荷电微孔陶瓷膜在应急饮水净化中的应用研究

以氧化镁和氧化钇为荷电剂,通过浸渍烧结工艺制备带正电荷微孔陶瓷膜,可通过筛分截留和正负电荷吸引作用吸附分离水中污染物.结果显示,荷电微孔陶瓷膜对水中微粒和微生物有很好的去除效果,净水浊度小于1.0 NTU,孔径大于0.45μm膜的细菌总数去除率大于99.9%,净水中未检测出大肠杆菌,不同孔径膜的大肠杆菌噬菌体f₂去除率均可达100%,细菌内毒素去除率大于99%.荷电微孔陶瓷膜具有良好的机械强度和净水效果,可用于应急饮水净化.     

MgO/SiO_2陶瓷微滤膜的制备及对达旦黄吸附性能

通过浸渍-热分解法对硅藻土陶瓷膜进行表面修饰,制备MgO/SiO_2荷正电陶瓷微滤膜,利用SEM、FT-IR、XRD、Zeta电势等技术对其组成结构及电性能进行分析.结果表明,荷电剂为立方相的MgO,且MgO牢固负载在陶瓷膜的表面,同时未改变基膜的微孔结构.在Mg~(2+)浓度为0.3mg/L、煅烧温度600℃条件下制备的荷电膜Zeta电势为21.5mV,对水中达旦黄的去除率可达99.0%,达旦黄饱和吸附量为3.07mg/cm~3.这表明通过浸渍-热分解法制备的MgO/SiO_2荷正电陶瓷微滤膜结构完整,具有较好的正电性能和达旦黄吸附性能,在染料废水处理领域将有很好的应用前景.     

纳米氧化镁表面修饰制备荷正电微孔陶瓷膜及其性能研究

以硅藻土陶瓷膜为基膜,氯化镁和尿素为原料合成含镁先驱体溶胶,通过浸渍-热分解法对硅藻土基膜进行表面改性制得纳米MgO/SiO_2荷正电微孔陶瓷膜,并对其组成结构及水中四环素去除性能进行研究。结果表明,荷正电的纳米MgO涂层呈现立方型晶粒,并均匀地附着在基膜表面,因此使得荷正电微孔陶瓷膜具有较高的电性能,并且在较宽的pH值范围内带正电,其等电点为10.8。最后对水中四环素的去除性能进行研究,结果表明荷正电微孔陶瓷膜对水中四环素具有很好的去除效果,在室温、常压条件下,其对四环素的COD去除率高达98.8%,色度去除率为99.7%。     

Y_2O_3/SiO_2荷正电陶瓷微孔膜对水中细菌内毒素去除性能

以硅藻土陶瓷微孔膜为基膜,采用浸渍-烧结工艺制备出Y_2O_3/SiO_2荷正电陶瓷微孔膜.SEM、EDS、XRD等表征分析表明,立方体晶型的纳米Y_2O_3作为荷正电剂附着在陶瓷膜表面,使陶瓷膜显示出较强的正电性,其等电点为8.3.基于静电吸附原理,荷正电陶瓷膜能有效吸附去除水中细菌内毒素,去除率最高可达99.6%.荷正电陶瓷微孔膜的研究为水中细菌内毒素的去除提供了一种可行的技术方法,有望应用于水中细菌内毒素的去除和分离.     

扫描电镜中荷电效应的分析

扫描电子显微镜要得到层次清晰、立体感强且分辨率高的高质量图像,荷电效应是一个重要的影响因素。对在扫描电子显微镜成像中荷电效应的成因及其解决办法进行了系统的分析。提出采用镀膜、降低加速电压及低真空的方法,可降低荷电效应的影响。     

不同荷电态对锂离子电池循环寿命的影响

通过对不同荷电态及不同搁置温度下单体电池的循环寿命测试,发现不同温度及荷电态对锂离子电池循环寿命影响很大。低荷电态下,温度对电池循环性能影响较小,但是在满荷电态下,电池在高温下的循环性能明显差于常温。20℃下,随着荷电态的增加,电池循环寿命依次增加。55℃下,随着荷电态的增加,电池循环寿命衰减严重。以此为依据,可以根据不同情况采取不同的搁置方法,从而提高锂离子电池的循环寿命。     

磁镜场约束中粒子运动的数值计算

由单粒子轨道理论,从分析磁镜场中荷电粒子的受力情况出发,应用计算机数值求解方法模拟了磁镜场中荷电粒子的运动情况.结果表明:与经典的理论分析结果不同,当荷电粒子的起始位置与磁轴的距离不等于其拉摩尔半径时,荷电粒子在平行磁轴方向和垂直磁轴平面中的速度分量存在着周期性变化,其周期为荷电粒子的拉摩尔周期;同时其损失锥的临界角随着荷电粒子起始位置与磁轴的距离的增大而略有减小.     

铸铝合金微弧氧化时间对陶瓷膜微观结构及性能的影响

目前,对铸铝合金表面微弧氧化的研究较少。为了提高高铁接触网铸造铝合金的使用寿命,采用恒流双向脉冲电源及硅酸盐体系在其表面制备了微弧氧化陶瓷膜。采用扫描电镜(SEM)、X射线衍射仪(XRD)、电化学测试、摩擦磨损试验等研究了不同氧化时间对陶瓷膜结构与性能的影响。结果表明:在硅酸盐电解液组分与电参数相同的情况下,随着氧化时间的延长,膜厚度逐渐增大,孔洞数量逐渐减少,孔径增大,且分布趋于均匀,陶瓷膜中的γ-Al2O3逐渐转变为α-Al2O3,陶瓷膜的硬度、耐磨性与耐腐蚀性得到明显的提高;氧化时间为25 min时,陶瓷膜的综合性能最优。     

荷电膜表面电性能对截留性能的影响

研究了流动电位和Zeta电位与无机盐溶液的浓度及测试压力的关系,以及随操作压力、无机盐溶液种类和浓度等因素的变化荷电膜对无机盐溶液截留性能的影响.结果表明,荷电膜由于离子吸附而带有负电荷,在低浓度溶液中荷电膜的表面电学性能对膜的截留性能有重要影响,而在高浓度溶液中荷电膜电性能的影响不大.     

放射性气溶胶同时荷电-凝并模型的开发

放射性气溶胶发生衰变时会引起表面电荷累积，带电颗粒间发生静电相互作用，影响气溶胶的演化和迁移。为了探究颗粒荷电对气溶胶凝并行为的影响，从气溶胶荷电-凝并机制出发，建立完整的荷电-凝并双变量群平衡方程，使用分区法和单元平均技术数值求解。开发适用于放射性气溶胶发生的荷电-凝并行为的计算模型，使用近似解析方法和经典实验进行验证分析。结果表明：荷电-凝并模型能够准确预测与放射性气溶胶同时发生的荷电-凝并行为，对颗粒荷电对凝并动力学行为的直接影响进行阐释。     

Electrostatic charge distribution in the dielectric layer of alumina electrostatic chuck

Electrostatic charge and its distribution in the dielectric layer of TiO₂- and Cr₂O₃-added alumina electrostatic chucks has been studied. The electrostatic potential was evaluated at various applied voltages by an electrostatic potential meter and it demonstrated the existence of charges with opposite polarities. Direct SEM observation and toner development of the charged ceramic surface was carried out to clarify the charge distribution. The charge contrast was not uniform on the ceramic microstructure and the charge was distributed in the form of grains. Taking into consideration these results, the relationship between electrostatic charge distribution and ceramic microstructure is discussed.     

Lifetime of ion-selective electrodes based on charged ionophores

The lifetime of solvent polymeric ion-selective electrodes (ISEs) is limited by leaching of the membrane components into the sample solutions. In this article, leaching of charged ionophores is discussed. Because of the electroneutrality principle, the loss of the charged ionophore into the sample must be accompanied by parallel transport of an ion of the opposite charge sign into the sample or by ion exchange with a sample ion of the same charge sign. Because ionic sites of high lipophilicity are available, the loss of ionic sites is, in general, not a concern. Therefore, it is assumed here that the cotransported or ion-exchanging ions are primary or interfering ions forming complexes with the ionophore. A general theory that allows quantification of ionophore lipophilicities and a discussion of changes in the membrane composition and selectivity with time is presented. A high complex stability and high analyte concentrations diminish the rate of ionophore loss into the sample if a charged ionophore is coextracted from the membrane into the sample together with an analyte ion of opposite charge. On the other hand, if the charged ionophore has the same charge sign as the ion that it binds, a large binding constant and high analyte concentrations enhance ionophore leaching into the sample. The model is applied to interpret results for an electrically charged ionophore, for which selectivity changes as a function of the leaching time were observed and the lipophilicity was determined with potentiometric measurements. Using the lipophilicities of neutral ionophores, as described previously, and the lipophilicities of charged ionophores, as described here, a direct comparison of the expected leaching rates of charged and neutral ionophores has become possible.     

Electrically charged filter materials

Filters made from ordinary textile fibres are too coarse to remove micrometre-sized dust particles, which are responsible for much respiratory disease. If, however, an electric charge is applied to the fibres, a filter can provide a very good respiratory protection. Fibres can be charged by triboelectric exchange, by corona or by induction; and charge levels can give rise to electric fields in the interstices of the filter, approaching the breakdown field of the air. Some of the effect of the charge is lost as the filters become loaded with dust, but charge stability during storage is high, with shelf lives of years being attainable. The author discusses the capture of particles by electric forces and electrically charged filter materials and their production methods. The measurement of electric charge on filters, charge stability during storage, filter performance when loaded with dust and the advantages and disadvantages of such filters, are also discussed     

Effect of Negatively Charged Ions on the Formation of Microarc Oxidation Coating on 2024 Aluminium Alloy

The present study deals with the effect of negatively charged ions on the ceramic coating formation on 2024 aluminium alloy during microarc oxidation (MAO) process. On the basis of the experimental results, two steps (the formation of an incipient film without arc presence and the growth of a ceramic coating with arc discharge) of MAO process have been observed. For comparison, four different negatively charged ions studied. It is proved that negatively charged ions strongly participated in the formation of an incipient film with high impedance value at the first step. The growth of ceramic coating depends on the combination between Al of the substrate and O from the electrolyte, and the negatively charged ions are little consumed. As an anodic oxide coating is prepared on the sample surface instead of the incipient film, the first step occurs easily and the growth of ceramic coating is accelerated. Furthermore, the mechanism of negatively charged ions in the formation of the MAO coating has been proposed.     

A method for estimating the composition of the mixture to be charged to get the desired composition in circulation in a single stage JT refrigerator operating with mixtures

It has been shown earlier in literature that the composition of the mixture in circulation at steady state is different from that charged into the system in Joule-Thomson refrigerators operating with mixtures. There are no methods in literature that help us charge a particular composition into the system in order to get the desired composition in circulation at steady state. Experiments were performed with 30 different charge compositions, two different heat exchangers, and two different heat loads to understand the relationship between the composition in circulation and that charged. Based on these experiments, a method is proposed for estimating the charge composition required to get the desired composition in circulation.     

沸石膜的合成方法及影响因素

沸石分子筛膜是分子筛微晶在微孔支撑体上均匀连续生长而形成的膜,它兼有无机膜与分子筛两者的物化性能特点,在吸附、分离、择形催化、离子交换等工业领域具有广阔的应用前景。本文综合阐述了沸石分子筛膜的主要制备方法及各自的特点,重点讨论了二次生长法中支撑体性质及晶种对膜生长及成膜性能的影响,提出了分子筛膜领域存在的问题及今后的研究方向。     

Charged species transport, separation, and dispersion in nanoscale channels: autogenous electric field-flow fractionation

Numerical methods are employed to examine the transport of charged species in pressure-driven and electroosmotic flow along nanoscale channels having an electric double-layer thickness comparable to the channel size. In such channels, the electric field inherent to the double layer produces transverse species distributions that depend on species charge. Flow along the channel thus yields mean axial species speeds that also depend on the species charge, enabling species separation and identification. Here we characterize field-flow separations of this type via the retention and plate height. For pressure-driven flows, we demonstrate that mean species speeds along the channel are uniquely associated with a single species charge, allowing species separation based on charge alone. In contrast, electroosmotic flows generally yield identical speeds for several values of the charge, and these speeds generally depend on both the species charge and electrophoretic mobility. Coefficients of dispersion for charged species in both planar and cylindrical geometries are presented as part of this analysis.     

乙烯/四氟乙烯共聚物薄膜驻极体的电荷储存稳定性

研究了经栅控恒压电晕充电的乙烯／四氟乙烯共聚物（ETFE）驻极体的电荷稳定性,并将其与几种重要的驻极体材料的储电性能进行了比较。结果显示,ETFE薄膜驻极体具有优良的电荷储存稳定性,负极性ETFE的电荷稳定性明显优于正极性样品。热处理工艺能明显改善ETFE驻极体的电荷储存寿命。本文还估算出两种极性ETFE驻极体的陷阱能级的活化能,阐明脱阱电荷的输运特性。     

The role of surface charge on the uptake and biocompatibility of hydroxyapatite nanoparticles with osteoblast cells

The objective of this study is to evaluate the effect of hydroxyapatite (HAP) nanoparticles with different surface charges on the cellular uptake behavior and in vitro cell viability and proliferation of MC3T3-E1 cell lines (osteoblast). The nanoparticles' surface charge was varied by surface modification with two carboxylic acids: 12-aminododecanoic acid (positive) and dodecanedioic acid (negative). The untreated HAP nanoparticles and dodecanoic acid modified HAP nanoparticles (neutral) were used as the control. X-ray diffraction (XRD) revealed that surface modifications by the three carboxylic acids did not change the crystal structure of HAP nanoparticles; Fourier transform infrared spectroscopy (FT-IR) confirmed the adsorption and binding of the carboxylic acids on the HAP nanoparticles' surfaces; and zeta potential measurement confirmed that the chemicals successfully modified the surface charge of HAP nanoparticles in water based solution. Transmission electron microscopy (TEM) images showed that positively charged, negatively charged and untreated HAP nanoparticles, with similar size and shape, all penetrated into the cells and cells had more uptake of HAP nanoparticles with positive charge compared to those with negative charge, which might be attributed to the attractive or repulsive interaction between the negatively charged cell membrane and positively/negatively charged HAP nanoparticles. The neutral HAP nanoparticles could not penetrate the cell membrane due to their larger size. MTT assay and LDH assay results indicated that as compared with the polystyrene control, greater cell viability and cell proliferation were measured on MC3T3-E1 cells treated with the three kinds of HAP nanoparticles (neutral, positive, and untreated), among which positively charged HAP nanoparticles showed the strongest improvement for cell viability and cell proliferation. In summary, the surface charge of HAP nanoparticles can be modified to influence the cellular uptake of HAP nanoparticles and the different uptake also influences the behavior of cells. These in vitro results may also provide useful information for investigations of HAP nanoparticle applications in gene delivery and intracellular drug delivery.