T. Botic, D. Drljaca, Dajana Dragic, P. Gvero, A. Borkovic, Slobodan Rakulj
Due to the limited availability of wood, as the highest quality raw material for the production of biomass pellets, increasing attention is being paid to the production and use of pellets from low-quality materials such as different types of agricultural waste. However, the complex chemical composition of these types of biomass often leads to various problems during their combustion. One of the biggest problems when it comes to burning biomass pellets is related to the low melting temperature of the resulting ash and its tendency to sintering. By modifying the chemical composition of biomass, it is possible to influence the method of combustion and the characteristics of residual ash. Modification of biomass composition can be carried out by chemical pretreatment with acids, which reduces the concentration of alkali metals and alleviates ash adhesion and the tendency to form slag. Pellets made from wood biomass, soy straw and chamomile waste from the process of processing medicinal plants were used for the tests in this work. Chemical pretreatment, which consisted in washing the pellet samples with a diluted solution of hydrochloric acid, resulted in mass loss in all cases. The amount of ash, after treatment in hydrochloric acid solution, was reduced by 72.15% - 93.27%, depending on the concentration of acid and the type of biomass.
{"title":"Pretreatment of biomass pellets by acid washing in order to reduce alkaline components","authors":"T. Botic, D. Drljaca, Dajana Dragic, P. Gvero, A. Borkovic, Slobodan Rakulj","doi":"10.7251/jcte2203013b","DOIUrl":"https://doi.org/10.7251/jcte2203013b","url":null,"abstract":"Due to the limited availability of wood, as the highest quality raw material for the production of biomass pellets, increasing attention is being paid to the production and use of pellets from low-quality materials such as different types of agricultural waste. However, the complex chemical composition of these types of biomass often leads to various problems during their combustion. One of the biggest problems when it comes to burning biomass pellets is related to the low melting temperature of the resulting ash and its tendency to sintering. By modifying the chemical composition of biomass, it is possible to influence the method of combustion and the characteristics of residual ash. Modification of biomass composition can be carried out by chemical pretreatment with acids, which reduces the concentration of alkali metals and alleviates ash adhesion and the tendency to form slag. Pellets made from wood biomass, soy straw and chamomile waste from the process of processing medicinal plants were used for the tests in this work. Chemical pretreatment, which consisted in washing the pellet samples with a diluted solution of hydrochloric acid, resulted in mass loss in all cases. The amount of ash, after treatment in hydrochloric acid solution, was reduced by 72.15% - 93.27%, depending on the concentration of acid and the type of biomass.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123964760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, the effect of incorporation of the plant extracts in a natural casing on the color and sensory attributes in fermented sausages, “sucuk” type, was evaluated. The sausages were produced in industrial conditions, stuffed into the pretreated natural casings, vacuum packaged, and stored at 4˚C for six months. Five groups of sausages were tested, C1 (natural casing without treatment), C2 (treated with 6% (v/v) ethanol), C3 (treated with ascorbic acid), A (treated with ethanol extract of Aronia melanocarpa), and D (treated with ethanol extract of Cornus mas). Based on the results, it was concluded that the use of Aronia extract had an effect on the color of the surface. During storage, there was an increase in lightness (L*) and the proportion of red color (a*), and also a slight increase in the proportion of yellow color (b*). There were no major changes in the color parameters on the cross-section of the sausage. Sensory testing of the sausage samples found that there was no difference between the tested samples in terms of external appearance, while the results of the "different from control" - DFC test showed that the A sample was visually more acceptable and had a nicer surface color.
{"title":"Effect of incorporation of the plant extracts in natural casing on the color of fermented sausages","authors":"Ana Velemir, S. Mandić, D. Savanović","doi":"10.7251/jcte2203020v","DOIUrl":"https://doi.org/10.7251/jcte2203020v","url":null,"abstract":"In this study, the effect of incorporation of the plant extracts in a natural casing on the color and sensory attributes in fermented sausages, “sucuk” type, was evaluated. The sausages were produced in industrial conditions, stuffed into the pretreated natural casings, vacuum packaged, and stored at 4˚C for six months. Five groups of sausages were tested, C1 (natural casing without treatment), C2 (treated with 6% (v/v) ethanol), C3 (treated with ascorbic acid), A (treated with ethanol extract of Aronia melanocarpa), and D (treated with ethanol extract of Cornus mas). Based on the results, it was concluded that the use of Aronia extract had an effect on the color of the surface. During storage, there was an increase in lightness (L*) and the proportion of red color (a*), and also a slight increase in the proportion of yellow color (b*). There were no major changes in the color parameters on the cross-section of the sausage. Sensory testing of the sausage samples found that there was no difference between the tested samples in terms of external appearance, while the results of the \"different from control\" - DFC test showed that the A sample was visually more acceptable and had a nicer surface color.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126204432","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}
Olga Pantic, R. Pjanovic, V. Panic, Sanja I. Savić, P. Spasojevic, Maja D. Markovic
Drug delivery system is an amazing tool which is widely used for drug protection and its controlled release in order to enhance drug bioavailability, reduce side effects and therefore to improve overall therapy. Hydrogels have been attracted great attention as drug carriers due to their great physicochemical properties, similarity to the living tissues and biocompatibility. One group of pH sensitive hydrogels are based on poly(methacrylic acid) (PMAA). These non-toxic hydrogels are used as drug delivery system because they swell as a response to the change in pH of external environment and drug is being released during the process. In present study, in order to improve the control of drug release rate, caffeine was encapsulated in liposomes which were further embedded into PMC hydrogel (PMCL). It was investigated how the change in neutralization degree of methacrylic acid affect the swelling degree of PMCL hydrogels and caffeine release in two environments at 37 °C for 24 h: 0.1 M hydrochloride acid (pH 1) and phosphate buffer with pH value of 6.8 (pH 6.8), as a simulation of pH environment in human stomach and intestines, respectively. Obtained results show that PMCL hydrogels have great potential for controlled release of poorly water-soluble drugs in human intestines.
{"title":"Effect of neutralization degree of methacrylic acid on hydrogel swelling and drug release","authors":"Olga Pantic, R. Pjanovic, V. Panic, Sanja I. Savić, P. Spasojevic, Maja D. Markovic","doi":"10.7251/jcte2203001p","DOIUrl":"https://doi.org/10.7251/jcte2203001p","url":null,"abstract":"Drug delivery system is an amazing tool which is widely used for drug protection and its controlled release in order to enhance drug bioavailability, reduce side effects and therefore to improve overall therapy. Hydrogels have been attracted great attention as drug carriers due to their great physicochemical properties, similarity to the living tissues and biocompatibility. One group of pH sensitive hydrogels are based on poly(methacrylic acid) (PMAA). These non-toxic hydrogels are used as drug delivery system because they swell as a response to the change in pH of external environment and drug is being released during the process. In present study, in order to improve the control of drug release rate, caffeine was encapsulated in liposomes which were further embedded into PMC hydrogel (PMCL). It was investigated how the change in neutralization degree of methacrylic acid affect the swelling degree of PMCL hydrogels and caffeine release in two environments at 37 °C for 24 h: 0.1 M hydrochloride acid (pH 1) and phosphate buffer with pH value of 6.8 (pH 6.8), as a simulation of pH environment in human stomach and intestines, respectively. Obtained results show that PMCL hydrogels have great potential for controlled release of poorly water-soluble drugs in human intestines.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131714756","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}
The paper reports on the synthesis and fluorescence characteristics of novel 1,8-naphthalimide fluorophore. It was configured as a “fluorophore-spacerreceptor” system able to act as a pH-probe via PET (photoinduced electron transfer) fluorescence sensing mechanism. Due to the tertiary amine receptor the novel probe showed “off-on” switching properties under the transition from alkaline to acid media. Also, the ability of the probe to detect metal ions in water/ dimethylformamide (1:1, v/v) has been evaluated by monitoring the changes of its fluorescence intensity. Among the tested metal ions (Cu2+, Pb2+, Zn2+, Ni2+, Hg2+, Fe3+) only the presence of Fe3+ was efficiently detected by fluorescence quenching mechanism.
{"title":"Synthesis and investigation of 1,8-naphthalimide derivative with sensor activity","authors":"P. Miladinova","doi":"10.7251/jcte2203006m","DOIUrl":"https://doi.org/10.7251/jcte2203006m","url":null,"abstract":"The paper reports on the synthesis and fluorescence characteristics of novel 1,8-naphthalimide fluorophore. It was configured as a “fluorophore-spacerreceptor” system able to act as a pH-probe via PET (photoinduced electron transfer) fluorescence sensing mechanism. Due to the tertiary amine receptor the novel probe showed “off-on” switching properties under the transition from alkaline to acid media. Also, the ability of the probe to detect metal ions in water/ dimethylformamide (1:1, v/v) has been evaluated by monitoring the changes of its fluorescence intensity. Among the tested metal ions (Cu2+, Pb2+, Zn2+, Ni2+, Hg2+, Fe3+) only the presence of Fe3+ was efficiently detected by fluorescence quenching mechanism.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133371540","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}
M. Zohorović, Abdel Đozić, Lj. Bojanović, V. Stuhli, Adisa Halilčević Kovač, Edisa Papraćanin, Emra Halilović, Jasmin Pandurović
Sludge generated in wastewater treatment processes must be treated in an adequate manner, and therefore disposed of in an environmentally friendly manner. The biggest obstacle to the efficient use of sludge is the high water content, therefore the development of methods to accelerate the sludge dewatering process is particularly important. For the purposes of the research, the waste sludge created in the process of purifying ammoniaphenol wastewater in the GIKIL factory was used. Sludge conditioning was performed by adding a commercial flocculant (0.1 % solution) in combination with pyrophyllite, kaolin clay and shredded cardboard. According to earlier research, the volume of waste sludge with the addition of a suitable flocculant could be reduced by more than 5 times compared to the initial amount, leaving behind a large amount of separated water that can be returned to the process. The results show that the addition of commercial flocculant in the amount of 0.8 % gives the best results (reduction of sludge volume by 78.8 %). A lower percentage was found in samples with a mixture of flocculants with pyrophyllite (78 %) and kaolin (77.6 %), while the combination of flocculants with waste cardboard was ineffective (64.4 %). Addition of flocculant to waste sludge resulted in a decrease in specific filtration resistance (1.15x107 s2/g). A decrease in specific resistance was also observed in flocculant/kaolin clay (0.8x107 s2/g) and flocculant/cardboard (1.09x107 s2/g) samples. Sludge conditioning also resulted in a reduction of suspended solids in the neonate compared to settled raw sludge without additives.
{"title":"Conditioning of waste sludge from biological wastewater treatment plant from gikil","authors":"M. Zohorović, Abdel Đozić, Lj. Bojanović, V. Stuhli, Adisa Halilčević Kovač, Edisa Papraćanin, Emra Halilović, Jasmin Pandurović","doi":"10.7251/jcte2203033z","DOIUrl":"https://doi.org/10.7251/jcte2203033z","url":null,"abstract":"Sludge generated in wastewater treatment processes must be treated in an adequate manner, and therefore disposed of in an environmentally friendly manner. The biggest obstacle to the efficient use of sludge is the high water content, therefore the development of methods to accelerate the sludge dewatering process is particularly important. For the purposes of the research, the waste sludge created in the process of purifying ammoniaphenol wastewater in the GIKIL factory was used. Sludge conditioning was performed by adding a commercial flocculant (0.1 % solution) in combination with pyrophyllite, kaolin clay and shredded cardboard. According to earlier research, the volume of waste sludge with the addition of a suitable flocculant could be reduced by more than 5 times compared to the initial amount, leaving behind a large amount of separated water that can be returned to the process. The results show that the addition of commercial flocculant in the amount of 0.8 % gives the best results (reduction of sludge volume by 78.8 %). A lower percentage was found in samples with a mixture of flocculants with pyrophyllite (78 %) and kaolin (77.6 %), while the combination of flocculants with waste cardboard was ineffective (64.4 %). Addition of flocculant to waste sludge resulted in a decrease in specific filtration resistance (1.15x107 s2/g). A decrease in specific resistance was also observed in flocculant/kaolin clay (0.8x107 s2/g) and flocculant/cardboard (1.09x107 s2/g) samples. Sludge conditioning also resulted in a reduction of suspended solids in the neonate compared to settled raw sludge without additives.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129918082","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}
Arsenic is a heavy metalloid that occurs frequently in nature. The most serious repercussions for human health occur when it is found in drinking water (It can harm the circulatory, pulmonary, and nervous systems, as well as cause skin and other organs cancer). This paper presents the values of arsenic concentration in the Republic of Serbia's groundwater from 2018 to 2020, based on lab tests completed by the Serbian Environmental Protection Agency. Bearing in mind the fact that the Decree on Limit Values of Pollutants in Surface and Groundwater and Sediment and Deadlines for Reaching Them (Official Gazette of RS No. 50/12) does not prescribe limit values for arsenic in groundwater, as well as the fact that 75% of drinking water is supplied from groundwater, the results of testing the concentration of arsenic in groundwater are compared with the maximum allowed concentration of arsenic in drinking water prescribed by the Ordinance on the Hygiene of Drinking Water (Official Gazette of the FRY No. 42/98 and 44/99, Official Gazette RS No. 28/19). The concentrations of arsenic in eight piezometers were found to be above the maximum allowed concentration limit for drinking water for all three years. Having in mind the stated facts, it is necessary to update the regulations of the Republic of Serbia concerning the limit values of pollutants in groundwater, and to include the limit values for arsenic in it. The amendment of the regulation requires more detailed research regarding the concentration and origin of arsenic in groundwater.
{"title":"Analysis of arsenic monitoring in underground water of the Republic of Serbia for 2018-2020","authors":"D. Plavšić, Dimitrije Isoski, A. Vidakovic","doi":"10.7251/jcte2203027p","DOIUrl":"https://doi.org/10.7251/jcte2203027p","url":null,"abstract":"Arsenic is a heavy metalloid that occurs frequently in nature. The most serious repercussions for human health occur when it is found in drinking water (It can harm the circulatory, pulmonary, and nervous systems, as well as cause skin and other organs cancer). This paper presents the values of arsenic concentration in the Republic of Serbia's groundwater from 2018 to 2020, based on lab tests completed by the Serbian Environmental Protection Agency. Bearing in mind the fact that the Decree on Limit Values of Pollutants in Surface and Groundwater and Sediment and Deadlines for Reaching Them (Official Gazette of RS No. 50/12) does not prescribe limit values for arsenic in groundwater, as well as the fact that 75% of drinking water is supplied from groundwater, the results of testing the concentration of arsenic in groundwater are compared with the maximum allowed concentration of arsenic in drinking water prescribed by the Ordinance on the Hygiene of Drinking Water (Official Gazette of the FRY No. 42/98 and 44/99, Official Gazette RS No. 28/19). The concentrations of arsenic in eight piezometers were found to be above the maximum allowed concentration limit for drinking water for all three years. Having in mind the stated facts, it is necessary to update the regulations of the Republic of Serbia concerning the limit values of pollutants in groundwater, and to include the limit values for arsenic in it. The amendment of the regulation requires more detailed research regarding the concentration and origin of arsenic in groundwater.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121603298","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}
Ljiljana Surčić, Tamara Tadić, A. Nastasović, Bojana Markovic, A. Onjia
Arsenic is a metalloid, which occurs in nature in various forms, but in natural waters mainly in the form of pentavalent oxyanion of arsenate As(V) and trivalent arsenite As(III), which dominates under anaerobic conditions. Arsenic water pollution is a serious problem due to its pronounced negative impact on human health. This paper describes the kinetic and equilibrium studies of the sorption mechanism of oxyanion As(V) in monocomponent aqueous solutions on a silanized magnetic amino-functionalized copolymer of glycidyl methacrylate and ethylene glycol dimethacrylate m-Si-PGME-deta. It has been shown that the sorption of As(V) on m-Si-PGME-deta is a rapid process, initially controlled by ion diffusion rate through solution. After achieving the saturation of the sorbent surface, the sorption rate decreases, because the sorption rate determines the process of intraparticle pore diffusion. The maximum sorption capacity is 5.61 μmolˑg-1.
砷是一种类金属，在自然界中以多种形式存在，但在天然水体中主要以五价砷酸盐As(V)和三价砷酸盐As(III)的氧阴离子形式存在，在厌氧条件下以三价砷酸盐As(III)为主。砷水污染是一个严重的问题，因为它对人类健康有明显的负面影响。本文研究了氧阴离子As(V)在单组分水溶液中吸附甲基丙烯酸甘油酯和乙二醇二甲基丙烯酸甘油酯- m- si - pgme - delta的硅烷化磁性氨基功能化共聚物的动力学和平衡机理。研究表明，As(V)在m- si - pgme - δ上的吸附是一个快速的过程，最初受离子在溶液中的扩散速率控制。在吸附剂表面达到饱和后，吸附速率降低，因为吸附速率决定了颗粒内孔隙扩散的过程。最大吸附量为5.61 μmol μ g-1。
{"title":"Kinetic and equilibrium study of arsenic sorption on silanized magnetic amino-functionalized nanocomposite","authors":"Ljiljana Surčić, Tamara Tadić, A. Nastasović, Bojana Markovic, A. Onjia","doi":"10.7251/jcte2102001s","DOIUrl":"https://doi.org/10.7251/jcte2102001s","url":null,"abstract":"Arsenic is a metalloid, which occurs in nature in various forms, but in natural waters mainly in the form of pentavalent oxyanion of arsenate As(V) and trivalent arsenite As(III), which dominates under anaerobic conditions. Arsenic water pollution is a serious problem due to its pronounced negative impact on human health. This paper describes the kinetic and equilibrium studies of the sorption mechanism of oxyanion As(V) in monocomponent aqueous solutions on a silanized magnetic amino-functionalized copolymer of glycidyl methacrylate and ethylene glycol dimethacrylate m-Si-PGME-deta. It has been shown that the sorption of As(V) on m-Si-PGME-deta is a rapid process, initially controlled by ion diffusion rate through solution. After achieving the saturation of the sorbent surface, the sorption rate decreases, because the sorption rate determines the process of intraparticle pore diffusion. The maximum sorption capacity is 5.61 μmolˑg-1.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131677873","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}
D. Drljaca, A. Borkovic, Dajana Dragic, T. Botic, Violeta Mićanović, G. Popovic, Ljiljana Vukic, P. Dugic
Adsorption, as an easy and effective technique, is widely used to remove a large number of dyes from aqueous solutions. Activated carbon is the most desirable adsorbent, but due to its high cost, its use is limited. Proving the possibility of adsorption and its efficiency performed on cheap adsorbents is a great challenge and interest of many researchers in the past few decades. In this paper, unmodified (P) and modified sawdust obtained in two ways (HCl treatment and NaOH treatment), labeled as PHCl and PNaOH, are used for the removal of the methylene blue dye. Adsorption experiments showed that the optimal time for adsorption is different, for the sample PNaOH – 30 min, for the sample P – 45 min, and for the sample PHCl – 60 min. By applying nonlinear kinetic models to the experimentally obtained data, it was found that the best model that describes this adsorption is pseudo-second-order model. By examining the effect of pH values on adsorption, different results were obtained (for samples P and PHCl the optimal pH value is pH=11, the PNaOH sample is effective in a wider range of pH values). The analysis of the effect adsorbent dose on adsorption process showed that the efficiency of dye removal decreases with increasing mass of adsorbents. The obtained values of the coefficient of determination in Freundlich's model for samples of unmodified (P) and modified sawdust (PNaOH) indicate that the adsorption of the methylene blue dye is multilayer type adsorption. For the PHCl sample, neither the Langmuir nor Freundlich model adequately described MB dye adsorption.
吸附法作为一种简单有效的技术，被广泛用于去除水中的大量染料。活性炭是最理想的吸附剂，但由于其成本高，其使用受到限制。在过去的几十年里，证明廉价吸附剂吸附的可能性及其效率是许多研究人员的一个巨大挑战和兴趣。本文采用HCl处理和NaOH处理两种方式得到的未改性(P)和改性木屑，分别标记为PHCl和PNaOH，用于去除亚甲基蓝染料。吸附实验表明，PNaOH -的最佳吸附时间为30 min, P -的最佳吸附时间为45 min, PHCl -的最佳吸附时间为60 min。通过对实验得到的数据进行非线性动力学模型分析，发现描述该吸附过程的最佳模型为伪二阶模型。通过考察pH值对吸附的影响，得到了不同的结果(P和PHCl样品的最佳pH值为pH=11, PNaOH样品在更大的pH值范围内有效)。吸附剂用量对吸附过程的影响分析表明，随着吸附剂质量的增加，对染料的去除率降低。对未改性木屑(P)和改性木屑(PNaOH)样品的Freundlich模型测定系数值表明，亚甲基蓝染料的吸附为多层吸附。对于PHCl样品，Langmuir和Freundlich模型都不能充分描述MB染料吸附。
{"title":"Methylene blue removal by adsorption on unmodified and modified wood sawdust","authors":"D. Drljaca, A. Borkovic, Dajana Dragic, T. Botic, Violeta Mićanović, G. Popovic, Ljiljana Vukic, P. Dugic","doi":"10.7251/jcte2102034d","DOIUrl":"https://doi.org/10.7251/jcte2102034d","url":null,"abstract":"Adsorption, as an easy and effective technique, is widely used to remove a large number of dyes from aqueous solutions. Activated carbon is the most desirable adsorbent, but due to its high cost, its use is limited. Proving the possibility of adsorption and its efficiency performed on cheap adsorbents is a great challenge and interest of many researchers in the past few decades. In this paper, unmodified (P) and modified sawdust obtained in two ways (HCl treatment and NaOH treatment), labeled as PHCl and PNaOH, are used for the removal of the methylene blue dye. Adsorption experiments showed that the optimal time for adsorption is different, for the sample PNaOH – 30 min, for the sample P – 45 min, and for the sample PHCl – 60 min. By applying nonlinear kinetic models to the experimentally obtained data, it was found that the best model that describes this adsorption is pseudo-second-order model. By examining the effect of pH values on adsorption, different results were obtained (for samples P and PHCl the optimal pH value is pH=11, the PNaOH sample is effective in a wider range of pH values). The analysis of the effect adsorbent dose on adsorption process showed that the efficiency of dye removal decreases with increasing mass of adsorbents. The obtained values of the coefficient of determination in Freundlich's model for samples of unmodified (P) and modified sawdust (PNaOH) indicate that the adsorption of the methylene blue dye is multilayer type adsorption. For the PHCl sample, neither the Langmuir nor Freundlich model adequately described MB dye adsorption.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130441388","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}
T. Botic, Sonja Bubić, Sara Lakić, A. Borkovic, Zoran Petrović
The professional literature dealing with specific aspects of adhesive joints in the footwear industry is mainly devoted to the procedures of preparation, bonding and testing of the connection between the upper and the sole material of fashion and sports footwear. However, there is little research related to the requirements and quality testing of adhesive joints of shoe upper parts. Safety and occupational footwear, which is intended for specific occupations such as firefighters, police officers, soldiers and others, as such has specific requirements in terms of resistance to various types of solvents, high and/ or low temperatures, shocks, etc., and in addition it should be comfortable and long-lasting. For these reasons, the upper of this type of footwear differs significantly from the footwear used in everyday life. It is usually a very complex construction and is made of a large number of different natural and artificial materials such as: leather, rubber, polyurethane, synthetic membranes, etc., which are interconnected by bonding or stitching. The aim of this study was to examine how the number of adhesive coatings and their characteristics affect the strength of the natural leather – rubber adhesive joint in the manufacture of shoes for special purposes. The strength of the leather-to-rubber adhesive joint depends significantly on the number of adhesive coatings and the viscosity of the adhesive.
{"title":"Resistance of the leather-rubber adhesive joint when making the shoe upper","authors":"T. Botic, Sonja Bubić, Sara Lakić, A. Borkovic, Zoran Petrović","doi":"10.7251/jcte2102008b","DOIUrl":"https://doi.org/10.7251/jcte2102008b","url":null,"abstract":"The professional literature dealing with specific aspects of adhesive joints in the footwear industry is mainly devoted to the procedures of preparation, bonding and testing of the connection between the upper and the sole material of fashion and sports footwear. However, there is little research related to the requirements and quality testing of adhesive joints of shoe upper parts. Safety and occupational footwear, which is intended for specific occupations such as firefighters, police officers, soldiers and others, as such has specific requirements in terms of resistance to various types of solvents, high and/ or low temperatures, shocks, etc., and in addition it should be comfortable and long-lasting. For these reasons, the upper of this type of footwear differs significantly from the footwear used in everyday life. It is usually a very complex construction and is made of a large number of different natural and artificial materials such as: leather, rubber, polyurethane, synthetic membranes, etc., which are interconnected by bonding or stitching. The aim of this study was to examine how the number of adhesive coatings and their characteristics affect the strength of the natural leather – rubber adhesive joint in the manufacture of shoes for special purposes. The strength of the leather-to-rubber adhesive joint depends significantly on the number of adhesive coatings and the viscosity of the adhesive.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124255964","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}
Zorica B. Eraković, Milos Stevanovic, I. Mladenović-Ranisavljević, S. Ilić-Stojanović, Tatjana Veličković, S. Žerajić
The paper analyses the current situation and perspectives of construction waste management in the territory of Jablanica district, Serbia. Considering the importance of construction waste management for the ecosystem, the state and perspectives are assessed through the assessment of the possibilities of reuse and recycling. According to Rulebook on waste categories with catalogue in Serbia, construction waste found at the landfill Donja Jajina is classified and observed in this research. Based on a six-month daily monitoring of the material flow of construction waste at the landfill in Dona Jajina, the current estimated state of the amount of waste as well as further growth of waste at the landfill is presented. Using MATLAB simulation code, predictions for the next 15 years are obtained, and conclusions are made. At the moment, concrete, brick, asphalt, as well as other construction waste are being buried at the landfill in Donja Jajina, and no further waste treatment is being done. The landfill has a lot of material that could be further used and put into use. It is necessary to build a stationary recycling plant on the landfill itself that would produce recycled aggregates and thereby reduce the use of natural aggregates.
{"title":"Material flow management of construction waste: case study Jablanica district, Serbia","authors":"Zorica B. Eraković, Milos Stevanovic, I. Mladenović-Ranisavljević, S. Ilić-Stojanović, Tatjana Veličković, S. Žerajić","doi":"10.7251/jcte2102028e","DOIUrl":"https://doi.org/10.7251/jcte2102028e","url":null,"abstract":"The paper analyses the current situation and perspectives of construction waste management in the territory of Jablanica district, Serbia. Considering the importance of construction waste management for the ecosystem, the state and perspectives are assessed through the assessment of the possibilities of reuse and recycling. According to Rulebook on waste categories with catalogue in Serbia, construction waste found at the landfill Donja Jajina is classified and observed in this research. Based on a six-month daily monitoring of the material flow of construction waste at the landfill in Dona Jajina, the current estimated state of the amount of waste as well as further growth of waste at the landfill is presented. Using MATLAB simulation code, predictions for the next 15 years are obtained, and conclusions are made. At the moment, concrete, brick, asphalt, as well as other construction waste are being buried at the landfill in Donja Jajina, and no further waste treatment is being done. The landfill has a lot of material that could be further used and put into use. It is necessary to build a stationary recycling plant on the landfill itself that would produce recycled aggregates and thereby reduce the use of natural aggregates.","PeriodicalId":424249,"journal":{"name":"GLASNIK HEMIČARA, TEHNOLOGA I EKOLOGA REPUBLIKE SRPSKE","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129012957","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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