附速率。     

低热固相法制备纳米MnO2/CNT超电容复合电极的循环稳定性

To improve the charge/discharge cycle stability of a nanostructured manganese dioxide electrode for supercapacitor applications, a series of nano-MnO2/carbon nanotube (CNT) hybrid electrode materials with different mass fractions of CNTs were prepared. The materials were prepared using a room-temperature solid-grinding reaction betweenMn(OAc)2·4H2Oand NH4HCO3 in the presence of CNTs to obtain a precursor. This was followed by calcination and an acid-treatment process and the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) surface analysis. XRD results indicated that the MnO2 in the composites was nanostructured 酌-MnO2. Electrochemical performance of the MnO2/CNT composite electrodes in 1 mol·L-1 LiOH alkaline aqueous electrolyte was studied and compared to a pure nano-MnO2 electrode without CNTs. The MnO2/CNT composite electrodes with 10% or 20% (w, mass fraction) CNTs showed far superior cycle stability than the pure MnO2 electrode. The MnO2/CNT composite electrode with 10% CNTs exhibited good cycling stability and also a high specific capacitance of 200 F·g-1 at a high charge/discharge current rate of 1000 mA·g-1.     

微电极结构Ag/ZnO/NiO三层复合膜的制备及光催化性能的研究

通过溶胶-凝胶结合光还原沉积法在普通玻璃片上制备了Ag-ZnO-NiO系复合薄膜。使用SEM,PL,XRD,UV-Vis等手段对薄膜的表面形貌,物相组成及光学性质作了考察和研究。XRD和UV-Vis分析表明复合薄膜中包含NiO和ZnO的双层异质结构;FESEM结果表明Ag和ZnO分别在其各自的衬底上生长但没有形成完全覆盖,PL光谱表明三层膜的发光强度小于双层膜和单层膜。使用甲基橙为模型底物测试了薄膜在紫外线下的光催化氧化能力,结果表明,三层复合薄膜Ag/ZnO/NiO的活性相比氧化锌单层薄膜和双层薄膜有不同程度的提高。这是由于上层薄膜不能完全包裹下层膜,导致在表面形成了许多微电极结构,这些微电极结构能够使光生电子空穴对得到有效分离。     

Fabrication of Bismuth/Multi-walled Carbon Nanotube Composite Modified Glassy Carbon Electrode for Determination of Cobalt

A bismuth/multi‐walled carbon nanotube (Bi/MWNT) composite modified electrode for determination of cobalt by differential pulse adsorptive cathodic stripping voltammetry is described. The electrode is fabricated by potentiostatic pre‐plating bismuth film on an MWNT modified glassy carbon (GC) electrode. The Bi/MWNT composite modified electrode exhibits enhanced sensitivity for cobalt detection as compared with the bare GC, MWNT modified and bismuth film electrodes. Numerous key experimental parameters have been examined for optimum analytical performance of the proposed electrode. With an adsorptive accumulation of the Co(II)‐dimethylglyoxime complex at ?0.8 V for 200 s, the reduction peak current is proportional to the concentration of cobalt in the range of 4.0×10^?10?1.0×10^?7 mol/L with a lower detection limit of 8.1×10^?11 mol/L. The proposed method has been applied successfully to cobalt determination in seawater and lake water samples.     

Biomimetic fabrication of hydroxyapatite-coated zirconia-magnesia composite and its application in the separation of proteins

In this work, biomimetic technique was proposed for the first time to prepare chromatographic packings (2HAp-ZM) for protein separation. By mimicking the mineralization procedures in vivo, this type of matrix with hydroxyapatite (HAp) coating and zirconia-magnesia (ZM) composite core was fabricated. Systematic characterizations, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and specific surface area analysis, were carried out to investigate the properties of the material. Results showed that the surface of 2HAp-ZM was composed of bead-like, amorphous or nanocrystalline HAp. The specific surface area, total pore volume, and average pore diameter of the resultant material were 25 m²/g, 0.09 cm³/g, and 14 nm, respectively. Furthermore, 2HAp-ZM exhibited good mechanical stability through repeated testing and its application as stationary phases for protein separation was then studied. Five model proteins (bovine serum albumin, trypsin, lysozyme, ribonuclease A, and cytochrome c) were successfully separated on 2HAp-ZM. Finally, the mass recovery of protein and the dynamic loading capacity were studied; the results were calculated to be no less than 93% and 80 μg/mL of blank column volume, respectively.     

DNA／聚（3-甲基噻吩）复合膜修饰电极的制备及其应用于研究8-羟基-2＇-脱氧鸟嘌呤核苷的伏安行为及测定

首先通过电聚合方法在玻碳电极表面制备了聚（3-甲基噻吩）（P3MT）修饰膜,然后在一定电位下将DNA分子电沉积到P3MT表面,制备了DNA／（P3MT）复合膜修饰玻碳电极．研究了8-羟基-2’-脱氧鸟嘌呤核苷（8-OH-dG）在该复合膜修饰电极上的伏安行为以及扫描速度、pH值和尿酸对其伏安行为和检测的影响．实验结果表明,该复合膜修饰电极结合了P3MT和DNA两者的优点,使8-OH-dG在复合膜修饰电极上的电化学行为明显改善,而且具有很好的重现性和稳定性．在0．1mol／LpH7．0的磷酸盐缓冲溶液（PBS）中,8-OH-dG的氧化峰电流与其浓度在0．28～4．2μmol／L和4．2～19．6μmol／L两个范围内成良好的线性关系,检出限为56nmol／L（S／N=3）．该研究可以为制备HPLC或毛细管电泳电化学检测器检测8-OH—dG打下一定的基础,因此在检测尿样中8-OH-dG的研究方面具有潜在的应用价值．     

Preparation and properties investigation of PMMA/silica composites derived from silicic acid

Hybrid materials based on silicic acid and polymethyl methacrylate (PMMA) were prepared by in situ bulk polymerization of a silicic acid sol and MMA mixture. Silicic acid sol was obtained by tetrahydrofuran (THF) extraction of silicic acid from water. Silicic acid was prepared by hydrolysis and condensation of sodium silicate in the presence of 3.6 M HCl. As a comparative study, PMMA composites filled by silica particles, which were derived from calcining the silicic acid gel, were prepared by a comparable in situ polymerization. Each set of PMMA/silica composites was subjected to thermal and mechanical studies. Residual THF in PMMA/silicic acid composites impacted the properties of the polymer composites. With increase in silica content, the PMMA composites filled with silica particles showed improved thermal and mechanical properties, whereas a decrease in thermal stability and mechanical strength was found for PMMA composites filled with silicic acid dissolved in THF. With a better compatibility with polymer matrix, silicic acid sol shows better reinforcement than silica particles in PMMA films prepared via blending of the corresponding THF solutions. Copyright © 2008 John Wiley & Sons, Ltd.