STUDY OF THE INTERACTION OF COMPONENTS IN THE NiSO4 – KNO3 – H2O SYSTEM

ABSTRACT

To theoretically substantiate the interaction of nickel sulfate and potassium nitrate, the physicochemical properties of diluted solutions were analyzed using the isomolar series method by measuring the pH, density, refractive index, and viscosity values ​​of the 0.01 M solution mixture based on the ratio of components in the [NiSO₄ (0.01 M)]:[KNO₃ (0.01 M)] system.

АННОТАЦИЯ

Для теоретического обоснования взаимодействия сульфата никеля и нитрата калия проведен анализ физико-химических свойств разбавленных растворов методом изомолярных серий путем измерения значений рН, плотности, показателя преломления и вязкости смеси 0,01 М растворов в зависимости от соотношения компонентов в системе [NiSO₄ (0,01 М)]:[KNO₃ (0,01 М)].

Keywords: nickel sulfate, potassium nitrate, isomolar sequence method, pH value, density, viscosity, refractive index.

Ключевые слова: cульфат никеля, нитрат калия, метод изомолярной последовательности, значение pH, плотность, вязкость, показатель преломления.

Introduction. The world's population is increasing daily, which is also causing an increase in the demand for quality food. This naturally requires a continuous system in the agricultural sector. Unfortunately, because the soil is harvested 3-4 times a year and its place is not sufficiently replenished, the decrease in soil fertility and the decline in productivity are observed as problematic situations all over the world [1; pp.242-249]. In this context, improving soil conditions and replenishing lost macro- and micronutrients to meet nutrient needs is one of the most important tasks facing agricultural producers [2; pp.566]. In agriculture, nutrients essential for plant growth and development in the soil are replenished by applying micronutrient fertilizers [3; pp.1-17].

More than three billion people worldwide suffer from diseases caused by micronutrient deficiencies. Of the 50 nutrients essential for human life, 17 are micronutrients. Therefore, the depletion of beneficial elements in the soil is important not only for plants but also for human health [4; c.207-208].

The microelements [5; c.45-50] iron, manganese, zinc, copper, molybdenum, boron, nickel, cobalt, and selenium, which are necessary and useful for plant life, play an important role in the physiological and biochemical processes in plants [6; 2024]. Based on the above information, information about the biological role of the microelement nickel, its participation in the structural structure of the plant, and its manifestation in the synthesis of cellular components - DNA, RNA, and protein- is presented in many literature. According to its biochemical properties, the microelement nickel is similar to iron and cobalt. Nickel in the soil stimulates microbiological processes, helps in the nitrification and mineralization of nitrogen compounds, and increases productivity [7; c.3-14].

To study the interaction of components in the NiSO₄ – KNO₃ – H₂O system, the inflection point associated with the formation of a new phase was studied using the isomolar series method [8; pp.145-146]. Through this method, the interaction of nickel sulfate and potassium nitrate in different ratios was theoretically substantiated. During the study, isomolar solutions of components with the same molar concentration were mixed in certain ratios based on the isomolar series method, and experimental analyses were carried out while maintaining a constant sum of the initial volumes. Based on the results obtained, the complex formation process of nickel sulfate and potassium nitrate was explained using graphical analysis.

Materials and methods. To theoretically substantiate the interaction of nickel sulfate and potassium nitrate, the physicochemical properties of diluted solutions were analyzed using the isomolar series method by measuring the pH, density, refractive index, and viscosity values ​​of the 0.01 M solution mixture based on the ratio of components in the [NiSO₄ (0.01 M)]:[KNO₃ (0.01 M)] system.

For the study, 0.01 M nickel sulfate and 0.01 M potassium nitrate solutions were initially prepared. Then, a gradually increasing amount of potassium nitrate solution was added to the nickel sulfate solution. The pH value, refractive index, viscosity, and density of the resulting mixtures were determined. All measurements were carried out in a water thermostat at a temperature of 20 ± 0.1°C.

The kinematic viscosity of the solution was measured with an accuracy of ±0.0001·10⁻¹ m²/s using a 0.82 mm diameter VPJ-4 capillary viscometer. The relative density was determined using a pycnometric analysis method [9]. The pH of the solution was measured using a FiveGo^TM F2 Mettler-Toledo pH apparatus.

Results and Discussion. The results of the dependence of the change in the physicochemical properties of solutions on the ratio of components in the NiSO₄ and KNO₃ system are shown in Figure 1 and Table 1.

Figure 1. Changes in the physicochemical properties of solutions depending on the ratio of components in the system [NiSO₄ (0.01 M) + KNO₃ (0.01 M)]

Analysis of the "pH - composition" diagram in the system [NiSO₄ (0.01 M)]:[KNO₃ (0.01 M)] shows that with an increase in the amount of 0,01 M potassium nitrate solution from 3 ml to 30 ml, the pH values ​​of the solutions decrease from 6,86 to 5,78, and with a ratio of [NiSO₄ (0,01 M)]:[KNO₃ (0,01 M)]=6:4, a break is observed at a pH value of 6,51. Such a change in the pH values ​​of the environment in this system is characteristic of the process of formation of a new compound.

Table 1.

Changes in the physicochemical properties of solutions depending on the ratio of components in the system [NiSO₄ (0.01 M) + KNO₃ (0.01 M)]

In the "Content - Density" diagrams, with an increase in the amount of potassium nitrate and a decrease in the amount of nickel sulfate, the density of the solutions gradually decreases from 0.9888 g/cm³ to 0.9822 g/cm³, and a change in the density value to 0.9859 g/cm³ is observed with a composition ratio of [NiSO₄ (0.01 M)]:[KNO₃ (0.01 M)]=6:4.

Analysis of the data of the “Composition - refractive index” diagram shows that the refractive indices in the system gradually decreased from 1,3334 to 1,3332 up to the ratio [NiSO₄ (0.01 M)]:[KNO₃ (0.01 M)]=6:4, and it can be noted that there was a significant break in the diagram. With increasing potassium nitrate content in the mixture, the refractive index value continued to decrease to 1,3331.

The viscosity values ​​of the solution of the studied system decrease from 1.0342 mm²/c to 0.9925 mm²/c with a decrease in the amount of 0.01 M nickel sulfate and an increase in the amount of 0.01 M potassium nitrate, which is also explained by the presence of a breaking point of 0.9942 mm²/c at a ratio of 6:4.

Conclusion. In summary, to study the interaction of micronutrient salts with mineral fertilizer components, using 0.01 M solutions of potassium nitrate and nickel sulfate, an isomolar series method was investigated, and the hydrogen index of the mixtures, density, viscosity, and refractive index characteristics were studied. As a result of studying mixtures prepared by pouring 0.01 M solutions in an isomolar sequence, it was found that there was a change point at a ratio of 6:4, which belonged to a new phase.

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