Pub Date : 2021-05-11DOI: 10.20450/MJCCE.2021.2045
S. Apostolov, G. Vastag
Preliminary assessment of the bioactive profile of azo derivatives was performed applying drug-likeness rules. As the presumed criteria of lipophilicity chromatographic parameters (RM0, m and C0) were calculated in mixtures water/ methanol and water/ acetonitrile by using reversed phase thin-layer chromatography (RPTLC C18/ UV254s). The relationships between chromatographic parameters and relevant software parameters of biological activity of azo derivatives were examined by linear regression and by two multivariate methods. Good linear relationships for each applied system were obtained. The multivariate methods show similarity of the chromatographic parameters (RM0, C0) with standard measure of lipophilicity and pharmacokinetic predictors. The chromatographic parameter m obtained in the same conditions exhibits better agreement with the drug-likeness and toxicity parameters. On the values of azo derivatives’ bioactivity parameters the polarity of the substituent has higher impact than its electronic effects.
{"title":"Chromatographic parameters as tools for predicting the biological activity of azo derivatives","authors":"S. Apostolov, G. Vastag","doi":"10.20450/MJCCE.2021.2045","DOIUrl":"https://doi.org/10.20450/MJCCE.2021.2045","url":null,"abstract":"Preliminary assessment of the bioactive profile of azo derivatives was performed applying drug-likeness rules. As the presumed criteria of lipophilicity chromatographic parameters (RM0, m and C0) were calculated in mixtures water/ methanol and water/ acetonitrile by using reversed phase thin-layer chromatography (RPTLC C18/ UV254s). The relationships between chromatographic parameters and relevant software parameters of biological activity of azo derivatives were examined by linear regression and by two multivariate methods. Good linear relationships for each applied system were obtained. The multivariate methods show similarity of the chromatographic parameters (RM0, C0) with standard measure of lipophilicity and pharmacokinetic predictors. The chromatographic parameter m obtained in the same conditions exhibits better agreement with the drug-likeness and toxicity parameters. On the values of azo derivatives’ bioactivity parameters the polarity of the substituent has higher impact than its electronic effects.","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47408936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-11DOI: 10.20450/MJCCE.2021.2100
Katerina Jancevska, G. Petrushevski, Mirjana Bogdanoska, T. Stafilov, S. Ugarkovic
Fast and simple closed-vessel microwave-assisted digestion procedure was developed for decomposition of three pharmaceutical dosage forms of ibuprofen such as tablets, suspension and gel, prior to elemental impurity analysis by one robust and precise ICP-OES method. Samples were digested by four-step microwave program consisting of a 10 min temperature gradient to 180°C, maintained at 180°C for 10 min, followed by 5 min ramping time to 210°C with holding time of 10 min on 210°C. Subsequently, ICP-OES method was developed and validated for simultaneous determination of selected elemental impurities. Results of recovery studies range between 77% and 105% for each element in all analyzed formulations. Correlation coefficients of the regression equations were higher than 0.999 for all analyzed elements. Validation results reveal that the proposed method is specific, accurate, and precise and could be applied for simultaneous quantitative analysis of multi element solutions in different pharmaceutical dosage forms of ibuprofen.
{"title":"ICP-OES elemental impurities study on different pharmaceutical dosage forms of Ibuprofen using microwave-assisted digestion procedure","authors":"Katerina Jancevska, G. Petrushevski, Mirjana Bogdanoska, T. Stafilov, S. Ugarkovic","doi":"10.20450/MJCCE.2021.2100","DOIUrl":"https://doi.org/10.20450/MJCCE.2021.2100","url":null,"abstract":"Fast and simple closed-vessel microwave-assisted digestion procedure was developed for decomposition of three pharmaceutical dosage forms of ibuprofen such as tablets, suspension and gel, prior to elemental impurity analysis by one robust and precise ICP-OES method. Samples were digested by four-step microwave program consisting of a 10 min temperature gradient to 180°C, maintained at 180°C for 10 min, followed by 5 min ramping time to 210°C with holding time of 10 min on 210°C. Subsequently, ICP-OES method was developed and validated for simultaneous determination of selected elemental impurities. Results of recovery studies range between 77% and 105% for each element in all analyzed formulations. Correlation coefficients of the regression equations were higher than 0.999 for all analyzed elements. Validation results reveal that the proposed method is specific, accurate, and precise and could be applied for simultaneous quantitative analysis of multi element solutions in different pharmaceutical dosage forms of ibuprofen.","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49093276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-11DOI: 10.20450/MJCCE.2021.2095
G. Stefkov, Ivana Cvetkovikj Karanfilova, Viktorija Labroska, Orhidea Krsteska, Bujar Qazimi, M. Karapandzova, Z. Gjoni, N. Bardhi, S. Kulevanova
Due to the presence of arbutin and hydroquinone in the bearberry plant (Arctostaphylos uva-ursi (L.) Spreng., Ericaceae), it is widely used as a urinary tract antiseptic and diuretic. The herbal substance consists of whole or cut dried leaves, and it should not contain less than 7.00% of anhydrous arbutin (Ph.Eur.10). The supply of this herbal substance in Balkan countries mainly comes from a wild plant harvested in the mountains. It is a common practice to collect the leaves during the flowering season of the plant (June-July). There is an abundance of wild growing natural populations of bearberry on Korab Mountain that represents a unique natural resource of this herbal substance for both countries, Albania and North Macedonia. The aim of the present study was to determine the arbutin content and to assess its variability in the bearberry leaves of seven wild populations from Korab Mountain. The leaves were collected monthly (May-October) during a period of 3 years (2014-2016). The HPLC assay (Ph.Eur.10) revealed that all populations have arbutin content over 7.00% (7.03-9.42%) and that the highest content of arbutin can be attained in September/October, during the phase after the fructification. Statistical analysis showed that there is significant difference between the content of arbutin in the different populations. The content was related to the altitude of the collection site and the collection month and year.
{"title":"Variability of the arbutin content in wild growing populations of Arctostaphylos uva-ursi (L.) Spreng from Korab Mountain, Western Balkan","authors":"G. Stefkov, Ivana Cvetkovikj Karanfilova, Viktorija Labroska, Orhidea Krsteska, Bujar Qazimi, M. Karapandzova, Z. Gjoni, N. Bardhi, S. Kulevanova","doi":"10.20450/MJCCE.2021.2095","DOIUrl":"https://doi.org/10.20450/MJCCE.2021.2095","url":null,"abstract":"Due to the presence of arbutin and hydroquinone in the bearberry plant (Arctostaphylos uva-ursi (L.) Spreng., Ericaceae), it is widely used as a urinary tract antiseptic and diuretic. The herbal substance consists of whole or cut dried leaves, and it should not contain less than 7.00% of anhydrous arbutin (Ph.Eur.10). The supply of this herbal substance in Balkan countries mainly comes from a wild plant harvested in the mountains. It is a common practice to collect the leaves during the flowering season of the plant (June-July). There is an abundance of wild growing natural populations of bearberry on Korab Mountain that represents a unique natural resource of this herbal substance for both countries, Albania and North Macedonia. The aim of the present study was to determine the arbutin content and to assess its variability in the bearberry leaves of seven wild populations from Korab Mountain. The leaves were collected monthly (May-October) during a period of 3 years (2014-2016). The HPLC assay (Ph.Eur.10) revealed that all populations have arbutin content over 7.00% (7.03-9.42%) and that the highest content of arbutin can be attained in September/October, during the phase after the fructification. Statistical analysis showed that there is significant difference between the content of arbutin in the different populations. The content was related to the altitude of the collection site and the collection month and year.","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42685840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-11DOI: 10.20450/MJCCE.2021.2240
Saša A. Horvat, J. Mihajlović, Tamara N. Rončević, Dušica D. Rodić
The aim of this research was the creation and validation of a procedure for determining the cognitive complexity of problem tasks in the field of salt hydrolysis. The procedure created included an assessment of the difficulty of concepts and an assessment of their interactivity. One of the research tasks was to determine whether there were misconceptions by students that might have influenced their achievement. There were 50 Bachelor of Science in Chemistry students who participated in the study. A knowledge test was used as a research instrument to assess the performance and a seven-point Likert scale to evaluate the invested mental effort. The validity of this instrument for the assessment of cognitive complexity was confirmed by a series of regression analyses, where acceptable and statistically significant correlation coefficients were obtained among the examined variables: student performance and invested mental effort as dependent variables and cognitive complexity as independent variable
{"title":"Procedure for the assessment of cognitive complexity: Development and implementation in the topic \"Hydrolysis of salts\"","authors":"Saša A. Horvat, J. Mihajlović, Tamara N. Rončević, Dušica D. Rodić","doi":"10.20450/MJCCE.2021.2240","DOIUrl":"https://doi.org/10.20450/MJCCE.2021.2240","url":null,"abstract":"The aim of this research was the creation and validation of a procedure for determining the cognitive complexity of problem tasks in the field of salt hydrolysis. The procedure created included an assessment of the difficulty of concepts and an assessment of their interactivity. One of the research tasks was to determine whether there were misconceptions by students that might have influenced their achievement. There were 50 Bachelor of Science in Chemistry students who participated in the study. A knowledge test was used as a research instrument to assess the performance and a seven-point Likert scale to evaluate the invested mental effort. The validity of this instrument for the assessment of cognitive complexity was confirmed by a series of regression analyses, where acceptable and statistically significant correlation coefficients were obtained among the examined variables: student performance and invested mental effort as dependent variables and cognitive complexity as independent variable","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46979978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-09DOI: 10.20450/MJCCE.2021.2220
F. Bayrak, A. Oral, K. Ay
Polyurethanes (PUs) are synthesized by the reaction of diisocyanates and diols and are widely used in furniture foams, thermal insulation, coatings, and adhesives. In this work, a 1,2,3-triazole-bridged dioxime (compound 6) as a diol source was synthesized from isomannide via tosylation, azidation, and cyclization-addition and used in the syntheses of new PUs. A new carbohydrate-based linear P-1 was synthesized by the reaction of 6 and 1,6-hexamethylene diisocyanate (1,6-HMDI). Besides, three new linear PUs (P-2, P-3, and P-4) were synthesized by the reaction of 6, isomannide compound (used in different molar ratios), and 1,6-HMDI. The thermal properties of the new PUs were determined by thermogravimetry (TG), their molecular structures were characterized by FTIR, 1H- and 13C-NMR, and the molecular weights of some polymers were determined by GPC/SEC. Additionally, the surface characteristics of the synthesized PUs were examined via scanning electron microscopy (SEM).
{"title":"Synthesis and characterization of novel 1,2,3-triazole-bridged oxime polyurethanes obtained from an isomannide derivative","authors":"F. Bayrak, A. Oral, K. Ay","doi":"10.20450/MJCCE.2021.2220","DOIUrl":"https://doi.org/10.20450/MJCCE.2021.2220","url":null,"abstract":"Polyurethanes (PUs) are synthesized by the reaction of diisocyanates and diols and are widely used in furniture foams, thermal insulation, coatings, and adhesives. In this work, a 1,2,3-triazole-bridged dioxime (compound 6) as a diol source was synthesized from isomannide via tosylation, azidation, and cyclization-addition and used in the syntheses of new PUs. A new carbohydrate-based linear P-1 was synthesized by the reaction of 6 and 1,6-hexamethylene diisocyanate (1,6-HMDI). Besides, three new linear PUs (P-2, P-3, and P-4) were synthesized by the reaction of 6, isomannide compound (used in different molar ratios), and 1,6-HMDI. The thermal properties of the new PUs were determined by thermogravimetry (TG), their molecular structures were characterized by FTIR, 1H- and 13C-NMR, and the molecular weights of some polymers were determined by GPC/SEC. Additionally, the surface characteristics of the synthesized PUs were examined via scanning electron microscopy (SEM).","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44021257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-05DOI: 10.20450/MJCCE.2021.2270
R. Gulaboski, V. Mirčeski, M. Lovrić
The accurate determination of the rate constant related to the electron transfer step of so-called “surface redox active compounds” by voltammetric measurements is very important because it is linked to the reactivity and stability of many biological and chemical systems such as redox enzymes, vitamins, hormones, and many more. Evaluation of the kinetics of the electron transfer is often challenging, especially when chemical equilibria are coupled to the electron transfer step. In this work, we theoretically consider some critical aspects of the time-related methodologies in square-wave voltammetry (SWV), which is designed to analyze the kinetics of the electron transfer step of surface mechanisms coupled with chemical reactions. We demonstrate with a series of simulated scenarios that caution must be taken when exploring the time-related analysis for kinetic characterizations for both surface CE and EC mechanisms. The main concern stems from the fact that the SW frequency simultaneously affects both the kinetics of electron transfer and that of chemical reactions as well. Under defined conditions, the SW frequency variation in the case of surface EC and CE mechanisms may produce unexpected features of the voltammetric patterns. In many scenarios, time-independent analysis, such as those related to the square-wave amplitude and potential increment, are seen as alternative tools to evaluate the rate parameter of electrode reactions.
{"title":"Critical aspects in exploring time analysis for the voltammetric estimation of kinetic parameters of surface electrode mechanisms coupled with chemical reactions","authors":"R. Gulaboski, V. Mirčeski, M. Lovrić","doi":"10.20450/MJCCE.2021.2270","DOIUrl":"https://doi.org/10.20450/MJCCE.2021.2270","url":null,"abstract":"The accurate determination of the rate constant related to the electron transfer step of so-called “surface redox active compounds” by voltammetric measurements is very important because it is linked to the reactivity and stability of many biological and chemical systems such as redox enzymes, vitamins, hormones, and many more. Evaluation of the kinetics of the electron transfer is often challenging, especially when chemical equilibria are coupled to the electron transfer step. In this work, we theoretically consider some critical aspects of the time-related methodologies in square-wave voltammetry (SWV), which is designed to analyze the kinetics of the electron transfer step of surface mechanisms coupled with chemical reactions. We demonstrate with a series of simulated scenarios that caution must be taken when exploring the time-related analysis for kinetic characterizations for both surface CE and EC mechanisms. The main concern stems from the fact that the SW frequency simultaneously affects both the kinetics of electron transfer and that of chemical reactions as well. Under defined conditions, the SW frequency variation in the case of surface EC and CE mechanisms may produce unexpected features of the voltammetric patterns. In many scenarios, time-independent analysis, such as those related to the square-wave amplitude and potential increment, are seen as alternative tools to evaluate the rate parameter of electrode reactions.","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43273221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-11DOI: 10.20450/mjcce.2020.2168
V. Stefov, V. Koleva, M. Najdoski, A. Cahil, Z. Abdija
Polycrystalline samples of struvite-type MgRbAsO 4 ·6H 2 O and MgTlAsO 4 ·6H 2 O in both protiated and deuterated forms have been prepared for the first time by a precipitation method. Detailed analysis of their infrared (IR) and Raman (R) spectra recorded at room temperature (RT) and liquid nitrogen temperature (LNT) has been carried out and assignment of the vibrational bands has been proposed. The observed spectral pictures confirm the isostructurality of the two arsenate salts in agreement with the structural data. Similarly to other struvite-type and structure-related arsenate salts, the n 1 (AsO 4 ) modes appear at higher frequencies than the n 3 (AsO 4 ) vibrations. Low intensity and temperature sensitive bands that could be assigned as due to stretching Mg–O vibrations and n 4 (AsO 4 ) modes are observed below 500 cm –1 in the LNT IR spectra of the studied compounds, at 472 cm –1 and 445 cm –1 for the rubidium analogue and at 470 cm –1 and 440 cm –1 for the thallium analogue. In the far-infrared and Raman spectra many bands are observed between 400 cm –1 and 200 cm –1 , most of which are sensitive to deuteration, suggesting that they are not pure but coupled and can be related to n(Mg–Ow) modes. On the other hand, a band around 405 cm –1 in the spectra of the protiated compounds most probably is due to n 2 (AsO 4 ) mode because of its frequency position, intensity and slight sensitivity to deuteration.
{"title":"Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate (struvite) and its isomorphous analogues. X. Vibrational spectra of magnesium rubidium arsenate hexahydrate and magnesium thallium arsenate hexahydrate","authors":"V. Stefov, V. Koleva, M. Najdoski, A. Cahil, Z. Abdija","doi":"10.20450/mjcce.2020.2168","DOIUrl":"https://doi.org/10.20450/mjcce.2020.2168","url":null,"abstract":"Polycrystalline samples of struvite-type MgRbAsO 4 ·6H 2 O and MgTlAsO 4 ·6H 2 O in both protiated and deuterated forms have been prepared for the first time by a precipitation method. Detailed analysis of their infrared (IR) and Raman (R) spectra recorded at room temperature (RT) and liquid nitrogen temperature (LNT) has been carried out and assignment of the vibrational bands has been proposed. The observed spectral pictures confirm the isostructurality of the two arsenate salts in agreement with the structural data. Similarly to other struvite-type and structure-related arsenate salts, the n 1 (AsO 4 ) modes appear at higher frequencies than the n 3 (AsO 4 ) vibrations. Low intensity and temperature sensitive bands that could be assigned as due to stretching Mg–O vibrations and n 4 (AsO 4 ) modes are observed below 500 cm –1 in the LNT IR spectra of the studied compounds, at 472 cm –1 and 445 cm –1 for the rubidium analogue and at 470 cm –1 and 440 cm –1 for the thallium analogue. In the far-infrared and Raman spectra many bands are observed between 400 cm –1 and 200 cm –1 , most of which are sensitive to deuteration, suggesting that they are not pure but coupled and can be related to n(Mg–Ow) modes. On the other hand, a band around 405 cm –1 in the spectra of the protiated compounds most probably is due to n 2 (AsO 4 ) mode because of its frequency position, intensity and slight sensitivity to deuteration.","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":"39 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2020-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41949119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-06DOI: 10.20450/mjcce.2020.2133
Habiddin Habiddin, E. Page
The ability to use Higher Order Thinking Skills (HOTS) plays a substantial role in determining students’ success in future studies. Therefore, it is important that students’ ability in this skill is continually refined by training and assessment. This paper explores the responses of first-year university students’ to a range of pictorial-style questions in chemical kinetics that require the use of HOTS. 80 food science and 57 chemistry students (137 in total) at The University of Reading (UoR) participated in the study. The results showed that many students demonstrated limited ability to answer HOTS questions. The implications for the teaching of chemical kinetics, particularly at the university level, are discussed.
{"title":"Probing students' higher order thinking skills using pictorial style questions","authors":"Habiddin Habiddin, E. Page","doi":"10.20450/mjcce.2020.2133","DOIUrl":"https://doi.org/10.20450/mjcce.2020.2133","url":null,"abstract":"The ability to use Higher Order Thinking Skills (HOTS) plays a substantial role in determining students’ success in future studies. Therefore, it is important that students’ ability in this skill is continually refined by training and assessment. This paper explores the responses of first-year university students’ to a range of pictorial-style questions in chemical kinetics that require the use of HOTS. 80 food science and 57 chemistry students (137 in total) at The University of Reading (UoR) participated in the study. The results showed that many students demonstrated limited ability to answer HOTS questions. The implications for the teaching of chemical kinetics, particularly at the university level, are discussed.","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2020-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47379554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-28DOI: 10.20450/mjcce.2020.2025
A. Kurt, H. Andan, M. Koca
A new conjugated polymer containing a bithiazole group is prepared by the polycondensation of 2,2'-diamino-4,4'-bithiazole and terephthaldialdehyde in the presence of glacial acetic acid. The kinetics of thermal degradation of the new polymer are investigated by thermogravimetric analysis at different heating rates. The temperature corresponding to the maximum rate loss shifts to higher temperatures with increasing heating rate. The thermal decomposition activation energies of the conjugated polymer in a conversion range of 3–15 % are 288.4 and 281.1 kJ/mol by the Flynn–Wall–Ozawa and Kissinger methods, respectively. The Horowitz–Metzger method shows that the thermodegradation mechanism of the conjugated polymer proceeds over a three-dimensional diffusion type deceleration D 3 mechanism. The optimum heating rate is 20 oC/min.
{"title":"Synthesis and characterization of a new conjugated polymer containing bithiazole group and its thermal decomposition kinetics","authors":"A. Kurt, H. Andan, M. Koca","doi":"10.20450/mjcce.2020.2025","DOIUrl":"https://doi.org/10.20450/mjcce.2020.2025","url":null,"abstract":"A new conjugated polymer containing a bithiazole group is prepared by the polycondensation of 2,2'-diamino-4,4'-bithiazole and terephthaldialdehyde in the presence of glacial acetic acid. The kinetics of thermal degradation of the new polymer are investigated by thermogravimetric analysis at different heating rates. The temperature corresponding to the maximum rate loss shifts to higher temperatures with increasing heating rate. The thermal decomposition activation energies of the conjugated polymer in a conversion range of 3–15 % are 288.4 and 281.1 kJ/mol by the Flynn–Wall–Ozawa and Kissinger methods, respectively. The Horowitz–Metzger method shows that the thermodegradation mechanism of the conjugated polymer proceeds over a three-dimensional diffusion type deceleration D 3 mechanism. The optimum heating rate is 20 oC/min.","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2020-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48164016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-26DOI: 10.20450/mjcce.2020.2150
M. Svetozarević, N. Šekuljica, Z. Knežević-Jugović, D. Mijin
As water contamination emerges as a serious threat to the environment, ventures for cleaner and sustainable solutions are continuously being developed. The present study investigates the ability of crude peroxidase extract from soybean seeds to degrade the anthraquinone dye Acid Violet 109. The influence of the essential parameters pH, dye concentration, hydrogen peroxide dosage, and temperature were inspected. The enzyme had 81.9 % biodegradation at pH 4 in 30 min with 0.1 U peroxidase, 40 mg/l dye concentration, and 1 mM hydrogen peroxide. Considering that substrate concentration can cause reaction inhibition, a kinetic study was performed. Kinetic data fitting using bisubstrate kinetics with a substrate inhibition model revealed the high inhibitory effect of the dye, which was confirmed by the inhibition constant, 7.123·10 –5 mM. Alongside the inhibition constant values, the Ping-Pong Bi-Bi model gave the maximum rates 15.788 and 14.321 mM/min for hydrogen peroxide and dye inhibition, respectively.
{"title":"Optimization and kinetic study of anthraquinone dye removal from colored wastewater using soybean seed as a source of peroxidase for environmental welfare","authors":"M. Svetozarević, N. Šekuljica, Z. Knežević-Jugović, D. Mijin","doi":"10.20450/mjcce.2020.2150","DOIUrl":"https://doi.org/10.20450/mjcce.2020.2150","url":null,"abstract":"As water contamination emerges as a serious threat to the environment, ventures for cleaner and sustainable solutions are continuously being developed. The present study investigates the ability of crude peroxidase extract from soybean seeds to degrade the anthraquinone dye Acid Violet 109. The influence of the essential parameters pH, dye concentration, hydrogen peroxide dosage, and temperature were inspected. The enzyme had 81.9 % biodegradation at pH 4 in 30 min with 0.1 U peroxidase, 40 mg/l dye concentration, and 1 mM hydrogen peroxide. Considering that substrate concentration can cause reaction inhibition, a kinetic study was performed. Kinetic data fitting using bisubstrate kinetics with a substrate inhibition model revealed the high inhibitory effect of the dye, which was confirmed by the inhibition constant, 7.123·10 –5 mM. Alongside the inhibition constant values, the Ping-Pong Bi-Bi model gave the maximum rates 15.788 and 14.321 mM/min for hydrogen peroxide and dye inhibition, respectively.","PeriodicalId":18088,"journal":{"name":"Macedonian Journal of Chemistry and Chemical Engineering","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2020-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43384896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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