Pub Date : 2019-07-04DOI: 10.1177/1468678319858149
Dragana Marković-Nikolić, M. Cakic, G. Petković, G. Nikolić
The sorption kinetics and thermodynamic parameters of phosphate removal from aqueous solution using quaternary ammonium–modified bottle gourd biomass as a sorbent were studied in a batch reactor. The cationic sorbent, containing trimethylammonium and hydroxypropyl groups, was obtained through the chemical reactions of the lignocellulosic Lagenaria vulgaris shell with (3-chloro-2-hydroxypropyl)trimethylammonium chloride. Experimental data of phosphate sorption from aqueous solutions of different initial concentrations (5–140 mg P L−1) have been analysed by reaction kinetics and diffusion models. The characteristic rate constants calculated by linear and non-linear regression analyses of the experimental results are presented. The phosphate sorption reaches equilibrium in 20–30 min, depending on the initial phosphate concentration. The maximum sorption capacity of quaternary ammonium–modified bottle gourd (QABG) sorbent was 18 mg P g−1 at 20 oC. The sorption system is best described by a non-linear equation of the pseudo first-order model (R2 > 0.996). The Weber–Morris model indicated that the sorption process took place in three steps, whereby the intra-particle diffusion is not the only rate-controlling step. In addition, the effect of temperature (20 oC–50 oC) on sorption kinetics was also investigated. The various thermodynamic parameters suggest that phosphate sorption is favoured and is an exothermic process. The activation energy and the sticking probability confirmed that anion exchange is the dominant mechanism. These results provide valuable information for the potential use of agricultural residues in the treatment of wastewaters.
{"title":"Kinetics, thermodynamics and mechanisms of phosphate sorption onto bottle gourd biomass modified by (3-chloro-2-hydroxypropyl) trimethylammonium chloride","authors":"Dragana Marković-Nikolić, M. Cakic, G. Petković, G. Nikolić","doi":"10.1177/1468678319858149","DOIUrl":"https://doi.org/10.1177/1468678319858149","url":null,"abstract":"The sorption kinetics and thermodynamic parameters of phosphate removal from aqueous solution using quaternary ammonium–modified bottle gourd biomass as a sorbent were studied in a batch reactor. The cationic sorbent, containing trimethylammonium and hydroxypropyl groups, was obtained through the chemical reactions of the lignocellulosic Lagenaria vulgaris shell with (3-chloro-2-hydroxypropyl)trimethylammonium chloride. Experimental data of phosphate sorption from aqueous solutions of different initial concentrations (5–140 mg P L−1) have been analysed by reaction kinetics and diffusion models. The characteristic rate constants calculated by linear and non-linear regression analyses of the experimental results are presented. The phosphate sorption reaches equilibrium in 20–30 min, depending on the initial phosphate concentration. The maximum sorption capacity of quaternary ammonium–modified bottle gourd (QABG) sorbent was 18 mg P g−1 at 20 oC. The sorption system is best described by a non-linear equation of the pseudo first-order model (R2 > 0.996). The Weber–Morris model indicated that the sorption process took place in three steps, whereby the intra-particle diffusion is not the only rate-controlling step. In addition, the effect of temperature (20 oC–50 oC) on sorption kinetics was also investigated. The various thermodynamic parameters suggest that phosphate sorption is favoured and is an exothermic process. The activation energy and the sticking probability confirmed that anion exchange is the dominant mechanism. These results provide valuable information for the potential use of agricultural residues in the treatment of wastewaters.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"28 1","pages":"267 - 285"},"PeriodicalIF":0.7,"publicationDate":"2019-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77823208","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 : 2019-07-03DOI: 10.1177/1468678319860023
M. Padervand, E. Jalilian
Bi24Br10+xAg x O31 nanosheets were prepared by a facile single-step co-precipitation method in the presence of 1-butyl-3-methylimidazolium bromide ionic liquid as the bromide source and template agent. The products were well characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, diffuse reflectance spectroscopy, nitrogen adsorption–desorption isotherms using Brunauer–Emmett–Teller analysis, Fourier transform infrared spectroscopy and transmission electron microscopy. The X-ray powder diffraction pattern confirmed the presence of both Bi24O31Br10 and AgBr crystalline phases in the structure. In addition, the scanning electron microscopy micrographs and transmission electron microscopy image indicated that the sample had sheet-like morphology and the thickness of the sheets was below 100 nm. According to the photocatalytic experiments, the product was exceptionally efficient for the degradation of Acid Blue 92 solutions under visible light. Also, the results of recycling experiments indicated the high capacity of the prepared nanosheets to effect repeated treatment of the wastewater solution, which is of great importance in being introduced as a catalyst in practical applications.
以1-丁基-3-甲基咪唑溴离子液体为溴化物源和模板剂，采用单步共沉淀法制备了Bi24Br10+xAg x O31纳米片。通过x射线粉末衍射、扫描电镜、能量色散x射线分析、漫反射光谱、布鲁诺尔-埃米特-泰勒分析、傅里叶变换红外光谱和透射电镜对产物进行了表征。x射线粉末衍射图证实了结构中存在Bi24O31Br10和AgBr两种晶相。此外，扫描电镜和透射电镜图像显示，样品具有片状形貌，片状厚度在100 nm以下。根据光催化实验，该产品在可见光下对酸性蓝92溶液的降解非常有效。回收实验结果表明，制备的纳米片具有较高的重复处理能力，对实际应用具有重要意义。
{"title":"Bi24Br10+xAg x O31 nanostructure, a new reusable photocatalyst for efficient removal of Acid Blue 92 from model wastewaters under visible light","authors":"M. Padervand, E. Jalilian","doi":"10.1177/1468678319860023","DOIUrl":"https://doi.org/10.1177/1468678319860023","url":null,"abstract":"Bi24Br10+xAg x O31 nanosheets were prepared by a facile single-step co-precipitation method in the presence of 1-butyl-3-methylimidazolium bromide ionic liquid as the bromide source and template agent. The products were well characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, diffuse reflectance spectroscopy, nitrogen adsorption–desorption isotherms using Brunauer–Emmett–Teller analysis, Fourier transform infrared spectroscopy and transmission electron microscopy. The X-ray powder diffraction pattern confirmed the presence of both Bi24O31Br10 and AgBr crystalline phases in the structure. In addition, the scanning electron microscopy micrographs and transmission electron microscopy image indicated that the sample had sheet-like morphology and the thickness of the sheets was below 100 nm. According to the photocatalytic experiments, the product was exceptionally efficient for the degradation of Acid Blue 92 solutions under visible light. Also, the results of recycling experiments indicated the high capacity of the prepared nanosheets to effect repeated treatment of the wastewater solution, which is of great importance in being introduced as a catalyst in practical applications.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"2 1","pages":"257 - 266"},"PeriodicalIF":0.7,"publicationDate":"2019-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72872639","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 : 2019-06-26DOI: 10.1177/1468678319825737
Rupali Yadav, R. Naik
The formation kinetics of the complex, [Ru(CN)5INH]3−, formed through the ligand substitution reaction between isoniazid (INH) and aquapentacyanoruthenate(II) ([Ru(CN)5H2O]3−), have been investigated, under pseudo first-order conditions, as a function of concentrations of [INH] and [Ru(CN)5H2O]3−, ionic strength and temperature at pH = 4.0 ± 0.02 in 0.2 M NaClO4 spectrophotometrically at 502 nm (λmax of intense yellow colour product [Ru(CN)5INH]3−) corresponding to metal-to-ligand charge-transfer transitions, in aqueous medium. The pseudo first-order condition was maintained by taking at least 10% excess of [INH] over [Ru(CN)5H2O]3−. The stoichiometry of the reaction product was found to be 1:1 which was further supported and characterized using elemental analysis, infrared, nuclear magnetic resonance and mass spectrometric techniques. Thermodynamic and kinetic parameters have also been computed, using the Eyring equation, and the values of ΔH≠, Ea, ΔG≠ and ΔS≠ were found to be 47.3 kJ mol−1, 49.8 kJ mol−1, −8.62 kJ mol−1 and 187.6 J K−1mol−1, respectively. The reaction was found to obey first-order kinetics with respect to [INH]. It exhibited a negative salt effect on the rate upon variation of ionic strength of the medium. A tentative mechanistic scheme was proposed on the basis of experimental findings.
在拟一阶条件下，研究了异烟肼(INH)与aquentacyanorthenate (II) ([Ru(CN)5H2O]3−)配体取代反应形成的络合物[Ru(CN)5INH]3−的形成动力学，以及[INH]和[Ru(CN)5H2O]3−浓度的函数。离子强度和pH = 4.0±0.02时0.2 M NaClO4在502 nm(强黄色产物[Ru(CN)5INH]3−的λmax)对应于水介质中金属到配体的电荷转移转变。当[INH]比[Ru(CN)5H2O]3−至少多10%时，伪一阶条件得以维持。通过元素分析、红外、核磁共振和质谱等技术对反应产物进行了进一步的支持和表征，发现其化学计量比为1:1。利用Eyring方程计算了反应的热力学和动力学参数，得到ΔH≠、Ea、ΔG≠和ΔS≠的值分别为47.3 kJ mol−1、49.8 kJ mol−1、- 8.62 kJ mol−1和187.6 jk−1mol−1。发现该反应在[INH]方面服从一级动力学。它对介质离子强度的变化率表现出负的盐效应。根据实验结果，提出了一种初步的机理方案。
{"title":"Kinetics and mechanism of formation of the complex [Ru(CN)5INH]3− through the ligand substitution reaction between the aquapentacyanoruthenate(II) anion and isoniazid","authors":"Rupali Yadav, R. Naik","doi":"10.1177/1468678319825737","DOIUrl":"https://doi.org/10.1177/1468678319825737","url":null,"abstract":"The formation kinetics of the complex, [Ru(CN)5INH]3−, formed through the ligand substitution reaction between isoniazid (INH) and aquapentacyanoruthenate(II) ([Ru(CN)5H2O]3−), have been investigated, under pseudo first-order conditions, as a function of concentrations of [INH] and [Ru(CN)5H2O]3−, ionic strength and temperature at pH = 4.0 ± 0.02 in 0.2 M NaClO4 spectrophotometrically at 502 nm (λmax of intense yellow colour product [Ru(CN)5INH]3−) corresponding to metal-to-ligand charge-transfer transitions, in aqueous medium. The pseudo first-order condition was maintained by taking at least 10% excess of [INH] over [Ru(CN)5H2O]3−. The stoichiometry of the reaction product was found to be 1:1 which was further supported and characterized using elemental analysis, infrared, nuclear magnetic resonance and mass spectrometric techniques. Thermodynamic and kinetic parameters have also been computed, using the Eyring equation, and the values of ΔH≠, Ea, ΔG≠ and ΔS≠ were found to be 47.3 kJ mol−1, 49.8 kJ mol−1, −8.62 kJ mol−1 and 187.6 J K−1mol−1, respectively. The reaction was found to obey first-order kinetics with respect to [INH]. It exhibited a negative salt effect on the rate upon variation of ionic strength of the medium. A tentative mechanistic scheme was proposed on the basis of experimental findings.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"69 1","pages":"244 - 256"},"PeriodicalIF":0.7,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90444474","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 : 2019-06-18DOI: 10.1177/1468678319825710
O. Soltani, M. Bozorgmehr, M. Momen-Heravi
The interaction of biotin and streptavidin in the presence and absence of a carbon nanotube was studied by molecular dynamics simulation. With respect to the Arrhenius dependence of the rate constants with temperature, those of streptavidin–biotin complex formation ( k 1 ) and streptavidin–biotin complex dissociation ( k − 1 ) were calculated from molecular dynamics simulation trajectories. Nanotube has reduced the amount of and k1 and k1. However, the biotin position in streptavidin does not change much. The results obtained from MMPBSA calculations show that the contribution of the van der Waals forces to both systems (in the absence and presence of the nanotube) was greater than that of electrostatic forces. The presence of the nanotube also led to the reduction of van der Waals and electrostatic forces in the interaction of biotin with streptavidin. However, this reduction was greater for electrostatic forces. In the absence of a nanotube, there are four hydrogen bonds between streptavidin and biotin, which are related to the residues Ser27, Tyr43, Ser45 and Ser88. In the presence of the nanotube, the hydrogen bonding of biotin with Ser45 is removed.
{"title":"Does the single-walled carbon nanotube affect the rate constant of binding of biotin to streptavidin? Molecular dynamics simulation perspective","authors":"O. Soltani, M. Bozorgmehr, M. Momen-Heravi","doi":"10.1177/1468678319825710","DOIUrl":"https://doi.org/10.1177/1468678319825710","url":null,"abstract":"The interaction of biotin and streptavidin in the presence and absence of a carbon nanotube was studied by molecular dynamics simulation. With respect to the Arrhenius dependence of the rate constants with temperature, those of streptavidin–biotin complex formation ( k 1 ) and streptavidin–biotin complex dissociation ( k − 1 ) were calculated from molecular dynamics simulation trajectories. Nanotube has reduced the amount of and k1 and k1. However, the biotin position in streptavidin does not change much. The results obtained from MMPBSA calculations show that the contribution of the van der Waals forces to both systems (in the absence and presence of the nanotube) was greater than that of electrostatic forces. The presence of the nanotube also led to the reduction of van der Waals and electrostatic forces in the interaction of biotin with streptavidin. However, this reduction was greater for electrostatic forces. In the absence of a nanotube, there are four hydrogen bonds between streptavidin and biotin, which are related to the residues Ser27, Tyr43, Ser45 and Ser88. In the presence of the nanotube, the hydrogen bonding of biotin with Ser45 is removed.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"96 1","pages":"234 - 243"},"PeriodicalIF":0.7,"publicationDate":"2019-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81285331","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 : 2019-06-10DOI: 10.1177/1468678319854871
Jiaying Zhang
The density functional theory method is employed to systematically explore the mechanism of syngas methanation on the Ni4/MCM-41 catalyst surface. The calculation results show that the optimal pathway of CH4 formation is CO + H → CHO + H → CH2O + H → CH3O → CH3 + H → CH4 with the rate-determining step of CH3O direct dissociation. Because the activation energy for the direct dissociation of CH3O species is much lower than that for the CH3OH formation (198.6 vs 264.8 kJ mol−1), there is almost no by-product CH3OH that appeared in the products of the syngas methanation over the Ni4/MCM-41 catalyst. Compared with other conventional nickel-based methanation catalysts, Ni4/MCM-41 catalyst is an excellent methanation catalyst with high selectivity of CH4.
{"title":"Study on syngas methanation mechanism over Ni4/MCM-41 catalyst based on density functional theory","authors":"Jiaying Zhang","doi":"10.1177/1468678319854871","DOIUrl":"https://doi.org/10.1177/1468678319854871","url":null,"abstract":"The density functional theory method is employed to systematically explore the mechanism of syngas methanation on the Ni4/MCM-41 catalyst surface. The calculation results show that the optimal pathway of CH4 formation is CO + H → CHO + H → CH2O + H → CH3O → CH3 + H → CH4 with the rate-determining step of CH3O direct dissociation. Because the activation energy for the direct dissociation of CH3O species is much lower than that for the CH3OH formation (198.6 vs 264.8 kJ mol−1), there is almost no by-product CH3OH that appeared in the products of the syngas methanation over the Ni4/MCM-41 catalyst. Compared with other conventional nickel-based methanation catalysts, Ni4/MCM-41 catalyst is an excellent methanation catalyst with high selectivity of CH4.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"54 1","pages":"222 - 233"},"PeriodicalIF":0.7,"publicationDate":"2019-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87148565","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 : 2019-05-27DOI: 10.1177/1468678319825740
Hasnia Abdeldjebar, Y. Belmiloud, Wassila Djitli, Sofiene Achour, M. Brahimi, B. Tangour
The tautomeric equilibrium of benzimidazolone and benzimidazolthione have been studied by the density functional theory method using the CAM-B3LYP functional together with the 6-311G(d,p) basis set. Two separate mechanisms have been investigated: a direct intramolecular transfer using the polarizable continuum model and an indirect proton transfer assisted by a molecule of solvent (C6H12, H2O, CH3OH, and H2O2). In both cases, the results obtained indicate that ketone and thione are the most stable forms. However, the enhanced height of the activation barrier for the four-center mechanisms describing the tautomerism reaction as a direct intramolecular transfer implicates a relatively disadvantaged process. The participation of a polar protic solvent molecule allows the lowering of the activation energy barrier. Potential energy profiles of keto-enol and thio-enol tautomerism assisted by methanol and water are very different. The former one describes a concerted mechanism but the latter does not because it is associated with asynchronous processes that take place during the thio-enol tautomerism.
{"title":"Proton transfer in the benzimidazolone and benzimidazolthione tautomerism process catalyzed by polar protic solvents","authors":"Hasnia Abdeldjebar, Y. Belmiloud, Wassila Djitli, Sofiene Achour, M. Brahimi, B. Tangour","doi":"10.1177/1468678319825740","DOIUrl":"https://doi.org/10.1177/1468678319825740","url":null,"abstract":"The tautomeric equilibrium of benzimidazolone and benzimidazolthione have been studied by the density functional theory method using the CAM-B3LYP functional together with the 6-311G(d,p) basis set. Two separate mechanisms have been investigated: a direct intramolecular transfer using the polarizable continuum model and an indirect proton transfer assisted by a molecule of solvent (C6H12, H2O, CH3OH, and H2O2). In both cases, the results obtained indicate that ketone and thione are the most stable forms. However, the enhanced height of the activation barrier for the four-center mechanisms describing the tautomerism reaction as a direct intramolecular transfer implicates a relatively disadvantaged process. The participation of a polar protic solvent molecule allows the lowering of the activation energy barrier. Potential energy profiles of keto-enol and thio-enol tautomerism assisted by methanol and water are very different. The former one describes a concerted mechanism but the latter does not because it is associated with asynchronous processes that take place during the thio-enol tautomerism.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"24 1","pages":"143 - 156"},"PeriodicalIF":0.7,"publicationDate":"2019-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89312481","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 : 2019-05-21DOI: 10.1177/1468678319850496
Joanna Drzeżdżon, Agnieszka Piotrowska-Kirschling, L. Chmurzyński, D. Jacewicz
The kinetics of the aquation reaction of the [VO(ida)(bipy)]·2H2O (VO(ida)(bipy)) complex (where ida = iminodiacetate anion and bipy = 2,2’-bipyridine) promoted by [Fe(H2O)6]3+ ions were investigated in aqueous solutions. Spectrophotometric studies were carried out at different temperatures in the range of 293.15–313.15 K. The concentration of the [Fe(H2O)6]3+ (Fe3+) ions was kept within the range of 2 × 10–4 to 8 × 10–4 mol L–1, and the concentration of VO(ida)(bipy) was 1 × 10–3 mol L–1. The values of the observable reaction rate constants were calculated based on the Glint computer program. Furthermore, the mechanism for the aquation of VO(ida)(bipy), induced by Fe(III) ions, has been proposed.
{"title":"Aquation reaction of iminodiacetate complex of oxidovanadium(IV) with 2,2’-bipyridine induced by Fe(III) ions: Kinetic studies","authors":"Joanna Drzeżdżon, Agnieszka Piotrowska-Kirschling, L. Chmurzyński, D. Jacewicz","doi":"10.1177/1468678319850496","DOIUrl":"https://doi.org/10.1177/1468678319850496","url":null,"abstract":"The kinetics of the aquation reaction of the [VO(ida)(bipy)]·2H2O (VO(ida)(bipy)) complex (where ida = iminodiacetate anion and bipy = 2,2’-bipyridine) promoted by [Fe(H2O)6]3+ ions were investigated in aqueous solutions. Spectrophotometric studies were carried out at different temperatures in the range of 293.15–313.15 K. The concentration of the [Fe(H2O)6]3+ (Fe3+) ions was kept within the range of 2 × 10–4 to 8 × 10–4 mol L–1, and the concentration of VO(ida)(bipy) was 1 × 10–3 mol L–1. The values of the observable reaction rate constants were calculated based on the Glint computer program. Furthermore, the mechanism for the aquation of VO(ida)(bipy), induced by Fe(III) ions, has been proposed.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"65 1","pages":"300 - 306"},"PeriodicalIF":0.7,"publicationDate":"2019-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84459262","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 : 2019-05-14DOI: 10.1177/1468678319848880
H. Saghafi, M. Vahedpour
Glyoxal can be important in atmospheric chemistry in terms of its ability to convert to secondary organic aerosols. In this study, the glyoxal-breaking reaction by two atmospheric active radicals, NO2 and NH2, has been investigated at the B3LYP and M06-2X levels in connection with 6-311++G(d,p) basis set. The formation of the most stable adducts from glyoxal with NO2/NH2 radical requires two hydrogen atom transfers. The accuracy of the predicted mechanisms in describing the hydrogen transfers was confirmed by atoms-in-molecules calculations and natural bond orbital analysis. The calculated results predict that hydrogen transfer process in both reactions at the M06-2X level is favourable from the kinetic and thermodynamic points of view. In the natural bond orbital analysis, the stabilization energy, E(2), delocalization corrections, at the B3LYP level is much higher than the same results at the M06-2X level (nearly twice). The activation thermodynamic parameters show that the first steps of the two reactions have lower barrier energy than the second steps. The Gibbs free energy values estimate that adducts of both the reactions at the mentioned method are spontaneous. The whole reaction of glyoxal + NH2 is more favourable than the whole reaction of glyoxal + NO2. The rate constants were calculated for the mentioned pathways using transition state theory for bimolecular steps and the fitted equations are reported.
{"title":"Atmospheric reactions of glyoxal with NO2 and NH2 radicals: Hydrogen abstraction mechanism and natural bond orbital analysis","authors":"H. Saghafi, M. Vahedpour","doi":"10.1177/1468678319848880","DOIUrl":"https://doi.org/10.1177/1468678319848880","url":null,"abstract":"Glyoxal can be important in atmospheric chemistry in terms of its ability to convert to secondary organic aerosols. In this study, the glyoxal-breaking reaction by two atmospheric active radicals, NO2 and NH2, has been investigated at the B3LYP and M06-2X levels in connection with 6-311++G(d,p) basis set. The formation of the most stable adducts from glyoxal with NO2/NH2 radical requires two hydrogen atom transfers. The accuracy of the predicted mechanisms in describing the hydrogen transfers was confirmed by atoms-in-molecules calculations and natural bond orbital analysis. The calculated results predict that hydrogen transfer process in both reactions at the M06-2X level is favourable from the kinetic and thermodynamic points of view. In the natural bond orbital analysis, the stabilization energy, E(2), delocalization corrections, at the B3LYP level is much higher than the same results at the M06-2X level (nearly twice). The activation thermodynamic parameters show that the first steps of the two reactions have lower barrier energy than the second steps. The Gibbs free energy values estimate that adducts of both the reactions at the mentioned method are spontaneous. The whole reaction of glyoxal + NH2 is more favourable than the whole reaction of glyoxal + NO2. The rate constants were calculated for the mentioned pathways using transition state theory for bimolecular steps and the fitted equations are reported.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"11 1","pages":"187 - 209"},"PeriodicalIF":0.7,"publicationDate":"2019-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82050022","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 : 2019-05-12DOI: 10.1177/1468678319845863
B. Mohtat, Seyyed Amir Siadati, M. Khalilzadeh
Changing the mechanism of the widely used 1,3-dipolar cycloaddition reaction from its usual asynchronous one-step pattern to the rarely observed stepwise form leads to the emergence of intermediates, side products, and other impurities. Thus, it is crucial to determine the nature of the mechanism of the 1,3-dipolar cycloaddition reaction between a special 1,3-dipole and a specified dipolarophile (by theoretical methods) before using them for synthesizing a desired product. In this study, therefore, we have investigated the possibility of some probable intermediates emergence in the 1,3-dipolar cycloaddition reaction between cyclobutadiene and thioformaldehyde S-oxide. The results showed that emergence of Int (B) (−52.1 kcal mol−1) via transition state (B-1) is favorable both thermodynamically and kinetically (in comparison with all other stepwise routes). That is, developing probable impurities should not be neglected at least in the cases of the reactions between some thioformaldehyde S-oxide and some dipolarophiles.
{"title":"Understanding the mechanism of the 1,3-dipolar cycloaddition reaction between a thioformaldehyde S-oxide and cyclobutadiene: Competition between the stepwise and concerted routes","authors":"B. Mohtat, Seyyed Amir Siadati, M. Khalilzadeh","doi":"10.1177/1468678319845863","DOIUrl":"https://doi.org/10.1177/1468678319845863","url":null,"abstract":"Changing the mechanism of the widely used 1,3-dipolar cycloaddition reaction from its usual asynchronous one-step pattern to the rarely observed stepwise form leads to the emergence of intermediates, side products, and other impurities. Thus, it is crucial to determine the nature of the mechanism of the 1,3-dipolar cycloaddition reaction between a special 1,3-dipole and a specified dipolarophile (by theoretical methods) before using them for synthesizing a desired product. In this study, therefore, we have investigated the possibility of some probable intermediates emergence in the 1,3-dipolar cycloaddition reaction between cyclobutadiene and thioformaldehyde S-oxide. The results showed that emergence of Int (B) (−52.1 kcal mol−1) via transition state (B-1) is favorable both thermodynamically and kinetically (in comparison with all other stepwise routes). That is, developing probable impurities should not be neglected at least in the cases of the reactions between some thioformaldehyde S-oxide and some dipolarophiles.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"51 1","pages":"213 - 221"},"PeriodicalIF":0.7,"publicationDate":"2019-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81549841","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 : 2019-05-09DOI: 10.1177/1468678319825723
M. Padervand, Fatemeh Mesri Fasandouz, A. Beheshti
CuO- and Ag2O-decorated g-C3N4 photocatalysts were prepared by appropriate chemical modification of carbon nitride nanosheets produced from programmed pyrolysis of urea. After comprehensive characterization by powder X-ray diffraction, diffuse reflectance spectroscopy, Fourier transform–infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis methods, their photocatalytic performances were examined for the removal of Acid Blue 92 azo dye, as a typical wastewater component from the textile industry. The X-ray diffraction patterns confirmed the presence of CuO and Ag2O nanoparticles on the surface of the sheets. In addition, diffuse reflectance spectra indicated a considerable reduction of the band gap of pure C3N4 by modification. The photoreaction was discussed mechanistically and the best operational parameters were found to achieve the highest efficiency under visible light.
{"title":"[Cu-Ag2]O–C3N4 nanoframeworks for efficient photodegradation of wastewaters","authors":"M. Padervand, Fatemeh Mesri Fasandouz, A. Beheshti","doi":"10.1177/1468678319825723","DOIUrl":"https://doi.org/10.1177/1468678319825723","url":null,"abstract":"CuO- and Ag2O-decorated g-C3N4 photocatalysts were prepared by appropriate chemical modification of carbon nitride nanosheets produced from programmed pyrolysis of urea. After comprehensive characterization by powder X-ray diffraction, diffuse reflectance spectroscopy, Fourier transform–infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis methods, their photocatalytic performances were examined for the removal of Acid Blue 92 azo dye, as a typical wastewater component from the textile industry. The X-ray diffraction patterns confirmed the presence of CuO and Ag2O nanoparticles on the surface of the sheets. In addition, diffuse reflectance spectra indicated a considerable reduction of the band gap of pure C3N4 by modification. The photoreaction was discussed mechanistically and the best operational parameters were found to achieve the highest efficiency under visible light.","PeriodicalId":20859,"journal":{"name":"Progress in Reaction Kinetics and Mechanism","volume":"2 1","pages":"175 - 186"},"PeriodicalIF":0.7,"publicationDate":"2019-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81881122","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}
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：