反渗透复合膜技术进展和展望

简要介绍反渗透复合膜的发展现状和趋势.自1978年全芳香族聚酰胺复合膜的成功及其产业化,大大地促进了膜科技和海水淡化的发展,膜的品种不断增多,膜的性能不断提高,低压、超低压、极低压、高脱盐率、高通量、耐污染和抗氧化等一系列的各种复合膜相继进入市场.文章简述了膜材料的选择、传递机理(如:溶解扩散模型、优先吸附-毛细孔流动模型、氢键传递和水与离子通道等)、新的功能单体合成、支撑膜的改进、界面聚合的参数调控和后处理、有机-纳米无机粒子杂化、水通道和离子通道的建立和仿生等的研究进展和发展趋势.     

火焰化学气相沉积法制备氮掺杂纳米TiO_2研究

用火焰化学气相沉积法,分别以氨气为氮源、TiCl4为TiO2前驱体,在丙烷-空气湍流火焰中氧化制备氮掺杂纳米TiO2颗粒,以及用TiCl4为TiO2前驱体,在丙烷-空气湍流火焰中氧化制备纳米TiO2颗粒,然后在管式炉中,在氨气的环境下高温煅烧制备氮掺杂纳米TiO2颗粒。利用X射线衍射仪、紫外可见光谱仪、透射电子显微镜、X射线光电子能谱等分析方法对两种方法所制备的样品进行表征。结果表明:在相同的氨气流量下,火焰化学气相沉积法直接制备的氮掺杂纳米TiO2颗粒在波长400～500 nm的可见光的吸收强度大,氮掺杂量多。     

纳米氧化镁合成过程中颗粒粒度及形状控制研究

采用化学沉淀-热分解法,合成粒度在20～120 nm的氧化镁粉体。采用透射电镜及X射线衍射分析,研究纳米氧化镁的粒度和形状的控制因素对纳米氧化镁颗粒形成过程的影响。结果表明:镁源及分散剂的种类、沉淀反应温度、样品干燥方式都是影响氧化镁粒度和形状的重要因素。在以Mg(NO3)2为镁源、n(Mg2+):n(OH-)=2:1、沉淀温度为30℃、体积分数为8%的乙二醇为分散剂、微波低火干燥2 min条件下,得到平均粒径为40 nm的氧化镁产品。前驱物的形状与产物纳米氧化镁的形状存在对应关系。     

复合Al_2O_3-SiO_2纳米颗粒的摩擦学性能研究

以硅烷偶联剂为改性剂对复合Al2O3-SiO2纳米颗粒进行原位改性,实现其在润滑油中均匀稳定的单分散。将改性后的复合Al2O3-SiO2纳米颗粒分别按质量分数为0、0.05%、0.1%、0.5%、1.0%的量加入到润滑油中制成试样,进行四球试验和止推圈试验。对摩擦实验中的摩擦系数、磨斑直径、磨损量、摩擦副表面形貌进行分析。结果表明:当复合Al2O3-SiO2纳米颗粒添加质量分数为0.5%时,摩擦系数和磨斑直径最小,止推圈的磨损量出现负磨损,摩擦表面的磨痕明显的变浅、变窄。说明摩擦过程中,复合Al2O3-SiO2纳米颗粒沉积在摩擦副表面,形成一层保护膜有效的保护了摩擦表面,抗磨减摩作用显著。     

Role of the Initial Formation of the Iron Nano-Particles in the Multi-Walled Carbon Nanotubes Growth Process

Careful preparation of the iron nano-particle catalyst for carbon nanotubes (CNTs) fabrication has crucial importance for initial growth of multi-wall carbon-nanotubes (MWCNTs). Thin iron layer was thermally deposited in a high vacuum onto the surface of the SiO2/Si wafer at about 300 K. The sample was heated up to 700℃ in a hydrogen atmosphere, and then the sample was heated once again at750℃ in ethylene atmosphere. After hydrogen treatment continuous Fe layer was changed into many well separated Fe nano-peaks. AFM, SEM and HR-TEM studies of deposited MWCNTs allow us to propose a growth mechanism for long, straight MWCNTs.     

Effect of energy density, pH and temperature on de-aggregation in nano-particles/water suspensions in high shear mixer

The effect of energy input, pH and temperature on de-aggregation of hydrophilic silicon dioxide powder (particle size 12 nm) in a high shear mixer was investigated. It has been found that de-aggregation is a two step process. Initially, at low energy input very large aggregates (3-1000 μm) are gradually broken into smaller secondary aggregates (2-100 μm) of a single modal size distributions. As the energy input increases primary aggregates (0.03-1 μm) are eroded from the secondary aggregates leading to bimodal size distributions with the first mode between 0.03 μm and 1 μm corresponding to the primary aggregates and the second mode between 2 μm and 100 μm corresponding to the secondary aggregates. At a sufficiently high energy density all secondary aggregates are broken into primary aggregates however, even at the highest energy density employed the primary aggregates could not be broken into single nano-particles. The temperature and the pH affect de-aggregation kinetics but do not alter de-aggregation pattern. Increasing pH at low temperature speeds up de-aggregation, whilst increasing pH at high temperature slows down de-aggregation process.     

纳米SiO_2用于含表面活性剂原水的处理

在含表面活性剂十二烷基硫酸钠(SDS)的低浊(6 NTU)高岭土原水中,投加纳米SiO_2进行动态混凝与静沉试验,借助图像分析技术与定量控制参数,探讨了纳米SiO_2的作用效果与形态学特性.结果表明:絮体的形成与生长具有分形特征,分形结构是影响颗粒混凝、絮团密实度与沉降特性的主要因素;SDS的存在对絮凝初期絮体的形成起阻碍作用,随后SDS与混凝剂的混合体共同对粒子作用,促进絮凝,絮体变大且密实,沉降性能改善;SDS和SiO_2对高岭土粒子存在竞争吸附;单独投加纳米SiO_2时形成的絮体小而脆弱,而以纳米SiO_2为助凝剂能促使PAC絮体结构向更密实的构型转变,对浊度和SDS的去除率提高.     

Enhancement of the photocatalytic reactivity of TiO2 nano-particles by a simple mechanical blending with hydrophobic mordenite (MOR) zeolite

The photocatalytic oxidation of gaseous acetaldehyde with O₂ on commercial TiO₂ nano-particles could be successfully enhanced by a simple mechanical blending with a high-silica mordenite (MOR) zeolite, the surface of which showed high hydrophobic properties. When the TiO₂ nano-particles of ca. 5–20 wt% were mixed with the MOR zeolite powders in an agate mortar for only 5 min, the blended TiO₂/MOR samples showed higher photocatalytic reactivity as compared to the pure TiO₂ nano-particles. Since the high-silica zeolite powders are highly transparent in UV light regions, the incident UV light is effectively irradiated onto the whole part of the TiO₂ nano-particles without any loss of light intensity. Furthermore, the siliceous MOR zeolite powders effectively adsorb the gaseous acetaldehyde molecules and supply them onto the surfaces of the blended TiO₂ nano-particles, resulting in an enhancement of the photocatalytic reactivity.     

一种具有片上译码/放大功能的微阵列电路及其与生物纳米系统的集成

提出了一种用SMIC 0.18μm CMOS混合信号工艺实现的全集成CMOS微阵列生物芯片,并成功地实现了其与一种新的生物纳米系统的集成. 该电路实现了19μm×19μm电极的4×4 (16单元）阵列,反相电极,电流模式放大器,译码电路,以及逻辑控制电路的单片集成,并能够提供-1.6~1.6V的组装电压,8bit的电位分辨率及39.8dB的电流增益,电源电压为1.8V,而失调和噪声电流分别为5.9nA和25.3pArms. 在实验中,利用该电路实现了对30nm聚乙烯醇包裹的磁性粒子的片上选择性组装,并对实验结果进行了讨论,从而验证了该电路的正确性和该集成方法的可行性.     

Excellent electro-oxidation of methanol and ethanol in alkaline media: Electrodeposition of the NiMoP metallic nano-particles on/in the ERGO layers/CE

Here, the Ni-based metallic nano-particles (Ni, NiMo and NiMoP) were electrodeposited on/in the surface of ERGO/CE substrate from a citrate-based electrolyte and their catalytic activities investigated towards methanol and ethanol electro-oxidation. The physicochemical characterizations of all prepared electrocatalysts were investigated by different electrochemical and non-electrochemical techniques. The electrocatalytic activities of the modified electrodes towards the electro-oxidation of methanol and ethanol were studied in 0.1 M NaOH solution by conventional electrochemical methods such as cyclic voltammetry and chronoamperometry. In the optimized electrodeposition conditions, the obtained electrochemical results indicate that the NiMoP/ERGO/CE displays dramatically improved electrocatalytic activity [J_pf (mA.cm⁻²) = 263.14 for methanol and J_pf (mA.cm⁻²) = 253.35 for ethanol], stability and poisoning tolerance towards the electro-oxidation of these fuels in alkaline solution. Finally, for comparison, the Ni (alone) and NiMo (binary) electrodeposited on/in the ERGO/CE (without P) and also studying the influence of the ERGO layers on the surface of CE, the NiMoP/CE (without ERGO) were prepared and applied as electrocatalysts.