Hydrogen Ion Activity Research Articles

Increasing impacts of ocean acidification on coral reefs under global warming

The rapid increase in atmospheric CO2 concentration in recent decades has influenced the marine system to a great extent with ocean acidification being one of the consequences. Ocean acidifications impact on calcifying marine organisms has long been the subject of scientific studies. To determine the effect of ocean acidification on hard coral reefs, we analyzed five ocean coastal regions, comparing the trend in regional surface hydrogen ion activity with the change in hard coral coverage. In each region, we included both historical measured data and predicted data using RCP models as an implication of the potential future. The outcome does not provide substantial evidence to confirm the hypothesis linking the two variables. Additionally, the direct association between these variables cannot be ascertained due to the influence of uncontrolled factors such as local pollution, ocean warming, and ocean currents.

Advantages of a novel in situ pH measurement for soilless media.

Rhizosphere pH determines nutrient bioavailability, but this pH is difficult to measure. Standard pH tests require adding water to growth media. This dilutes hydrogen ion activity and increases pH. We used a novel, in situ, pointed-tip electrode to estimate rhizosphere pH without dilution. Measurements from this electrode matched a research-grade pH meter in hydroponic nutrient solutions. We then compared measurements from this electrode to saturated paste and pour-through methods in peat moss, coconut coir, and pine bark. The pointed-tip electrode was unable to accurately measure pH in the highly-porous pine bark media. Adding deionized water to the other media at container capacity using the saturated paste method resulted in a pH that was 0.59 ± 0.30 units higher than the initial in situ measurement at the top of the container. This increase aligns with established solution chemistry principles. Measurements of pH using the pour-through method were 0.38 ± 0.24 pH units higher than in situ measurements at the bottom of the container. We conclude that in situ pH measurements are not subject to dilution and are thus more representative of the rhizosphere pH than the saturated paste and pour-through techniques.

Thermodynamic properties of common salts in aqueous solutions

A relationship between the activity of hydrogen ions and charge activity in an aqueous solution has been developed in a previous study. That study also revealed that the potential energy of an aqueous solution can be obtained by multiplying the charge activity with electrostatic potential of the solution. In this study, negative potential energy equalling Gibbs energy of four common salt (NaCl, KCl, NaNO3 and KNO3) solutions were quantified using the charge activity. Then the entropies of those salt solutions were computed using the Gibbs energy, enthalpy, and the charge activity. Charge activities were computed using the pH of those solutions at room temperature. It was found that potential energy, Gibbs energy, enthalpy and entropy of a solution is related to the charge activity of a solution, not the ionic charge number as previously thought. When the concentrations of NaCl, KCl, NaNO3 and KNO3 increased in single solutions the entropies of those solutions tend to decrease allowing them to achieve orderly states leading the salt particles to crystalise. The findings of this study will lead to better understanding and utilization of thermodynamic properties during crystallization which is vital important in brine recovery.

Investigating pH and other electrical properties of potassium salt solutions

A recent study of ours reported that pH of common salts varies with concentration at room temperature. It can either increase in case of basic salts or decrease in case of acidic salts. In this study, pH values of four kind of potassium salts were investigated and their pH values increased with salt concentrations. It was reasoned that the concentration of hydrogen ions equalled the concentration of positive charges/protons in a solution, so a relationship between the activity of hydrogen ions and charge activity was developed. Further, the well-established equations for pH with hydrogen-ion activity and electrostatic/cell potential were extended to charge activity. Potential energy, the product of charge activity and electrostatic/cell potential, was presented and discussed.

State Primary Standard of the pH Indicator of Hydrogen Ion Activity in Aqueous Solutions Get 54-2019

State Primary Standard of the pH Indicator of Hydrogen Ion Activity in Aqueous Solutions Get 54-2019

A comprehensive and internally consistent mineral dissolution rate database: Part I: Primary silicate minerals and glasses

Mineral dissolution rates control the temporal evolution of many natural processes on the surface and upper crust of the Earth. This is the first of a series of papers describing the development and implementation of a comprehensive and internally consistent database of the dissolution rates of the major rock-forming minerals. In this paper, we describe the retrieval and regression of the dissolution rates of the primary rock-forming silicates, including quartz and other SiO2 polymorphs, feldspars, pyroxenes, amphiboles, micas, volcanic glass, and olivines. Owing to the limited fluid chemistry data available for many of the published experimental studies, BET surface area normalized mineral and most glass dissolution rates (r) were regressed usingr=∑iAiaH+nieEaiRT1−exp−AσRTwhere Ai stands for pre-exponential factors, aH+ corresponds to the hydrogen ion activity, ni refers to reaction orders, T designates absolute temperature, R denotes the gas constant, Eai represents activation energies, σ stands for Temkin's average stoichiometric number, and A denotes the chemical affinity of the dissolution reaction. Where relevant data were lacking, rates were extrapolated assuming that mineral dissolution follows similar trends within the same mineral group. Regression was performed using least-squares algorithms. The average difference between calculated and measured rates ranged from 0.1 to 0.7 log units depending on the mineral. The obtained rate equations were implemented into the carbfix.dat database for direct use in the PHREEQC software but can be extended to other geochemical modeling software, such as TOUGHREACT.

IoT based system for real-time monitoring the hydrogen-ion activity in water bodies

The paper presents design and principle of operation of a mobile combined pH meter. Sensor’s network underlying the IoT system for monitoring water bodies hydrogen ions activity in real time was demonstrated. The measuring device was tested on liquids with different pH levels. The obtained measurement results were compared using a stationary pH meter OHAUS Starter 3100.

The application of logarithmic charts when evaluating the equilibrium concentrations of all particles in acid-base systems

Until recently, due to the absence of other suitable approaches, equilibrium concentrations in acid-base systems have been studied exclusively by measuring the pH of a solution. However, this method can not be used for organic (non-aqueous) solvent solutions. It is known that the ionic strength of a solution, which is a fundamental component in assessing the activity coefficient and the thermodynamic dissociation constant of an electrolyte, is influenced by the ions present in the system. The concentration of these ions is variable during interactions in aqueous and more complex non-aqueous solutions, which differ significantly in their physicochemical properties (boiling temperature, structure, permittivity, autoprotolysis constant, solvating ability, dipole moment, viscosity, etc.). Meanwhile, in order to obtain more objective and valid estimates of acid-base interactions, in addition to the activity of hydrogen ions, appropriate account should be taken of the equilibrium concentrations of all particles in the solution, which affect its ionic strength. In this article, on the basis of the law of mass action and equations describing equilibrium processes, the ionic product of a solvent, electrical neutrality and material balance in a solution, the corresponding equations were derived and a method was proposed for considering the effect of the concentrations of all particles in the system (not only hydrogen ions – pH), significantly affecting the properties of acid-base equilibrium systems. The proposed method can also be used to obtain the dependence of the equilibrium concentrations of all process substances on the state of the medium (test solution), determined by various chemical and instrumental methods in logarithmic coordinates, which makes it pos-sible to directly assess the equilibrium concentra- tions of all particles present in the system.

Results of Pilot Comparisons of National Standards for the Activity of Hydrogen Ions in Aqueous Solutions

Results of Pilot Comparisons of National Standards for the Activity of Hydrogen Ions in Aqueous Solutions

The enigma of environmental pH sensing in plants.

Environmental pH is a critical parameter for innumerable chemical reactions, myriad biological processes and all forms of life. The mechanisms that underlie the perception of external pH (pHe) have been elucidated in detail for bacteria, fungi and mammalian cells; however, little information is available on whether and, if so, how pHe is perceived by plants. This is particularly surprising since hydrogen ion activity of the substrate is of paramount significance for plants, governing the availability of mineral nutrients, the structure of the soil microbiome and the composition of natural plant communities. Rapid changes in soil pH require constant readjustment of nutrient acquisition strategies, which is associated with dynamic alterations in gene expression. Referring to observations made in diverse experimental set-ups that unambiguously show that pHe per se affects gene expression, we hypothesize that sensing of pHe in plants is mandatory to prioritize responses to various simultaneously received environmental cues.

Особливості змін фізико-хімічних властивостей сироватки та сиру кисломолочного, вироблених із молока корів української чорно-рябої молочної породи з різними генотипами капа-казеїну в процесі зберігання

The article presents experimental materials on the study of changes in the whey and cottage cheese physicochemical properties which are made from the milk of Ukrainian black-and-white dairy cows with different kappa-casein genotypes during storage. The experimental part of the work was carried out in the conditions of a pedigree plant for breeding Ukrainian black-and-white dairy breed of the «Profintern» unit of the State Enterprise «Gontarivka» in the Institute of Animal Science of the National Academy of Agrarian Sciences (NAAS). Based on the analysis results of the chemical composition, there were no significant differences between the groups for most indicators during storage in the period from the first to the 15th day, although in absolute values they can be placed in the following order: cottage cheese made from milk of cows with the BB genotype, AB and AA. It was found that the concentration of active acidity, similar to most quality indicators of cottage cheese, was determined at the beginning of storage by a higher value in cows with genotype BB by 0.9 and 0.5% compared to animals with genotypes AA and AB. With the extension of the shelf life, the rate of acid formation tended to decrease and on the 15-th day was 3.8–3.1%, compared the initial values. In contrast, the difference between the samples from the representatives with the BB and AA genotype in terms of the activity of hydrogen ions during this period was 1.6% and the AB genotype – 0.9%. Despite the fact that the duration of storage had a negative effect on the hydrogen ions’ concentration in cottage cheese, made from cow’s milk with different genotypes of kappa-casein, its moisture-retaining properties, on the contrary, have improved. It was found that cottage cheese and whey, regardless of the cows’ genotype at the kappa-casein locus, during storage have a relatively stable composition and meet the requirements of the current DSTU. The recommended shelf life is 15 days. The best combination of the studied parameters in the production of BB genotype cows reflects the higher course of metabolic processes in the body, which led to an improvement in its quality.

Results of pilot comparisons of national standards for the activity of hydrogen ions in aqueous solutions

The enormous needs in ensuring the measurement of the hydrogen index in various industries and the national economy of Russia make the measurement of the hydrogen index one of the most important methods for monitoring aqueous media. In 2013, work was carried out to enter into the State Register of Measuring Instruments of the Russian Federation a buffer solution and a standard titer with a pH value of 7.00 – a working pH standard of the 2nd category, which is one of the most demanded of non-standard solutions for verification and calibration pH measuring instruments. To confirm the metrological characteristics, pilot comparisons were organized within COOMET. This article presents the results of a pilot comparison to determine the pH of a phosphate buffer solution – a working standard of рН=7.00. 8 metrological institutes and 10 metrological organizations took part in the comparisons. The results obtained showed that the overwhelming majority of the participants in the comparisons presented the results of pH measurements, which have an uncertainty not exceeding ±0.03 of the average value, which is an acceptable criterion for measuring the pH.

Impact of the electrochemical treatment on physical and chemical properties of water activated in various devices using electrochemical activation technology

Introduction. Currently, there are various technologies for water treatment and water purification, including ozonation of water, water treatment with UV radiation, ion exchange, magnetization. Electrochemical treatment of water by direct electric current, in which activated water is formed, characterized by many anomalous properties, is a modern approach to water treatment and water treatment. Purpose of the study. The study of the physicochemical properties of water-activated in devices of different manufacturers with different designs. Material and methods. To activate the water, activators were used: AP-1, Melesta, Zdrava, the filter of electrochemical water purification “ Izumrud”. The activity of hydrogen ions and the redox potential of water were measured using an Ecotest-120 ionomer with a switch. To measure the electrical conductivity of the solutions, an Expert-002 conductometer was used. Free chlorine was determined by the photocolorimetric method on a Spectroquant Multy colorimeter. Antioxidant activity was determined spectrophotometrically using a mediator system of potassium ferro-ferricyanide. Results. Chloride ions make a decisive contribution to the change in the physicochemical characteristics of anolyte upon activation of water. Sulfates and bicarbonates do not affect the prooxidant activity of the anolyte. The relaxation of catholytes obtained in membrane activators proceeds by a gradual increase in ORP, while the relaxation of activated water in the Zdrava diaphragmless activator proceeds in an oscillatory mode and is characterized by sharp changes in ORP. Anolytes are stable over time and slightly change the pH and ORP during storage. The activation of certain types of water in a diaphragmless activator does not lead to a decrease in the ORP, but its significant growth. Conclusion. Electrochemically activated water is a general term that hides in each case an unknown substance with an unpredictable effect. The use of standard devices even when using the same water sample, as a rule, leads to different physicochemical characteristics of activated water. When using different types of water, physicochemical characteristics differ significantly. The use of electrochemically activated water is unsafe.

Is there still a need for the antimony electrode 100 years after its introduction as a pH sensor?

Although the glass electrode, first mentioned in the literature over 100 years ago, is still the preferred analytical tool for determining hydrogen ion activity in aqueous media, there are a number of applications for other sensors that also measure pH. Even if they do not correspond to the measuring performance of the glass electrode in terms of, e.g., accuracy, reproducibility, and long-term stability, they open up the feasibility of using electrochemical sensors even where the operation with glass electrodes is not possible. This applies in particular to scenarios in which extreme and harsh environmental conditions prevail. Currently relevant here are, for example, measurements in geothermal plants or directly on arable land in agricultural production. In the present article, new electrochemical devices based on antimony electrodes are presented especially for these purposes; in addition, the use of the antimony electrode as a basic electrode for the CO2 determination according to the Severinghaus principle is reported on.

Solvent Extraction of Copper from Sulfate–Chloride Solutions Using LIX 84-IC and LIX 860-IC

ABSTRACT The effect of chloride ions on the copper extraction equilibria, the rate of extraction, copper/iron selectivity, and chloride extraction was studied for organic phases containing pure ketoxime (LIX 84-IC) and pure nonylaldoxime (LIX 860N-IC). In these systems, the used aqueous phase contained total chloride concentrations from 0 to 110 g/l. It was determined that the chloride ions in the aqueous solution had a large negative effect on the extraction equilibria for LIX 84-IC and a small effect for LIX 860N-IC. This deleterious effect is attributed to an increase in the hydrogen ion activity coefficient in the presence of chloride ions. The chloride accelerated the rate of copper extraction even though the reaction was fast in all the tested conditions. An increase in the temperature from 25°C to 35°C affected positively the extraction equilibria for LIX 84-IC.

Detailed Analysis of Estimated pH, Activity Coefficients, and Ion Concentrations between the Three Aerosol Thermodynamic Models.

In this work, we utilize a rich set of simulated and ground-based observational data in Tianjin, China to examine and compare the differences in aerosol acidity and composition predicted by three popular thermodynamic equilibrium models: ISORROPIA II, the Extended Aerosol Inorganics Model vision IV (E-AIM IV), and the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients model (AIOMFAC). The species used to estimate aerosol acidity for both simulated and ambient data were NH4+, Na+, SO42-, NO3-, and Cl-. For simulated data, there is good agreement between ISORROPIA II and E-AIM IV predicted acidity in the forward and metastable mode, resulting from the hydrogen ion activity coefficient (γ(H+)) and the molality (m(H+)) showing opposite trends. While almost all other inorganic species concentrations are found to be similar among the three models, such is not the case for the bisulfate ion (HSO4-), which is linked to m(H+). We find that differences in predicted bisulfate between the three models primarily result from differences in the treatment of the HSO4- ↔ H+ + SO42- reaction for highly acidic conditions. This difference in bisulfate is responsible for much of the difference in estimated pH for the ambient data (average pH of 3.5 for ISORROPIA II and 3.0 for E-AIM IV).

Quantifying the Cross-Sensitivity of Glass pH Electrodes in Alkaline Solutions

Standard glass pH electrodes are ubiquitous instruments used in research and in classrooms to measure the hydrogen ions present in a solution. While many chemists and educators have communicated ways to support teaching conceptual understanding of solution pH and the function of pH probes and dyes, the community lacks a methodology that enables students to move beyond a qualitative discussion of pH probe cross-sensitivity to other cations such as Li+ and Na+. Here, we present an affordable method whereby students learn to quantify such instrumental limitations and cross-sensitivities. The reversible hydrogen electrode (RHE) detects changes in hydrogen ion activity via electrochemical potential and serves as the baseline in this study to standardize the cation sensitivity of several glass membrane pH probes. Increasing additions of a salt, e.g., NaCl, in their corresponding alkali solutions, e.g., 0.10 M NaOH, were used to observe the shift in measured pH between the RHE (nominally only H+) and glass pH probes (H+ plus other cations). The generated working curves were found to be specific to each glass pH electrode, the cation identity, and the solution pH. Taken together, this report provides a methodology that equips instructors and research mentors to teach undergraduates about systematic error associated with instrumentation and specifically how to improve the accuracy of pH probe measurements in saline or alkaline environments.

Cost Effective Smart Hydroponic Monitoring and Controlling System Using IoT

Hydroponic System is a system in which farmers cultivate different plants without utilizing the soil. The authors have proposed IoT system that monitors and controls all parameters of hydroponic system like water level, pH, humidity and temperature through mobile application. In proposed system, the authors have used an ESP32 micro-controller that is controlled pump. The pump will draw water from a reservoir which is connected to a regular water line. If the water level of the reservoir falls down to a certain level, the system will send an SMS to the Farmer. The farmer can control the water line and make the reservoir full by mobile application. An LDR and DHT11 humidity sensor is used to control the light and temperature of the farm. In system, we also used pH sensor where pH sensor is a scientific instrument that measures the hydrogen-ion activity in water-based solutions and indicating its acidity or alkalinity expressed as pH.

A continuous-flow and on-site mesocosm for ocean acidification experiments on benthic organisms

Mesocosm experiments conducted for ecological purposes have become increasingly popular because they can provide a holistic understanding of the biological complexities associated with natural systems. This paper describes a new outdoor mesocosm designed for CO2 perturbation experiments of benthos. Manipulated the carbonate chemistry in a continuous flow-through system can be parallelized with diurnal changes, while irradiance, temperature, and nutrients can vary according to the local environment. A target hydrogen ion activity (pH) of seawater was sufficiently stabilized and maintained within 4 h after dilution, which was initiated by the ratio of CO2-saturated seawater to ambient seawater. Specifically, pH and CO2 partial pressure (pCO2) levels gradually varied from 8.05–7.28 and 375–2,691 μatm, respectively, over a range of dilution ratios. This mesocosm can successfully manipulate the pH and pCO2 of seawater, and it demonstrates suitability for ocean acidification experiments on benthic communities. Key words: carbonate chemistry; CO2 partial pressure; continuous flow-through system; ocean acidification

Model of fish population dynamics with calculation of individual growth rate and hydrological situation scenarios

Introduction: Populations of commercially valuable fish species develop in aquatic ecosystems according to internal mechanisms of their evolutionary adaptations, which do not always suit the environmental conditions which can change due to anthropogenic pressure. Often the factors of reservoir eutrophication or introduction of new species into the ecosystem aggravate the competitive confrontation of the populations. The changes spread by domino effect and complicate the development of a strategy for rational exploitation of biological resources. Species under non-optimal anthropogenic conditions are vulnerable. Purpose: Developing a model for introduced population dynamics, implemented as a group of scenarios for a volatile environment. Results: We developed a computational model of a population to describe the scenarios for its adaptation to environmental conditions. The scenarios include the pace of dimensional development and nutrition of fish. The model includes a unit for calculating diets, taking into account the hydrological situation factors: the oxygen content and the activity of hydrogen ions. The model is capable of operating in two modes: under standard environmental conditions (without specifying the hydrological situation) and with preset conditions for anthropogenic changes. Our approach allowed us to predict changes in the population structure with variability in abiotic factors. The model demonstrate the risk of taking out the fish which make the greatest contribution to the biomass growth rate. Practical relevance: The model was identified using the data on whitefish population in the Lake Sevan. It is suitable for computer simulation experiments, which made it possible to describe specific features of scenarios of population dynamics for the cases of increased fishing, limited feeding and changes in the hydrological conditions of the lake.