Pub Date : 2020-03-02DOI: 10.2298/hemind191011003s
M. Sovilj, Momčilo Đ. Spasojević
This paper presents a review of some hydrodynamic parameters in pulsed sieve-plate extraction columns. The hydrodynamic parameters in liquid-liquid systems in these columns were analyzed regarding the effects of operating and geometrical parameters. The values of Sauter mean drop diameter were function of the existing work flow regimes in the column device defined as mixer-settler, emulsion and dispersion regimes. It was concluded that the dispersed-phase holdup was a function of the mean drop diameter and dispersed-phase superficial velocity. An increase in the dispersed-phase holdup induced an increase in the interface area in the liquid-liquid system. Knowledge of the value of the dispersed-phase holdup can be used for calculation of the volumetric mass transfer coefficient, one of the important factor in the design of the column extractor. It was concluded that the increase in the dispersed-phase superficial velocity is causing a decrease in axial dispersion. On the other hand, an increase in the continuous-phase superficial velocity is causing the increase in the axial dispersion coefficient. Some of the empirical equations proposed in literature for calculations of the hydrodynamic parameters were presented. These correlations, derived for determination of the hydrodynamic parameters in pulsed sieve-plate extraction columns, can be used for the design of these liquid-liquid extraction columns.
{"title":"Hydrodynamics of pulsed sieve-plate extraction columns","authors":"M. Sovilj, Momčilo Đ. Spasojević","doi":"10.2298/hemind191011003s","DOIUrl":"https://doi.org/10.2298/hemind191011003s","url":null,"abstract":"This paper presents a review of some hydrodynamic parameters in pulsed sieve-plate extraction columns. The hydrodynamic parameters in liquid-liquid systems in these columns were analyzed regarding the effects of operating and geometrical parameters. The values of Sauter mean drop diameter were function of the existing work flow regimes in the column device defined as mixer-settler, emulsion and dispersion regimes. It was concluded that the dispersed-phase holdup was a function of the mean drop diameter and dispersed-phase superficial velocity. An increase in the dispersed-phase holdup induced an increase in the interface area in the liquid-liquid system. Knowledge of the value of the dispersed-phase holdup can be used for calculation of the volumetric mass transfer coefficient, one of the important factor in the design of the column extractor. It was concluded that the increase in the dispersed-phase superficial velocity is causing a decrease in axial dispersion. On the other hand, an increase in the continuous-phase superficial velocity is causing the increase in the axial dispersion coefficient. Some of the empirical equations proposed in literature for calculations of the hydrodynamic parameters were presented. These correlations, derived for determination of the hydrodynamic parameters in pulsed sieve-plate extraction columns, can be used for the design of these liquid-liquid extraction columns.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88867223","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 : 2020-03-02DOI: 10.2298/hemind190905005p
V. Pavkov, G. Bakić, Vesna Maksimovic, A. Petrovic, N. Mitrović, Ž. Mišković
One of the important tasks of evaluating the integrity of mechanical process elements and structures is to determine the local mechanical properties. In this paper, experimental and numerical analyses of the mechanical behavior of an output inter-heater tube, made of 12H1MF heat-resistant steel, was performed after 200,000 h of exploitation. During exploitation, the tube was exposed to various mechanisms of damage including gas corrosion. The tube was cut from a pipe system during reparations of a thermal power plant, and then cold-deformed by bending to obtain a U-bend tube, which was then used in the experiment. For this purpose, a specimen holder made of structural steel S235 was specifically designed to test such a sample. The U-bend tube was then exposed to the external compressive load during the experiment. Experimental research was based on the application of the 3D digital image correlation (DIC), while a finite element method (FEM) was applied in numerical simulation performed by using the Abaqus software package. The 3D DIC is an optical and contactless experimental method that allows measurements of displacement fields and deformations of geometrically complex structures. The Aramis system was used for the experimental analysis as well as for verification of the numerical model. During the experiment, the von Mises strain field was measured at the top of the U-bend tube, in the tightening zone, as it represents a critical place for crack initiation and propagation during the work of an inter-heater. Based on the obtained results and a comparative analysis of experimental and numerical values of the von Mises strain field at the U-bend tube, deviation of the model predictions of about 18 % was determined. The FEM predicted smaller values of the von Mises strain field compared to the DIC method. This is the result of an incomplete geometry applied in the model due to deformation that occurred in the bend zone of the U-bend tube, loss of material and the tube surface damage due to the influence of gas corrosion during 200,000 h of exploitation. Experimental analysis has confirmed that the U-bend tube, after 200,000 h of exploitation, can remain in service even if it is damaged due to the effect of gas corrosion.
{"title":"Experimental and numerical analyses of an U-bend tube made of an output inter-heater tube after exploitation","authors":"V. Pavkov, G. Bakić, Vesna Maksimovic, A. Petrovic, N. Mitrović, Ž. Mišković","doi":"10.2298/hemind190905005p","DOIUrl":"https://doi.org/10.2298/hemind190905005p","url":null,"abstract":"One of the important tasks of evaluating the integrity of mechanical process\u0000 elements and structures is to determine the local mechanical properties. In\u0000 this paper, experimental and numerical analyses of the mechanical behavior\u0000 of an output inter-heater tube, made of 12H1MF heat-resistant steel, was\u0000 performed after 200,000 h of exploitation. During exploitation, the tube was\u0000 exposed to various mechanisms of damage including gas corrosion. The tube\u0000 was cut from a pipe system during reparations of a thermal power plant, and\u0000 then cold-deformed by bending to obtain a U-bend tube, which was then used\u0000 in the experiment. For this purpose, a specimen holder made of structural\u0000 steel S235 was specifically designed to test such a sample. The U-bend tube\u0000 was then exposed to the external compressive load during the experiment.\u0000 Experimental research was based on the application of the 3D digital image\u0000 correlation (DIC), while a finite element method (FEM) was applied in\u0000 numerical simulation performed by using the Abaqus software package. The 3D\u0000 DIC is an optical and contactless experimental method that allows\u0000 measurements of displacement fields and deformations of geometrically\u0000 complex structures. The Aramis system was used for the experimental analysis\u0000 as well as for verification of the numerical model. During the experiment,\u0000 the von Mises strain field was measured at the top of the U-bend tube, in\u0000 the tightening zone, as it represents a critical place for crack initiation\u0000 and propagation during the work of an inter-heater. Based on the obtained\u0000 results and a comparative analysis of experimental and numerical values of\u0000 the von Mises strain field at the U-bend tube, deviation of the model\u0000 predictions of about 18 % was determined. The FEM predicted smaller values\u0000 of the von Mises strain field compared to the DIC method. This is the result\u0000 of an incomplete geometry applied in the model due to deformation that\u0000 occurred in the bend zone of the U-bend tube, loss of material and the tube\u0000 surface damage due to the influence of gas corrosion during 200,000 h of\u0000 exploitation. Experimental analysis has confirmed that the U-bend tube,\u0000 after 200,000 h of exploitation, can remain in service even if it is damaged\u0000 due to the effect of gas corrosion.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79153440","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 : 2020-03-02DOI: 10.2298/hemind200201006o
B. Obradovic
Adsorption processes are widely used in different technological areas and industry sectors, thus continuously attracting attention in the scientific research and publications. Design and scale-up of these processes are essentially based on the knowledge and understanding of the adsorption kinetics and mechanism. Adsorption kinetics is usually modeled by using several well-known models including the pseudo-first and pseudo-second order models, the Elovich equation, and the intra-particle diffusion based models. However, in the scientific literature there are a significant number of cases with the inappropriate use of these models, utilization of erroneous expressions, and incorrect interpretation of the obtained results. This paper is especially focused on applications of the pseudo-second order, intra-particle diffusion and the Weber-Morris models, which are illustrated with typical examples. Finally, general recommendations for selection of the appropriate kinetic model and model assumptions, data regression analysis, and evaluation and presentation of the obtained results are outlined.
{"title":"Guidelines for general adsorption kinetics modeling","authors":"B. Obradovic","doi":"10.2298/hemind200201006o","DOIUrl":"https://doi.org/10.2298/hemind200201006o","url":null,"abstract":"Adsorption processes are widely used in different technological areas and\u0000 industry sectors, thus continuously attracting attention in the scientific\u0000 research and publications. Design and scale-up of these processes are\u0000 essentially based on the knowledge and understanding of the adsorption\u0000 kinetics and mechanism. Adsorption kinetics is usually modeled by using\u0000 several well-known models including the pseudo-first and pseudo-second order\u0000 models, the Elovich equation, and the intra-particle diffusion based models.\u0000 However, in the scientific literature there are a significant number of\u0000 cases with the inappropriate use of these models, utilization of erroneous\u0000 expressions, and incorrect interpretation of the obtained results. This\u0000 paper is especially focused on applications of the pseudo-second order,\u0000 intra-particle diffusion and the Weber-Morris models, which are illustrated\u0000 with typical examples. Finally, general recommendations for selection of the\u0000 appropriate kinetic model and model assumptions, data regression analysis,\u0000 and evaluation and presentation of the obtained results are outlined.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82502914","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 : 2020-03-02DOI: 10.2298/hemind190910002v
M. Vlachou, N. Pippa, A. Siamidi, Aimilia Kyrili
In the context of the present study, the thermal behavior of furosemide and the solid state excipients, sodium alginate, poly(ethylene oxide), poly(vinylpyrrolidone), lactose mono-hydrate and magnesium stearate, using Differential Scanning Calorimetry (DSC), was probed. It was found that the thermal behavior of these solid-state pharmaceutical excipients and furosemide correlates nicely with the literature relevant data. Regarding the furosemide-excipients mixtures, the DSC scans appear as a compilation of the thermal curves of each excipient. This suggests that the formulations containing these mixtures, may retain their stability over time. This information, which arises from the cooperativity of materials, their thermal stability and behavioris very helpful for the research and development of safe and effective pharmaceutical formulations. DSC experiments were also carried out with chimeric bilayers (called ?liposomes?), composed of hydrogenated soy phosphatidylcholine (HSPC) and poly(n-butylacrylate)-b-poly(acrylic acid) block copolymer with 70 % content of poly(acrylic acid (PnBA-b-PAA 30/70) with the addition of furosemide at the molar ratio of 9:0.1:1.0 in the system HSPC:PnBA-b-PAA 30/70:furosemide. Chimeric liposomal systems were characterized as ?fluid-like? by their DSC curves, which may be potentially translated as an easy way for release of furosemide from the advanced delivery system.
{"title":"Thermal analysis studies on the compatibility of furosemide with solid state and liquid crystalline excipients","authors":"M. Vlachou, N. Pippa, A. Siamidi, Aimilia Kyrili","doi":"10.2298/hemind190910002v","DOIUrl":"https://doi.org/10.2298/hemind190910002v","url":null,"abstract":"In the context of the present study, the thermal behavior of furosemide and the solid state excipients, sodium alginate, poly(ethylene oxide), poly(vinylpyrrolidone), lactose mono-hydrate and magnesium stearate, using Differential Scanning Calorimetry (DSC), was probed. It was found that the thermal behavior of these solid-state pharmaceutical excipients and furosemide correlates nicely with the literature relevant data. Regarding the furosemide-excipients mixtures, the DSC scans appear as a compilation of the thermal curves of each excipient. This suggests that the formulations containing these mixtures, may retain their stability over time. This information, which arises from the cooperativity of materials, their thermal stability and behavioris very helpful for the research and development of safe and effective pharmaceutical formulations. DSC experiments were also carried out with chimeric bilayers (called ?liposomes?), composed of hydrogenated soy phosphatidylcholine (HSPC) and poly(n-butylacrylate)-b-poly(acrylic acid) block copolymer with 70 % content of poly(acrylic acid (PnBA-b-PAA 30/70) with the addition of furosemide at the molar ratio of 9:0.1:1.0 in the system HSPC:PnBA-b-PAA 30/70:furosemide. Chimeric liposomal systems were characterized as ?fluid-like? by their DSC curves, which may be potentially translated as an easy way for release of furosemide from the advanced delivery system.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75204777","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 : 2020-01-01DOI: 10.2298/HEMIND210104002C
S. Cvijić, S. Ibrić, J. Parojčić
The importance of biopharmaceutical considerations in pharmaceutical development and drug characterization has been well recognized both by pharmaceutical industry and regulatory authorities as a tool to establish predictive relationships between drug product quality attributes ( in vitro data) and its clinical performance ( in vivo data). In the present paper, contemporary biopharmaceutics toolkit including in vivo predictive dissolution testing, Biopharmaceutics Classification System, physiologically based pharmacokinetic and biopharmaceutics modeling and simulation, in vitro-in vivo co rrelation and biowaiver, are reviewed with regards to relevant general principles and applicability. The recently introduced innovative strategy for patient-centric drug development using an integrated systems approach grounded in fundamental biopharmaceutics concepts, clinical insights and therapeutic drug delivery targets, described as Biopharmaceutics Risk Assessment Roadmap (BioRAM) is also presented. Further development in the field will benefit from joint efforts and exchange of knowledge and experiences between pharmaceutical industry and regulatory authorities for the common goal to accelerate development of effective and safe drug products designed in accordance with patients’ needs and expectations.
{"title":"Integrated biopharmaceutical approach in pharmaceutical development and drug characterization: General concept and application","authors":"S. Cvijić, S. Ibrić, J. Parojčić","doi":"10.2298/HEMIND210104002C","DOIUrl":"https://doi.org/10.2298/HEMIND210104002C","url":null,"abstract":"The importance of biopharmaceutical considerations in pharmaceutical development and drug characterization has been well recognized both by pharmaceutical industry and regulatory authorities as a tool to establish predictive relationships between drug product quality attributes ( in vitro data) and its clinical performance ( in vivo data). In the present paper, contemporary biopharmaceutics toolkit including in vivo predictive dissolution testing, Biopharmaceutics Classification System, physiologically based pharmacokinetic and biopharmaceutics modeling and simulation, in vitro-in vivo co rrelation and biowaiver, are reviewed with regards to relevant general principles and applicability. The recently introduced innovative strategy for patient-centric drug development using an integrated systems approach grounded in fundamental biopharmaceutics concepts, clinical insights and therapeutic drug delivery targets, described as Biopharmaceutics Risk Assessment Roadmap (BioRAM) is also presented. Further development in the field will benefit from joint efforts and exchange of knowledge and experiences between pharmaceutical industry and regulatory authorities for the common goal to accelerate development of effective and safe drug products designed in accordance with patients’ needs and expectations.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84479184","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 : 2020-01-01DOI: 10.2298/hemind200709032a
S. Alnouri, M. Kijevčanin, Mirko Stijepovic
This paper utilizes a stochastic optimization approach using genetic algorithms, for conducting rigorous pipe size sensitivity assessments onto the design of pressure relief networks. By sampling high performance candidates, only the finest options can survive. The pressure relief network system that was investigated in this work was previously reported in literature. The problem is constrained and involves minimizing a cost objective function that evaluates the overall network performance, in which the best pipe size combination should be selected for each segment within the network. The overall goal of this paper was to seek cost-effective designs for the pressure relief piping system by exploring different ranges of pipe diameters that are available for each segment in the network and comparing how the overall design of the system is affected, when the number of pipe size options to select from is varied.
{"title":"Pipe size sensitivity in pressure relief networks using genetic algorithms","authors":"S. Alnouri, M. Kijevčanin, Mirko Stijepovic","doi":"10.2298/hemind200709032a","DOIUrl":"https://doi.org/10.2298/hemind200709032a","url":null,"abstract":"This paper utilizes a stochastic optimization approach using genetic algorithms, for conducting rigorous pipe size sensitivity assessments onto the design of pressure relief networks. By sampling high performance candidates, only the finest options can survive. The pressure relief network system that was investigated in this work was previously reported in literature. The problem is constrained and involves minimizing a cost objective function that evaluates the overall network performance, in which the best pipe size combination should be selected for each segment within the network. The overall goal of this paper was to seek cost-effective designs for the pressure relief piping system by exploring different ranges of pipe diameters that are available for each segment in the network and comparing how the overall design of the system is affected, when the number of pipe size options to select from is varied.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76045348","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 : 2020-01-01DOI: 10.2298/HEMIND201026001S
Marija Stevanović, L. Stanojević, B. Danilović, S. Stojanović, S. Najman, M. Cakic, D. Cvetković
The aim of the presented work was to investigate the potential of aqueous extract of cultivated strawberry (Fragaria x ananassa Duch.) leaves for stabilization of silver nanoparticles (AgNPs-E) synthesized at room (RT) and boiling temperature (BT). The synthesis and stability of AgNPs-E were monitored by UV-Vis spectroscopy confirming high stability of the AgNPs-E in the dark at room temperature. The Fourier-transform infrared spectra suggest that molecules containing oxygen and nitrogen functional groups (NH, (NH)C=O, CNO, C-O-C and OH) participate in the reduction and stabilization of formed nanoparticles. As determined by the DPPH test, AgNPs-E synthesized at RT exerted higher antioxidant activity as compared to AgNPs-E synthesized at BT (EC50 values of 0.025 and 0.039 mg cm-3, respectively). Also, the AgNPs-E synthesized at RT exerted higher antibacterial activity against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Bacillus subtilis and Bacillus luteus. Examination of the AgNPs-E on HeLa and MDCK cell lines showed concentration-dependent and cell line specific effects on the cell viability as evaluated by the MTT test. The obtained results indicate that synthesized AgNPs-E can be used as a base material in production of pharmaceutical preparations for potential skin applications.
本研究的目的是研究栽培草莓(Fragaria x ananassa Duch.)叶水提物在室温(RT)和沸点(BT)下合成银纳米粒子(AgNPs-E)的稳定性。通过紫外可见光谱对AgNPs-E的合成和稳定性进行了监测，证实了AgNPs-E在室温下具有较高的稳定性。傅里叶红外光谱表明，含氧和氮官能团(NH， (NH)C=O, CNO, C-O-C和OH)的分子参与了纳米颗粒的还原和稳定。DPPH试验表明，RT法合成的AgNPs-E抗氧化活性高于BT法合成的AgNPs-E (EC50值分别为0.025和0.039 mg cm-3)。RT合成的AgNPs-E对大肠杆菌、金黄色葡萄球菌、单核增生李斯特菌、枯草芽孢杆菌和黄体芽孢杆菌具有较高的抑菌活性。AgNPs-E在HeLa和MDCK细胞系上的检测显示，MTT试验评估了AgNPs-E对细胞活力的浓度依赖性和细胞系特异性影响。所得结果表明，合成的AgNPs-E可作为潜在的皮肤应用药物制剂的基础材料。
{"title":"Aqueous extract of strawberry (Fragaria x ananassa Duch.) leaves as a stabilizing agent in the synthesis of bio-active silver nanoparticles","authors":"Marija Stevanović, L. Stanojević, B. Danilović, S. Stojanović, S. Najman, M. Cakic, D. Cvetković","doi":"10.2298/HEMIND201026001S","DOIUrl":"https://doi.org/10.2298/HEMIND201026001S","url":null,"abstract":"The aim of the presented work was to investigate the potential of aqueous extract of cultivated strawberry (Fragaria x ananassa Duch.) leaves for stabilization of silver nanoparticles (AgNPs-E) synthesized at room (RT) and boiling temperature (BT). The synthesis and stability of AgNPs-E were monitored by UV-Vis spectroscopy confirming high stability of the AgNPs-E in the dark at room temperature. The Fourier-transform infrared spectra suggest that molecules containing oxygen and nitrogen functional groups (NH, (NH)C=O, CNO, C-O-C and OH) participate in the reduction and stabilization of formed nanoparticles. As determined by the DPPH test, AgNPs-E synthesized at RT exerted higher antioxidant activity as compared to AgNPs-E synthesized at BT (EC50 values of 0.025 and 0.039 mg cm-3, respectively). Also, the AgNPs-E synthesized at RT exerted higher antibacterial activity against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Bacillus subtilis and Bacillus luteus. Examination of the AgNPs-E on HeLa and MDCK cell lines showed concentration-dependent and cell line specific effects on the cell viability as evaluated by the MTT test. The obtained results indicate that synthesized AgNPs-E can be used as a base material in production of pharmaceutical preparations for potential skin applications.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78082177","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 : 2019-12-29DOI: 10.2298/hemind190719031b
Damir Barbir, Pero Dabic, Mario Meheš
Unique antibacterial properties of silver have been known since the time of Egyptian pharaohs. With the discovery of antibiotics at the beginning of the twentieth century, silver is mostly pushed out from conventional medicine. However, with the excessive use of antibiotics, antibiotic-resistant super bacteria have appeared. Therefore, there is an increased interest in studying the antibacterial effects of colloidal silver. In this paper, the influence of various concentrations of silver nitrate on formation of colloidal silver particles in the solution was investigated. Colloidal silver was prepared by a chemical precipitation method using sodium borohydride as a reducing agent. As influence factors, color of the solution, Tyndall effect, UV/Vis absorption, and nanoparticle size estimated by PWHM (Peak Width at Half Maximum) and Mie methods were used. By increasing the silver concentration, color of the solution ranged from light yellow to dark yellow. All solutions showed Tyndall's effect equally. By the UV/Vis analysis it was found that the solutions absorbed radiation in the wavelength range 390-402 nm, and the intensity increased with increasing silver nitrate concentrations. By the PWHM and Mie methods silver nanoparticle sizes were estimated in the range 12-20 nm.
{"title":"The use of PWHM and Mie methods in estimation of colloidal silver particle size obtained by chemical precipitation with sodium borohydride","authors":"Damir Barbir, Pero Dabic, Mario Meheš","doi":"10.2298/hemind190719031b","DOIUrl":"https://doi.org/10.2298/hemind190719031b","url":null,"abstract":"Unique antibacterial properties of silver have been known since the time of Egyptian pharaohs. With the discovery of antibiotics at the beginning of the twentieth century, silver is mostly pushed out from conventional medicine. However, with the excessive use of antibiotics, antibiotic-resistant super bacteria have appeared. Therefore, there is an increased interest in studying the antibacterial effects of colloidal silver. In this paper, the influence of various concentrations of silver nitrate on formation of colloidal silver particles in the solution was investigated. Colloidal silver was prepared by a chemical precipitation method using sodium borohydride as a reducing agent. As influence factors, color of the solution, Tyndall effect, UV/Vis absorption, and nanoparticle size estimated by PWHM (Peak Width at Half Maximum) and Mie methods were used. By increasing the silver concentration, color of the solution ranged from light yellow to dark yellow. All solutions showed Tyndall's effect equally. By the UV/Vis analysis it was found that the solutions absorbed radiation in the wavelength range 390-402 nm, and the intensity increased with increasing silver nitrate concentrations. By the PWHM and Mie methods silver nanoparticle sizes were estimated in the range 12-20 nm.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82458991","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 : 2019-12-29DOI: 10.2298/hemind190803034s
I. Sutjahja, A. F. M. Moshiur Rahman, R. Putri, A. Swandi, R. Anggraini, S. Wonorahardjo, D. Kurnia, S. Wonorahardjo
This paper reports electrofreezing experiments on the inorganic phase-change material (PCM) CaCl2?6H2O by using an insulated copper electrode that is commonly sold in the market. The effect of the applied voltage or electric field to the nucleation process is measured by the nucleation temperature, freezing temperature, supercooling degree, induction time, time for supercooling, and time for crystallisation. It is found that, compared to the zero field, the freezing temperature remains nearly constant while the nucleation temperature increases with increasing applied field, leading to a reduction in the supercooling degree. The decrease in the supercooling degree is approximately 6 K for an applied voltage of V = 5.0 kV or E = 107 V m-1. With the increase in the applied field the induction time decreased considerably along with reduction of the measured data spread as compared to the no-voltage case, while the crystallisation time for the phase transformation prolonged. The overall phenomena are analysed in terms of modification of the Gibbs free energy for crystallisation owing to the applied field, with the mechanism involving bubble generation and formation of a copper-chloride complex.
本文报道了无机相变材料(PCM) CaCl2?6H2O通过使用绝缘铜电极，通常在市场上出售。施加电压或电场对成核过程的影响是通过成核温度、冻结温度、过冷度、感应时间、过冷时间和结晶时间来测量的。结果表明，与零场相比，随着施加磁场的增大，凝固温度基本保持不变，而成核温度则升高，导致过冷度降低。当施加电压V = 5.0 kV或E = 107 V m-1时，过冷度降低约6 K。与无电压情况相比，随着施加电场的增加，感应时间大大减少，测量数据的传播也减少，而相变的结晶时间延长。从吉布斯自由能的结晶变化的角度分析了整个现象，其机制涉及气泡的产生和氯化铜络合物的形成。
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Pub Date : 2019-12-29DOI: 10.2298/hemind190704032t
S. Tošić, S. Mitić, A. Pavlović, Emilija T. Pecev-Marinković, D. Kostić, S. Rančić
A simple, rapid, sensitive and selective kinetic spectrophotometric method for determination of Fe(III) traces was elaborated in this paper. It is based on the catalytic effect of Fe(III) ions on oxidation of potassium salt of disulphonated hydroquinone (K2S2Hy) by hydrogen peroxide in acidic media, at a constant ionic strength. At the working temperature of 20?C and the wavelength of 450.0 nm, optimal conditions for determination of iron were found so that iron (III) can be determined by the proposed method in the concentration range of 1.87 to 18.7 ng cm-3. Corresponding RSD values were determined to be in the range 4.22 to 10.33 %. The limit of detection (LOD) calculated in two ways was found to be 1.07 ng cm-3 i.e. 1.11 ng cm-3 Fe(III). In order to assess the selectivity of the method effects of different ions on the reaction rate were also determined. It was found that presence of oxalates and citrates in the w/w ratio to Fe(III) 1:1 under selected experimental conditions interferes with determination of iron. Then the method was applied for determination of Fe(III) traces in white radish juice. The results agreed well with those obtained by atomic absorption spectrometry.
本文介绍了一种简便、快速、灵敏、选择性的动力学分光光度法测定痕量铁(III)的方法。它是基于铁(III)离子在一定离子强度下在酸性介质中对过氧化氢氧化二磺化对苯二酚(K2S2Hy)钾盐的催化作用。工作温度为20?在波长为450.0 nm时，找到了测定铁的最佳条件，该方法可在1.87 ~ 18.7 ng cm-3的浓度范围内测定铁(III)。相应的RSD值在4.22 ~ 10.33%之间。两种方法计算的检出限(LOD)为1.07 ng cm-3即1.11 ng cm-3 Fe(III)。为了评价该方法的选择性，还测定了不同离子对反应速率的影响。在选定的实验条件下，草酸盐和柠檬酸盐与Fe(III)的w/w比为1:1，会干扰铁的测定。将该法应用于白萝卜汁中痕量铁的测定。结果与原子吸收光谱法测定结果吻合较好。
{"title":"Analytical application of the reaction system disulphonated hydroquinone-hydrogen peroxide for the kinetic spectrophotometric determination of iron traces in acidic media","authors":"S. Tošić, S. Mitić, A. Pavlović, Emilija T. Pecev-Marinković, D. Kostić, S. Rančić","doi":"10.2298/hemind190704032t","DOIUrl":"https://doi.org/10.2298/hemind190704032t","url":null,"abstract":"A simple, rapid, sensitive and selective kinetic spectrophotometric method for determination of Fe(III) traces was elaborated in this paper. It is based on the catalytic effect of Fe(III) ions on oxidation of potassium salt of disulphonated hydroquinone (K2S2Hy) by hydrogen peroxide in acidic media, at a constant ionic strength. At the working temperature of 20?C and the wavelength of 450.0 nm, optimal conditions for determination of iron were found so that iron (III) can be determined by the proposed method in the concentration range of 1.87 to 18.7 ng cm-3. Corresponding RSD values were determined to be in the range 4.22 to 10.33 %. The limit of detection (LOD) calculated in two ways was found to be 1.07 ng cm-3 i.e. 1.11 ng cm-3 Fe(III). In order to assess the selectivity of the method effects of different ions on the reaction rate were also determined. It was found that presence of oxalates and citrates in the w/w ratio to Fe(III) 1:1 under selected experimental conditions interferes with determination of iron. Then the method was applied for determination of Fe(III) traces in white radish juice. The results agreed well with those obtained by atomic absorption spectrometry.","PeriodicalId":9933,"journal":{"name":"Chemical Industry","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86521811","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}
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