Mohr Titration Research Articles

Fabrication of biocompatible and biodegradable cloth-based sweat sensors using polylactic acid (PLA) via stencil transparent film-printing

Cloth-based sensors are gaining attention for creating microfluidic wearable sensors for continuous monitoring of sweat biomarkers because of their flexibility, low cost, and natural hydrophilicity making them suitable for integration into everyday products. Here, we present a novel, low-cost and simple fabrication approach to create a cloth-based sensor ready for use as a sweat sensor while being environmentally friendly using biocompatible and biodegradable material, polylactic acid (PLA), and a stencil transparent film-printing method. The method provided high-resolution structures with narrowest hydrophilic channels and hydrophobic barriers measuring 1.90 ± 0.34 mm and 1.23 ± 0.14 mm, respectively. Various designs for detecting sweat biomarkers, including pH, lactate, and chloride, were generated by simply adjusting the stencil transparent film designs. For pH detection, a square-shaped cloth-based sensor was constructed and different natural indicators was used as biocompatible and non-toxic reagents to measure pH providing the detection in the pH range of 1–14. In lactate determination, an enzymatic assay with nanoceria as colorimetric probes was used in a spot format, offering a lactate detection range of 2.5–25 mM, effectively distinguishing between normal and abnormal muscle fatigue patients at a cut-off level of 12.5 mM sweat lactate. For chloride, a distance-based format was employed using the reverse Mohr titration assay, resulting in a detection range of 10–100 mM. Finally, the analysis of lactate and chloride in artificial sweat was successfully demonstrated yielding the recovery in the acceptable range demonstrating accurate measurements of the fabricated cloth-based sensors.

A novel method for Ion Exchange Capacity characterization applied to Anion Exchange Membranes for Water Electrolysers

Hydrogen production from water electrolysis, hydrogen fuel cells and redox flow batteries are the right approach for the renewable energy sector because the electricity generated by solar, wind, photovoltaic, hydroelectric can be managed with a carbon-free approach. These technologies all have in common one fundamental component: the membrane. Different types of membranes have been developed for both cationic and anionic exchange, and recently, research activity focalized on improving their performances is very fervent. One fundamental characteristic of a membrane is its Ion Exchange Capacity (IEC), i.e. the density of charged functionalizing groups. Within our research project NEMESI, funded by EU-PNRR (ID: RSH2B_000002), and dedicated to Anion Exchange Membrane Water Electrolysis, we studied and validated a novel alternative method to measure IEC. The present titration methods have limitations for the need of dedicated hardware or qualitative inspection of their color-turning endpoint. The proposed method, based on the redox titration of potassium ferricyanide with ascorbic acid, allows a quantitative and independent assessment based on both potentiometric and spectrophotometric measurements, along with the usually adopted visual observation, as the yellow-colored ferricyanide is reduced to colorless ferrocyanide. Moreover, if compared to the classical Mohr titration with silver nitrate, the new method can be carried out at variable ferricyanide concentrations during the addition of the ascorbic acid, so a complete curve of the redox reaction can be constructed: the initial ferricyanide ion load of the membrane (IEC) can thus be derived in a more precise way than with a single-point evaluation. Only one Ag/AgCl reference electrode and a platinum working electrode are required without any power supply/potentiostat. The proposed method was validated using Anion Exchange Membranes with known IEC.

Nuclear magnetic resonance as a tool to determine chlorine percentage of chlorinated paraffin mixtures

A new simple method for chlorine percentage calculations (method C), from proton nuclear magnetic resonance (1H NMR) spectroscopy, has been established and applied to an industrial chlorinated paraffin (CP) mixture and 13 single-chain CPs of known carbon chain lengths. Two modified methods (method A and B), originating from the work of Sprengel et al., have been utilized on the same single-chain mixtures. All samples were analysed by 1H NMR and two-dimensional heteronuclear quantum coherence (HSQC) for this purpose. All three methods worked well for medium chlorinated (45–55% Cl) single-chain mixtures of known carbon chain lengths. Method A yielded the best result for mixtures of lower chlorine content (<45% Cl), method C gave better estimations for higher chlorine contents (>55% Cl). Compared to Mohr's titration, method A showed a deviation of 0.7–7.8% (3.6% average), method B 4.1–11.3% (7.0% average) and method C 0.6–11.6% (5.2% average), for all 13 single-chain mixtures. The new method C is the only method that could be applied for determining the chlorine percentage of industrial mixtures of multiple, unknown chain lengths.

Role of Ionic Concentration and Distribution in Anionic Conductivity: Case Study on a Series of Cobaltocenium-Containing Anion Exchange Membranes with Precise Structure Control

Three new anion exchange membranes (AEMs) (P1, P2, P3) with varied numbers (1, 2, 3) of cobaltocenium substituents were synthesized by ring-opening metathesis polymerization (ROMP). The living polymerization characteristic of ROMP endows the resulting AEMs with tunable ionic concentration and precise structure control, which provide an ideal model to investigate the influence of ionic concentration and substituent on the ion-conducting property of AEMs. According to Mohr titration and the alternating-current impedance method, the as-prepared AEMs demonstrated an obvious ionic concentration and substituent influence on ionic conductivity in an ordering of P2 > P3 > P1. In addition, the hydrophilic/hydrophobic microphase separation structures of the three AEMs were observed by atomic force microscopy (AFM), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS). To further verify the relationship between ionic concentration, substituent, and ionic conductivity, molecular simulation was also used to calculate the ionic diffusivity of the three AEMs, and the result of simulation computation was consistent with the experimental result. Moreover, a tentative anion exchange membrane fuel cell (AEMFC) performance test also indicates the corresponding sequence of P2 > P3 > P1. The current work may provide an effective method for the rational design and preparation of AEMs, as well as guidance in investigating the structure–property relationship.

Standard Operating Protocol for Ion-Exchange Capacity of Anion Exchange Membranes

Ion-exchange capacity (IEC) is the measure of a material’s capability to displace ions formerly incorporated within its structure. IEC is a key feature of anion-exchange membranes (AEM), as it determines the AEM’s ability to conduct the ions required to sustain the electrochemical reactions where they are utilized. As an intrinsic property, measuring the IEC accurately is essential to study AEMs and understand their performance within devices. In this method article, a facile and accurate standard operating procedure (SOP) to measure the IEC of AEMs is proposed. When compared to conventional acid-base back-titration or Mohr titration, the proposed method combines the fast reaction between silver and halide ions and the accuracy of the potentiometric titration, providing a convenient and precise protocol for researchers in the field.

Online fully-automatic high precision steam dryness monitoring system

Steam dryness monitoring is significant for high-efficiency steam turbines used in power generation and boilers. Although steam dryness is a crucial process variable, Mohr titration involves expensive and complex calorimeter equipment and considerable time and effort. This paper proposes an online fully-automatic high precision steam dryness monitoring system. The automatic determination of titration endpoint using the optical method, vital steps for this system, was discussed. The design shows high repeatability and precision (about 1% at 300 mg/L). The system also has high linearity, and the R2 is 0.9999. The limit of the detection is about 15 mg/L. The measuring time is about 2 min for one measurement, which is much faster than manual titration. Thirty-eight water samples collected were tested, showing an excellent anti-interference characteristic.

Commercial anion exchange resin modified with azolates for remarkable separation of SO2 from CO2

It is still challenging to prepare solid materials with improved SO2 capture performance from readily available chemicals through facile routes. In this work, we proposed to modify Amberlite® IRA-900 − a commercial anion exchange resin with azolates (i.e., imidazolate, triazolate and tetrazolate), to prepare a new kind of solid materials for reversible SO2 capture. The major purpose is to utilize the multiple-site strong interaction of azolates with SO2, and special attention was paid to the performance of SO2 separation from CO2. The modified IRA-900 samples were characterized by FTIR spectra, elemental analysis, Mohr titration and low-temperature N2 adsorption. The SO2 separation performance of modified IRA-900 samples was examined systematically by both single gas and mixed gas adsorption experiments. It is found that the tetrazolate-modified IRA-900 sample displays remarkable performance for the separation of SO2 from CO2, with high SO2 capacities (3.15 mmol/g at 25 °C and 11.1 kPa) and large SO2/CO2 selectivities (907 for at 0.1/0.9 v/v and 25 °C). The SO2 separation mechanism of tetrazolate-modified IRA-900 sample was also examined in details with the help of spectroscopic and theoretical methods.

Has the Reduction of Salt in the Bread’s Composition Played a Role in Reducing Blood Pressure in Morocco?

Abstract Objectives Overconsumption of sodium can cause several noncommunicable diseases such as hypertension which alone is responsible for 10% of cardiovascular disease. According to the Moroccan Ministry of Health 2018, the prevalence of hypertension in Morocco rose from 33.6% in 2000 to 29.3% in 2018. Bread is the main vehicle of salt for daily food intake in Morocco the objective of this research is the evaluation of the impact of 5 years of awareness campaigns (2011–2016) on the incentive of bakers to reduce the amount of salt used in the preparation of commercial white bread and on improvement of their knowledge and nutritional practices related to salt. Methods Knowledge, attitudes and nutritional practices (KAB) on sodium were assessed using a questionnaire during interviews in 2012, 2014 and 2016 with 1218 bakeries in Casablanca, Morocco. The questionnaire covered subjects on diseases linked to overconsumption of salt, the recommended daily intake and their adhesions to gradually reducing salt in the preparation of bread. The amount of sodium chloride in commercial bread was measured by the Mohr titration method. Bread samples were collected and analyzed in 160 bakeries in 2011 and 2016. Results The KAB survey revealed that in 2016, for bakers, 92.9% knew at least that overconsumption of salt causes blood pressure, 72.8% were engaged or started to reduce the sodium added in the preparation of bread and 98.3% of bakers market around 10% of bread without salt. Analysis of the bread revealed that the added sodium chloride increased from 17.42 ± 1.28 g/kg in 2011 to 13.1 ± 2.24 g/kg in 2016, equivalent to a decrease of 26, 3% over five years (0.94 g per year). The amount of salt measured in 2017–2018 in the bread of 6 Moroccan cities showed an average rate varying between 12.85 and 16.9 g/kg. Conclusions This study highlights the effectiveness of awareness campaigns through the CAP to reduce the use of salt in breadmaking. Knowing that the daily consumption of bread in Morocco varied between 360 and 500 g. This 26.3% reduction in salt in bread certainly has a positive impact on CVD protection and would be attributed to the reduction in the prevalence of blood pressure obtained in 2018 among Moroccans. Funding Sources University II Hassan Facuty of Sciences Ben M'Sik Casablanca. World Health Organization.

Is the reduction of salt in the bread consumed in Morocco could be a means of protection against cardiovascular diseases?

Over-consumption of sodium is closely linked to hypertension, stroke and other cardiovascular diseases (CVD). According to the Moroccan Ministry of Health 2019, the prevalence of hypertension in Morocco decreased from 33.6% in 2000 to 29.3% in 2017. Bread is one of the most important sources of sodium in several countries, including Morocco. This study aims to assess the impact of 5 years of awareness campaigns (2011–2016) in reducing the quantity of sodium chloride used in preparing commercial white bread, and in improving nutritional knowledge and practices related to sodium. Nutritional knowledge, attitudes and practices (KAP) about sodium were assessed using a questionnaire in interviews in 2012, 2014 and 2016 with 1218 bakeries in Casablanca, Morocco. The questionnaire covered topics on the consequences of sodium over-consumption and recommended daily intake. The quantity of sodium chloride in commercial bread was measured by Mohr's titration method. Bread samples were collected and analyzed from 160 bakeries in 2011 and 2016. The KAP survey revealed that in 2016 for bakers that 92.9% knew at least that over consumption of salt causes blood pressure, 72.8% were committed or started reducing added sodium in bread preparation and 98.3% of bakers market bread without salt. Analysis of bread revealed that added sodium chloride decreased from 17.42 ± 1.28 g/kg in 2011 to 13.1 ± 2.24 g/kg in 2016, which is equivalent to a decrease of 26.3% on five years (0.94 g per year). The quantity of salt measured on 2017–2018 in the bread of 6 Moroccan cities showed an average rate varying between 12.85 and 16.9 g/kg. This study highlights the effectiveness of awareness campaigns through the KAP for reducing the use of salt in bread-making. Knowing that the daily consumption of bread in Morocco varied between 360 and 500 g, this reduction of 26.3% of the salt in the bread certainly has a very positive impact on the CVD protection.

The Utilization of Ozone As an Alternatif Chlorine Substitution to Increase Quality of Arenga Starch (Arenga pinnata)

This study was aimed to determine the optimum conditions of flour bleaching with ozonation techniques and compare the effect of chlorination results. The process of bleaching flour with ozonation process is carried out in batch system. The research procedure is to vary the time 0, 30, 60, 90, 120, 150, and 180 minutes. Variation in pH 4, 6, native pH of flour, 8, 10 and 1: 3 (b / v) concentration of flour against water. Ozone concentration 0.325 g ozone / hour. The effect of the addition of chlorine is soaked for 180 minutes with the concentration of chlorine to the flour of 0.325% (w / w) and theconcentrationofflour towaterthatis1: 3.The resultsobtainedwerecarriedout by means of data sampling on purpose and were carried out by white degree analysis, organoleptic test, chlorine content test and protein content test. The results of the research that has been done, that the optimum conditions for the bleaching process of flour using ozone are pH 4 with 180 minutes obtained the value of Brightness L* = 93.32, b* = 5.10. Organoleptic results give results that respondents prefer the results of the ozonation process with the classification of odor, color and texture in a row is 9; 8.5;8.6.Theresultsofapositive,andquantitativequalitativechlorinecontenttestwith an Argentometric Mohr titration produced 0.01% (w / w) per 10 g of palm sugar.

Fabrication and application of a gold nanoparticle-based colorimetric device for the determination of NaCl in seawater and estuarine water

Salinity plays an important role in regulating the marine and estuarine ecosystem. In order to understand the effects of salinity in seawater and its influence on nearby estuaries, accurate, rapid, sensitive and selective methods are needed for sodium chloride determination. Therefore, this study offers a colorimetric assay method based on gold nanoparticles (average size of 7 nm) for determining sodium chloride concentrations in seawater and estuarine water. This provides a foundation for developing a reliable long-term salinity monitoring and sensing platform. The colorimetric assay from the interaction of gold nanoparticles with free sodium chloride in the water resulted in colour change which was detected by naked eye. Images of the colorimetric assay response were prudently analysed using the Colorgrab application and CIELab colour management in order to accurately fabricate the Lovibond colorimetric wheel for the quantification of sodium chloride in aqueous samples. The fabricated colorimetric device was applied to screen the levels of salinity along the coastal seawater and estuaries of Durban in KwaZulu-Natal. The results were comparable with those obtained using the traditional methods (ion chromatography and Mohr titration). Sodium chloride concentration in seawater ranged from 30 to 35 ppT. There was evidence of salt intrusion in Umgeni estuary with sodium chloride concentration decreasing to 5 ppT in a distance of approximately 400 m away from the sea. Overall, the developed AuNP colorimetric sensor proved to be an affordable tool, simple to use and provide analytical data that is accurate in a short time.

ANALISA KESADAHAN TOTAL DAN KADAR KLORIDA AIR DI KECAMATAN TANGGULANGIN SIDOARJO

Subdistrict Tanggulangin was relatively close to the source of the Lapindo mud flow, the release of mud content into the water will cause the death of aquatic organisms and lead to serious consequences for humans who depend their life on these waters. Therefore, researchers seek to determine the total water hardness and chloride content in Tanggulangin district. Water make up the population and sample, taken from 15 points in Tanggulangin, Sidoarjo. Total hardness determination was conducted using complexometric titration method, whereas chloride content wasperformed using argentometry Mohr titration method. Water sample from 3 of 10 regions in Tanggulangin is drinkable, namely the sample A (320 mg / L), sample C (170 mg / L), sample E (304 mg / L), sample F (298 mg / L), sample I (372 mg / L), samples J (340 mg / L). While the in the othersamples, the content of total hardness exceeds the maximum threshold (&gt; 500 mg / L) which means unfit for consumption, and 5 of the 10 areas in the district is drinkable, namely the sample A (123.2 mg / L), sample C (49.7 mg / L), sample E (245.7 mg / L), sample I (182.4 mg / L), and samples J (64mg / L).

Comparative studies on the salt content of white bread and wholemeal bread

Bread contributes to the high salt daily intake of human which can cause increased blood pressure and cardiovascular health problems. Salt in bread has some important functions that affect the bread quality. However, some government organization regulated to reduce salt in bread production. Hence, this study aims to explain the salt content in commercial white bread and wholemeal bread by Mohr titration and Atomic Absorption Spectroscopy (AAS). Based on statistical analysis by using F test and t-test can be concluded there is no significant difference of salt content in both types of bread (p>0.05), however the result by Mohr titration was significantly higher than by AAS (p<0.05).

Analisa Kesadahan Total dan Kadar Klorida Air Di Kecamatan Tanggulangin Sidoarjo

Subdistrict Tanggulangin was relatively close to the source of the Lapindo mud flow, the release of mud content into the water will cause the death of aquatic organisms and lead to serious consequences for humans who depend their life on these waters. Therefore, researchers seek to determine the total water hardness and chloride content in Tanggulangin district. Water make up the population and sample, taken from 15 points in Tanggulangin, Sidoarjo. Total hardness determination was conducted using complexometric titration method, whereas chloride content was performed using argentometry Mohr titration method. Water sample from 3 of 10 regions in Tanggulangin is drinkable, namely the sample A (320 mg / L), sample C (170 mg / L), sample E (304 mg / L), sample F (298 mg / L), sample I (372 mg / L), samples J (340 mg / L). While the in the other samples, the content of total hardness exceeds the maximum threshold (&gt; 500 mg / L) which means unfit for consumption, and 5 of the 10 areas in the district is drinkable, namely the sample A (123.2 mg / L), sample C (49.7 mg / L), sample E (245.7 mg / L), sample I (182.4 mg / L), and samples J (64 mg / L).

Chlorination of Carbon Nanotubes Obtained on the Different Metal Catalysts

In this paper, a chlorination method is proposed for simultaneous purification and functionalization of carbon nanotubes, thus increasing their ability to use. Carbon nanotubes were obtained by CVD method through ethylene decomposition on the nanocrystalline iron or cobalt or bimetallic iron‐cobalt catalysts. The effects of temperature (50, 250, and 450°C) in the case of carbon nanotubes obtained on the Fe‐Co catalyst and type of catalyst (Fe, Co, Fe/Co) on the effectiveness of the treatment and functionalization were tested. The phase composition of the samples was determined using the X‐ray diffraction method. The quantitative analysis of metal impurity content was validated by means of the thermogravimetric analysis. Using X‐ray Photoelectron Spectroscopy (XPS), Energy Dispersive Spectroscopy (EDS) analysis, and also Mohr titration method, the presence of chlorine species on the surface of chlorinated samples was confirmed.

Determination of chloride by multisyringe flow injection analysis and sequential injection analysis with potentiometric detection

This paper reports for the first time a multisyringe flow injection analysis (MSFIA) method with potentiometric detection for the automated determination of chloride in waters. The methodology developed was applied to the determination of chloride in mineral, tap and waste waters and the results achieved were compared with those obtained by a potentiometric sequential injection analysis (SIA) method reported in the literature. When Mohr titration was carried out for validating the results offered by both techniques, no significant differences were found. The linear ranges were between 6 and 3500 mg l −1 for MSFIA and 10 and 3500 mg l −1 for SIA; the UPAC limits of detection were 2.7 mg l −1 for MSFIA and 1.6 mg l −1 for SIA; reproducibility was ca. 0.8% for MSFIA and 0.4% for SIA and, sampling rates were of 30 and 15 injections h −1 for MSFIA and SIA, respectively. These results provide evidence of superior performance of MSFIA over SIA for the determination of chloride.

The influence of hydrogen peroxide and pH on the Mohr titration

The official Japanese method for determination of chloride in hot-spring waters requires any H 2S present to be oxidized with hydrogen peroxide in ammoniacal medium. When this was done, and the solution was titrated with silver nitrate at pH 9.7, the indicator colour changed from yellow to brownish grey, owing to reduction of silver ions to the metal by hydrogen peroxide. The effect can be eliminated by adjusting the pH to 7.0–7.5 before the titration.

Simultaneous equilibria involving insoluble salts

This demonstration is derived from and involves the same reactions as the Mohr titration of chloride ion with silver nitrate solution using potassium chromate as an indicator.

Precipitation titrations in terms of the Pourbaix diagram

Suggests that Pourbaix potential-pH diagrams may be applied for uses other than in connection with various oxidation-reduction reagents and procedures; the example shown in detail is the Mohr titration, the precipitation of chloride with silver ion using chromate ion as an indicator.

Analyses of chlorine dioxide, chlorous acid, chlorite, chlorate, and chloride in composite mixtures

An analytical procedure was devised to determine chlorine dioxide, chlorous acid, and chlorite, chlorate, and chloride ions in composite mixtures. Chlorine dioxide was determined spectrophotometrically at 360 mµ. After the removal of chlorine dioxide by passing air through the solution, the total concentration of chlorous acid and chlorite ion in the solution was determined spectrophotometrically at 250 mµ where the two species have the same molar absorptivity. The total concentration of chlorous acid, chlorite ion, and chlorate ion was determined by iodimetric titration. Chloride ion was determined by the Mohr titration in neutral solution.