Chloride Ion Selective Electrode Research Articles

A highly sensitive, long-time stable Ag/AgCl ultra-micro sensor for in situ monitoring chloride ions inside the crevice using SECM

Tracking the variation of Cl− timely within the crevice is of great significance for comprehending the dynamic mechanism of crevice corrosion. The reported chloride ion selective electrodes are difficult to realize the long-time Cl− detection inside the confined crevice, due to their millimeter size or a relative limited lifespan. For this purpose, an Ag/AgCl ultra-micro sensor (UMS) with a radius of 12.5 μm was fabricated and optimized using laser drawing and electrodeposition techniques. Results show the AgCl film's structure is significantly impacted by the deposited current density, and further affects the linear response, life span and stability of Ag/AgCl UMS. The UMS prepared at current density of 0.1 mA/cm2 for 2 h shows a rapid response (several seconds), excellent stability and reproducibility, strong acid/alkali tolerance, sufficient linearity (R2 > 0.99), and long lifespan (86 days). Moreover, combined with the potentiometric mode of scanning electrochemical microscope (SECM), the Ag/AgCl UMS was successfully applied to monitor the in-situ radial Cl− concentration in micro-regions inside a 100 μm gap of stainless steel. The findings demonstrated that there was obvious radial difference in Cl− concentration inside the crevice, where the fastest rise in Cl− concentration was at the opening. The proposed method which combines the UMS with SECM has attractive practical applications for microzone Cl− monitoring in real time inside crevice. It may further promote the study of other localized corrosion mechanism and the development of microzone ions detection method.

A half-cell reaction approach for pH calculation using a solid-state chloride ion-selective electrode with a hydrogen ion-selective ion-sensitive field effect transistor

Here, we explicitly define a half-cell reaction approach for pH calculation using the electrode couple comprised of the solid-state chloride ion-selective electrode (Cl-ISE) as the reference electrode and the hydrogen ion-selective ion-sensitive field effect transistor (ISFET) of the Honeywell Durafet as the hydrogen ion H+-sensitive measuring or working electrode. This new approach splits and isolates the independent responses of the Cl-ISE to the chloride ion Cl− (and salinity) and the ISFET to H+ (and pH), and calculates pH directly on the total scale pHtotalEXT in molinity (mol (kg-soln)−1) concentration units. We further apply and compare pHtotalEXT calculated using the half-cell and the existing complete cell reaction (defined by Martz et al. (2010)) approaches using measurements from two SeapHOx sensors deployed in a test tank. Salinity (on the Practical Salinity Scale) and pH oscillated between 1 and 31 and 6.9 and 8.1, respectively, over a six-day period.In contrast to established Sensor Best Practices, we employ a new calibration method where the calibration of raw pH sensor timeseries are split out as needed according to salinity. When doing this, pHtotalEXT had root-mean squared errors ranging between ±0.0026 and ±0.0168 pH calculated using both reaction approaches relative to pHtotal of the discrete bottle samples pHtotaldisc. Our results further demonstrate the rapid response of the Cl-ISE reference to variable salinity with changes up to ±12 (30 min)−1. Final calculated pHtotalEXT were ≤±0.012 pH when compared to pHtotaldisc following salinity dilution or concentration. These results are notably in contrast to those of the few in situ field deployments over similar environmental conditions that demonstrated pHtotalEXT calculated using the Cl-ISE as the reference electrode had larger uncertainty in nearshore waters. Therefore, additional work beyond the correction of variable temperature and salinity conditions in pH calculation using the Cl-ISE is needed to examine the effects of other external stimuli on in situ electrode response. Furthermore, whereas past work has focused on in situ reference electrode response, greater scrutiny of the ISFET as the H+-sensitive measuring electrode for pH measurement in natural waters is also needed.

An Investigation of Electrochemical Dechlorination of Wrought Iron Specimens from the Marine Environment

The research shows the benefits provided by the use of electrochemical treatment, with the application of impressed current combining the use of a porous medium for the dechlorination of large iron structures removed and/or located in the marine environment. Considering the previous work for the dechlorination of the paddle wheel of the shipwreck “Patris”, located in the Aegean Sea, this study aims to determine the optimum parameters of the amount of current density, the time and the use of the porous medium to stimulate the chloride ion diffusion into an alkaline solution. Specimens of wrought iron coming from the shipwreck were electrochemically treated and the efficiency of the method was verified by the determination of the chloride concentration removal using a chloride ion selective electrode. Samples of corrosion products before and after treatment were analyzed for chloride content using SEM-EDX analysis. The results found that changing the porous medium every 24 h with replenished alkaline solution and using a stainless steel mesh is the best approach for the dechlorination of the specimens. This electrochemical method, is economical and fast, and can be applied to the conservation of large iron structures in situ, coming from and/or located near a marine environment with less waste than the traditional dehlorination methods.

Chloride Ion-Selective Electrode with Solid-Contact Based on Polyaniline Nanofibers and Multiwalled Carbon Nanotubes Nanocomposite.

Use of the nanocomposite of chloride-doped polyaniline nanofibers and multiwalled carbon nanotubes (PANINFs-Cl:MWCNTs) for construction of ion-selective electrodes with solid-contact sensitive to chloride ions has been described. Many types of electrodes were tested, differing in the quantitative and qualitative composition of the layer placed between the electrode material and the ion-selective membrane. Initial tests were carried out, including tests of electrical properties of intermediate solid-contact layers. The obtained ion-selective electrodes had a theoretical slope of the electrode characteristic curve (-61.3 mV dec-1), a wide range of linearity (5 × 10-6-1 × 10-1 mol L-1) and good potential stability resistant to changing measurement conditions (redox potential, light, oxygen). The chloride contents in the tap, mineral and river water samples were successfully determined using the electrodes.

MIP-202 catalyst-integrated solid-contact potentiometric chloride sensor for versatile multiphasic detection of a sulfur mustard simulant

Existing sensor devices for sulfur mustard (HD) detection are commonly bulky, sluggish in response, or not sensitive enough to detect HD contamination owing to its low aqueous solubility. Herein, we describe the development of a miniaturized catalytic electrochemical sensor, in both portable and wearable configurations, for the real-time, remote/on-site wireless detection of low micromolar levels of the HD simulant, 2-chloroethyl ethyl sulfide (CEES). The screen-printed CEES potentiometric sensor relies on coating a new solid-contact chloride ion-selective electrode (Cl-ISE) with a biomimetic zirconium metal-organic framework (Zr-MOF), MIP-202-based reagent layer for catalytic CEES hydrolysis and electrochemical detection of the liberated Cl anion. We describe and characterize the use of the green MIP-202 Zr-MOF towards such CEES hydrolysis, and demonstrate its superior catalytic performance versus the established MOF catalysts UiO-66 and HKUST-1 using proton nuclear magnetic resonance (1H NMR) analysis. The attractive analytical performance of the resulting strip and textile-based sensors has been demonstrated for the detection of CEES contamination in multiphasic samples ranging from aqueous buffered solutions, drinking water to aqueous buffered aerosols.

Mean activity coefficients of KCl in the KCl–K2B4O7–H2O solutions at 288.15 K determined by cell potential method and their application to the prediction of solid–liquid equilibria of the KCl–K2B4O7–H2O system

• The unreported mixed ion interaction of Pitzer parameters in KCl–K 2 B 4 O 7 –H 2 O solutions at 288.15 K were obtained in this work. • The experimental and predicted solubilities were compared to verify the rationality of fitting parameters. After measuring the cell potential of the cell without liquid junction K-ISE | KCl ( m 1 ), K 2 B 4 O 7 ( m 2 ) | Cl-ISE with the calibrated potassium ion and chloride ion selective electrode, the mean activity coefficients of KCl in KCl–K 2 B 4 O 7 –H 2 O solutions are calculated by the Nernst equation. The single parameters β (0) , β (1) , C Φ of K 2 B 4 O 7 , and the mixed ion interaction parameters θ Cl, B 4 O 5 (OH) 4 and ψ K,Cl, B 4 O 5 (OH) 4 of the Pitzer model were determined by programming solver and mean activity coefficients in this work. Furthermore, Pitzer equation is also used to evaluate the mean activity coefficient of potassium tetraborate in the KCl–K 2 B 4 O 7 –H 2 O solutions, as well as the osmotic coefficients, water activity and excess Gibbs free energy of the mixed solutions. Additionally, the experimental measurements of phase equilibria in the ternary system KCl–K 2 B 4 O 7 –H 2 O at 288.15 K are investigated in this work. The solubilities of the salts in the ternary system at 288.15 K are predicted by using Pitzer equation and the obtained ion parameters. The comparision of experimental and calculated phase diagram is presented in detail. The prediction results show that the predicted data are in accordance with the experimental data.

Low-Cost Potentiometric Sensor for Chloride Measurement in Continuous Industrial Process Control.

Recently, the new updates in legislation about drinking water control and human health have increased the demand for novel electrochemical low-cost sensors, such as potentiometric ones. Nowadays, the determination of chloride ion in aqueous solutions has attracted great attention in several fields, from industrial processes to drinking water control. Indeed, chloride plays a crucial role in corrosion, also influencing the final taste of beverages, especially coffee. The main goal is to obtain devices suitable for continuous and real-time analysis. For these reasons, we investigated the possibility to develop an easy, low-cost potentiometric chloride sensor, able to perform analysis in aqueous mediums for long immersion time and reducing the need of periodic calibration. We realized a chloride ion selective electrode made of Ag/AgCl sintered pellet and we tested its response in model solutions compatible with drinking water. The sensor was able to produce a stable, reproducible, and accurate quantification of chloride in 900 s, without the need for a preliminary calibration test. This opens the route to potential applications of this sensor in continuous, in situ, and real time measurement of chloride ions in industrial processes, with a reduced need for periodic maintenance.

Electrochemical chloride extraction from contaminated concrete structures using anodic nickel electrode

ABSTRACT An attempt was made, at the laboratory level, to apply new external anode of an electrochemical chloride extraction (ECE) system based on Ni chemical deposition on concrete specimen surface. The procedure relied on electroless bath chemical deposition to apply anodic electrode of nickel on concrete samples. The procedures and experimental conditions of the nickel deposition on the concrete were carefully addressed. The influence of Ni films characteristics, as external anode in ECE system, on the chloride electrochemical extraction (ECE) process was investigated. ECE performance in comparison with the use of traditional titanium mesh was investigated. Several analytical tools were applied to both characterise the obtained Ni films and to study the efficiency of ECE process. These include scanning electron microscopy (SEM) to explore the morphology of the nickel films and the electron probe micro analysis (EPMA) that was performed simultaneously with SIM to gain composition analysis of the samples. Finally, chloride ion selective electrode (ISE) analytical tool was applied to study the efficiency of ECE process.

Anion-Responsive Manganese Porphyrin Facilitates Chloride Transport and Induces Immunogenic Cell Death

Anion-Responsive Manganese Porphyrin Facilitates Chloride Transport and Induces Immunogenic Cell Death

Functionalized biochar electrodes for asymmetrical capacitive deionization

Electrosorption-based capacitive deionization (CDI) has become a viable process for brackish water desalination. In this study, activated Douglas-fir biochar is used as a low-cost carbon-based alternative electrode with adsorption capacity comparable to activated carbon obtained from biomass precursors. Adding functional groups to the activated biochar enhanced salt removal capacity, providing cation and anion selectivity. The functionalized electrodes were prepared by Nafion and p-phenylenediamine treatment, respectively, which introduced sulfonate and amine functional groups to the electrode. These modification methods are versatile and can be easily performed without sophisticated laboratory environment. These modified biochar electrodes were characterized by SEM-EDX and XPS. Cyclic voltammetry and galvanostatic charge/discharge measurements were performed to analyze the electrochemical properties of both types of electrodes and the electrosorption capacity was evaluated in a 3D-printed capacitive deionization flow cell using a chloride ion-selective electrode. It was found that an asymmetrical cell with Nafion cathode and amine biochar anode increased removal capacity by 54% over the activated biochar symmetrical cell (identical anode and cathode), with 6.01 mg NaCl/g biochar at the symmetrical cell and 9.25 mg g−1 for the asymmetrical cell. This work shows that biochar can be engineered and explored broadly as an inexpensive sustainable electrode material for asymmetrical capacitive deionization.

Application of electron probe micro analysis and ion selective electrode techniques to monitorthe efficiency of electrochemical chloride extraction in cementitious materials

ABSTRACT Electrochemical chloride extraction (ECE) from laboratory prepared mortar samples has been applied considering two experimental configurations; using different external anodes and studying the influence of aggregate size.ECE experimental conditions together with analytical procedures were carefully addressed. Combination of two analytical methods has been employed to monitor the efficiency of chloride extraction process; chloride ion selective electrode (ISE) to obtain free chloride cumulative amount in the external anolyte solution upon applying ECE, and electron probe micro analysis (EPMA)to gain depth profile information of chloride in the mortar samples before and after ECE process. A comparison between three X-ray detection based analytical techniques has been briefly reviewed. ECE performance was discussed and recommendations were introduced.

A fully screen-printed potentiometric chloride ion sensor employing a hydrogel-based touchpad for simple and non-invasive daily electrolyte analysis.

This is the first report demonstrating proof of concept for the passive, non-invasive extraction and in situ potentiometric detection of human sweat chloride ions (Cl- ions) using a stable printed planar liquid-junction reference electrode-integrated hydrogel-based touch-sensor pad without activities such as exercise to induce perspiration, environmental temperature control, or requiring cholinergic drug administration. The sensor pad was composed entirely of a screen-printed bare Ag/AgCl-based chloride ion-selective electrode and a planar liquid-junction Ag/AgCl reference electrode, which were fully covered by an agarose hydrogel in phosphate-buffered saline (PBS). When human skin contacted the hydrogel pad, sweat Cl- ions were continuously extracted into the gel, followed by in situ potentiometric detection. The planar liquid-junction Ag/AgCl reference electrode had a polymer-based KCl-saturated inner electrolyte layer to stabilize the potential of the Ag/AgCl electrode even with a substantial change in the chloride ion concentration in the hydrogel pad. We expect this fully screen-printed sensor to achieve the low-cost passive and non-invasive daily monitoring of human Cl- ions in sweat in the future.

TiO2/Activated Biochar Hybrid Material Prepared By Ultrasonication and Heat Treatment for Capacitive Deionization

TiO2-doped activated biochar was successfully prepared as a hybrid electrode material for capacitive deionization. The introduction of TiO2 has the advantages of low cost, high chemical stability, hydrophilicity, and eco-friendliness. Activated biochar was treated with titanium isopropoxide (TTIP) and isopropyl alcohol solution by an ultrasound assisted process followed by calcination at 400 °C. The physical and chemical properties of the resulting material was characterized by XPS, XRD, SEM, and TEM. Cyclic voltammetry was performed to analyze the electrochemical properties of the prepared electrodes. Furthermore, the performance of TiO2-biochar electrode was evaluated in a 3D-printed CDI cell and the salt removal capacity was examined using a chloride ion-selective electrode. It was shown that the removal capacity was enhanced from 5.1 mg/g NaCl (activated biochar) to 8.6 mg/g NaCl. The increase in capacity is associated with a better wettability of the electrode, which increases the number of surface-active sites and promotes a more efficient ion diffusion inside the biochar pores. This result is beneficial to improve biochar application as an inexpensive alternative electrode material with metal oxide modification.

Simultaneous kinetic-potentiometric determination of levodopa and carbidopa using multivariate calibration methods

Partial least squares (PLS) and principle component regression (PCR) multivariate calibration methods were applied to the simultaneous determination of carbidopa and levodopa using kinetic data from novel potentiometry methods. These methods were based on the rate of chloride ion production in the reaction of carbidopa and levodopa with N-chlorosuccinimide (NCS) which was monitored by a chloride ion-selective electrode. The experimental data shows suitability of ion-selective electrodes (ISEs) to be used as detectors not only for the direct determination of chloride ion but also for simultaneous kinetic-potentiometric analysis using chemometric methods. These methods are based on the differences observed in the production rate of chloride ions. The results show that simultaneous determination of carbidopa and levodopa can be performed in their concentration ranges of 1.0-14.0 and 0.5-25.0 μg/mL, respectively. The total relative standard errors for applying PCR and PLS methods to 9 synthetic samples in the concentration range of 2.0-13.0 μg/mL for carbidopa and 1.0-18.0 μg/mL for levodopa were 4.81 and 4.29, respectively. The effects of certain additives used as excipients upon the reaction rate were determined to assess selectivity of the method. Both methods (PLS and PCR) were validated using a set of synthetic sample mixtures and then were successfully applied to the determination of carbidopa and levodopa in several commercially available mixture formulations. The recoveries were satisfactory and comparable to those obtained by applying the reference Pharmacopoeia method of high performance liquid chromatography.

New Poly Vinyl Chloride Ion Selective Electrode for Potentiometric Analysis of Propranolol in its Pharmaceutical Formulations and Human Fluids

New, simple, sensitive and rapid method for the determination of propranolol in the pharmaceutical preparations and human fluids. The Buildup and electrochemical response characteristics of a poly vinyl chloride (PVC) selective membrane electrode for the determination of propranolol (POP) are described in this research. The proposed electrodes was composed of propranolol-bromophenol blue as ion-exchanger and Di-butyl phthalate (DBPH) (electrode A), tris (2-ethylhexyl) phosphate (TEHP) (electrode B), and ortho-nitrophenyloctylether (ONPOE) (electrode C), as plasticizers. The slope was 50.94, 57.77, and 49.75 mV/decade for electrode A, B and C. the linear range was 5 ×10-5 – 1×10-2, 1×10-4 – 1×10-2, and 5×10-5 – 1×10-2 M, a detection limit of 4.2×10-5, 8.9×10-5, and 4.8×10-5 M, lifetime of 21, 42, and 1-day, respectively. Electrode B gives the best results, so the application of pharmaceutical and human fluids was based upon this electrode, the recovery percentage was 103, 101, 102.5, and 104 for POP tablet 10mg, tablet 40mg, urine and plasma by standard addition method, respectively.

Printed Wearable Sensor Patch for Multi-Analytes Detection in the Sweat Range

Printed Wearable Sensor Patch for Multi-Analytes Detection in the Sweat Range

Improving chloride ion penetration resistance of cement mortar by strong base anion exchange resin

How to improve the chloride penetration resistance of reinforced concrete in marine environment has always been an important research topic. In this paper, based on the adsorption properties of strong basic anion exchange resin (SB-AER) for chloride ion, SB-AER, silica fume (SF) and fly ash (FA) were milled into ternary admixtures with particle size less than 75 μm. The effect of SB-AER on chloride ion penetration resistance of mortar was studied. In this experiment, the mechanical properties and compactness of mortar with different SB-AER content were tested by pressure testing machine and ultrasonic nondestructive flaw detector. The microstructure of mortar was observed by scanning electron microscope (SEM). The chloride ion binding capacity of mortar with different SB-AER content was qualitatively and quantitatively analyzed by chloride ion selective electrode method. All the results show that under the appropriate SB-AER content, the ternary admixture can effectively improve the chloride penetration resistance and mechanical properties of mortar. SB-AER-3 group (SB-AER, SF and FA are 3%, 5% and 10% of cement weight, respectively) has the best performance in these two aspects.

A Targeted Grouting and Water Blocking Method Based on Hydrological Tracer Testing and Its Engineering Applications

Hydrological tracer testing is an effective way to determine the law of recharge and the transport of groundwater. In karst collapse mine water treatment, the hydrological tracing test can determine information such as the runoff velocity and the pattern of underground runoff, so that targeted grouting becomes possible. In this paper, NaCl was used as a tracer, and the content of the tracer was determined by the chloride ion selective electrode method. The NaCl concentration–time curve was plotted, and we obtained a tracer test method that can determine the runoff of the karst quantificationally. The method can quantificationally obtain the groundwater transport velocity, runoff pattern, and connectivity. This combination of grouting rate, grouting pressure, and setting time realized the localized targeted grouting and achieved a significant water damage control effect.

Estimation of Hypochlorites in Commercial Bleaching Solutions by Cl-ISE and Platinum Electrode

Chloride ion-selective and platinum electrodes were successfully applied in the determination of hypochlorites in commercial bleaching solutions. The results obtained with Cl-ISE are compared to those obtained with Pt electrodes since the reactions are oxidation-reductions where the Pt responds to their potential change. A clear change and jump at equivalence points were found and titration curves are in S form which were approved by first and second derivatives. The percentages obtained with Cl-ISE are relatively larger than results with Pt electrode which are due to practical errors, interference of I-ions and little Cl-by-Product of hypochlorite manufacture. In general, almost both electrodes offered results in the range of 3–8% solutions of hypochlorites within the period of storage. Low results may by due to wasting and decomposition by temp, transferring, dilution and stirring the solution.

Calibration free solid contact electrodes with two PVC based membranes

A new type of solid contact ion-selective electrodes (ISEs) with two PVC-based sandwiched membranes are described. The first membrane contains suspension of halogen salts of silver and alkaline metals as well as silver nanoparticles and is placed on Ag substrate or conducting substrate covered with silver. It acts as a solid contact of an ion-selective electrode when covered with the second PVC membrane sensitive to potassium, sodium or chloride ions. In this way, the potassium, sodium and chloride electrodes characterized by very stable and reproducible standard potentials and slope were obtained. For example, all tested potassium electrodes with KBr/AgBr based solid contact exhibited E° values equal to: −191.2 ± 1.7 mV and the slope values equal to: −57.1 ± 0.8 mV/pK. Similarly, good results were also obtained for sodium and chloride ISEs. The solid contact offered allows to fabricate so-called “calibration free” ion-sensors.