Effect of various factors on the synthesis of ionexchange membranes and IR-spectral description of their structure with a fure converter

Introduction. Physico-chemical methods (membrane, electrochemical, etc.) play a major role in the protection of water resources and their rational use. This allows to improve the quality of water and to treat wastewater. The repeated use of water resources in technological processes leads to the saving of fresh water and the reduction of waste water. The use of multifunctional highly resistant ionites and membranes in this field allows production of import-substituting ionites and membranes in waste-free technologies, softening of mineral waters and industrial wastewater, as well as extraction of gold and other metals from industrial waste. Many scientists have synthesized polymeric materials with ionizable properties based on diglycidyl derivatives [Turayev et al., 2013]. The term “membrane” is translated from the Latin language and means bark, shell, and was first used in France in 1748 by Abbot Nolle in the purification of water-alcohol mixture. In 1890, the German physicist and chemist V.F. The system of electromembranes was founded by Ostwald and the theory of the membrane potential between the membrane and the solution was founded. But it was not until the 50s of the 20th century that the synthesis of ion-carrying polymer membranes in electrochemistry was widely developed [Laskorin et al., 1961]. “Развитие науки и технологий” Научно–технический журнал №1/2025 78 Кимё ва кимёвий технологиялар Consists in obtaining and analyzing the research results of complexes with divalent salts of copper, mercury and lead based on the products of reaction of dimethylolthiourea and dimethylolurea with polyethylene terephthalate and orthophosphate with a new composition. IRspectroscopy method was used to obtain information about the structure and properties of the obtained complexes. Experimental part. Amide polymers synthesized on the basis of self-polymerization of dimethylolthiourea and dimethylolurea with orthophosphoric acid and polyethylene terephthalate contain electron-donating atoms - oxygen, nitrogen, phosphorus, which can form internal molecular compounds with mercury (II). The synthesized membranes have the appearance of a thin film, are insoluble in solvents, and dissolve in certain amounts in water, ethanol, DMFA and DMSO. The resulting membrane was thermally processed. The thermal stability of the membrane was determined by the method of differential thermal analysis.In order to study the physico-chemical, physico-mechanical and sorption properties of the synthesized membrane, they were transferred to the active OH- form. High molecular weight products of dimethylolthiourea and dimethylolurea synthesized by themselves with orthophosphoric acid and polyethylene terephthalate have been found to have high exchange and complex formation properties when they are transferred to the OH-form in an aqueous solution of sodium hydroxide. Complex compounds are formed faster in the medium of methyl alcohol than in other solvents (ethanol, water). The resulting product complexes have sufficient thermal stability. The IR-spectroscopy method was used to obtain information about the structure and properties of the obtained product complexes. The bond strength between the metal and various ligands was studied. The absorption lines of C = O - and - C - H - bonds in the IR spectra of the polymer of dimethylolurea itself with polyethylene terephthalate and orthophosphoric acid were observed in the region of 1600 cm -1 and 1400 cm -1, respectively. [Figs1,2]. Fig.1. IR-spectrum of the membrane based on dimethylolurea and polyethylene terephthalate The line at 1600 cm-1 shifts to the high-frequency region of 20-40 cm-1 in complex compounds of dimethylolcarbamide itself with polyethylene terephthalate, orthophosphoric acid, and the mercury (II) salt of the polymer. C = O valence vibration frequency bond increases due to the formation of C = O → Me+2 [Figs 3,4] “Фан ва технологиялар тараққиёти” Илмий–техникавий журнал №1/2025 79 Химия и химические технологии Fig. 2. IR-spectrum of the membrane based on dimethylolurea and orthophosphoric acid It follows that the ability of the metal ion to form a complex is determined by the magnitude of the shift of the characteristic absorption line of the polymer ligand. The change in the vibrational frequency of the C – H group indicates the formation of the O → Me bond, which involves p - and d - electronic orbitals. The exchange capacity of the membrane and its exchange volume depend on the nature of all the active groups identified in the membrane.If the exchange takes place only in the counterion part during the experiment or production process, then we are talking about the working volume of the membrane. This value depends on pH and the filtration rate of the solution through the membrane layer, the size of the membrane particles, the ion exchange columns, the electrolyte concentration and temperature, the nature of the ion exchange and the solvent. Fig.3. IR-spectrum of the complex connection of the membrane based on dimethylolurea and polyethylene terephthalate with mercury (II) ion In the course of the research, an aliquot of the filtrate was prepared after the equilibrium was established by adding the membrane in the form of OH-- to the neutral salt solution in the determination of the static exchange volume (SEV). It is possible to find a full exchange rate only in static conditions. When a solution of reagents is used in the exchange, the opposite ions bound to “Развитие науки и технологий” Научно–технический журнал №1/2025 80 Кимё ва кимёвий технологиялар the given membrane form a less dissociable compound, and this reaction goes to the end. Strong alkalis are used as reagents. Fig.4. IR-spectrum of the complex combination of the membrane based on dimethylolurea and orthophosphoric acid with mercury (II) ion During the sorption process, membranes were immersed in 0.1 N NaOH solution for 2 days and transferred to OH-- form. After that, the membranes were cut into pieces with a diameter of 10 mm and a length of 25 cm, and a solution of CuCl2, HgSO4, and PbSO4 salts of 0.1 N was passed through the membrane surface at a rate of 2 ml/m. As a result of the inspection, it was found that the membrane was saturated with ions for 2 hours. The following formula was used for this: ( ) V С С СЕ р  − = 0 g Here, CE is the amount of metal ion absorbed in a given membrane, mmol/g; C0, Cp — concentration of metal ion solution before and after sorption in mmol/dm3; V- solution volume, ml; g- membrane weight, g. The table below shows that the membranes have a good exchange rate. This is of interest in studying the kinetic properties of membranes.Sorption of 0.1 normal solutions of copper mercury and lead on membranes was studied. Synthesized membranes well sorb passing metal ions. The studied ions can be placed in the following series according to the degree of sorption on the membrane: Сu 2+> Hg 2+>Pb 2+ In order to find the field of application of the synthesized membranes, the sorption properties of these polymers were studied in detail and they were compared with many ionomers. Result and discussion. The sorption kinetics of copper ion in the synthesized membrane was studied in its 0.1 N sulfate solution. For this, the change of copper sorption over time was determined. It was found that the membrane obtained on the basis of dimethylolurea and orthophosphoric acid has the property of high sorption of copper ion.(Fig5) In addition, the resulting membrane has good sorption properties for many other metal ions. It is also selective for heavy organic compounds and some precious metals. A new ion-carrying membrane was synthesized based on dimethylolurea and orthophosphoric acid. During the sorption process, membranes were immersed in 0.1 N NaOH solution for 2 days and transferred to OH-- form. “Фан ва технологиялар тараққиёти” Илмий–техникавий журнал №1/2025 81 Химия и химические технологии 2,5 1,5 mg*ekv/g 0,5 60 80 100 120 140 160 220 240 260 280 320 340 380 400 time. minute Fig. 5. Volume of dynamic exchange of Cu2+ ion per unit of time. IR-spectra of the ion-carrying membrane based on dimethylolurea and ammonium phosphate were recorded in the range from cm-1 to 3502 cm-1. In this case, the vibrations between 610 cm-1 and 720 cm-1 correspond to the C-O bond. Between 720 cm-1 and 760 cm-1 (CH2)x group vibrations are recorded. Vibrations recorded at 1010-1065 cm-1 indicate that CH2 groups can form cycles in the membrane. CH2 groups were recorded in the range 1410-1480 cm-1. The observation of deformation flat vibration characteristic for secondary amines in the range 1580-1640 cm-1 indicates the presence of -NH- group. Valence vibrations at 3450-3600 cm-1 are also characteristic of primary amines, which also indicate the presence of NH group in the membrane [Fig5]. Table 1. IR-spectra of UFAP-1 membrane and complexes formed by its sorption Compound υ (NH) δ (NH) υ (CH2) δ(CH2) Me-H Me-O UFAP-1 3320 1601 1105 1454 - - [CuL2]SO4 3310 1643 1010 1410 - 457 [NiL2]SO4 3360 1640 1090 1415 409 485 [CoL2]SO4 3305 1640 1085 1405 428 476 [ZnL2]SO4 3345 1640 1074 1425 415 488 [СrL3]Cl3 3364 1640 1074 1435 422 485 In the synthesized complex compounds, the Cu-H bond at 422 cm-1, Cr-H bond at 422 cm-1, Zn-H at 419 cm-1, Ni-H at 409 cm-1 and Co-H at 422 cm-1 are recorded. . This can also be seen in the decrease of the absorption region of the secondary amino-group valence vibrations appearing in the region of 3360 cm-1. In this case, the absorption area of the amino group is 3340 cm-1, chromium is 3281 cm-1, zinc complex is 3357 cm-1, nickel complex is 3348 cm-1, and cobalt is 3350 cm-1 decrease was noted. Absorption areas characteristic of the Me-O bond in the range of 457-482 cm-1 were observed in complexes with metal sulfate sorption (Table 1, Figure 6). Analysis of the IR-spectrum of UFA-1 ionite modified with Khovdak bentonite showed that new absorption spectra at 1298 cm-1 (R=O bond) and 2120 cm-1 (-OH bond of R-(OH)) appear in it. After coordination, it was noted that the absorption frequency of the R=O bond decreased by 826 cm-1, and the valence vibrations of -OH and secondary amino groups increased by 7-42 cm-1 and 23-115 cm-1, respectively. From this we can say that the coordination went through the oxygen atom of the R=O bond (Table 2, Figure 7.) “Развитие науки и технологий” Научно–технический журнал №1/2025 82 Кимё ва кимёвий технологиялар Table 2. IR-spectra of UFAP-1-B ionite and its complexes formed by sorption Compound υ (NH) υ (P=O) υ (CH2) δ(CH2) Me-H Me-O UFAP-1-B 3295 1290 1076 1448 - - [CuL2]SO4 3293 1285 1078 1450 - 465 [NiL2]SO4 3289 1293 1074 1452 412 466 [CoL2]SO4 3294 1295 1072 1448 409 455 [ZnL2]SO4 3298 1296 1072 1450 411 462 [СrL3]Cl3 3285 1298 1070 1454 408 481 Fig.6. IR spectrum of Cu(II) ion absorbed by ionite Fig.7. IR spectrum of Co(II) ion absorbed by ionite Conclusion. It was found that the ion-carrying membrane obtained on the basis of dimethylolurea and orthophosphoric acid has the property of high sorption of copper ion. According to the results of the obtained IR-spectra, CH2 groups can form a cycle in the structure of the “Фан ва технологиялар тараққиёти” Илмий–техникавий журнал №1/2025 83 Химия и химические технологии membrane. The observation of a characteristic deformation plane vibration for secondary amines indicates the presence of a -NH- group