Defense of the dissertation of Muslimova Indira for the degree of Doctor of Philosophy (PhD) in the specialty «8D05306 - %!s(*string=0xc001da03e0)»
L.N. Gumilyov Eurasian National University, a dissertation defense for the degree of Doctor of Philosophy (PhD) by Muslimova Indira on the topic «Development of methods for the modification of poly(ethylene terephthalate) track-etched membranes for the separation of water-oil mixtures» in the field of «8D05306 – %!s(*string=0xc001da03e0)».
The dissertation was carried out at the «Chemistry» of L.N. Gumilyov Eurasian National University.
The language of defense is russian
Reviewers:
Тажбаев Еркеблан Муратович
Кливенко Алексей Николаевич
Temporary members of the Dissertation Committee:
Ирмухаметова Галия Серикбаевна
Искаков Ринат Маратович
Джумадилов Талкыбек Кожатаевич
Берилло Дмитрий Александрович
Зазыбин Алексей Георгиевич
Нечаев Александр Николаевич
Academic Advisors:
The defense will take place on October 27, 2023, at 03:00 PM in the Dissertation Council for the training direction «8D05 – %!s(*string=0xc001da03f0)» in the specialty «8D05306 – %!s(*string=0xc001da03e0)» of L.N. Gumilyov Eurasian National University. The defense meeting is planned to be held online.
Link: https://clck.ru/35jKGZ
Address: https://clck.ru/35jKGZ
Abstract (English): ANNOTATION on the dissertation of Muslimova Indira Bazarbayevna on the topic "Development of methods for the modification of poly(ethylene terephthalate) track-etched membranes for the separation of water-oil mixtures", submitted for the degree of Doctor of Philosophy (PhD) in the educational program 8D05306 - Chemistry. General characteristics of the research. The thesis is devoted to the surface modification of poly(ethylene terephthalate) track-etched membranes (PET TeMs) by methods based on polycondensation and graft polymerization of monomers with different chemical nature to obtain hydrophobic and stimuli-responsive membranes for their application in the separation of water-oil mixtures. The dissertation is presented in the form of a series of articles published in accordance with the requirements of paragraph 5-1 of the Regulations on awarding degrees, approved by the order of the Minister of Education and Science of the Republic of Kazakhstan from 31 March 2011 № 127 (registered in the Register of state registration of normative legal acts under № 6951) as amended by the Order of the Minister of Education and Science of the Republic of Kazakhstan from 30.04.2020 № 170, amended by the Order of the Acting Minister of Education and Science of the Republic of Kazakhstan from 09.03.2021 № 98. 04.2020 № 170 and in accordance with the Order of the Minister of Education and Science of the RK from 09.03.2021 № 98 as amended by the Acting Minister of Science and Higher Education of the RK from 09.01.2023 № 7. Relevance of the work. Water pollution by various organic solvents and substances is a global environmental problem and in this regard, there is a need to find effective methods of separation of water-oil emulsions. More than 75% of oil product pollution enters the hydrosphere in "normal", non-accident situations due to imperfections in the technologies used. In addition to industrial effluents from petrochemical, metallurgical and engineering plants, the source of water pollution is also rainwater, which accumulates on roads and on the premises of motor transport companies, petrol stations, car washes and other municipal services. From the other hand, there is the problem of cleaning waste oils and various organic solvents from water with the aim to reuse them. Various methods such as flotation, coagulation, extraction, biodegradation et al. can be used for this purpose. One of the most promising technologies among them is membrane separation. Membrane technologies has great potential in the separation of water/oil mixtures as it is more cost effective, energy efficient and environmentally friendly than other modern separation methods. The total number of publications for the keyword "oil-water separation" reaches 25237 papers for the year 2022 alone, for the current period of 2023 the number of papers has already reached to 23090 according to “Sciencedirect” database, the number of publications are gradually increasing, reflecting the growing interest and rapid development in this field. Current research focuses on optimizing membrane properties and developing new methods to improve membrane performance. Many published works is devoted to the use of hydrophobic membranes and stimuli-responsive membranes for the separation of water-oil emulsions. The most popular among then are pH-sensitive polymers such as 4-vinylpyridine, acrylic acid and methacrylic acid. Typically, polymers are used that contain pH-responsive functional groups in the structure: pyridine, carboxyl and tertiary amino groups, which are able to accept or release protons when the pH media of the media changes. The most popular materials for the deposition of stimuli-responsive polymers are nanofiber and hollowfiber membranes, sieves, graphene foam, porous anodic aluminium oxide and other materials. At the same time, there is a few works on the use of TeMs in the separation of water-oil emulsions, and absolutely no work on the use of stimuli-responsive TeMs for these purposes. Whereas, TeMs made from polymer films by irradiation with accelerated heavy ions have unique properties such as narrow pore size distribution, small thickness and a given number of pores per unit area, and such membranes are characterised by high selectivity of separation. In this regard, we believe that the use of these types of membranes as model membranes is relevant in the field of membrane technology development. The dissertation research is devoted to the development of surface modification methods of track-etched membranes produced in Kazakhstan for effective separation of both direct and reverse model water-oil emulsions. Objects of the studies. PET TeMs obtained by irradiation of PET film with accelerated 84Kr15+ ions with energy of 1.75 MeV/nucleon on the heavy ion accelerator DC-60 (Astana), pore fluence of 1*108 and 1.5*106 ions/cm2 and nominal thickness of 12-23 μm are the objects of research. Purpose of the thesis research. The purpose of the research is development of methods for obtaining membranes with specified hydrophilic-hydrophobic properties for their application in separation of water-oil mixtures and investigation of the regularities of change of physicochemical properties of TeMs surface depending on modification conditions. Tasks of the thesis research: 1. Hydrophobization of PET TeMs by polycondensation of trichloroctylsilane; 2. Hydrophobization of PET TeMs by photoinitiated graft polymerization of stearyl methacrylate; 3. Preparation of pH-responsive TeMs by photoinitiated grafted RAFT block copolymerization of styrene and 4-vinylpyridine on PET TeMs; 4. Study and establish regularities of changes in physicochemical properties (degree of grafting, water contact angle, pore diameter, strength) of PET TeMs from the conditions of the modification reaction; 5. Characterization of membranes before and after modification by a complex of instrumental physicochemical analysis methods; 6. Testing of modified track-etched membranes in the separation of water-oil mixtures on the example of direct and reverse model water-oil emulsions (using chloroform, cetane, hexane, cyclohexane as organic component). Research Methods. The obtained samples were studied by FTIR, UV-vis spectroscopy, scanning electron microscopy, atomic force microscopy, lying drop method, energy dispersive X-ray analysis, gas permeability method etc. To evaluate the accuracy and reliability of the results, statistical methods were used to calculate Student's confidence interval, standard deviation and measurement error. Taking into account the Student's confidence interval, the reproducibility of the results at three points is achieved with a probability of 95%. The standard deviation and the measurement error do not exceed 10%. Scientific novelty of the study. The scientific novelty of the work is as follows: - The results of the hydrophobization of PET TeMs by polycondensation of trichlorooctylsilane on the membrane surface are presented for the first time. Optimisation of trichlorooctylsilane concentration in o-xylene and reaction time was carried out. The obtained hydrophobic PET TeMs were tested in the separation of chloroform-water and cetane-water model water-in-oil emulsions. - For the first time, the conditions of modification of PET TeMs by photoinitiated graft polymerization of stearyl methacrylate on the surface of membrane with different pore diameters were investigated in order to increase its hydrophobicity. The optimum conditions (monomer concentration and UV irradiation time) were determined that lead the highest water contact angle with minimal change in pore structure. Hydrophobized PET TeMs were tested in the separation of model emulsions using model systems of cetane-water and chloroform-water. - The process of photoinitiated grafted RAFT block copolymerization of styrene and 4-vinylpyridine on PET TeMs was investigated for the first time. The optimal reaction conditions (monomer concentration, UV irradiation time and RAFT-agent:initiator ratio) at which the change of hydrophilic-hydrophobic properties of the membrane surface is achieved under the change of pH media were established. - The obtained pH-responsive PET TeMs-g-polystyrene-g-poly-4 vinylpyridine were tested for the first time in the separation of direct and reverse cetane-water, hexane-water and cyclohexane-water model water-oil emulsions. Provisions for the defense: 1. Separation of chloroform-water and cetane-water emulsions with 99% efficiency and 1100 L/h×m2 is achieved by making PET TeMs hydrophobic (CA 99±3º) by polycondensation of trichloroctylsilane at 15 mM concentration for 24 hours. 2. Photoinitiated graft polymerization of stearyl methacrylate on the PET TeMs surface (at a monomer concentration of 5%, UV-irradiation time of 60 min) leads to hydrophobization of the membrane (CA 109º), which allows efficient separation of chloroform-water and cetane-water emulsions up to 4000 L/h×m2 (900 mbar) and 2100 L/h×m2 (600 mbar), respectively, with separation efficiencies of 97-99%. 3. Graft RAFT polymerization of styrene onto PET TeMs at a monomer concentration of 2 vol%, RAFT agent:initiator molar ratio = 1:10 and grafting time of 60 min lead to membrane hydrophobicity with CA of 97±3º. 4. Grafting RAFT polymerization of 4-vinylpyridine onto PET TeMs g-polystyrene (at a monomer concentration of 2 vol%, molar ratio RAFT agent:initiator = 1:10 and grafting time of 45 min) to obtain block copolymers poly-4-vinylpyridine-g-polystyrene leads to obtaining pH responsive PET TeMs (at pH = 7-9 the membrane surface has a CA of 95º, at pH = 2 the membrane has a CA of 58º). 5. The separation of the model direct and reverse water-oil emulsions (cetane-water, hexane-water and cyclohexane-water) with an efficiency of 95-99% is achieved by PET TeMs-g-polystyrene-g-poly-4-vinylpyridine membranes by changing the pH of the solution medium. Theoretical significance of the results. The present dissertation research contributes to the knowledge in the field of development of methods for modification of PET TeMs for efficient separation of water-oil mixtures by expanding the understanding of methods and technological parameters using polycondensation and graft polymerization reactions of trichlorooctylsilane, stearyl methacrylate, styrene and 4-vinylpyridine, which allows to create membranes with specified hydrophobic-hydrophilic properties. The obtained research results can be used as a basis for further research and development in this field. Practical significance of the results. The research results have potential practical application in the separation of water-oil emulsions with high efficiency of 95-99%. For example, in various industries, such as oil refining, metallurgy, mechanical engineering and many others, effective separation of emulsions will improve the quality of production, reduce environmental pollution in the reuse of water. A patent for Utility Model No. 7839 "Method of modifying track membranes for separation of forward and reverse emulsions" was received. The personal contribution of the PhD student consists in planning, direct implementation of the experimental part of the work, analysis and interpretation of the obtained data. The results of the investigation of the modified membranes surface by SEM and AFM methods were discussed jointly with the staff of the technological laboratory of track-etched membranes and the laboratory of solid state physics of the Astana branch of the Institute of Nuclear Physics of the Ministry of Energy of the Republic of Kazakhstan and the laboratory of nanoprocesses and technologies of the state scientific institution "A.V. Lykov Institute of Heat and Mass Transfer of the National Academy of Sciences of Belarus". The results were discussed with the scientific supervisors and the foreign consultant. Description of the PhD student's contribution to each publication. The PhD student has published a total of 7 papers on the topic of the dissertation research, 3 of which were published in journals in the first and second quartile of impact factor according to Journal Citation Reports from Clarivate Analytics. In the paper "Stimuli-responsive track-etched membranes for separation of water-oil emulsions" (2023, IF - 4.562, Q2, 1 citation), the PhD student is first and corresponding author. In preparation for this publication, the PhD student contributed significantly to the drafting of the article, the planning and execution of the study, the validation, analysis and interpretation of experimental data on the grafted RAFT block copolymerisation of styrene and 4-vinylpyridine on PET TeMs and the testing of the resulting membranes in the separation of water-oil mixtures, as well as a patent for utility model no. 7839 "Process for modifying track membranes for the separation of direct and inverse emulsions" was received. In preparation for the article "Graft Polymerisation of Stearyl Methacrylate on PET Track-Etched Membranes for Oil-Water Separation" (2022, IF - 4.967, Q1, 5 citations) published in the peer-reviewed journal "Polymers", the PhD student was also directly involved in writing the article and performing the photoinitiated graft polymerisation of stearyl methacrylate on PET TeMs surface. The PhD student carried out and collected experimental data on the modification of PET TeMs by trichlorooctylsilane polycondensation in preparation for the publications "Preparation of hydrophobic PET track-etched membranes for separation of oil-water emulsion" (2021, IF -4. 562, Q2, 12 citations) in the journal "Membranes" and the article "Hydrophobization of PET track membranes with trichloroctylsilane for use in the separation of water-oil mixtures" in the national journal "BULLETIN of L.N. Gumilyov ENU. Chemistry. Geography. Ecology series" (2021). Theses of the reports " Modification of track-etched membranes based on PET by UV graft block copolymerization of styrene and 4-vinylpyridine" (Perm, Russia, 2021) and "Preparation of stimuli-responsive track-etched membranes for separation of water-oil emulsions" (Nara, Japan, 2022) were presented and reported by the PhD student at international conferences. Relation of the work to research program. The work was carried out within the framework of scientific projects of grant financing AP09057934 "Development of novel membranes for separation of water-oil mixtures" (2021-2023), BRFFR T22MS-029 (funded by the Belarusian Republican Fundamental Research contract dated 04. 05.2022) and Project "Zhas Galym" for 2022-2024 years of the Scientific Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan AP14972816 "Stimuli-responsive track-etched membranes for separation of water-organic emulsions". Approval of the work. The main provisions, conclusions and scientific results of the study were presented and discussed at the All-Russian scientific and practical conference with international participation "Resource-saving and ecologically safe processes in chemistry and chemical technology" (Perm, Russia, 2021), at the 14th International Online Symposium "Ionising Radiation and Polymers" (Nara, Japan, 2022). A patent for Utility Model No. 7839 "Method of modifying track membranes for separation of forward and reverse emulsions" was received.
Conclusion of the Research Ethics Committee
Defense of the dissertation: https://youtu.be/tq-wVRjG0ys?si=oG4Bwj1-LMJ_PEZE
