Pub Date : 2022-01-01DOI: 10.31489/2022ch2/2-22-14
N. A. Medvedeva, A. Mironova, N. Skryabina, M. Plotnikova, D. Fruchart, M. G. Shcherban
The microstructure transformation of ternary Ti-Cr-V alloys after introduction of hydrogen has been analyzed for a long time. Assessment of the impact of vanadium concentration and ratio Ti and V concentrations on composition stability has been carried out. Investigated alloys system corresponds to relation (TiCr1.8)100–xVx.The atomic ratio Ti/Cr is constant. Vanadium content changes with the step 20 at. %. The hydrogen charging has been carried out in a thermostatic three-electrode electrochemical cell using 1M KOH electrolyte (ic = 10–30 mA/cm2) at 293 K during three hours. It was established that the hydrogen introduction leads to surface migration of alloy components. Their distribution oscillates as time passed. This is due to the fact that hydrogen interacts differently with titanium and vanadium. The electrolytic hydrogen introduction initiates deformation of the crystal lattice and self-diffusion of alloy atoms. The statistically nonuniform distribution of electrolytic hydrogen increases the intensity of the process. The relaxation of internal stresses leads to a further redistribution of components. The observed changes depend on the vanadium content in the alloys and have a different character inside the grain and near grain boundaries. The significant changing has been established for (TiCr1.8)60V40.
{"title":"The effect of aging on the microstructure of alloys (ТiСr1.8)100–xVx after electrolytic hydrogen charging","authors":"N. A. Medvedeva, A. Mironova, N. Skryabina, M. Plotnikova, D. Fruchart, M. G. Shcherban","doi":"10.31489/2022ch2/2-22-14","DOIUrl":"https://doi.org/10.31489/2022ch2/2-22-14","url":null,"abstract":"The microstructure transformation of ternary Ti-Cr-V alloys after introduction of hydrogen has been analyzed for a long time. Assessment of the impact of vanadium concentration and ratio Ti and V concentrations on composition stability has been carried out. Investigated alloys system corresponds to relation (TiCr1.8)100–xVx.The atomic ratio Ti/Cr is constant. Vanadium content changes with the step 20 at. %. The hydrogen charging has been carried out in a thermostatic three-electrode electrochemical cell using 1M KOH electrolyte (ic = 10–30 mA/cm2) at 293 K during three hours. It was established that the hydrogen introduction leads to surface migration of alloy components. Their distribution oscillates as time passed. This is due to the fact that hydrogen interacts differently with titanium and vanadium. The electrolytic hydrogen introduction initiates deformation of the crystal lattice and self-diffusion of alloy atoms. The statistically nonuniform distribution of electrolytic hydrogen increases the intensity of the process. The relaxation of internal stresses leads to a further redistribution of components. The observed changes depend on the vanadium content in the alloys and have a different character inside the grain and near grain boundaries. The significant changing has been established for (TiCr1.8)60V40.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86484826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.31489/2022ch3/3-22-22
O. Avazova, R.Yu. Milushevа, I. Nurgaliev, S. Rashidova
The interaction of chitosan (ChS) and the Bombyx mori protein on different pH ranges was studied, and the fundamental possibility of obtaining complexes of ChS with the Bombyx mori protein was revealed. The for-mation of a polymolecular complex of protein with ChS in aqueous solutions was confirmed by the results of physico-chemical methods. It is shown that the ChS structure is characterized by a certain rigidity and iono-genicity. The results indicate the complexation of the pupae protein with ChS in 2% acetic acid in the range of pH = 4.8–6.7. The detected changes and shifts of the absorption bands in the IR spectra confirm the occur-rence of the complex formation reaction between the molecules of ChS and protein at pH = 4.8–6.7, which is characterized by absorption bands in the IR spectra at 1641 cm–1, 1538 cm–1 and 1068 cm–1. Quantum-chemical DFT study of ChS complexes with amino acids (AAs) was carried out. The stability of complexes of ChS with AAs (ChS-AA) was shown except for the complex formed with histidine in the gas phase. The calculation results indicate the presence of a strong thermodynamic driving force in the complexation of ChS with AAs.
{"title":"Polymolecular Complexes of Chitosan with the Bombyx Mori Protein","authors":"O. Avazova, R.Yu. Milushevа, I. Nurgaliev, S. Rashidova","doi":"10.31489/2022ch3/3-22-22","DOIUrl":"https://doi.org/10.31489/2022ch3/3-22-22","url":null,"abstract":"The interaction of chitosan (ChS) and the Bombyx mori protein on different pH ranges was studied, and the fundamental possibility of obtaining complexes of ChS with the Bombyx mori protein was revealed. The for-mation of a polymolecular complex of protein with ChS in aqueous solutions was confirmed by the results of physico-chemical methods. It is shown that the ChS structure is characterized by a certain rigidity and iono-genicity. The results indicate the complexation of the pupae protein with ChS in 2% acetic acid in the range of pH = 4.8–6.7. The detected changes and shifts of the absorption bands in the IR spectra confirm the occur-rence of the complex formation reaction between the molecules of ChS and protein at pH = 4.8–6.7, which is characterized by absorption bands in the IR spectra at 1641 cm–1, 1538 cm–1 and 1068 cm–1. Quantum-chemical DFT study of ChS complexes with amino acids (AAs) was carried out. The stability of complexes of ChS with AAs (ChS-AA) was shown except for the complex formed with histidine in the gas phase. The calculation results indicate the presence of a strong thermodynamic driving force in the complexation of ChS with AAs.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73024325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.31489/2022ch2/2-22-15
I.L. Stadnik, F. Abilkanova, Ye. V. Kudryavtseva, S. Nikolskiy, A. Masalimov
This paper presents the results of an ESR spectroscopic study of the intermolecular proton exchange kinetics with some isomers of aminocaproic acid, such as 2-aminohexanoic and 6-aminohexanoic acids in the toluene indifferent medium. A stable semiquinone radical, namely 3,6-di-tert-butyl-2-hydroxyphenoxyl, was used as a spin probe. The ESR spectra were recorded on a RE-1306 spectrometer. The obtained dynamic spectra of the intermolecular proton exchange process are given in this article. Modeling of the proton exchange ESR spectra was carried out using a previously developed program, which is based on a four-jump model of this reaction and modified Bloch equations. The kinetic parameters of the process of acid-base interaction of the spin probe with amino acids and the activation barrier of the reaction were estimated with a minimum error based on a comparison of the model spectra with the experimental ones. The obtained data were analyzed and compared with previously known information. It was found that the reaction rate of the intermolecular proton exchange between 3,6-di-tert-butyl-2-hydroxyphenoxy and studied aliphatic amino acids is comparable to the same with aliphatic carboxylic acids. But in our case, there is an increase in the activation barrier, which apparently is associated with a negative effect on the intramolecular hydrogen bonding process between the amino and the carboxyl groups in the amino acid molecule
{"title":"ESR-study of the proton exchange with aliphatic amino acids in toluene","authors":"I.L. Stadnik, F. Abilkanova, Ye. V. Kudryavtseva, S. Nikolskiy, A. Masalimov","doi":"10.31489/2022ch2/2-22-15","DOIUrl":"https://doi.org/10.31489/2022ch2/2-22-15","url":null,"abstract":"This paper presents the results of an ESR spectroscopic study of the intermolecular proton exchange kinetics with some isomers of aminocaproic acid, such as 2-aminohexanoic and 6-aminohexanoic acids in the toluene indifferent medium. A stable semiquinone radical, namely 3,6-di-tert-butyl-2-hydroxyphenoxyl, was used as a spin probe. The ESR spectra were recorded on a RE-1306 spectrometer. The obtained dynamic spectra of the intermolecular proton exchange process are given in this article. Modeling of the proton exchange ESR spectra was carried out using a previously developed program, which is based on a four-jump model of this reaction and modified Bloch equations. The kinetic parameters of the process of acid-base interaction of the spin probe with amino acids and the activation barrier of the reaction were estimated with a minimum error based on a comparison of the model spectra with the experimental ones. The obtained data were analyzed and compared with previously known information. It was found that the reaction rate of the intermolecular proton exchange between 3,6-di-tert-butyl-2-hydroxyphenoxy and studied aliphatic amino acids is comparable to the same with aliphatic carboxylic acids. But in our case, there is an increase in the activation barrier, which apparently is associated with a negative effect on the intramolecular hydrogen bonding process between the amino and the carboxyl groups in the amino acid molecule","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87952647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. A. Bekturov, R. I. Moustafine, S. Kudaibergenov, V. Khutoryanskiy
This review is focused on synthetic, natural and semi-natural polyampholytes and their ability to form interpolymer complexes with other polyelectrolytes and non-ionic polymers. It provides definition, classification and overview of physicochemical properties of polyampholytes. The conformation and phase behaviour of intrinsically disordered proteins and semi-natural polyampholytes derived from aminoacids is discussed. The ability of synthetic, natural and semi-natural polyampholytes to form interpolymer complexes with water-soluble polymers is considered. Most of the research in this area is focused on interpolyelectrolyte complexes of polyampholytes with oppositely charged polyelectrolytes; however, there are also studies demonstrating the formation of hydrogen-bonded complexes. The nature of the complexation is often affected by solution pH and also isoelectric point of polyampholytes. The complexation between polyampholytes and other polymers may lead to formation of colloidal dispersions (nano- and microparticles), liquid-liquid phase separation (called complex coacervation), fully soluble polycomplexes or physically cross-linked gels. A substantial body of studies in this area were focused on the complexes formed by proteins. Application of interpolymer complexes formed by polyampholytes in biotechnology, medicine, encapsulation technologies, separation science, biocatalysis, food science and pharmaceutics is discussed.
{"title":"Interpolymer Complexes of Synthetic, Natural and Semi-Natural Polyampholytes: A Review","authors":"E. A. Bekturov, R. I. Moustafine, S. Kudaibergenov, V. Khutoryanskiy","doi":"10.31489/2022ch3/3-22-9","DOIUrl":"https://doi.org/10.31489/2022ch3/3-22-9","url":null,"abstract":"This review is focused on synthetic, natural and semi-natural polyampholytes and their ability to form interpolymer complexes with other polyelectrolytes and non-ionic polymers. It provides definition, classification and overview of physicochemical properties of polyampholytes. The conformation and phase behaviour of intrinsically disordered proteins and semi-natural polyampholytes derived from aminoacids is discussed. The ability of synthetic, natural and semi-natural polyampholytes to form interpolymer complexes with water-soluble polymers is considered. Most of the research in this area is focused on interpolyelectrolyte complexes of polyampholytes with oppositely charged polyelectrolytes; however, there are also studies demonstrating the formation of hydrogen-bonded complexes. The nature of the complexation is often affected by solution pH and also isoelectric point of polyampholytes. The complexation between polyampholytes and other polymers may lead to formation of colloidal dispersions (nano- and microparticles), liquid-liquid phase separation (called complex coacervation), fully soluble polycomplexes or physically cross-linked gels. A substantial body of studies in this area were focused on the complexes formed by proteins. Application of interpolymer complexes formed by polyampholytes in biotechnology, medicine, encapsulation technologies, separation science, biocatalysis, food science and pharmaceutics is discussed.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84424456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aigerim Ayazbayeva, S. Nauryzova, V. Aseyev, A. Shakhvorostov
Cross-linked polyampholyte nanogels consisting of neutral N-isopropylacrylamide (NIPAM), negatively charged sodium salt of 2-acrylamido-2-methylpropanesulfonate (AMPS), and positively charged (3-acryl-amidopropyltrimethylammonium chloride (APTAC) monomers were synthesized via conventional redox ini-tiated free radical copolymerization using N,N-methylenebis(acrylamide) (MBAA) as a crosslinking agent. The resulting nanogels were characterized by means of FTIR and 1H NMR spectroscopy, dynamic light scat-tering (DLS) and zeta-potential measurements. Surface morphology was analyzed using scanning electron microscopy. Due to the presence of thermally responsive NIPAM units and varying molar ratios of anionic (AMPS) and cationic (APTAC) units, the resulting nanogels were responsive to multiple stimuli in aqueous media and can be used for controlled delivery of dyes. Thus, the NIPAM90-APTAC7.5-AMPS2.5 nanogel with an excess of the cationic units was chosen for immobilization of the anionic dye, methyl orange (MO), whereas the NIPAM90-APTAC2.5-AMPS7.5 nanogel with an excess of the anionic units was chosen for immo-bilization of the cationic dye, methylene blue (MB). The release kinetics of the dyes from the nanogel was studied depending on the phase transition temperature and the salt content. Mechanism of the dye release from the nanogel matrix was determined using the Ritger-Peppas equation. Disappearance of the ionic con-tacts between the charged groups of the nanogels and the ionic dyes was suggested to be the main reason for the diffusion of the dyes through the dialysis membrane into external solution.
{"title":"Immobilization of Methyl Orange and Methylene Blue within the Matrix of Charge-Imbalanced Amphoteric Nanogels and Study of Dye Release Kinetics as a Function of Temperature and Ionic Strength","authors":"Aigerim Ayazbayeva, S. Nauryzova, V. Aseyev, A. Shakhvorostov","doi":"10.31489/2022ch3/3-22-4","DOIUrl":"https://doi.org/10.31489/2022ch3/3-22-4","url":null,"abstract":"Cross-linked polyampholyte nanogels consisting of neutral N-isopropylacrylamide (NIPAM), negatively charged sodium salt of 2-acrylamido-2-methylpropanesulfonate (AMPS), and positively charged (3-acryl-amidopropyltrimethylammonium chloride (APTAC) monomers were synthesized via conventional redox ini-tiated free radical copolymerization using N,N-methylenebis(acrylamide) (MBAA) as a crosslinking agent. The resulting nanogels were characterized by means of FTIR and 1H NMR spectroscopy, dynamic light scat-tering (DLS) and zeta-potential measurements. Surface morphology was analyzed using scanning electron microscopy. Due to the presence of thermally responsive NIPAM units and varying molar ratios of anionic (AMPS) and cationic (APTAC) units, the resulting nanogels were responsive to multiple stimuli in aqueous media and can be used for controlled delivery of dyes. Thus, the NIPAM90-APTAC7.5-AMPS2.5 nanogel with an excess of the cationic units was chosen for immobilization of the anionic dye, methyl orange (MO), whereas the NIPAM90-APTAC2.5-AMPS7.5 nanogel with an excess of the anionic units was chosen for immo-bilization of the cationic dye, methylene blue (MB). The release kinetics of the dyes from the nanogel was studied depending on the phase transition temperature and the salt content. Mechanism of the dye release from the nanogel matrix was determined using the Ritger-Peppas equation. Disappearance of the ionic con-tacts between the charged groups of the nanogels and the ionic dyes was suggested to be the main reason for the diffusion of the dyes through the dialysis membrane into external solution.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89468802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.31489/2022ch2/2-22-20
A. Ryabykh, O. Maslova, S. Beznosyuk, A. Masalimov
The interaction of the superoxide radical ion O2– with the active site of Cu, Zn-superoxide dismutase was studied by computer simulation using the ORCA software package version 5.0.2 at the level of density functional theory using the PBE functional and the basis sets of functions def2-SVP, def2-SVPD and def2-TZVPD. The main characteristics for two processes of electron transfer in the catalytic cycle of radical ion deactivation were obtained: reaction potential ΔG0, total reorganization energy λtot, activation energy ΔG≠, overlap matrix element HDA, and transfer rate constant k according to Marcus. The variable factor in the modeling was the presence of the Zn2+ ion in the active site of the enzyme. Two variants of the electron transfer mechanism were considered: one carried out with the help of ligands and another occurring in the immediate vicinity of an oxygen-containing particle and a copper ion. It has been established that the presence of the Zn2+ ion contributes to a large extent only to the second electron transfer from the Cu+ ion to the protonated form of the radical ion, to the hydroperoxide radical HO2. Other things being equal, the zinc ion increases the electron transfer rate constant by five times through specific interactions.
{"title":"The role of zinc ion in the active site of copper-zinc superoxide dismutase","authors":"A. Ryabykh, O. Maslova, S. Beznosyuk, A. Masalimov","doi":"10.31489/2022ch2/2-22-20","DOIUrl":"https://doi.org/10.31489/2022ch2/2-22-20","url":null,"abstract":"The interaction of the superoxide radical ion O2– with the active site of Cu, Zn-superoxide dismutase was studied by computer simulation using the ORCA software package version 5.0.2 at the level of density functional theory using the PBE functional and the basis sets of functions def2-SVP, def2-SVPD and def2-TZVPD. The main characteristics for two processes of electron transfer in the catalytic cycle of radical ion deactivation were obtained: reaction potential ΔG0, total reorganization energy λtot, activation energy ΔG≠, overlap matrix element HDA, and transfer rate constant k according to Marcus. The variable factor in the modeling was the presence of the Zn2+ ion in the active site of the enzyme. Two variants of the electron transfer mechanism were considered: one carried out with the help of ligands and another occurring in the immediate vicinity of an oxygen-containing particle and a copper ion. It has been established that the presence of the Zn2+ ion contributes to a large extent only to the second electron transfer from the Cu+ ion to the protonated form of the radical ion, to the hydroperoxide radical HO2. Other things being equal, the zinc ion increases the electron transfer rate constant by five times through specific interactions.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"171 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83677208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.31489/2022ch3/3-22-18
A. Mashentseva, N. A. Aimanova, N. Parmanbek, L. Altynbaeva, D. Nurpeisova
The features of obtaining composite track-etched membranes based on copper microtubes using various com-positions of a deposition solution and various types of reducing agents such as formaldehyde (Cu_CHOH@PET), dimethylamine borane (Cu_DMAB@PET), glyoxylic acid (Cu_Gly@PET) were studied in this research. The structure and composition of the membrane composites were studied by scanning elec-tron microscopy and X-ray phase analysis. It was shown that in the case of using dimethylamine borane as a reducing agent, the obtained composites consisted of copper(I) oxide (37.4 %) and copper(0) (62.6 %), in other cases single-component copper microtubes were obtained. The reduction reaction of chromium(VI) ions was used in order to evaluate the catalytic ability of prepared composites. It was shown that the removal effi-ciency of chromium ions reached up to the 95–97 % in the case of single-component composites; the pres-ence of a copper(I) oxide phase in the structure of the Cu_DMAB@PET composites significantly reduced the activity of catalysts and under similar conditions only 41% of the contaminant was removed from the reaction system. The degradation reaction of Cr(VI) was found to follow the Langmuir-Hinshelwood mechanism and a pseudo-first-order kinetic model. The calculated value of the reaction rate constant ka for composites of the Cu_DMAB@PET composition (0.017 min–1) was more than 9 times less than that of composites obtained us-ing glyoxylic acid (0.156 min–1) and more than 15 times less than the ka value of Cu_CHOH@PET samples (0.249 min–1). Effect of temperatures on the catalytic ability of composites was studied in the temperature range of 10–38 °C. Some thermodynamic characteristics such as activation energy, enthalpy and entropy of activation were calculated. It was found that the minimum value of the activation energy was obtained for the Cu_CHOH@PET samples.
{"title":"Application of the Cu@PET Composite Track-Etched Membranes for Catalytic Removal of Cr(VI) Ions","authors":"A. Mashentseva, N. A. Aimanova, N. Parmanbek, L. Altynbaeva, D. Nurpeisova","doi":"10.31489/2022ch3/3-22-18","DOIUrl":"https://doi.org/10.31489/2022ch3/3-22-18","url":null,"abstract":"The features of obtaining composite track-etched membranes based on copper microtubes using various com-positions of a deposition solution and various types of reducing agents such as formaldehyde (Cu_CHOH@PET), dimethylamine borane (Cu_DMAB@PET), glyoxylic acid (Cu_Gly@PET) were studied in this research. The structure and composition of the membrane composites were studied by scanning elec-tron microscopy and X-ray phase analysis. It was shown that in the case of using dimethylamine borane as a reducing agent, the obtained composites consisted of copper(I) oxide (37.4 %) and copper(0) (62.6 %), in other cases single-component copper microtubes were obtained. The reduction reaction of chromium(VI) ions was used in order to evaluate the catalytic ability of prepared composites. It was shown that the removal effi-ciency of chromium ions reached up to the 95–97 % in the case of single-component composites; the pres-ence of a copper(I) oxide phase in the structure of the Cu_DMAB@PET composites significantly reduced the activity of catalysts and under similar conditions only 41% of the contaminant was removed from the reaction system. The degradation reaction of Cr(VI) was found to follow the Langmuir-Hinshelwood mechanism and a pseudo-first-order kinetic model. The calculated value of the reaction rate constant ka for composites of the Cu_DMAB@PET composition (0.017 min–1) was more than 9 times less than that of composites obtained us-ing glyoxylic acid (0.156 min–1) and more than 15 times less than the ka value of Cu_CHOH@PET samples (0.249 min–1). Effect of temperatures on the catalytic ability of composites was studied in the temperature range of 10–38 °C. Some thermodynamic characteristics such as activation energy, enthalpy and entropy of activation were calculated. It was found that the minimum value of the activation energy was obtained for the Cu_CHOH@PET samples.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"104 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72790610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Macroporous physical poly(vinyl alcohol)-based (PVA) cryogels were prepared originating from the dime-thylsulfoxide solutions of the polymer that contained urea additives. The variables of the cryotropic gel-formation process were its temperature and the concentration of the added urea, which caused the increase in the rigidity and heat endurance of the resultant cryogels, as well as promoted widening of the macropores in the gel matter. Subsequent rinsing of the DMSO-swollen cryogels with the water excess resulted in the water-swollen PVA cryogels with simultaneous further increase in their rigidity. These gel matrices were tested with respect of their potential to operate as the polymeric carriers in the drug delivery systems. Loading of such water-swollen cryogels with a model drug, ε-amino caproic acid, and then studies of its release kinetics revealed that urea content in the initial PVA solutions used for the freeze-thaw-induced formation of the DMSO-swollen cryogels played the key role for the release characteristics of the drug-loaded water-swollen gel carrier. Namely, PVA cryogels prepared in the presence of a higher concentration of urea possessed the larger pores and, as a result, the drug release occurred somewhat faster.
{"title":"Cryostructuring of Polymeric Systems. 61. Physicochemical Properties of Poly(vinyl alcohol) Cryogels Prepared on the Basis of Urea-Containing DMSO-Solutions of the Polymer and Evaluation of the Resultant Gel Materials as Potential Drug Carriers","authors":"D. A. Michurov, O. Kolosova, V. Lozinsky","doi":"10.31489/2022ch3/3-22-7","DOIUrl":"https://doi.org/10.31489/2022ch3/3-22-7","url":null,"abstract":"Macroporous physical poly(vinyl alcohol)-based (PVA) cryogels were prepared originating from the dime-thylsulfoxide solutions of the polymer that contained urea additives. The variables of the cryotropic gel-formation process were its temperature and the concentration of the added urea, which caused the increase in the rigidity and heat endurance of the resultant cryogels, as well as promoted widening of the macropores in the gel matter. Subsequent rinsing of the DMSO-swollen cryogels with the water excess resulted in the water-swollen PVA cryogels with simultaneous further increase in their rigidity. These gel matrices were tested with respect of their potential to operate as the polymeric carriers in the drug delivery systems. Loading of such water-swollen cryogels with a model drug, ε-amino caproic acid, and then studies of its release kinetics revealed that urea content in the initial PVA solutions used for the freeze-thaw-induced formation of the DMSO-swollen cryogels played the key role for the release characteristics of the drug-loaded water-swollen gel carrier. Namely, PVA cryogels prepared in the presence of a higher concentration of urea possessed the larger pores and, as a result, the drug release occurred somewhat faster.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75147690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.31489/2022ch3/3-22-11
B.Kh. Мussabayeva, Zh. S. Kassymova, L. Orazzhanova, A. Klivenko, A. Sabitova, B.B. Bayahmetova
The interpolyelectrolyte complex of the composition [chitosan]:[alginate] = [1]:[4] was prepared by mixing a hydrochloric acid solution of cationic polyelectrolyte chitosan and an aqueous solution of anionic polyelectro-lyte sodium alginate. The complex of chitosan and sodium alginate biopolymers was first used as a soil struc-turizer. Due to low humus and light mechanical composition, the dark chestnut soil of the dry-steppe zone of the East Kazakhstan region is subjected to erosion. Introducing a polymer complex into the specified soil con-tributed to the improvement of wind resistance, an increase in humidity, and a decrease in water permeability. The soil surface treated with a complex of biopolymers showed pronounced resistance to the action of planar and trickle water erosion due to aggregation of particles with a diameter of < 0.01 mm. The fraction of soil particles obtained by mechanical destruction of structured aggregates with a diameter of 3-1 mm has a well-expressed ability to self-aggregate during the humidification - drying process. The results of the vegetation and field experience in tillage with an interpolyelectrolyte complex showed a positive effect of the complex on the growth and development of radish of the Rubin variety and, as a result, an increase in radish yield by 2 times was achieved. The obtained results indicate the effectiveness of the structuring action of the chitosan-alginate complex for poorly structured soils.
{"title":"Interpolyelectrolyte Complex Chitosan – Alginate for Soil Structuring","authors":"B.Kh. Мussabayeva, Zh. S. Kassymova, L. Orazzhanova, A. Klivenko, A. Sabitova, B.B. Bayahmetova","doi":"10.31489/2022ch3/3-22-11","DOIUrl":"https://doi.org/10.31489/2022ch3/3-22-11","url":null,"abstract":"The interpolyelectrolyte complex of the composition [chitosan]:[alginate] = [1]:[4] was prepared by mixing a hydrochloric acid solution of cationic polyelectrolyte chitosan and an aqueous solution of anionic polyelectro-lyte sodium alginate. The complex of chitosan and sodium alginate biopolymers was first used as a soil struc-turizer. Due to low humus and light mechanical composition, the dark chestnut soil of the dry-steppe zone of the East Kazakhstan region is subjected to erosion. Introducing a polymer complex into the specified soil con-tributed to the improvement of wind resistance, an increase in humidity, and a decrease in water permeability. The soil surface treated with a complex of biopolymers showed pronounced resistance to the action of planar and trickle water erosion due to aggregation of particles with a diameter of < 0.01 mm. The fraction of soil particles obtained by mechanical destruction of structured aggregates with a diameter of 3-1 mm has a well-expressed ability to self-aggregate during the humidification - drying process. The results of the vegetation and field experience in tillage with an interpolyelectrolyte complex showed a positive effect of the complex on the growth and development of radish of the Rubin variety and, as a result, an increase in radish yield by 2 times was achieved. The obtained results indicate the effectiveness of the structuring action of the chitosan-alginate complex for poorly structured soils.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78114256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, the reentrant solvation of dual nanocomposite hydrogel poly-N-isopropylacryl-amide/Laponite/SiO2 (PNIPAM/Laponite/SiO2) upon shrinkage/reswelling process has been investigated. Depending on the unique hierarchical microstructure of inorganic hybrid crosslinking of Laponite and SiO2 as well as the preferential interaction of polar solvents with PNIPAM chains, the hydrogel exhibited rapid coil-to-globule-to-coil transition in water-polar solvent mixtures. The solvation behavior could be controlled through varying types of organic solvents. Shrinkage in water-polar solvent mixtures occurred as a conse-quence of strong interaction between polar solvents and PNIPAM chains, whereas reswelling resulted from the direct interaction of the solvent molecules with the intermolecular water in the hydrogel. The attractive competing effects on forming hydrogel-water and hydrogel-polar solvent hydrogen bonds were considered to be indispensable to the solvation. The rapid response rate was attributed to the synergistic effect of the unique heterogeneous microstructure with inorganic hybrid crosslinking and preferential interaction of polar solvents with polymer chains. The mechanism proposed in this paper provides a new reference on design of smart soft matter systems. Moreover, several solvation effects described in this paper can be incorporated in theory of cononsolvent-induced conformational transitions in the nanocomposite hydrogels with inorganic hybrid crosslinking.
{"title":"Solvents Triggered Coil-to-Globule-to-Coil Transition of Dual Nanocomposite Hydrogels with Inorganic Hybrid Crosslinking","authors":"Juan Du, Shimei Xu","doi":"10.31489/2022ch3/3-22-2","DOIUrl":"https://doi.org/10.31489/2022ch3/3-22-2","url":null,"abstract":"In this paper, the reentrant solvation of dual nanocomposite hydrogel poly-N-isopropylacryl-amide/Laponite/SiO2 (PNIPAM/Laponite/SiO2) upon shrinkage/reswelling process has been investigated. Depending on the unique hierarchical microstructure of inorganic hybrid crosslinking of Laponite and SiO2 as well as the preferential interaction of polar solvents with PNIPAM chains, the hydrogel exhibited rapid coil-to-globule-to-coil transition in water-polar solvent mixtures. The solvation behavior could be controlled through varying types of organic solvents. Shrinkage in water-polar solvent mixtures occurred as a conse-quence of strong interaction between polar solvents and PNIPAM chains, whereas reswelling resulted from the direct interaction of the solvent molecules with the intermolecular water in the hydrogel. The attractive competing effects on forming hydrogel-water and hydrogel-polar solvent hydrogen bonds were considered to be indispensable to the solvation. The rapid response rate was attributed to the synergistic effect of the unique heterogeneous microstructure with inorganic hybrid crosslinking and preferential interaction of polar solvents with polymer chains. The mechanism proposed in this paper provides a new reference on design of smart soft matter systems. Moreover, several solvation effects described in this paper can be incorporated in theory of cononsolvent-induced conformational transitions in the nanocomposite hydrogels with inorganic hybrid crosslinking.","PeriodicalId":9421,"journal":{"name":"Bulletin of the Karaganda University. \"Chemistry\" series","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81042796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：