SYNTHESIS AND STRUCTURE ANALYSIS OF NEW HIGH PERMEABILITY ION EXCHANGE MEMBRANE

ABSTRACT

In this paper, a studying of the synthesis of a new highly permeable nano and microporous ion exchange membrane based on a polyaniline-linked copolymer. Initially, cellulose acetate (SAT), synthesized from local raw materials - cotton cellulose, was purified and dried. Then, aniline (AN), sulfoaniline (SA), and SAT are reacted method in situ at low temperature in the presence of hydrochloric acid and ammonium persulfate catalysts to form sulfopolyanilineacetatecellulose (SPAAS) copolymer. The obtained SPAAS copolymer was dissolved in various N-methyl-2-pyrrolidone (NMP) and treated with special pore-forming agents glycerin (GL), acetone (AT) and other fillers, and was initially moulded into a porous membrane by moulding at 45-50 ⁰C in a 50-60% humidity environment. SPAAS was synthesized based on the use of different molar ratios of starting materials, reaction temperature and reaction time, and the optimal process conditions were determined. In addition, the composition of the synthesized SPAAS and its raw materials was determined based on the infrared spectrum (IR spectrum), and the elemental composition and surface morphology were determined based on scanning electron microscopy (SEM), and their data were presented.

АННОТАЦИЯ

В данной работе изучен синтез новой высокопроницаемой нано и микропористой ионообменной мембраны на основе сополимера полианилина. Первоначально ацетат целлюлозы (АЦ), синтезированный из местного сырья — хлопковой целлюлозы, очищался и высушивался. Затем анилин (АН), сульфоанилин (СА) и САТ реагируют in situ при низкой температуре в присутствии катализаторов соляной кислоты и персульфата аммония с образованием сополимера сульфополианилинацетатцеллюлозы (СПААС). Полученный сополимер СПААС растворяли в различных N-метил-2-пирролидонах (НМП) и обрабатывали специальными порообразователями: глицерином (ГЛ), ацетоном (АТ) и другими наполнителями, а затем первоначально формовали в пористую мембрану методом формования при температуре 45-50 ⁰C  и влажности 50-60%. Синтез СПААС производился на основе использования различных молярных соотношений исходных веществ, температуры и времени реакции, а также были определены оптимальные условия процесса. Кроме того, состав синтезированного СПААС был определен на основе инфракрасного спектра (ИК-спектра), а элементный состав и морфология поверхности были определены на основе сканирующей электронной микроскопии (СЭМ), и их данные представлены.

Keywords: Ion exchange membrane, sulfopolyanilineacetatecellulose, aniline, sulfoaniline, cellulose acetate.

Ключевые слова: Ионообменная мембрана, динитроцеллюлозаполианилин, анилин, сульфоанилин, ацетат целлюлозы.

1. INTRODUCTION

Membrane treatment is a crucial technique for maintaining and wisely using water resources, improving water quality, and enabling the reuse of water in technological processes using physico-chemical wastewater detoxification methods [1], [2]. Because it is simple to use and quite inexpensive, membrane technology is one of the many methods for extracting different cations and anions from solutions [3]. Ion exchange membranes are the most popular and very effective kind of membranes. Ion exchange membranes (IEM) offer a lot of promise, particularly in the industrial sector where they are employed for high-efficiency material purification, synthesis of novel materials, energy production, and mixture separation [4], [5].

Ion exchange membranes are also frequently made using cellulose and its esters as a starting point for fabrication. Cellulose acetate, ethyl cellulose, and cellulose nitrate have all been used to generate a variety of nano and microporous membranes [6]. Nitrocellulose, for instance, is a crucial substrate in the manufacturing of anion exchange membranes, which are used to detect and separate proteins from solutions with low concentrations [7]. Porous, thin films with a kerosene size are formed from ethyl cellulose, and materials that serve as separators and conductors are produced by adding the required ingredients to it [8], [9]. Furthermore, an ion-exchange nanocomposite was created by using an in situ chemical oxidation polymerization technique to join microcrystalline cellulose and polyaniline. When it came to the operations of removing heavy metals and different dyes from wastewater, this nanocomposite performed well [10], [11]. Recycled polyaniline-based high ion exchange membranes with improved electrical conductivity and ion exchange are used [12], [13]. We modified cellulose acetate and sulfoaniline with polyaniline to create a novel nano and microporous ion exchange membrane, taking into consideration the characteristics of the  materials.

2. Experimental part

2.1 Materials and Methods

The following materials and equipment are needed to prepare the ion exchange membrane and its raw materials. Aniline (AN) 98%, dimethyl ether (DME) 98%, sulfoaniline (SA) 96%, acetone (AT) 96%, ammonium persulfate (APS) 96 %, glycerin (GL) 96%, N-methyl-2-pyrrolidone (NMP) 98%, isobutyl alcohol (IBA) 99%, ethylene glycol(ETG) 98%, hydrochloric acid 24%, and distilled water. Refractory flasks, a thermometer and a magnetic stirrer were used to carry out the reaction processes.

2.1. Synthesis of sulfopolyanilineacetatecellulose copolymer.

In a three-necked flask equipped with a reflux condenser and an automatic stirrer, 5 g (0.05 mol) of aniline was placed, 3 g of ground acetocellulose was added, and the mixture was stirred for 5 minutes at 10 °C. In the next step, 2 g of m-aniline sulfonic acid solution was added to the reaction flask. After that, 75 ml (0.7 mol) of the catalysts hydrochloric acid and ammonium persulfate solutions were slowly added dropwise, and the reaction mixture was stirred intensively for 3.5 hours while cooling to 2-4 °C. As a result, a dark blue powder-like mass was formed. The resulting powdery mass was poured into a beaker and neutralized by first washing it in ammonia and distilled water. Then the porcelain was poured into a bowl and dried in a drying cabinet for 24 hours at a temperature of 40-50 °C. The resulting product consists of small, porous, dark blue particles, with a reaction yield of 76%. The reaction scheme for the synthesis of sulfopolyanilineacetatecellulose is shown in Figure 1.

Figure 1. SPAAS copolymer synthesis reaction

Table 1.

 To study the effect of concentration, time, and temperature of reactants on product yield

2.2. Obtaining an ion exchange membrane based on sulfo polyaniline acetate cellulose.

26.5 g of n-methyl pyrrole was placed in a three-necked flask equipped with an automatic stirrer, 4 g of SPAAS was added, and the mixture was stirred for 40 minutes at 30-35 °C. Then, 1.5 g of isobutyl alcohol and 12 g of acetone were added, and the reaction mixture was heated to 35-40 °C with intensive stirring. As a result, the color of the solution changed from blue to dark blue. In the next step, 1 g of a 10% solution of glycerol was added to the flask and stirred for 1.5 hours, resulting in a uniform dark blue cast solution. In the next step, the product mixing rate was increased, and the mixture was stirred for 3 hours at a temperature of 4-45 °C. The resulting solution of each nano- and microporous ion exchange membrane was poured into a polyvinyl chloride mold made from a cast solution. The membrane thickness was controlled by controlling the volume of solution poured into the mold. The synthesis of SPADNS membrane was also carried out under different conditions and fillers.

Figure 2. SPAASNm ion exchange membrane

3. Characterization

3.1 Infrared spectrum (IR) of synthesized SPAASNm4 membrane and raw materials.

Based on the relevant literature, the study of a substance’s infrared spectrum was first investigated. The SHIMADZU IR-Fire spectrophotometer, made in Japan, was used to investigate the infrared spectra of the synthesized SPAANS membrane at 400 cm^-1 and 4500 cm^-1. The analysis based on the IR spectrum is presented in Figures 3.

3.2 Scanning Electron Microscope (SEM).

A Touch Scope electron microscopy (SEM) campaign from China JEOL Ltd. used JSM scanning to examine the morphological structure of the membrane. Using SEM, the porosity and elemental analysis of thin membranes were ascertained the analysis of results obtained based on SEM is presented in Figures 4-6.

3.1. Results and Discussion

3.1.1 3.1.1 IR spectroscopic analysis of substances.

IR spectrometer of SPAANS membrane. The analysis of the obtained results is presented in Figures 3.

Figure 3. Sulfopolyanilineacetatecellulose (SPAAS) copolymer Ik-spectrum

In the values ​​of Fig 3, the valence vibrations of the –OH bonds are located in the area of 3189,95 cm^-1, the valence vibrations of the –CH= bonds are located in the range of 2659,13 cm^-1, the valence vibrations of the >C=NH– bonds are located in the range of 1420,97 cm^-1, the valence vibrations of the –CO–CH₃ bonds are located in the range of 1281,05  cm^-1, the valence vibrations of the –O– bonds are located in the range of 1420,97 cm^-1, the valence vibrations of the –S–OH bonds are located in the range of 1068,86 cm^-1 and valence vibrations of  >CH₂ bonds are visible in the region of 731.02 cm^-1. Based on the results presented below, we can see that the valence vibrations in the SPAAS copolymer correspond to the chemical formula of the substances we recommended.

3.1.2 Scanning electron microscopic (SEM) analysis of SPAAS ion exchange membranes.

Initially, the SEM scanning area covered an area of ​​100 μm at a magnification of up to 10 μm when studying the surface morphology to determine the membrane porosity required for the SPAASm ion exchange membrane. It was found that the pores formed in this membrane were small in size and partially disordered. Photographs of the surface of the SPAASm ion exchange membrane are shown in Figure 4.

As we can see from the images below, the nano and micro pores in the membrane are sufficient to perform the permeability properties of the membranes. These pores are formed by the dissolution and evaporation of various pore formers. In this case, the required yield can be further increased if special conditions and the correct ratio of pore-forming substances are used.

Figure 5. SEM images of the prepared SPAASm membrane IMG1 (1st) is a view of the overall membrane at 200 micrometers: C-k carbon, N-k nitrogen, S-k sulfur, O-k oxygen mass

Figure 6. Energy dispersive spectrum and compositional element ratios of the ion exchange membrane synthesized on the basis of polyanilinenitracellulose

The SEM images below show that the surface morphology of the synthesized membrane with nano- and micropores is suitable for use in the ion exchange process.

Conclusion

Synthesis processes of new nano and microporous ion exchange membranes based on polyaniline, sulfoaniline and cellulose acetate were carried out. Initially, the raw materials for the synthesis of ion exchange membrane SPAASm were used in different ratios and the required optimal ratios were determined. At the same time, the reaction environment and temperature affecting the product of raw material synthesis were determined, and raw materials were synthesized based on this.

At the next stage, SPAAS raw material was transformed into a nano and microporous ion exchange membrane with the help of various solvents and pore formers. Optimum conditions were also found for the resulting membrane using different levels of air humidity and temperature. The bonding nature of the atoms of the synthesized substances for the membrane a was studied by infrared spectroscopy (IR). The element composition and surface morphology of the membrane were determined using a Scanning Electron Microscope (SEM). These obtained results indicate the formation of SPAAS ion exchange membrane with nano and micro holes.

References:

1. Tomi Muringayil Jozef, Husayn E. Al-Hazmiy, Bogna Śniatała, Amin Esmoili, Sajjod Habibzoda. Nanoparticles and nanofiltration for wastewater treatment:From polluted to fresh water. Environmental Research 238 (2023). – PP. 117-114. 10.1016/j.envres.2023.117114
2. Nasrin Nomanifar, Mojtaba Davoudi, Akram Ghorbanian, Ali Asghar Najafpoor, Ahmad Hosseinzadeh. Fe recovery from drinking water treatment sludge for reuse in tannery wastewater treatment: Machine learning and statistical modelling. Journal of Water Process Engineering. 60 (2024). – PP. 105-224. [Electronic resource] URL: https://doi.org/10.1016/j.jwpe.2024.105224
3. Y. S. et al. Synthsis of a New Ion Exchange Membrane and its Surface Morphology//Recent Contributions to Physics. – 2024. – Vol. 91. – №. 4.
4. Eun Joo Park, Siddharth Komini Babu and Yu Seung Kim. Gas Permeability Test Protocol for Ion-Exchange Membranes. Frontiers in Energy Research.10 (2022). – PP. 1–7. [Electronic resource] URL: https://doi.org/10.3389/fenrg.2022.945654
5. Y. Tan, H. Yang, J. Cheng, and J. Hu, ‘ScienceDirect Preparation of hydrogen from metals and water without CO 2 emissions,’ International Journal of Hydrogen Energy. 47 (2022). – PP. 38134–38154. [Electronic resource] URL: https://doi.org/10.1016/j.ijhydene.2022.09.002
6. Y. Apel, O. V. Bobreshova, A. V. Volkov, V. V. Volkov, and V. V. Nikonenko. Prospects of Membrane Science Development.  Membranes and Membrane Technologies. 1 (2019). – PP.  45–63. [Electronic resource] URL:  https://doi.org/10.1134/S2517751619020021
7. Bozorov Y. et al. Obtaining Heterogeneous Membranes from Aniline-based Epoxy Resin and 2-Aminobutanedioic Acid-based Ionites//Journal of universal science research. – 2025. – Vol. 3. – №. 5. – PP. 688-691.
8. J. Strnad, M. Kincl, and J. Bene. Overlimiting mechanisms of heterogeneous cation- and anion-exchange membranes: A side-by-side comparison. Desalination. 571 (2024). – PP. 117-093. [Electronic resource] URL:  https://doi.org/10.1016/j.desal.2023.117093
9. Turaev H.H. et al. Synthesis of Ion-Exchange Resins for Producing Membranes Based on Epichlorohydrin and Secondary Amines//Multidisciplinary Journal of Science and Technology. – 2024. – Vol. 4. – №. 3. – PP. 334-336. Y. Qian, L. Huang, Y. Pan, X. Quan, H. Lian, and J. Yang, ‘Dependency of migration and reduction of mixed Cr2O72- , Cu2+ and Cd2+ on electric field, ion exchange membrane and metal concentration in microbial fuel cells. Separation and Purification Technology.’ 192 (2018). – PP. 78-87. [Electronic resource] URL: https://doi.org/10.1016/j.seppur.2017.09.049
10. R. Phukan, L. Guttierez, W. De Schepper, and M. Vanoppen, ‘Short term fouling tests on homogeneous and heterogeneous anion-exchange membranes from food and bio-based industrial streams: Foulant identification and characterization. Separation and Purification Technology.’ 322 (2023). – PP. 124-247. [Electronic resource] URL:  https://doi.org/10.1016/j.seppur.2023.124247
11. Yokubjon Bozorov, Khait Turaev, Rustam Alikulov, Masud Karimov et al. Ion exchange membranes in environmental applications: Comprehensive review. Chemosphere, 2025, Vol. 377. – PP. 144-327. [Electronic resource] URL: https://doi.org/10.1016/j.chemosphere.2025.144327
12. W. Lan, Y. Xiao, M. Zhang, Y. Cao, and M. Fan. Effect of one- and two-dimensional nanomaterials on polysulfone-based anion exchange membranes for fuel cells. Polymer. 309 (2024). – PP. 127-458. [Electronic resource] URL: https://doi.org/10.1016/j.polymer.2024.127458
13. Sh B. Y. et al. Synthesis and analysis of nitrocellulose membrane based on local raw materials //Gospodarka i Innowacje. – 2023. – Vol. 39. – PP. 50-55.