用氟离子选择电极测定水中的氟

氟的测定方法主要有茜素铜比色法、硝酸钍容量法及氟离子选择电极法。前两种方法虽然准确度高，但消耗试剂多，费时，且硝酸钍有放射污染而很少使用。离子选择电极法具有操作简便、响应速度快等特点，适用批量样品测定。     

氟离子选择电极法测定磷酸中氟含量

<正>湿法磷酸中的氟不仅使设备严重腐蚀,而且对环境及人体都有危害。本文介绍采用氟离子选择电极法测定磷酸中氟含量及测定中应注意的问题。1实验部分1.1主要仪器及试剂主要仪器及试剂按GB/T 1872—1995执行。1.2样品处理称取磷酸试样0.2～0.3 g(精确至0.000 1 g)     

离子选择电极法分析非离子／阴离子表面活性剂体系

利用自制表面活性剂离子选择电极,采用电位滴定法测定了非离子表面活性剂脂肪醇聚氧乙烯醚(AEO9)与阴离子表面活性剂十二烷基硫酸钠(SDS)混合溶液中的SDS浓度。当AEO9与SDS的摩尔比约小于2∶1时,可用此种方法定量测定混合体系中的SDS的浓度,与滴定单一SDS溶液的结果对照,相对误差在1%以内。     

Innovation in potentiometry: 3D-printed polylactic acid-based ion-selective bulk electrode membranes

Journal of Applied Electrochemistry - Although ion-selective membrane-based potentiometric sensors have already proved their analytical performance in several fields of life, their applicability is...     

Design of an ion-selective electrode analytical system for monitoring copper in electrochemical reactors

A flow-through cell using ion-selective electrodes has been designed for continuous on-line monitoring of electrochemical reactors. A full range of design considerations is discussed and the characteristics of the cell investigated. Optimal operating conditions are found, of which solution flow rate and constancy of temperature are particularly important. The cell was also designed to have a rapid response time and minimal dead volume so as to give continuous measurements of gradually changing metal ion concentrations. Performance has been evaluated using laboratory-simulated conditions and pilot-plant operation of the Ecocell, a rotating-cylinder electrode reactor for the electrowinning of copper from dilute solutions (10–1000 ppm).Nomenclature C ₀ initial metal ion concentration (ppm) - C _t metal ion concentration at timet (ppm) - E potential (V) - E ^{0, 1} a constant potential (V) - F Faraday constant (= 96498 C) - k apparent rate constant (s^–1) - r volumetric flow rate (cm³ s^–1) - R universal gas constant (= 8.314 J K^–1) - T absolute temperature (K) - t time (s) - V volume of gradient device (cm³) - relaxation time (s)     

Estimation of ion-site association constants in ion-selective electrode membranes by modified segmented sandwich membrane method

A method aimed at potentiometric estimation of the association of ions with ion-exchanger sites and charged ionophores in ion-selective electrode membranes is proposed. The method relies on the measurements of segmented sandwich membrane potentials. It is shown theoretically that the quantification of ion association requires use of weakly associated ionic additive whose concentration in the working segment of the sandwich must be varied. This is in contrast with well-established technique of ion to neutral ionophore complexation measurements. The advantages and limitations of the novel method are critically evaluated. Association of ions in plasticized poly(vinylchloride) membranes is studied experimentally. Experimental results are provided related to the association of K⁺, Na⁺, Cs⁺, and NH₄⁺, and also Ca²⁺ with commonly used sites: tetra(p-Cl-phenyl)borate anion and calcium-selective lipophilic ion-exchanger bis[4-(1,1,3,3-tetramethylbutyl)phenyl]phosphate.     

用线性回归方程计算离子选择电极法测定的氟含量

研究一种基于氟离子选择电极的线性范围,提出了用四点校正法和线性回归方法计算测定氟含量的方法,w(F)在0.02%～5.00%,回收率94%～100.2%,相对标准偏差(RSD)0.4%～2.1%。该方法具有准确、简便、快速、灵敏、选择性好的特点,明显优于传统的测定计算方法。     

硫化罐计算机群控系统

硫化罐计算机群控系统由硫化罐、液压站、蒸汽管路、压力和温度检测系统及计算机控制系统组成，可同时控制1～12台硫化罐并检测硫化参数，自动控制硫化罐内、外腔压力和温度，保存每次硫化的生产记录以供随时查阅和打印。该系统自动化程度高，操作便捷，安全可靠，有利于稳定和提高产品质量。     

Response of an ion-selective electrode to butylmethylimidazolium and other ionic liquid cations. Applications in toxicological and bioremediation studies

The response of an ion-selective membrane electrode to 1-butyl-3-methylimidazolium (BMIm) and other ionic liquid cations is presented. The sensing membrane comprised the ionic liquid BMIm-PF₆ in a plasticized PVC matrix. The electrode showed a fast, stable and Nernstian response over a wide concentration range. The partition coefficients of the imidazolium cations between water and the membrane were obtained. A relationship between these values and the toxicity of the corresponding imidazolium chlorides was found. The sensor was applied to the determination of BMIm in spiked water and to monitor the biosorption of BMIm by dry biomass.     

In situ synchrotron radiation grazing incidence X-ray diffraction—A powerful technique for the characterization of solid-state ion-selective electrode surfaces

An in situ surface study of the iron chalcogenide glass membrane ion-selective electrode (ISE) in aqueous media has been undertaken using a tandem technique of mixed potential/synchrotron radiation grazing incidence X-ray diffraction (SR-GIXRD) and atomic force microscopy (AFM). This work has simultaneously monitored the mixed potential and in situ surface diffraction patterns of this crystalline glassy material, showing that the observed gradual shift of the electrode potential in the anodic direction is linked to the preferential dissolution of the GeSe (1 1 1), GeSe (1 0 1) and GeSe (1 4 1) and/or Sb₂Se₃ (0 1 3), Sb₂Se₃ (2 2 1) and Sb₂Se₃ (0 2 0) surfaces. Expectedly, these observations are internally consistent with preferential oxidative attack of the crystalline regions of the membrane comprising GeSe and/or Sb₂Se₃, as evidenced by AFM imaging of the electrode surface. Clearly, this work corroborates the results of previous ex situ surface studies on the iron chalcogenide glass ISE, whereby it was shown that alkaline saline solutions have a tendency to alter the surface chemistry and concomitant response characteristics of the ISE.     

Method for monitoring chloride levels in steam condensate in thermal power plants using reverse osmosis membranes and an ion-selective electrode

Current methods for monitoring chloride in steam condensate in thermal power plants cannot measure the recommended target level (2 ppb) or are too complex and maintenance intensive for smaller plants. We propose a new relatively low-cost, easy-to-use, low-maintenance method, in which chloride in steam condensate is separated and concentrated with reverse osmosis membranes and the chloride in the concentrate stream is measured using an ion-selective electrode. This concentration-and-measurement system was demonstrated to accurately and quickly detect changes in chloride levels in steam condensate at operationally relevant levels (2–10 ppb) and as low as 0.6 ppb.     

Uranyl ion-selective optical test strip

A novel, optical sensor, test strip has been developed for the spectrophotometric determination of trace amounts of uranyl ions, UO₂²⁺, based on immobilization of C.I. Mordant Blue 29 (Chromazurol S)/cetyl N,N,N-trimethyl ammonium bromide ion pair on a triacetyl cellulose membrane. Optimization of the sensor for the detection of low levels of uranyl ion is described. The test strip responded linearly to uranyl ions between 3.0 × 10^?7 and 6.0 × 10^?5 mol L^?1; the reproducibility of the sensor at a medium level of UO₂²⁺ activity was ±0.55%. The optical sensor can be regenerated using 0.01 mol L^?1 HCl or 0.01 mol L^?1 NaF solution after 10 min. The developed test strip was used in the determination of UO₂²⁺ in ground water samples.     

Continuous ion-selective separations by shock electrodialysis

Water purification remains a challenge across sectors worldwide, especially the efficient removal of specific (toxic or valuable) dissolved ions at low salinity. In this article, shock electrodialysis (SED) is shown for the first time to have this capability, by demonstrating continuous separation of magnesium ions from aqueous mixtures of NaCl and MgCl₂. By systematically measuring the composition of all input and output streams, the mechanisms that drive selectivity, current efficiency, and desalination are revealed, as well as strategies to improve performance. For solutions initially rich in sodium, highly selective (> 98%) continuous removal of magnesium can be achieved with only moderate (50–70%) total salt removal. This remarkable selectivity is associated with super-diffusive ion transport, mediated by charged double layers in a porous glass frit, behind a steady deionization shockwave in cross flow.     

Computer-controlled apparatus for automated development of continuous flow methods

An automated apparatus to assist in the development of analytical continuous flow methods is described. The system is capable of controlling and monitoring a variety of pumps, valves, and detectors through an IBM PC-AT compatible computer. System components consist of two types of peristaltic pumps (including a multiple pump unit), syringe pumps, electrically and pneumatically actuated valves, and an assortment of spectrophotometric and electrochemical detectors. Details of the interface circuitry are given where appropriate. To demonstrate the utility of the system, an automatically generated response surface is presented for the flow injection determination of iron(II) by its reaction with 1,10-phenanthroline.     

Thermodynamics of ionic-association in aqueous solutions of Ca and Mg organic salts using ion-selective electrode technique—I. Formates, acetates, propionates and butyrates

The divalent selective electrode together with high precision solid state, digital pH -mv -meter makes broader application of potentiometry in physical and inorganic chemistry a certainty. The above set-up is used to determine the stoichiometric constants, K, for Ca and Mg ions association with formates, acetates, propionates and butyrates at 25°, 35° and 45°C in aqueous media. The K-values were converted to infinite dilution K_A values were found to be 8.4 LM⁻¹, 10.4 LM⁻¹, 19.1 LM⁻¹ and 19.3 LM⁻¹ for calcium salts of formate, acetate, propionate and butyrate respectively. Also K_A values for Mg salts of formate, acetate, propionate and butyrate were found to be 7.8 LM⁻¹, 9.5 LM⁻¹, 13.1 LM⁻¹ and 13.1 LM⁻¹ respectively. Other thermodynamic parameters such as ΔG°, ΔH° and ΔS° are also obtained from the variation of K_A with temperature for each salt. The data are interpreted relative to each other on basis of pK_a of the corresponding organic acid. Their temperature behaviour is similar to those salts derived from strong acids such as sulphates, rather than weak acids.     

微机励磁装置在硫酸装置余热发电中的应用

分析了BLK-5同步发电机微机励磁装置在120 kt/a硫铁矿制酸余热发电3 000 kW发电机组励磁系统的相应配置和使用情况,实践证明:该微机励磁装置功能齐全,结构简单,维护方便,性能优越,使用后不仅提高了系统控制精度、可靠性和稳定性,而且有效解决了余热发电装置运行可靠性差、励磁系统故障率高等一系列的问题,大大降低了余热发电机组的故障率,减少了维修工时和员工的劳动强度,增加了一定的社会效益和经济效益。