Pub Date : 2020-07-01DOI: 10.2298/hemind200304018p
J. Prodanović, Bojana Šarić, M. Šćiban, D. Kukić, V. Vasić, S. Popović, M. Antov
Natural coagulants from a crude water extract of common bean seed showed very good efficiency of turbidity removal from water of ~89 % under optimal coagulation conditions, which were determined using response surface methodology (RSM). However, they also increased the content of organic matter in treated model water by ~66 %, which is the main drawback of usage of natural coagulants, in general. Thus, ultrafiltration was applied for processing of the crude water extract in order to separate biomolecules, which exhibit the coagulation activity. Four fractions obtained by ultrafiltration were applied in coagulation tests under the same conditions as the crude extract, and the 4 th fraction (molecules with molecular weights >30 kDa) with the predominant content of proteins with molecular weights 50 – 60 kDa, achieved almost as high efficiency of turbidity removal (75 %) as the crude extract. At the same time, the content of organic matter in treated water increased just for 16 % in comparison to the blank (model water processed in the same way but without coagulant). After optimization of process parameters by RSM for usage of the 4 th fraction, the coagulation activity increased further to 80 %.
{"title":"Ultrafiltration as a simple purification method of a water extract of common bean seed as a natural coagulant","authors":"J. Prodanović, Bojana Šarić, M. Šćiban, D. Kukić, V. Vasić, S. Popović, M. Antov","doi":"10.2298/hemind200304018p","DOIUrl":"https://doi.org/10.2298/hemind200304018p","url":null,"abstract":"Natural coagulants from a crude water extract of common bean seed showed very good efficiency of turbidity removal from water of ~89 % under optimal coagulation conditions, which were determined using response surface methodology (RSM). However, they also increased the content of organic matter in treated model water by ~66 %, which is the main drawback of usage of natural coagulants, in general. Thus, ultrafiltration was applied for processing of the crude water extract in order to separate biomolecules, which exhibit the coagulation activity. Four fractions obtained by ultrafiltration were applied in coagulation tests under the same conditions as the crude extract, and the 4 th fraction (molecules with molecular weights >30 kDa) with the predominant content of proteins with molecular weights 50 – 60 kDa, achieved almost as high efficiency of turbidity removal (75 %) as the crude extract. At the same time, the content of organic matter in treated water increased just for 16 % in comparison to the blank (model water processed in the same way but without coagulant). After optimization of process parameters by RSM for usage of the 4 th fraction, the coagulation activity increased further to 80 %.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"74 1","pages":"211-220"},"PeriodicalIF":0.9,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49620125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.2298/hemind191203017m
D. Majstorović, M. Mirković, M. Kijevčanin, E. Živković
The aim of this research is the experimental determination of density, viscosity, refractive index and speed of sound for binary mixtures of the ester ethyl acetate and alcohols. Experimental measurements were carried out for two systems with 1-propanol and 1-butanol at atmospheric pressure and in a temperature range 288.15 - 323.15 K. Results of experimental measurements were further used to determine excess molar volumes, viscosity deviations, refractive index deviations, and excess isentropic compressibility for each investigated mixture. These calculated data were correlated using the empirical Redlich-Kister equation. Positive values of the excess molar volume and isentropic compressibility appear for both analysed systems, while values of viscosity and refractive index deviations are negative. The structure and specific characteristics of different molecules in considered mixtures and determined non-ideal behaviour allow the insight into the possible type of interactions in the mixture, interstitial accommodation and structural effects.
{"title":"Analysis of thermophysical properties of binary systems containing ethyl acetate and 1-propanol or 1-butanol","authors":"D. Majstorović, M. Mirković, M. Kijevčanin, E. Živković","doi":"10.2298/hemind191203017m","DOIUrl":"https://doi.org/10.2298/hemind191203017m","url":null,"abstract":"The aim of this research is the experimental determination of density, viscosity, refractive index and speed of sound for binary mixtures of the ester ethyl acetate and alcohols. Experimental measurements were carried out for two systems with 1-propanol and 1-butanol at atmospheric pressure and in a temperature range 288.15 - 323.15 K. Results of experimental measurements were further used to determine excess molar volumes, viscosity deviations, refractive index deviations, and excess isentropic compressibility for each investigated mixture. These calculated data were correlated using the empirical Redlich-Kister equation. Positive values of the excess molar volume and isentropic compressibility appear for both analysed systems, while values of viscosity and refractive index deviations are negative. The structure and specific characteristics of different molecules in considered mixtures and determined non-ideal behaviour allow the insight into the possible type of interactions in the mixture, interstitial accommodation and structural effects.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"74 1","pages":"163-185"},"PeriodicalIF":0.9,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44205767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-01DOI: 10.2298/hemind190925008n
M. Novakovic, Jovana Z Milanovic, D. Grujić, S. Stanković
Liquid transport in textile fabrics determines thermal comfort during high physical activity of a person when liquid perspiration is produced and needs to be transferred away from the skin to keep the thermal balance. In this investigation, an attempt was made to get some indications of how the combination of the fabric composition, geometry and dimensional stability, and the moisture content influences liquid transfer properties of plain weft knitted fabrics. Therefore, the knitted fabrics made from pure hydrophilic (hemp fibres), pure hydrophobic (acrylic fibres) and a hydrophilic/hydrophobic (hemp/acrylic) fibre blend underwent a trial wear and care period. TheMaldenMills water distribution test was performed for the knitted fabrics with different moisture contents (0-30 %) in order to evaluate the effect on liquid transfer properties. Water transfer ability and water holding capacity of the knitted fabrics were also determined after undergoing the wear trial test. The obtained results were analysed with respect to macro and micro scales of porosity of knitted fabrics. It has been shown that the geometric configuration of the complex porous network in knitted fabrics influenced their liquid transfer properties in the whole moisture content range regardless of the composition. Despite the reconfiguration of the pore system in the knits during the trial period, their liquid transfer properties were still dependent on the pore size and distribution.
{"title":"Liquid transfer properties of textile fabrics as a function of moisture content","authors":"M. Novakovic, Jovana Z Milanovic, D. Grujić, S. Stanković","doi":"10.2298/hemind190925008n","DOIUrl":"https://doi.org/10.2298/hemind190925008n","url":null,"abstract":"Liquid transport in textile fabrics determines thermal comfort during high physical activity of a person when liquid perspiration is produced and needs to be transferred away from the skin to keep the thermal balance. In this investigation, an attempt was made to get some indications of how the combination of the fabric composition, geometry and dimensional stability, and the moisture content influences liquid transfer properties of plain weft knitted fabrics. Therefore, the knitted fabrics made from pure hydrophilic (hemp fibres), pure hydrophobic (acrylic fibres) and a hydrophilic/hydrophobic (hemp/acrylic) fibre blend underwent a trial wear and care period. TheMaldenMills water distribution test was performed for the knitted fabrics with different moisture contents (0-30 %) in order to evaluate the effect on liquid transfer properties. Water transfer ability and water holding capacity of the knitted fabrics were also determined after undergoing the wear trial test. The obtained results were analysed with respect to macro and micro scales of porosity of knitted fabrics. It has been shown that the geometric configuration of the complex porous network in knitted fabrics influenced their liquid transfer properties in the whole moisture content range regardless of the composition. Despite the reconfiguration of the pore system in the knits during the trial period, their liquid transfer properties were still dependent on the pore size and distribution.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"74 1","pages":"119-132"},"PeriodicalIF":0.9,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43526757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-01DOI: 10.2298/hemind190717007u
M. Urošević, Ljubiša Nikolić, S. Ilić-Stojanović, Aleksandar Zdravković, V. Nikolić
Copolymeric hydrogels of poly(N-isopropylmethacrylamide-co-N-isopropylacrylamide), p(NIPMAM/NIPAM), are synthesized by radical polymerization of N-isopropylmethacrylamide (NIPMAM) and N-isopropylacrylamide (NIPAM) monomers by using the cross-linker ethylen glycol dimethacrylate (EGDM). The synthesized copolymeric p(NIPMAM/NIPAM) hydrogels, starting monomers and the cross-linker were structurally characterized by using Fourier transform infrared spectroscopy (FTIR). The amounts of residual reactants in the synthesized hydrogels were determined by high-pressure liquid chromatography (HPLC). Swelling of p(NIPMAM/NIPAM) hydrogels was investigated in relation to the temperature and pH value of the solution. The obtained values of residual monomer quantities are within acceptable limits and in the range from 2.69 to 5.25 mg g -1 for NIPMAM and 14.55 to 30.80 mg g -1 for NIPAM. The synthesized p(NIPMAM/NIPAM) hydrogels are negatively thermosensitive. The most common mechanisms of transport of a swelling solution in p(NIPMAM/NIPAM) hydrogels are polymer chain relaxation, (Case III), and the anomalous type of diffusion (non-Fickian diffusion). The maximal equilibrium swelling degree of 51.19 was reached by the p(NIPMAM/NIPAM) hydrogel with 1.5 mol% of EGDM at the temperature of 25 o C and pH 4, whereas the lowest one of 0.98 was exhibited by the hydrogel with 3 mol% of EGDM at the temperature of 80 o C and pH 7. Due to their low content of residual reactants and a satisfactory degree of swelling at various pH values, synthesized p(NIPMAM/NIPAM) hydrogels can be applied as carriers for the controlled release of pharmaceutically active substances.
以交联剂二甲丙烯酸乙二醇酯(EGDM)为原料，将n -异丙基甲基丙烯酰胺(NIPMAM)与n -异丙基丙烯酰胺(NIPAM)单体自由基聚合，合成了聚(n -异丙基甲基丙烯酰胺-co- n -异丙基丙烯酰胺)共聚水凝胶p(NIPMAM/NIPAM)。利用傅里叶红外光谱(FTIR)对合成的共聚物p(NIPAM /NIPAM)水凝胶、起始单体和交联剂进行了结构表征。采用高压液相色谱法测定合成水凝胶中残留反应物的含量。研究了p(NIPAM /NIPAM)水凝胶的溶胀与溶液温度和pH值的关系。所得的残留单体量值在可接受的范围内，NIPAM的范围为2.69至5.25 mg g -1, NIPAM的范围为14.55至30.80 mg g -1。合成的p(NIPAM /NIPAM)水凝胶具有负热敏性。p(NIPAM /NIPAM)水凝胶中溶胀溶液最常见的输运机制是聚合物链弛豫(案例III)和异常扩散(非菲克扩散)。当温度为25℃，pH为4时，加入1.5 mol% EGDM的p(NIPAM /NIPAM)水凝胶的平衡溶胀度最大，为51.19;当温度为80℃，pH为7时，加入3 mol% EGDM的水凝胶的平衡溶胀度最小，为0.98。合成的p(NIPAM /NIPAM)水凝胶由于其残留反应物含量低，在各种pH值下都有令人满意的溶胀程度，可以作为药物活性物质控释的载体。
{"title":"Synthesis and characterization of poly(N-isopropylmethacrylamide-co-N-isopropylacrylamide) copolymers","authors":"M. Urošević, Ljubiša Nikolić, S. Ilić-Stojanović, Aleksandar Zdravković, V. Nikolić","doi":"10.2298/hemind190717007u","DOIUrl":"https://doi.org/10.2298/hemind190717007u","url":null,"abstract":"Copolymeric hydrogels of poly(N-isopropylmethacrylamide-co-N-isopropylacrylamide), p(NIPMAM/NIPAM), are synthesized by radical polymerization of N-isopropylmethacrylamide (NIPMAM) and N-isopropylacrylamide (NIPAM) monomers by using the cross-linker ethylen glycol dimethacrylate (EGDM). The synthesized copolymeric p(NIPMAM/NIPAM) hydrogels, starting monomers and the cross-linker were structurally characterized by using Fourier transform infrared spectroscopy (FTIR). The amounts of residual reactants in the synthesized hydrogels were determined by high-pressure liquid chromatography (HPLC). Swelling of p(NIPMAM/NIPAM) hydrogels was investigated in relation to the temperature and pH value of the solution. The obtained values of residual monomer quantities are within acceptable limits and in the range from 2.69 to 5.25 mg g -1 for NIPMAM and 14.55 to 30.80 mg g -1 for NIPAM. The synthesized p(NIPMAM/NIPAM) hydrogels are negatively thermosensitive. The most common mechanisms of transport of a swelling solution in p(NIPMAM/NIPAM) hydrogels are polymer chain relaxation, (Case III), and the anomalous type of diffusion (non-Fickian diffusion). The maximal equilibrium swelling degree of 51.19 was reached by the p(NIPMAM/NIPAM) hydrogel with 1.5 mol% of EGDM at the temperature of 25 o C and pH 4, whereas the lowest one of 0.98 was exhibited by the hydrogel with 3 mol% of EGDM at the temperature of 80 o C and pH 7. Due to their low content of residual reactants and a satisfactory degree of swelling at various pH values, synthesized p(NIPMAM/NIPAM) hydrogels can be applied as carriers for the controlled release of pharmaceutically active substances.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"74 1","pages":"103-117"},"PeriodicalIF":0.9,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44728627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","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/hemind190722004k
N. Karic, Jelena D. Rusmirović, Maja Djolic, T. Kovačević, L. Pecić, Ž. Radovanović, A. Marinković
Oxidized starch, an additive used in paper manufacturing and products for construction industry, is usually produced using harmful oxidant, such as hypochlorites or periodates. In this study, a simple and efficient eco-friendly laboratory and industrial procedures for starch oxidation were developed. The procedure involves application of small amounts of more environmentally friendly oxidant, hydrogen peroxide, a novel special metal complex catalyst such as copper(II) citrate and copper(II) ricinoleate and biobased plasticizers. Optimization procedure, with respect to the quantity of hydrogen peroxide and temperature in the presence of iron(II) sulphate catalyst, was performed by using the response surface methodology. Comparative analysis of the use of the other catalysts that is copper(II) sulphate, copper(II) citrate and copper(II) ricinoleate, indicated copper(II) citrate as the catalyst of choice. Improvement of starch is achieved using three plasticizers: ricinoleic acid (RA), diisopropyl tartarate, as well as epoxidized soybean, linseed and sunflower oils. The effects of hydrogen peroxide and catalyst concentrations, as well as the reaction temperature in the presence of naturally based plasticizers on the physicochemical, thermal and morphological properties of oxidized starch are presented. According to the results obtained in initial experiments, the optimal industrial process is based on the use of copper(II) citrate (0.1 %) as a catalyst and RA (3 %) as a plasticizer.
{"title":"Preparation and properties of hydrogen peroxide oxidized starch for industrial use","authors":"N. Karic, Jelena D. Rusmirović, Maja Djolic, T. Kovačević, L. Pecić, Ž. Radovanović, A. Marinković","doi":"10.2298/hemind190722004k","DOIUrl":"https://doi.org/10.2298/hemind190722004k","url":null,"abstract":"Oxidized starch, an additive used in paper manufacturing and products for construction industry, is usually produced using harmful oxidant, such as hypochlorites or periodates. In this study, a simple and efficient eco-friendly laboratory and industrial procedures for starch oxidation were developed. The procedure involves application of small amounts of more environmentally friendly oxidant, hydrogen peroxide, a novel special metal complex catalyst such as copper(II) citrate and copper(II) ricinoleate and biobased plasticizers. Optimization procedure, with respect to the quantity of hydrogen peroxide and temperature in the presence of iron(II) sulphate catalyst, was performed by using the response surface methodology. Comparative analysis of the use of the other catalysts that is copper(II) sulphate, copper(II) citrate and copper(II) ricinoleate, indicated copper(II) citrate as the catalyst of choice. Improvement of starch is achieved using three plasticizers: ricinoleic acid (RA), diisopropyl tartarate, as well as epoxidized soybean, linseed and sunflower oils. The effects of hydrogen peroxide and catalyst concentrations, as well as the reaction temperature in the presence of naturally based plasticizers on the physicochemical, thermal and morphological properties of oxidized starch are presented. According to the results obtained in initial experiments, the optimal industrial process is based on the use of copper(II) citrate (0.1 %) as a catalyst and RA (3 %) as a plasticizer.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"74 1","pages":"25-36"},"PeriodicalIF":0.9,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46440328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","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/hemind190625001v
Milan Vukic, Janic Hajnal Elizabet, S. Mastilovic, P. D. Vujadinovic, M. Ivanovic, M. D. Soronja-Simovic
This paper presents relationship between the rheological properties of dough and individual polymer swelling properties in wheat flour mill streams. The swelling properties were measured by applying the Solvent Retention Capacities (SRC) tests. Significant correlation coefficients were determined for certain rheological parameters. In an effort to extract additional insights from the properties measured, a multivariate analysis was used to develop relationships between the studied parameters. To determine relevant relationships among the parameters, the data exploration step by the Principal Component Analysis was performed. Then, multivariate Partial Least Squares Regression (PLSR) models were developed, to predict certain empirical rheology parameters based on the SRC parameters. The processing of experimental data indicated the possibility of using SRC parameters for predicting rheological properties in conjunction with a suitable mathematical model. The presented approach may be useful for rapid prediction of wheat flour mill streams characteristics and for optimization of the end-flour performances.
{"title":"Application of solvent retention capacity tests for prediction of rheological parameters of wheat flour mill streams","authors":"Milan Vukic, Janic Hajnal Elizabet, S. Mastilovic, P. D. Vujadinovic, M. Ivanovic, M. D. Soronja-Simovic","doi":"10.2298/hemind190625001v","DOIUrl":"https://doi.org/10.2298/hemind190625001v","url":null,"abstract":"This paper presents relationship between the rheological properties of dough and individual polymer swelling properties in wheat flour mill streams. The swelling properties were measured by applying the Solvent Retention Capacities (SRC) tests. Significant correlation coefficients were determined for certain rheological parameters. In an effort to extract additional insights from the properties measured, a multivariate analysis was used to develop relationships between the studied parameters. To determine relevant relationships among the parameters, the data exploration step by the Principal Component Analysis was performed. Then, multivariate Partial Least Squares Regression (PLSR) models were developed, to predict certain empirical rheology parameters based on the SRC parameters. The processing of experimental data indicated the possibility of using SRC parameters for predicting rheological properties in conjunction with a suitable mathematical model. The presented approach may be useful for rapid prediction of wheat flour mill streams characteristics and for optimization of the end-flour performances.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"74 1","pages":"37-49"},"PeriodicalIF":0.9,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45800898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","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/hemind190906010t
J. Tolmač, S. Prvulović, M. Nedić, D. Tolmač
The paper presents results of experimental research and simulation of the main parameters of crude oil pipeline transport. In Serbia, 70 % of the produced oil belongs to a paraffin type, of which over 25 % has a high content of paraffin. High-content paraffin oil usually has a high pour point. The paraffin content in crude oil from Vojvodina, Serbia, is in the range 7.5 to 26 %, and the oil pour temperature varies from 18 to 36?C. The imported crude oil has a flow point max. 8?C. Homogenization, i.e. mixing of domestic and imported crude oil, improves the transport properties and decreases the pour point. After homogenization, the crude oil is pre-heated, and then transported by a pipeline to the refinery for further processing. Heating induces modification of crude oil physical properties, especially flow properties so to prevent wax formation within the oil pipeline. The aim of this paper was to determine operating parameters and flow characteristics for a particular oil pipeline (428 mm inner diameter, 91,000 m length) under real operating conditions. By heating in the range of 20 - 50?C, the viscosity of crude oil was reduced, approaching the viscosity of water. The pipeline is isolated (100 mm thick isolation) and buried into in the ground (1 m depth). It is found that the heat transfer coefficient has a dominant influence on the cooling rate of the oil in the pipeline. The heat transfer coefficient is mainly determined by the isolation thickness so that it was determined as 0.60 W m-2 K-1 for + 100 mm thickness, while it was 2.20 W m-2 K-1 for the non-isolated pipeline. Heat losses through the main pipeline ranged from 36 - 110 kJ m-1 h-1 (10 - 30 W m-1). The difference between the starting and the ending temperature of crude oil ranged from 10 to 12?C. Such a decrease of ?t = 10 oC and, consequently, the increase in viscosity induced a noti-ceable increase in the pressure drop and pump power by 3 to 4 %, at the maximum flowrate of 0.194 m3 s-1 (700 m3 h-1). The cooling rate during transportation under stationary thermal and hydraulic conditions is in the range 0.52 ? 0.5 oC h-1. In the case of domestic oil (Vojvodina, Serbia) transport, the downtime should not exceed 24 h, since stopping and cooling of the oil would result in formation of solid paraffin particles followed by oil gelation.
{"title":"Analysis of the main parameters of crude oil pipeline transport","authors":"J. Tolmač, S. Prvulović, M. Nedić, D. Tolmač","doi":"10.2298/hemind190906010t","DOIUrl":"https://doi.org/10.2298/hemind190906010t","url":null,"abstract":"The paper presents results of experimental research and simulation of the main parameters of crude oil pipeline transport. In Serbia, 70 % of the produced oil belongs to a paraffin type, of which over 25 % has a high content of paraffin. High-content paraffin oil usually has a high pour point. The paraffin content in crude oil from Vojvodina, Serbia, is in the range 7.5 to 26 %, and the oil pour temperature varies from 18 to 36?C. The imported crude oil has a flow point max. 8?C. Homogenization, i.e. mixing of domestic and imported crude oil, improves the transport properties and decreases the pour point. After homogenization, the crude oil is pre-heated, and then transported by a pipeline to the refinery for further processing. Heating induces modification of crude oil physical properties, especially flow properties so to prevent wax formation within the oil pipeline. The aim of this paper was to determine operating parameters and flow characteristics for a particular oil pipeline (428 mm inner diameter, 91,000 m length) under real operating conditions. By heating in the range of 20 - 50?C, the viscosity of crude oil was reduced, approaching the viscosity of water. The pipeline is isolated (100 mm thick isolation) and buried into in the ground (1 m depth). It is found that the heat transfer coefficient has a dominant influence on the cooling rate of the oil in the pipeline. The heat transfer coefficient is mainly determined by the isolation thickness so that it was determined as 0.60 W m-2 K-1 for + 100 mm thickness, while it was 2.20 W m-2 K-1 for the non-isolated pipeline. Heat losses through the main pipeline ranged from 36 - 110 kJ m-1 h-1 (10 - 30 W m-1). The difference between the starting and the ending temperature of crude oil ranged from 10 to 12?C. Such a decrease of ?t = 10 oC and, consequently, the increase in viscosity induced a noti-ceable increase in the pressure drop and pump power by 3 to 4 %, at the maximum flowrate of 0.194 m3 s-1 (700 m3 h-1). The cooling rate during transportation under stationary thermal and hydraulic conditions is in the range 0.52 ? 0.5 oC h-1. In the case of domestic oil (Vojvodina, Serbia) transport, the downtime should not exceed 24 h, since stopping and cooling of the oil would result in formation of solid paraffin particles followed by oil gelation.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68381652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","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/hemind190909009z
S. Zorić, M. Bečelić-Tomin, B. Dalmacija
The primary goal of a water supply system is the protection of human health by providing microbiologically and chemically safe drinking water. Significant changes in water quality require sufficiently robust systems for water preparation, performances of which are unaffected by present variations and changing operational conditions. Water turbidity is an important parameter for the water filtration control and efficiency of disinfection. The efficiency of turbidity removal in the drinking water treatment plant ?Vodovod? in Banjaluka under normal and emergency operating conditions was examined in this paper. At normal conditions the maximal detected value was 25 NTU while at emergency operating conditions it was above 240 NTU. Robustness evaluation of the water clarification system was performed separately for periods of normal and emergency operating conditions (during and after emptying the accumulation). The robustness index was calculated based on a more stringent target turbidity value (0.5 NTU) than that specified by the current legislation, which represents a new criterion in the risk analysis in the existing practice. Data processing results indicate high operational stability of technological units under normal conditions. The filtered water quality was below the target value during most of the time of filter operation in all cycles. The recorded turbidity value was ? 0.3 NTU for 92.9 % of filtered water samples. Analysis of the water turbidity data has shown that 17% of all taken measurements under emergency operating conditions (336 samples) had higher turbidity than the target value (0.5 NTU). Large variations in raw water turbidity over short periods of times during the emergency operating conditions, present a problem for prompt response in the drinking water plant. Calculated robustness index values point to inadequate efficiency of the water clarification process in a certain number of filter operating cycles. We have found a significant impact of the plant operating conditions on the filtered water turbidity under emergency conditions, such as suboptimal coagulation and flocculation conditions as well as the nature of suspended and colloid particles inducing turbidity and insufficient particle interactions with the coagulant. Along with the negative influence on water turbidity, excessive coagulant dosage leads to increased concentrations of residual aluminum in filtered water. Optimization of emergency working conditions could be performed based on adequate monitoring of water sources, which would further decrease potential risks of pathogen appearance in drinking water.
{"title":"Robustness analysis of technological units for drinking water clarification: Normal and emergency operating conditions","authors":"S. Zorić, M. Bečelić-Tomin, B. Dalmacija","doi":"10.2298/hemind190909009z","DOIUrl":"https://doi.org/10.2298/hemind190909009z","url":null,"abstract":"The primary goal of a water supply system is the protection of human health by providing microbiologically and chemically safe drinking water. Significant changes in water quality require sufficiently robust systems for water preparation, performances of which are unaffected by present variations and changing operational conditions. Water turbidity is an important parameter for the water filtration control and efficiency of disinfection. The efficiency of turbidity removal in the drinking water treatment plant ?Vodovod? in Banjaluka under normal and emergency operating conditions was examined in this paper. At normal conditions the maximal detected value was 25 NTU while at emergency operating conditions it was above 240 NTU. Robustness evaluation of the water clarification system was performed separately for periods of normal and emergency operating conditions (during and after emptying the accumulation). The robustness index was calculated based on a more stringent target turbidity value (0.5 NTU) than that specified by the current legislation, which represents a new criterion in the risk analysis in the existing practice. Data processing results indicate high operational stability of technological units under normal conditions. The filtered water quality was below the target value during most of the time of filter operation in all cycles. The recorded turbidity value was ? 0.3 NTU for 92.9 % of filtered water samples. Analysis of the water turbidity data has shown that 17% of all taken measurements under emergency operating conditions (336 samples) had higher turbidity than the target value (0.5 NTU). Large variations in raw water turbidity over short periods of times during the emergency operating conditions, present a problem for prompt response in the drinking water plant. Calculated robustness index values point to inadequate efficiency of the water clarification process in a certain number of filter operating cycles. We have found a significant impact of the plant operating conditions on the filtered water turbidity under emergency conditions, such as suboptimal coagulation and flocculation conditions as well as the nature of suspended and colloid particles inducing turbidity and insufficient particle interactions with the coagulant. Along with the negative influence on water turbidity, excessive coagulant dosage leads to increased concentrations of residual aluminum in filtered water. Optimization of emergency working conditions could be performed based on adequate monitoring of water sources, which would further decrease potential risks of pathogen appearance in drinking water.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68381669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","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/HEMIND200709028K
Azhar U. Khan, Sunil K. Sharma, A. Gehlot, Mona Gupta, Mahboob Alam
In this study, steroidal sitosteryl hydrogen phthalate (stigmast-5-en- 3 b -yl hydrogen phthalate) was synthesized by the reaction of 3b-sitosterol and phthalic anhydride using silica gel as a solid support under microwave irradiation (MWI). The comparative study of microwave assisted synthesis and conventional synthesis of the steroidal compound in a hazardous solvent revealed that the former method provided shortened reaction times at increased yields. The compounds obtained by the two procedures were characterized by infrared spectroscopy, proton, carbon-13 nuclear magnetic resonance ( 1 H and 13 C NMR) and high-resolution mass spectrometry. The synthesized compound was screened for in vitro antifungal activity against Aspergillus niger and Candida albicans by the Kirby-Bauer Well Diffusion method. The synthesized compound was subjected to the molecular docking simulation with a receptor (CYP51). The findings of the antifungal and docking studies revealed that the synthesized sitosteryl hydrogen phthalate could be considered as a suitable inhibitor of Lanosterol 14a-demethylase (CYP51). In addition, the molecular docking approach was applied to design hypothetical derivatives of sitosteryl hydrogen phthalate inhibitors against the antifungal target and to compare findings with the binding score of the molecular synthesized 3b-sitosteryl hydrogen phthalate.
{"title":"Antifungal screening and molecular docking simulation of silica supported synthesized sitosteryl hydrogen phthalate using microwave irradiation","authors":"Azhar U. Khan, Sunil K. Sharma, A. Gehlot, Mona Gupta, Mahboob Alam","doi":"10.2298/HEMIND200709028K","DOIUrl":"https://doi.org/10.2298/HEMIND200709028K","url":null,"abstract":"In this study, steroidal sitosteryl hydrogen phthalate (stigmast-5-en- 3 b -yl hydrogen phthalate) was synthesized by the reaction of 3b-sitosterol and phthalic anhydride using silica gel as a solid support under microwave irradiation (MWI). The comparative study of microwave assisted synthesis and conventional synthesis of the steroidal compound in a hazardous solvent revealed that the former method provided shortened reaction times at increased yields. The compounds obtained by the two procedures were characterized by infrared spectroscopy, proton, carbon-13 nuclear magnetic resonance ( 1 H and 13 C NMR) and high-resolution mass spectrometry. The synthesized compound was screened for in vitro antifungal activity against Aspergillus niger and Candida albicans by the Kirby-Bauer Well Diffusion method. The synthesized compound was subjected to the molecular docking simulation with a receptor (CYP51). The findings of the antifungal and docking studies revealed that the synthesized sitosteryl hydrogen phthalate could be considered as a suitable inhibitor of Lanosterol 14a-demethylase (CYP51). In addition, the molecular docking approach was applied to design hypothetical derivatives of sitosteryl hydrogen phthalate inhibitors against the antifungal target and to compare findings with the binding score of the molecular synthesized 3b-sitosteryl hydrogen phthalate.","PeriodicalId":12913,"journal":{"name":"Hemijska Industrija","volume":"74 1","pages":"377-388"},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68381710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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