Actual problems of modern science, education and training

Research Methodology. Reagents and equipment. 1.598 g of Pb (NO₃)₂ measured on an analytical balance is placed in a 1 l measuring flask and dissolved in water, and the measuring flask is diluted to the mark “bi-distilled water”. 1 mg of Pb corresponds to 1 ml of the resulting solution [14].
A solution of a mixture of medium phosphoric acid, acetic and boric acids is prepared in a 1 l measuring flask. From each of them, the necessary amount of substances is measured to prepare a 0.04 M solution. The pH value of the resulting universal buffer solution is 1.81. The following volume of 0.2 N NaOH solution is added to 100 ml of this mixture to obtain a buffer solution with the desired pH value [15].
0.0154 g of amido black organic reagent measured on an analytical balance is placed in a 250 ml volumetric flask, dissolved in distilled water and diluted to the mark “bi-distilled water”. Ready standard solution is 1x10^-5M.
From synthetic polymer fibers with different composition: 0.2000 g of orange- colored ion exchange material (PPA) obtained by modifying polyacrylonitrile fiber with polyethylene polyamine; furthermore, 0.2000 g of polyacrylonitrile fiber modified with polyethylene polyamine and dichloroethane (PPD) fibers were measured on an analytical balance.
To record the diffuse reflectance spectra from a solid surface and study the dependence of the reflectance (R), the function of the reflectance F (R) on various factors, an X-Rite one pro recording spectrophotocolorimeter and a UV-ViS SPECORD 50 double-beam recording spectrophotometer were used [16].
pH optimum conditions of chemical reactions were controlled by METTLER TOLEDO pH meter.
Various fibrous materials (polyacrylonitrile type) containing various functional groups have been tested as a solid phase. The sorbent was used in the form of disks with a diameter of 20 mm and weighing 30–40 mg in a wet state, for which the disks were kept in a 0.1 M solution of hydrochloric acid, washed with distilled water, and then stored in Petri dishes [17].
FT/IR spectra of complex and immobilized azo dye ligand were analyzed using Perkin Elmer-Spectrum 100 spectrometer technique, and its value was recorded as 4000-400 cm^-1.
UV-Vis electronic absorption spectra of the complex in the solid phase and the ligand in water (c=1.0x10^-5 mol/dm³) were studied on a SPECORD 50 spectrophotometer and its value was determined to be 490-620 nm.
The analytical signal was taken as the difference between the diffuse reflectance coefficients (∆R) measured at 620 nm of the disks after the sorption of the element from the control and analyzed solutions and the reaction with the reagent on the solid phase.
The study was carried out in static and dynamic modes. In a static mode, 10.0 ml of reagent solution was injected into 50.0 ml flasks, and the carrier disk was lowered therein and stirred for 5-8 minutes. Holding the carrier with a glass rod, the reagents were decanted, the immobilized carrier was washed with distilled water, and it was immersed in the analyzed solution. In the dynamic mode, the analyzed solution was passed through the immobilized disk at a rate of 10 ml/min.
The degree of retention of amido-black (R%) on the carrier was calculated by the formula: R=100^.A/A₀, where A is the optical density of the reagent after immobilization, A₀ is the optical density before immobilization.