Modeling of electrochemical deionization across length scales: Recent accomplishments and new opportunities

Theoretical models have recently been used to simulate deionization technology by capturing electrochemical processes at atomistic, electrode, and plant length scales in electrodialysis, capacitive deionization using electric double layers, and Faradaic deionization using intercalation materials and redox-active polymers. We review the salient features of such models, identifying their major accomplishments in quantifying energy consumption and ion removal, analyzing the feasibility of large-scale systems, and discovering new electrode materials and understanding their deionization mechanisms. After summarizing strengths and weaknesses of recent modeling strategies, we identify research directions to expand modeling capabilities that can be used to inform electrode material/microstructure design, to assign energy losses to electrode-scale mechanisms, to bridge length scales, and to capture Faradaic kinetic/diffusion processes.     

功能化石墨烯/活性炭复合电极及不对称电容器脱盐

以3-氨丙基三乙氧基硅烷(AMPTS)修饰氧化石墨(GO)还原合成氨基功能化石墨烯(GP-NH₂). 傅里叶变换红外(FTIR)光谱和X射线能谱(EDX)分析证明了氨基基团的成功接枝. 以GP-NH₂为添加剂, 制备胺化石墨烯/活性炭(GP-NH₂/AC)复合电极, 并以GP-NH₂/AC 为正极, AC电极为对电极, 组装不对称电容器(AC||GPNH₂/AC)用于电容脱盐. 实验表明, AC||GP-NH₂/AC 单循环脱盐量为7.63 mg·g^-1, 电流效率达77.6%. 利用磺酸重氮盐接枝石墨烯制备磺化石墨烯(GP-SO₃H)及磺化石墨烯/活性炭(GP-SO₃H/AC)复合电极. 并以GPSO₃H/AC为负极, GP-NH₂/AC 为正极, 组装不对称电容器(GP-SO₃H /AC||GP-NH₂/AC)用于电容脱盐, 其平均脱盐速率可达0.99 mg·g^-1·min^-1, 比纯AC电极提高了接近5倍. 充放电速率提高了30%; 而且由于正、负极表面固有电荷的存在, 大大降低了反离子效应, 电流效率由40% (纯AC||AC对称电容器)提高到92.8%. 表明电极内功能化导电石墨烯的存在既提高了导电性, 又兼具离子选择性的作用, 从而明显改善电极的脱盐性能.     

梳齿式微机械加速度计静态模型的辨识

讨论了一种梳齿式微机械加速度计的静态模型。从加的静态输入入手，求得加速度计平衡的输出关系式，还讨论了敏感输入轴垂直的横向加速度输入分量对输出的影响。在理论分析的基础上，根据离心机试验结果求得加速度计的静态模型。     

多段电容式锅炉液位测量系统设计

由于传统的锅炉汽包水位测量多采用差压式水位计、云母水位计等方法,测量过程中存在汽水分界面不明显,需要温度、压力补偿及投入麻烦等缺陷,为解决上述问题,提出了一种基于电容数字转换技术专用芯片Pcap01的智能多段式液位测量系统,并且应用HART通讯单元访问传感器的测量过程参数、设备组态、校准等信息。对多段电容式液位测量系统的总体方案、传感器设计、电容测量电路、HART通讯电路的设计进行了详细论述,同时设计了HART通讯软件和液位测量采集软件。对所设计的多段电容式锅炉液位测量系统经过试验表明,该液位计精度高、操作简单方便,解决了传统液位测量的缺陷,可以满足实际现场要求。     

Equivalent circuit of Warburg impedance

Justification is presented for the principles of construction of the simplest equivalent circuit for Warburg impedance that follow from the properties of the conductivity function (CF) and logarithmic conductivity function (LCF) of RC two-terminal networks with lumped and distributed parameters. The possibility is shown of presenting CF in the form of a sum of parameters of the same type or in the form of a product of factors of two types. The methods of construction of asymptotic LCFs are considered. Relationships are obtained that allow modeling Warburg impedance with two and three serial capacitive circuits on the basis of the performed analysis.     

Features of particle excitation in high-frequency capacitive discharge

The efficiencies of excitation of different atomic and molecular levels of a gaseous medium by a low-current high-frequency capacitive discharge (HFCD) and a dc discharge are compared theoretically. It is shown that for transitions between lower vibrational levels of molecules an increase in spectral line intensity by a factor of 1.2–1.6 is observed, and for neon transitions from high-lying levels, by a factor of 1.5–3.0. The stability of low-current HFCD is experimentally investigated for different configurations of gas-discharge gaps. The results of these investigations are used in developing compact planar and coaxial HFCD lasers. B. I. Spepanov Institute of Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220071. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 291–296, May–June, 1997.     

Ion flux's pressure dependence in an asymmetric capacitively coupled rf discharge in NF<Subscript>3</Subscript>

Starting from an analytical macroscopic/phenomenological model yielding the self-bias voltage as a function of the absorbed radio-frequency (rf) power of an asymmetric capacitively coupled discharge in NF₃ this paper studies the dependence of the ion flux onto the powered electrode on the gas pressure. An essential feature of the model is the assumption that the ions' drift velocity in the sheath near the powered electrode is proportional to E ^α, where E=−ΔU (U being the self-bias potential), and α is a coefficient depending on the gas pressure and cross section of elastic ion-neutral collisions. The model also considers the role of γ-electrons, stochastic heating as well as the contribution of the active electron current to the global discharge power balance. Numerically solving the model's basic equations one can extract the magnitude of the ion flux (at three different gas pressures) in a technological etching device (Alcatel GIR 220) by using easily measurable quantities, notably the self-bias voltage and absorbed rf power.     

超级电容器用无定形V2O5电容性能研究

本文采用淬冷法制备了V₂O₅样品。采用FTIR、XRD对其进行了表征。结果表明所制样品为无定形V₂O₅。通过循环伏安法和恒电流充放电测试研究其电容特性，并探讨了电化学反应机理。电化学性能测试结果表明，水基电解液种类及浓度、电压范围、扫描速度、电流密度均对无定形V₂O₅ 电容性能产生影响。在1 mol·L^-1 NaNO₃溶液中，电位窗口为-0.2～0.8 V(vs SCE)范围内，5 mV·s^-1的扫描速度下，无定形V₂O₅具有良好的电容性能；在250 mA·g^-1的电流密度下，比电容为185.1 F·g^-1，循环性能良好。     

A capacitive sensor based on molecularly imprinted polymers and poly( p -aminobenzene sulfonic acid) film for detection of pazufloxacin mesilate

A novel capacitive sensor for pazufloxacin mesilate (pazufloxacin) determination was developed by electropolymerizing p-aminobenzene sulfonic (p-ABSA) and molecularly imprinted polymers (MPs), which was synthesized through thermal radical copolymerization of metharylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of pazufloxacin template molecules, on the gold electrode surface. Furthermore, 1-dedecanethiol was used to insulate the modified electrode. Alternating current (ac) impedance experiments were carried out with a Model IM6e to obtain the capacitance responses. Under the optimum conditions, the sensor showed linear capacitance response to pazufloxacin in the range of 5 ng·mL⁻¹ to 5 μg·mL⁻¹ with a relative standard deviation (RSD) 5.3% (n=7) and a detection limit of 1.8 ng·mL⁻¹. The recoveries for different concentration levels of pazufloxacin samples varied from 94.0% to 102.0%. Electrochemical experiments indicated the capacitive sensor exhibited good sensitivity and selectivity and showed excellent parameters of regeneration and stability. Supported by the National Natural Science Foundation of China (Grant No. 20675064), the Natural Science Foundation of Chongqing City (Grant No. CSTC-2004BB4149 and 2005BB4100) and High Technology Project Foundation of Southwest University (Grant No. XSGX02).     

A capacitive sensor based on molecularly imprinted polymers and poly(p-aminobenzene sulfonic acid) film for detection of pazufloxacin mesilate

A novel capacitive sensor for pazufloxacin mesilate (pazufloxacin) determination was developed by electropolymerizing p-aminobenzene sulfonic (p-ABSA) and molecularly imprinted polymers (MIPs), which was synthesized through thermal radical copolymerization of metharylic acid (MAA) and ethyl-ene glycol dimethacrylate (EGDMA) in the presence of pazufloxacin template molecules, on the gold electrode surface. Furthermore, 1-dedecanethiol was used to insulate the modified electrode. Alter-nating current (ac) impedance experiments were carried out with a Model IM6e to obtain the capaci-tance responses. Under the optimum conditions, the sensor showed linear capacitance response to pazufloxacin in the range of 5 ng·mL-1 to 5 μg·mL-1 with a relative standard deviation (RSD) 5.3% (n=7) and a detection limit of 1.8 ng·mL-1. The recoveries for different concentration levels of pazufloxacin samples varied from 94.0% to 102.0%. Electrochemical experiments indicated the capacitive sensor exhibited good sensitivity and selectivity and showed excellent parameters of regeneration and stabil-ity.