Electrolytic Conductivity Measurements Research Articles

A novel method for measuring electrolytic conductivity with a polarization impedance control function

The article presents an idealized model of the differential method utilized in conductometry to measure electrolytic conductivity (EC). It identifies the main drawback of the widely used differential method: the inability to control the influence of polarization impedance on EC measurement results. A criterion for the absence of error caused by polarization effects is proposed, involving equality between the ratios of resistance differences and cell constant differences. A novel method for EC measurement, termed the double differential method, is introduced. This method relies on repeated differential impedance measurements and incorporates an additional third impedance measurement of a virtual liquid column. The new approach enables the identification of polarization impedance influence on EC measurements and the calculation of measurement errors for correction. A 3 times lower type A measurement uncertainty value can be achieved by averaging the corrected results.

Symmetric and Dissymmetric Pseudo‐gemini Amphiphiles Based on Propoxylated Ethyl Piperazine and Fatty Acids

AbstractNovel symmetric and dissymmetric pseudo‐gemini surfactants are synthesized using ethylpiperazine, propylene oxide and six different fatty acids (capric, lauric, myristic, palmitic, stearic, oleic) as starting materials. The synthesis follows a simple pathway excluding heating or catalyst. Important surface activity properties including critical micelle concentration (CMC), surface tension at CMC (γCMC), surface pressure at CMC (πCMC), negative logarithm of concentration to achieve 20 mN/m reduction in surface tension (pC20), minimum area at interface (Amin) and maximum surface excess concentration (Γmax) are obtained through surface tension and electrolytic conductivity measurements. Antimicrobial properties of the synthesized amphiphiles are evaluated using disk diffusion method and are compared to those of standard antibiotic agents. Particle size distribution patterns are obtained using dynamic light scattering (DLS). This work investigates the effect of dissymmetry on various surface activity and antimicrobial properties. Dissymmetric pseudo‐gemini amphiphiles have a few times higher CMC compared to analogous symmetric surfactants. However, better antimicrobial properties are observed when there is some dissymmetry between hydrophobic groups.

Characterization and Application of a Synthesized Novel Poly(chlorobis(1,10-phenanthroline)resorcinolcobalt(II) chloride)-Modified Glassy Carbon Electrode for Selective Voltammetric Determination of Cefadroxil in Pharmaceutical Formulations, Human Urine, and Blood Serum Samples.

Cefadroxil belongs to the β-lactam antibiotics, mainly used for the treatment of various bacterial infections, caused by Gram-positive and Gram-negative bacteria. However, it is also encountering serious bacterial resistance, necessitating continuous monitoring of its level in pharmaceutical and biological samples. This study presents a selective, accurate, and precise square-wave voltammetric method based on a novel poly(chlorobis(1,10-phenanthroline)resorcinolcobalt(II)chloride)-modified glassy carbon electrode (poly(CP2RCoC)/GCE) for determination of cefadroxil (CDL). UV-vis spectroscopy, FT-IR spectroscopy, metal and halide estimation, CHN elemental analysis, and electrolytic conductivity measurement results confirmed the synthesis of the title complex modifier. Electrode characterization results revealed modification of the surface of the electrode by an electroactive and a conductive polymer film (poly(CP2RCoC)/GCE), leading to an improved effective electrode surface area. In contrast to the bare electrode, the appearance of an irreversible oxidative peak at a much reduced potential with a 7-fold current enhancement at poly(CP2RCoC)/GCE showed the catalytic effect of the modifier toward oxidation of CDL. The square-wave voltammetric current response of poly(CP2RCoC)/GCE showed a linear dependence on the concentration of CDL in the range of 1 × 10-7-3.0 × 10-4 M with a detection limit of 4.3 × 10-9. The CDL level in the selected two tablet brands was in the range of 97.25-100.00% of their labeled values. The spike recovery results in tablet, human blood serum, and urine samples were 98.85-101.30, 99.20-100.39, and 98.10-99.99%, respectively. Interference recovery results with a less than 4.74% error, lower LoD, and wider dynamic range than the previously reported methods validated the potential applicability of the present method with excellent accuracy and sensitivity based on the novel mixed-ligand complex-modified GCE (poly(CP2RCoC)/GCE) for determination of CDL in various real samples with a complex matrix.

Electrolytic conductivity measurements for ten ionic liquids

Electrolytic conductivity measurements for a total of ten ionic liquids (ILs) (four N-alkyl-N-methyl pyrrolidinium cations [Cnmpyr] and six 1-(methyl)benzyl-3-alkyl imidazolium cations ([Bnmim] or [MeBnCnmim]), all paired with bistriflimide [Tf2N] anions) are reported at p = 0.1 MPa over T = 293.15 – 323.15 K. All samples were thoroughly dried under vacuum and their water content before and after measurements was determined by Karl Fischer titration. For the conductivity measurements, an impedance bridge technique was used in conjunction with a sealed cell equipped with platinum black electrodes. The cell constant (Kcell = 101 m − 1) was determined with standard aqueous KCl solutions before and after measurements. The results show that electrolytic conductivity increases with increasing temperature in both families of ILs, while conductivity decreases as the length of the IL side chain increases, which is associated with increase in IL viscosity. Conductivities of the pyrrolidinium ILs were consistent with other data for these compounds already reported in the literature. The conductivities of the 1-(methyl)benzyl-3-alkyl imidazolium ILs are reduced by ∼70-90% compared to the analogous 1-alkyl-3-methylimidazolium ILs

Indonesian proficiency testing for electrolytic conductivity measurement of synthetic wastewater: a comparison of performance evaluation based on four standardized performance statistics

Indonesian proficiency testing for electrolytic conductivity measurement of synthetic wastewater: a comparison of performance evaluation based on four standardized performance statistics

A FOUR TERMINAL AXIAL-BISHIELDED NETWORKS

An impedance measurement object with an H-shaped four-terminal equivalent substitution circuit is considered. An error analysis was performed for sensors whose non-informative supply resistances are of the same order or exceed the measured impedance. A new definition of four-terminal impedance has been proposed, namely four-terminal axial be-shielded (FTABS) measuring object. Based on such new definition, the scheme of axial-bishielded bridges is proposed for precision measurement of temperature and electrolytic conductivity of liquids. Such bridges differ from the well-known coaxial bridges since the former ones have an additional circuit for equipotential protection, which is located between the flow circuits of direct and reverse currents. References 18, figures 7.

Determination of Diffusion Coefficients of Heavy Metal Ions (Ni3+, Zn2+, Ba2+, and Mn2+) at Infinite Dilution through Electrolytic Conductivity Measurements

One important parameter to examine the behavior and mass transfer properties of heavy metal ions is the diffusion coefficient. Due to the costly methods of its determination, a simple process correlating the molar conductivity data to diffusion coefficient was utilized. Molar conductivity data were determined for five (5) different dilute concentrations of the chlorides of the heavy metal ions (Ni3+, Zn2+, Ba2+, and Mn2+) and at temperatures ranging from 303.15 to 323.15 K. The infinite dilution diffusion coefficients of the heavy metals were estimated using the Nernst-Haskell equation and Nernst-Einstein equation. The molar conductivity and the diffusion coefficients values of the ions were in the order of Ba2+ > Mn2+ > Zn2+ > Ni3+ with the Ba2+ having the highest molar conductivity with a correlated infinite dilution diffusion coefficient of 1.6565 × 10-9 m2/s at 303.15 K. This study was able to predict the values of the infinite dilution diffusion coefficient of heavy metal ions and could contribute to a better understanding of the mobility of heavy metal ions in a water environment

Synthesis and characterization of naphthaldiimine-based ruthenium(III) complexes; homogenous catalytic hydrogenation and isomerization of internal and terminal alkenes

This study is concerned with synthesis and characterization of four naphthaldiimine ligands and their ruthenium(III) complexes. The tetradentate diimines were synthesized by a Schiff condensation reaction between 2-hydroxy-1-naphthaldehyde and various aliphatic diamines with chains of 2, 4, 5 and 6 carbon atoms. Analytical, mass spectra, thermal and electrolytic solution conductance measurements demonstrated the molecular formulas of the prepared Ru(III) complexes. A distorted octahedron stereochemistry was proposed for these six-coordinate naphthaldiimine-based Ru(III) complexes. Processing of X-ray diffraction data of 1 and 2 by the computer program Expo 2014 confirmed the final structural formulas that were determined based on spectroscopic and magnetic studies. The catalytic potential of the newly synthesized naphthaldiimine-based Ru(III) complexes in the hydrogenation of 1-hexene and cyclohexene was investigated. The Ru(III) catalysts catalyzed the double bond migration of 1-hexene to give trans-2-hexene which catalytically isomerizes to the stereo isomer cis-2-hexene. The induction step of the catalytic cycle is the formation of the actual catalyst, metal hydride (Ru(III)-H), that was generated in situ during the hydrogenation reaction. Several parameters controlling the catalytic reactions including the structure of the Ru(III) complex, the phase type of catalysis, and the quantity and nature of the solvents used were investigated. Various experiments made it possible to suggest a mechanism for the hydrogenation reactions.

Study Interionic Attraction of anionic dyes by Electrolytic Conductivity Measurement

Measurements of conductivity in aqueous solution are recommended for studying the behavior of some dyes. The conductivity of two azo dyes C.I. Acid Red 151 (AR 151) and C.I. Mordant green 17 (MG17) have been studied. The ionization degree, α and Van,t Hoff’s factor ,i, were calculated; their values decrease with increasing dye concentration and increase with increasing temperature. The mobility, µ, the activation energy, E, were also calculated. The findings indicate that interionic attractions and connections are present. Dyes ions tend to self-associate. Since these textile dyes were applied from aqueous systems, it is important to understand the association of dyes. The molecular aggregation of two sulphonated dyes studied by measuring the electrolytic conductivity in aqueous solutions as a function of dye concentration and temperature. Aggregation number, aggregation constant and shape of aggregate were calculated. As expected the aggregation number decreases with increasing temperature, and that tends to J-aggregation which enhance the devices performance such as xerography, sensors in presence of different additives.

Seasonal variability in the supply of dissolved matter to catchments of basins without outlets in northern Poland, measured by selected physiochemical indicators

The aim of the study is to determine the seasonal variability in the size of dissolved matter supplied to selected kettle ponds located in the glacial areas of northern Poland, using selected physicochemical indicators. The study area consisted of the drainage basin of the Parsęta River and a small catchment of the Borucinka River that flows across the Kaszubskie Lake District in northern Poland. Measurements of pH, electrolytic conductivity, oxygenation, and water temperature were performed in the field. The concentration of Ca2+, Mg2+, Na+, K+, HCO3-, SO42-, Cl-, NH4+, NO3-, PO43- was measured in the laboratory. Also, the atmospheric precipitation was determined using automatic precipitation stations. Climate conditions served as the primary determinants of seasonal change in the supply of dissolved matter to basins without outlets in the drainage basin. This is especially true of atmospheric precipitation and the effects of vegetation in the contact zone between precipitation and the biosphere. In the case of biogenic substances, one of the main factors was the length of the vegetation season. The main determinant of the hydrochemical state of kettle ponds was land use.

Primary level electrolytic conductivity measurements at National Metrology Institute of Turkey (TUBITAK UME)

Primary level electrolytic conductivity measurements at National Metrology Institute of Turkey (TUBITAK UME)

The Relationship Between Post-harvest Storage Conditions and Membrane Leakage in the Context of Blackheart in Potato Tubers

The relationship between potato (Solanum tuberosumL.) tuber membrane permeability and storage conditions were examined. Tubers from four potato cultivars were stored for 1 year at 2 °C and4 °C, and tubers transferred from 4 °C to 2 °C for 48 hours. Electrolyte conductivity measurements taken from two discs of four potato cultivars with six biological replicates as well as different tissues types including the pith, cortex and parenchyma. The results showed that the longer the storage time and lower the temperature, the higher the electrolyte conductivity of the tissues. And different tissue types pith, cortex and parenchyma had different electrolyte conductivity susceptibility pattern under different storage conditions. Overall, the parenchyma has highest electrolyte leakage and following are pith, cortex has lowest among three different tissue types. However, cultivars that are resistant to Blackheart, surprisingly had higher electrolyte conductivity compared to the Blackheart-susceptible cultivars. Overall, the work demonstrates that storage conditions have a significant effect on membrane leakage but that this doesn’t appear to relate directly to susceptibility to Blackheart.

Effect of Introducing Nonideal Capacitance in the Estimation of the Solution Resistance for Accurate Electrolytic Conductivity Measurements.

The standardization of secondary electrolytic conductivity cells requires the use of a certified reference material. The accepted certification method involves electrochemical impedance spectroscopy (EIS) to estimate the material’s solution resistance. This method normally assumes that the impedance’s imaginary component can be neglected; and hence, the measured impedance approximates the real impedance. Thus, a linear extrapolation of the impedance versus the period (inverse frequency) yields solution resistance. However, experimental impedance data usually do not exhibit a linear behavior over the spectra of frequency, which strongly suggest that the ideal capacitive assumption may not strictly apply. To account for the observed nonlinear behavior, we have proposed to introduce the concept of a constant phase element (CPE) to the analysis of impedance. This approach leads to the development of a relationship that improves the fitting of experimental data and improves the accuracy of the estimation, by establishing a critical frequency where extrapolation should be done. Finally, we are presenting simulated results to demonstrate how sizeable capacitive effects can influence the determination of solution resistance, and a final analysis to estimate the impact on constant cell or electrolytic conductivity values.

A theoretical study on resistance of electrolytic solution: Measurement of electrolytic conductivity

We propose a theoretical approach to determine the conductivity of electrolytic solution using sine waveform voltage as a triggering signal. The approach is based on the acquisition of the complex impedance in two-electrode conductance cell by analyzing the equivalent circuit. We deduce the formula of resistance in electrolytic solution by doing a series of calculations in transformation, simplification, and replacement for the complex impedance and solving the quadratic equation with unknown solution resistance. Even though there exists electrode polarization or the distributed capacitance which may affect the measurement, we can still obtain the electrolytic conductivity. In this paper, we focus on deducing the expression for the value of resistance in electrolytic solution. To our knowledge, this is the first report on directly deducing the resistance’s value. In particular, the extent of the electrode polarization is also analyzed and mathematically formulated. The experimental results show that the method proposed in this paper can achieve high precision.

UNCERTAINTY ESTIMATION FOR THE MEASUREMENT OF ELECTROLYTIC CONDUCTIVITY BY SECONDARY METHOD USING CELL TYPE D

Electrolytic conductivity measurement is one of the important parameters to evaluate the concentration of dissolved substances in a solution and has been widely used in various fields of life, science, and technology. It was being used for process control and quality assurance. The traceability of the measuring results is a crucial requirement to guarantee reliability. The electrochemistry laboratory - chemical metrology Indonesia has started to develop a secondary method for electrolytic conductivity measurement. The objective of this work is to provide a traceability chain for electrolytic conductivity measurement in Indonesia through secondary reference material of Potassium Chloride (KCl) 1 M. The secondary reference material of KCl 1 M can be used as a standard for calibrating the conductivity meter, especially in seawater analysis. The secondary reference material that is developed has an electrolytic conductivity value of about 111 mS/cm and was measured using cell type D from ZMK, Germany. This cell is made from glass with two platinization electrodes inside. The distance of the electrodes is 60 mm, and the diameter of the electrode is 20 mm. The uncertainty measurement was estimated according to the ISO GUM recommendation by identifying all possible uncertainty sources in the electrolytic conductivity measurement process. The result showed that the expanded uncertainty of electrolytic conductivity measurement for KCl 1 M by a secondary method using cell type D was 0.33% at k=2 for 95% confidence level with a repeatability of the measurements and cell constant as the biggest sources of uncertainty which contributed as 80% and 17%, respectively.

Competency evaluation on electrolytic conductivity measurement in Indonesia by an unofficial bilateral comparison between RCChem-LIPI and NIMT

The Research Centre for Chemistry—Indonesian Institute of Sciences (RCChem-LIPI) organized an unofficial bilateral comparison on electrolytic conductivity with the Electrochemistry Laboratory—National Institute of Metrology Thailand (NIMT). The electrochemical laboratory RCChem-LIPI, as a Designated Institute for Chemical Metrology in Indonesia, started to develop the secondary method on electrolytic conductivity measurement in 2016. Therefore, the purpose of this unofficial bilateral comparison was to test the ability of RCChem-LIPI laboratory and see the capacity building progress in doing the conductivity measurement. There were two samples containing potassium chloride prepared by RCChem-LIPI, and both samples had the electrolytic conductivity value in the range of 1000 µS cm−1 to 20000 µS cm−1. The samples were sent to NIMT and then measured at the same time duration. The results were compared, analyzed and evaluated based on their assigned values. The assigned values were 15309 µS cm−1 and 6650 µS cm−1 for samples A and B, respectively. The deviation for each measurement result was determined, and the uncertainties were also calculated from the data reported by both laboratories. The data evaluation and analysis confirm that the measurement results for both participant laboratories were in agreement with the assigned value of this unofficial bilateral comparison.

Estimation of diffusion coefficients of ascorbate-based ions at infinite dilution through electrolytic conductivity measurements

Ascorbic acid is a naturally-occurring organic compound that has high water solubility. One significant parameter that can describe the mobility and transport of ascorbic acid and its mineral salts in water systems is the diffusion coefficient. Molar conductivity data were determined from electrolytic conductivity data measured at different concentrations of ascorbate-based ions (dilute region) and temperatures (293.15 to 313.15 K). From these data, the infinite dilution diffusion coefficients of the ascorbic acid and mineral salts in water were estimated using the Nernst-Haskell Equation. The Nernst-Einstein Equation was used to predict the infinite dilution self-diffusion coefficients of the representative ascorbate-based ions ([H+], [Na+], and [Ca2+]). For most temperatures and concentrations considered, the Ca2+ cation had the highest molar conductivity but the [H+] cation had the highest correlated infinite dilution self-diffusion coefficient of 11.4105 × 10−9 m2/s at 313.15 K. The [Na+] and [Ca2+] cations had values of correlated infinite dilution self-diffusion coefficient of 2.6263 × 10−9 m2/s and 2.4045 × 10−9 m2/s at 313.15 K, respectively. The molar conductivity and diffusion coefficient of the ions at infinite dilution were in the order of [H+] > [Na+] > [Ca2+]. It was found that an increase in temperature also increases the diffusion coefficient. This study was able to estimate infinite dilution diffusion coefficient data for ascorbate-based ions. Thus, the results of this study can serve as a basis and reference for future researches to have a better understanding of the fate and transport of ascorbate-based ions in the environment.

A Study of the Physical Properties of Li-Ion Battery Electrolytes Containing Esters

Adding esters as co-solvents to Li-ion battery electrolytes can improve low-temperature performance and rate capability of cells. This work uses viscosity and electrolytic conductivity measurements to evaluate electrolytes containing various ester co-solvents, and their suitability for use in high-rate applications is probed. Among the esters studied, methyl acetate (MA) outperforms other esters in its impact on the conductivity and viscosity of the electrolyte. Therefore, viscosity and conductivity were measured as a function of temperature and LiPF6 concentration for electrolytes ethylene carbonate (EC): linear carbonate: MA in the ratio 30:(70-x):x, where linear carbonate = {ethyl methyl carbonate (EMC), dimethyl carbonate (DMC)}, and x = {0, 10, 20, 30}. Adding MA leads to an increase in conductivity and decrease in viscosity over all conditions. Calculations of electrolyte properties from a model based on a statistical-mechanical framework, the Advanced Electrolyte Model (AEM), are compared to all measurements and excellent agreement is found. All electrolytes studied roughly agree with a Stokes’ Law model of conductivity. A Walden analysis shows that the ionicity of the electrolyte is not significantly impacted by either MA content or LiPF6 concentration. Li[Ni0.5Mn0.3Co0.2]O2/graphite cells containing MA were cycled at charging rates up to 2C and showed improved cycling performance.

Addressing the challenges of traceable electrolytic conductivity measurements in water

This paper addresses the challenges of making accurate and traceable electrolytic conductivity cell constant calibrations and sensor system calibration measurements over a wide range of conductivity, from 5.5 µS m−1 (ultrapure water) up to 140 000 µS m−1, where stable and reliable commercial certified reference materials (CRMs) are available. The challenges of making electrolytic conductivity measurements in the time domain versus the frequency domain are discussed and the relationship between the two domains is analysed in terms of a Gaver–Stehfest algorithm for inverse Laplace transform. Data from a commercial current-step-pulse-based sensor reader operating in the time domain are compared with accurate and traceable data from a closed-flow-loop electrolytic conductivity measurement system operating in the frequency domain and traceable to the SI length unit. In the high conductivity range, the readouts of the sensor reader are observed to deviate from traceable conductivity values by up to 10 times the estimated standard measurement uncertainty, which is in the range 0.07%–0.17%. If accurate conductivity calibrations are required (<1%), the usual method of calibrating a conductivity sensor system at a high conductivity level, where CRMs are available, and relying on the same calibration for low conductivity measurements is, therefore, risky.

Bridging the Gap Between Ultrapure Water and Reference Materials in Electrolytic Conductivity Measurements

This paper reports a closed-flow-loop electrolytic conductivity measurement system enabling calibration of conductivity sensors from the conductivity level of ultrapure water (UPW) at $5.5~\mu \text{S}$ /m up till the range of 10 to 140 mS/m, where stable certified reference materials (CRMs) for conductivity are available. The system is traceable to the SI unit system. A comparison made with another electrolytic conductivity measurement system, which is based on Jones-type conductivity cells designed to be used primarily for conductivities larger than ~10 mS/m, shows an agreement better than 0.1%. The most commonly used calibration method of conductivity sensors is based on CRMs and the extrapolation of the data to low conductivity values ( $ /m). In contrast, the present closed-flow-loop electrolytic conductivity measurement system is based on the measurements made at conductivity levels where the sensor is used; it is, therefore, a better alternative.