34 results on '"izoterma"'
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2. АДСОРБЦИЯ ПАРОВ БЕНЗОЛА НА УГЛЕРОДНЫХ АДСОРБЕНТАХ ПОЛУЧЕННЫХ НА ОСНОВЕ ОТХОДОВ РАСТИТЕЛЬНОСТИ.
- Author
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ПАЙГАМОВ, Р. А., ЭШМЕТОВ, И. Д., and ВАЛИЕВА, О. М.
- Abstract
Background. Wood processing produces waste, which is a valuable raw material for various industries. Purpose. Studying the possibility of obtaining import-substituting coal adsorbents from wood waste, the characteristics of the adsorption of organic substances and the thermodynamics of adsorption on their surface. Methodology. Adsorption isotherms of benzene vapor and sorption-structural parameters on new coal adsorbents were studied using a high-vacuum calorimetric installation. Originality. Based on the adsorption of benzene vapor, the structural and sorption properties of coal adsorbents obtained by activating waste maple trunks with potassium alkali were determined. Findings. According to the adsorption isotherms of Coal + KOH (1:5), the adsorption of benzene in the studied systems: 3.8 times more than Coal-500, 2.2 times more than Coal + KOH (1:1), Coal turned out to be 1,8 times higher. than +KOH (1:2), 1.5 times higher than Coal+KOH (1:3) and 1.2 times higher than Coal+KOH (1:4). [ABSTRACT FROM AUTHOR]
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- 2024
3. The stabilized waste dust as a constituent modifying properties of wood-cement composites.
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MELICHAR, Tomáš, VASAS, Silvestr, KEPRDOVÁ, Šárka, BYDŽOVSKÝ, Jiří, SCHMID, Pavel, and HÁJKOVÁ, Iveta
- Abstract
Copyright of Waste Forum is the property of Czech Environment Management Center (CEMC) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2024
4. Anti-corrosion properties of expired ropinirole (ERN System) drug as inhibitor for mild steel in 1M HCl.
- Author
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Kani, Shakul Hameed Musthafa, Sathiq, Mohamed Kani Anwar, Syed Abuthahir, Syed Mohamed Syed Ismail, Sheit, Hameed Mohamed Kasim, and Raja, Maharajan
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ROPINIROLE ,MILD steel ,CANCER chemotherapy ,SEROTONIN ,ELECTRIC capacity - Abstract
Copyright of Materials Protection (0351-9465) is the property of Engineers Society for Corrosion Republic of Serbia, Belgrade and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
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5. ИССЛЕДОВАНИЕ ПРОЦЕССА ПОЛУЧЕНИЯ ПЕРКАРБОНАТА КАЛИЯ.
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ЭРКАЕВА, Н. А., КАИПБЕРГЕНОВ, А. Т., КУЧАРОВ, Б. Х., and ЭРКАЕВ, А. У.
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HYDROGEN peroxide , *SODIUM bicarbonate , *POTASSIUM carbonate , *SOLUBILITY , *LIQUIDUS temperature , *PEROXIDES - Abstract
Background. Among household chemicals, bleaching agents stand out: for bleaching linen and auxiliary agents used in the washing process. In both cases bleaching agents are used. Purpose is to develop a technology for producing potassium peroxycarbonate from potassium car- bonate in the presence of hydrogen peroxide. Methodology. Chemical, radiographic, electron microscopic, isothermal methods of analysis. Originality. Data on the solubility of K2CO3 -H2O2-H2O at -10 and 0°C were obtained. The liquidus curve of the solubility diagram of the K2CO3 -H2O2-H2O system, at the studied temperatures, is characterized by the presence of three branches of crystallization of the initial components and a new compound of the composition - K2CO3·3H2O2. Findings. A method has been developed for the preparation of sodium and potassium peroxycar- bonates from potassium and sodium carbonates in the presence of hydrogen peroxide. Crystallization is car- ried out in a polythermal mode, and the slow cooling of the saturated solution causes the formation of a coarse-crystalline precipitate of the peroxide compound, with lamellar and cylindrical particles, up to 1-3 mm. [ABSTRACT FROM AUTHOR]
- Published
- 2023
6. APPLICATION OF ACTIVATED BENTONITE FOR THE REMOVAL OF DIRECT AND REACTIVE DYE FROM AQUEOUS SOLUTIONS.
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ZDRAVKOVIĆ, ALEKSANDAR S., STANKOVIĆ, NOVICA J., RISTIĆ, NEBOJŠA N., and PETKOVIĆ, GORAN M.
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BENTONITE , *REACTIVE dyes , *AQUEOUS solutions , *ADSORPTION kinetics , *FOURIER transform infrared spectroscopy , *X-ray powder diffraction - Abstract
The aim of this study was to determine adsorptive properties of acid-activated bentonite clay for the removal of Direct Red 173 (DR 173) and Reactive Red 22 (RR 22) dyes from aqueous solutions. Raw and modified clay were characterized by the following methods: Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). The efficiency of activated clay adsorption was investigated depending on process parameters: the adsorbent dose, pH, temperature, initial dye concentration, and contact time. Experimental data were analyzed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms as well as kinetic models of pseudo-first order, pseudo-second order and intra-particle diffusion. The process of dye adsorption was best described by Langmuir, Temkin, and Dubinin-Radushkevich isotherms (R2 > 0.97). Pseudo-second order model (R2 > 0.99) had the highest correlation with the obtained kinetic results. The positive value of ΔH° indicated that adsorption of dyes by activated bentonite clay is an endothermic process. The activated bentonite exhibited good regenerative ability in the 0.1 M NaOH solution. Maximum adsorption capacities of acid-activated bentonite clay at 25 °C for DR 173 and RR 22 dyes were 356.65 and 109.58 μmol g-1, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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7. ORANGE TREE LEAVES, A PERFECT ADSORBENT FOR THE REMOVAL OF Cd(II), Co(II) AND Zn(II) FROM WASTEWATER.
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NOURBAKHSH, NAVID, MOUSAVI, HASSAN ZAVVAR, KOLVARI, ESKANDAR, and KHALIGH, AISAN
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ORANGES , *ADSORPTION isotherms , *SEWAGE , *LEAVES , *HEAVY metals , *AGRICULTURAL wastes , *LEAD removal (Sewage purification) - Abstract
The present study explores the uptake capacity of low-cost agricultural waste for the removal of heavy metals, Co2+, Cd2+ and Zn2+, from aqueous solution. Studies conformed to Freundlich, Langmuir and Temkin adsorption isotherms. The values of constants for the thermodynamic and kinetic isotherms were found. The kinetic isotherm experiment data could be well described with the pseudo-second order kinetic model and thermodynamic studies indicated that the adsorption processes were spontaneous and endothermic with orange tree leaves under natural conditions. Experiments showed that Cd2+, Co2+ and Zn2+ adsorption increased with increasing pH and decreased with increasing the temperature and concentration of solutions. This study indicates that the developed method based on orange tree leaves is very simple, low-cost, fast and trusty for the removal of heavy metal ions from water and wastewater samples. [ABSTRACT FROM AUTHOR]
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- 2019
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8. STUDY OF ESSENTIAL OILS ADSORPTION ON THREE PHOSPHATE FERTILIZERS.
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BENALI, NEJIB, BEN DAOUD, HOUCINE, FARHATI, MANEL, TIZAOUI, CHEDLY, and ROMDHANE, MEHREZ
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ESSENTIAL oils , *PHOSPHATE fertilizers , *DIAMMONIUM phosphate , *FREUNDLICH isotherm equation - Abstract
In this paper, we report the study of essential oils adsorption on three phosphate fertilizers: monoammonium phosphate (MAP), diammonium phosphate (DAP) and triple superphosphate (TSP), with the aim to prepare a bifunctional product which can be used as a fertilizer and biopesticide. Essential oils were isolated by steam distillation from Eucalyptus salubris and Artemisia herbaalba and analysed by GC-MS and GC-FID. About 12 and 22 constituents were identified and quantified in these oils, respectively. The kinetic adsorption study of essential oils showed that DAP and TSP exhibited high adsorption capacities compared with MAP (DAP (0.143 g/g) and TSP (0.139 g/g) for E. salubris essential oil and (DAP (0.135 g/g) and TSP (0.134 g/g) for A. herba-alba essential oil). The adsorption isotherms of all identified components in the E. salubris essential oil were determined and the Langmuir and Freundlich models were used to describe the experimental data. Langmuir model fitted well the isotherms of the majority of the essential oil components (1,8-cineole, α-pinene, β-pinene, isopinocarveol, β-eudesmol, α-phellandrene, pinocarvone, p-cymene and spathulenol) and only terpineol and globulol isotherm data followed the Freundlich model. The selectivity was affected by the abundance of each component in the crude essential oil and the polarity of terpenic components. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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9. DYE REMOVAL FROM ARTIFICIAL WASTEWATER USING HETEROGENEOUS BIO-FENTON SYSTEM.
- Author
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SHOJAAT, RAHIM, KARIMI, AFZAL, SAADATJOO, NAGHI, and ABER, SOHEIL
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DYES & dyeing , *NANOPARTICLES , *COLOR , *CHEMICAL engineering , *PARTICLES - Abstract
In the present study, GOx/MnFe2O4/calcium alginate nano-composite was prepared by the trapping enzyme/nanoparticles in calcium alginate. The prepared absorbent was applied for decolorization of artificial dye wastewater of acid red 14 (AR14) by heterogeneous bio-Fenton system. Kinetic and isotherm studies were carried out. The decolorization of acid red 14 followed the Michaelis- Menten, pseudo-first order and pseudo-second order kinetic models. Good correlation coefficients were obtained by fitting the experimental data to Michaelis- Menten and pseudo-second order kinetic models. The adsorption isotherms were described by Langmuir, Freundlich and Temkin isotherms. Among the three isotherm models, the Freundlich model was fitted with the equilibrium data obtained from adsorption of AR14 onto MnFe2O4/calcium alginate; while Temkin isotherm gave the best correlation for adsorption on MnFe2O4 nanoparticles. The effect of various parameters such as initial pH of solution, initial dye concentration, and contact time on the adsorption of AR14 on MnFe2O4 and MnFe2O4/ /calcium alginate as well as dye enzymatic decomposition was studied. The decolorization of AR14 with initial concentration of 10 mg.L-1 by using GOx//MnFe2O4/calcium alginate was 60.17%. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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10. REMOVAL OF DISPERSE BLUE 56 AND DISPERSE RED 135 DYES FROM AQUEOUS DISPERSIONS BY MODIFIED MONTMORILLONITE NANOCLAY.
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AHMADISHOAR, JAVAD, BAHRAMI, S. HAJIR, MOVASSAGH, BARAHMAN, AMIRSHAHI, SEYED HOSEIN, and ARAMI, MOKHTAR
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DYES & dyeing , *AQUEOUS solutions , *DISPERSION (Chemistry) , *MONTMORILLONITE , *NANOSTRUCTURED materials - Abstract
In this study modified montmorillonite was used as an adsorbent for the removal of two selected disperse dyes i.e., Disperse Blue 56 (DB) and Disperse Red 135 (DR) from dye dispersions. The adsorption equilibrium data of dyes adsorption were investigated by using Nernst, Freundlich and Langmuir isotherm models. The adsorption kinetics was analyzed by using different models including pseudo-first-order, pseudo-second-order, Elovich and Intraparticle diffusion model. The Freundlich isotherm was found to be the most appropriate model for describing the sorption of the dyes on modified nanoclay. The best fit to the experimental results was obtained by using the pseudo-second-order kinetic equation, which satisfactorily described the process of dye adsorption. Although different kinetic models may control the rate of the adsorption process, the results indicated that the main rate limiting step was the intraparticle diffusion. The results showed that the proposed modified montmorillonite could be used as an effective adsorbent for the removal of disperse dyes even from highly concentrated dispersions. [ABSTRACT FROM AUTHOR]
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- 2017
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11. Efficacy of Locust Beans Husk Char in Heavy Metal Sequestration.
- Author
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Ajayi-Banji, Ademola A., Ewemoje, Temitayo A., and Ajimo, Adeniyi A.
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CAROB ,SOLID waste management ,BIODEGRADABLE materials ,AGRICULTURAL wastes ,SORBENTS ,SORPTION ,MANAGEMENT - Abstract
Copyright of Environmental Research, Engineering & Management / Aplinkos Tyrimai, Inžinerija ir Vadyba is the property of Institute of Environmental Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2015
- Full Text
- View/download PDF
12. REMOVAL OF CADMIUM (II) FROM AQUEOUS SOLUTION USING FERMENTED GRAPE MARC AS A NEW ADSORBENT.
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GRUDIĆ, VESELINKA, ŠĆEPANOVIĆ, JELENA, and BOŠKOVIĆ, IVANA
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CADMIUM analysis , *AQUEOUS solutions , *GRAPES , *FERMENTATION , *CHEMICAL equilibrium - Abstract
Biosorption of cadmium from aqueous solutions using fermented grape marc, as well as influence of the most important factors, such as: contact time, granulation of biosorbent and the initial concentration of metal ions, is investigated in this paper. The equilibrium sorption of cadmium ions is achieved after 15-20 min, depending on the initial concentration of metal ions. Such a short time needed to achieve the equilibrium indicates that mass sorption is the dominant process. Langmuir, Freundlich and Dubinin-Radushkevich isotherms were used to describe the equilibrium sorption process, and the Langmuir model was found to be the most convenient. Maximum of sorption capacity is 20 mg g-1. EDS spectrum analysis showed that the process of ion exchange is one of the main sorption mechanisms. Minor changes observed in the FTIR spectrum of grape marc after the sorption of Cd(II) ions indicate the formation a bond between metal ions and partially ionized carboxyl and phenol groups from the biomass. The results of this study confirmed that fermented grape marc, due to its porous structure and characteristic chemical composition, is a good sorption material. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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13. Influence of Coal Particle Size on Coal Adsorption and Desorption Characteristics.
- Author
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Zhang, Lei, Aziz, Naj, Ren, Ting, Nemcik, Jan, and Tu, Shihao
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COAL ,PARTICLE size determination ,GAS absorption & adsorption ,DESORPTION ,ADSORPTION isotherms ,LANGMUIR isotherms - Abstract
Copyright of Archives of Mining Sciences is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2014
- Full Text
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14. Termiskās apstrādes ietekme uz illītu saturošu Latvijas mālu īpatnējo virsmu.
- Author
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Lakevičs, Vitālijs, Kaplinova, Olga, Stepanova, Valentīna, Dušenkova, Inga, and Bērziņa-Cimdiņa, Līga
- Abstract
Copyright of Material Science & Applied Chemistry is the property of RTU Publishing House and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
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15. Potenciálne využitie oxidu titaničitého ako adsorbenta farbív.
- Author
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HODOSSYOVÁ, Renata, CHMIELEWSKÁ, Eva, and DONOVALOVÁ, Jana
- Abstract
Copyright of Waste Forum is the property of Czech Environment Management Center (CEMC) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
16. BIOSORPTION OF LANTHANUM AND CERIUM FROM AQUEOUS SOLUTIONS USING TANGERINE (Citrus reticulata) PEEL: EQUILIBRIUM, KINETIC AND THERMODYNAMIC STUDIES.
- Author
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TORAB-MOSTAEDI, MEISAM
- Subjects
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LANTHANUM , *SORPTION , *CERIUM , *AQUEOUS solutions , *MANDARIN orange , *THERMODYNAMICS , *METAL ions , *CHEMICAL kinetics - Abstract
Biosorption of lanthanum (III) and cerium (III) from aqueous solution by tangerine (Citrus reticulate) peel has been investigated in a batch system as a function of pH, biosorbent dosage, contact time, and temperature. The equilibrium pH was found to severely affect the biosorption performance; pH 5.0 was found to be an optimum pH for favorable biosorption of La (III) and Ce (III). The biosorption of lanthanum and cerium was investigated by the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Maximum biosorption uptakes, according to the Langmuir model, were obtained as 154.86 and 162.79 (mg/g) for La(III) and Ce(III), respectively. The biosorption kinetic was tested with pseudo-first order and pseudo-second order models. The results showed that the kinetics of the biosorption process were described by the pseudo-second order model very well. Thermodynamic parameters including the change of Gibbs free energy (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) for both sorption systems were determined at four different temperatures. The results showed that the biosorption of La(III) and Ce(III) on tangerine (C. reticulate) peel is a spontaneous and endothermic process. FTIR analysis demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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17. Removal of Cu(II) and Pb(II) from aqueous solutions by lacit acid bacteria
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izoterma ,lactic acid bacteria ,bakterie kwasu mlekowego ,isotherm ,Cu(II) ,biosorpcja ,Pb(II) ,biosorption - Abstract
Celem pracy było porównanie zdolności usuwania Cu(II) i Pb(II) z roztworu wodnego przez bakterie kwasu mlekowego (LAB). Badano wpływ różnych parametrów, tj. stężenia jonów metali, pH i czas kontaktu, na proces usuwania jonów miedzi i ołowiu. Do opisu izoterm adsorpcji jonów metali przez biomasę LAB zastosowano modele Langmuira i Freundlicha. Uzyskane dane doświadczalne były lepiej dopasowane do modelu Langmuira niż Freundlicha. Sorbent wykazał maksymalną zdolność sorpcyjną, wynoszącą 11,07 i 10.51 mg · g–1 odpowiednio dla jonów Cu(II) i Pb(II). Optymalne warunki biosorpcji obu jonów metali wynosiły: pH 6,0 i czas równowagi 40 minut. Omówiono również udział grup funkcyjnych na powierzchni biomasy w procesie biosorpcji., The aim of the study was to compare the removal of Cu(II) and Pb(II) from aqueous solution by lactic acid bacteria (LAB). Effect of various process parameters, viz., initial metal ions concentration, pH, and contact time has been studied for the removal of copper and lead ions. Langmuir and Freundlich models were applied to describe the biosorption isotherm of the metal ions by LAB biomass. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The sorbent showed the maximum sorptive capacity amounting to be 11.07 and 10.51 mg · g–1 for Cu(II) and Pb(II) ions, respectively. The optimum conditions were pH 6.0 with equilibrium time of 40 min for both metal ions. The involvement of functional groups on the surface of dried biomass in biosorption process is also discussed.
- Published
- 2015
18. Razvoj i primena eko-sorbenata na bazi modifikovane ligno-celulozne biomase
- Author
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Bojić, Danijela., Nikolić, Goran, Onjia, Antonije, and Veljković, Vlada
- Subjects
izoterma ,sorption ,organic pollutants ,isotherm ,aktivni ugalj ,sorpcija ,teški metali ,thermodynamics ,organski polutanti ,kinetics ,pH sredine ,Lagenaria vulgaris ,biosorbent ,solution pH ,activated carbon ,termodinamika ,heavy metals ,kinetika - Abstract
The subject of this doctoral dissertation was the development of two new eco-sorbents, biosorbent and activated carbon, based on modified lignocellulosic precursor – shell of Lagenaria vulgaris plant, intended for the removal of cationic, weakly polar and non-polar pollutants from waste and natural polluted water. A literature review showed that there had not been any systematic evaluation of the application of similar sorbent based on L. vulgaris. Also, this plant, more popular because of its healing properties, grows well in a wide area in the whole world, is simple for cultivation and obtained in a high yield. Biosorbent was obtained by the chemical modification of L. vulgaris shell with concentrated sulfuric acid in a process called "cold carbonation". Activated carbon was synthesized in a two-stage thermal modification of the shell of this plant, by the process of thermal carbonization, and then activation by steam at high temperature. Textural analysis of the biosorbent surface showed that this material has, typically, a small specific surface area, which is not of crucial importance for its sorption characteristics. In contrast, activated carbon has very high specific surface area and porosity, because of the efficient activation of the material by the steam. On the surface and in the interior of the activated carbon particles micropores predominate, while the amount of mesopores is relatively small. The morphological analysis of biosorbent by scanning electron microscopy showed the presence of numerous macropores, channels and cavities, plant vessels that provide a large contact surface of biosorbent with the aqueous phase. This is of great importance for the efficient diffusion of sorbate molecules, especially when it comes to high initial concentrations. The same analysis showed that a typical particle of activated carbon also has numerous channels and macro pores, which provide good contact with the aqueous phase and the effective mass exchange. In the case of activated carbon, the macroporozity enables efficient contact with the aqueous phase and micropores inside the activated carbon particles. EDS analysis confirmed that biosorbent has a high amount of carbon and sulfur, which is a result of dehydration and sulfonation of biomass with sulfuric acid treatment. Elemental analysis of the active carbon surface confirms the presence of a large amount of carbon, compared to the precursor, which explains the changes that come in a two-stage synthesis process - thermal carbonization and activation of the steam. The chemically modified biosorbent was applied for the removal of cationic pollutants from water, such as Ni(II) ions and cationic dye methylene blue. Results of the effects of contact time on the sorption of cationic pollutants by biosorbent showed that during the first stage of treatment, over a period of 5 – 10 min, depending on the initial concentration, about 95 % of the sorbate was removed from water. This is followed by the slower phase that goes to equilibrium, which in the case of Ni(II) ions lasts 10 to 30 min, and in the case of methylene blue (MB) 20 to 90 min, for applied initial concentrations ranges. The effects of the initial pH, investigated in the ranges of 2 – 6 and 2 – 11, in the case of nickel and MP, respectively, show that this parameter has a relatively small effect on the uptake of cationic pollutants. Although the efficiency of the Ni(II) ions and MP removal by biosorbent in an acidic environment is somewhat lower than in a neutral one, it is still significantly higher as compared to other biosorbents, whose affinity for cations in such an environment is negligible. This influence of pH on the sorption of cations by biosorbent is a result of the strong acidic sulfonic group presence, which is completely dissociated under these conditions. The analysis of the effects of the pollutants initial concentration on the removal efficiency by biosorbent indicates that at relatively low initial concentrations (up to 100 mg dm–3 for Ni (II), or up to 200 mg dm–3 for MP) removal efficiency is very high (> 95 % ), but with a further increase of concentration, the efficiency decreases. It is assumed that at relatively low concentrations of adsorbates number of the free active centers on the biosorbent surface is much larger than the number of cations, which is why effective sorption takes place independently of the increase in the initial concentration. The effect of temperature was investigated in the range of 15 – 45°C. The results show that the sorption slightly increases with increasing the initial temperature, for both pollutants, probably due to increased diffusion efficiency. With a further increase of temperature, removal efficiency of Ni(II) starts to decrease due to desorption, while the sorption of MP does not change in these conditions. Most likely, in the case of MP, the crucial influence of temperature is that on the diffusion of large molecules of dye. The relatively low effect of temperature on the removal efficiency of cationic pollutants, confirms that the sorption by biosorbent is mainly based on ion exchange. The values of the Gibbs free energy are negative at all tested temperatures, indicating the spontaneous nature of the biosorption process. The value of the enthalpy change for the sorption on biosorbent is between the values of physisorption and chemisorption, which confirms that the dominant sorption mechanism is ion exchange. The sorption capacity of activated carbon were investigated with organic pollutants, drug ranitidine and herbicide 2,4-dichlorophenoxy acetic acid. Activated carbon has shown high affinity for both investigated pollutants, which is why the sorption process was very fast, especially in the first phase. To achieve equilibrium, the sorption process took more time, bearing in mind that in the second phase the sorption took place on the inner surface of the activated carbon and micropores, where the diffusion is proportionally slower. The effect of pH indicates significant specificity, which is due to the nature of activated carbon, and investigated sorbate. In the case of ranitidine removal, efficiency is the lowest in a very acidic medium. At approximately neutral pH, the sorption of ranitidine is favored, with a certain decline in the alkaline medium. The reason for this pH effect can be the positive charge of protonated molecule at lower pH values, causing electrostatic repulsion with positively charged functional groups on the surface of the activated carbon, in accordance with the value pHpzc. In the case of 2,4-D, the highest removal efficiency is achieved in a strongly acidic medium. In these conditions, the herbicide is a neutral molecule, and thus it has the desirable hydrophobic properties and minimal solubility in water. The increase of pH leads to a slight reduction of the removal efficiency. Total variation of the removal efficiency in a wide range of pH was less than 10 %, indicating a relatively small influence of this parameter to the process. The effects of the initial concentration of pollutants show that the sorption at activated carbon occurs with the high efficiency over a wide area of concentration, because of high sorption capacity of activated carbon for ranitidine and 2,4-D, which is the result of a very developed surface and a large number of micropores. The effects of temperature on the sorption on activated carbon indicate a certain exothermicity of the process, which is consistent with the thermodynamic parameters, bearing in mind the negative values of ΔG and ΔH. Vibration energy of the molecule sorbed on the surface of activated carbon increases with temperature, and finally reaches a sufficient level to carry out desorption. The relatively low value of the enthalpy changes and the positive value of entropy changes, i.e. the increase of the degree of freedom, all indicate the physical interaction between the sorbate and sorbent. For all investigated temperatures, the change of Gibbs free energy is negative, and therefore it can be concluded that the sorption on the activated carbon is spontaneous in nature. The kinetic results of the sorption on biosorbent were fitted with four theoretical models, in order to determine the limiting stage of the process. Kinetic modeling points out that the results were the best fitted with the reaction model of pseudo-second-order, intraparticle diffusion model and Chrastil’s diffusion model. It is obvious that the process of sorption on the biosorbent is under the simultaneous control of the surface reaction, and diffusion through the boundary layer. Bearing in mind that it is a heterogeneous process, diffusion is a more significant limiting factor, because the process of ion exchange takes place relatively quickly. In the kinetics terms, sorption on activated carbon is also under the laws of the pseudosecond- order model and diffusion models. As regards the diffusion phenomena, in the case of activated carbon intraparticle diffusion is a more significant factor compared to boundary layer diffusion, having in mind high specific surface and the microporosity of activated carbon. Investigation of the equilibrium phenomena of sorption process on biosorbent shows that the experimental results can be best described by Lengmir and Temkin isotherms, which have a maximum value of R2, low relative deviation and values of the maximum sorption capacity closest to experimental. The reason for the mixed isothermal mode of sorption on biosorbent lies in the presence of energy differences between the active sites on the surface and those in the interior of the sorbent particles; and between the sulfonic group and oxygen functional groups. Sorption on active carbon, in isothermal sense, is a complex process that can be best described by Sips and Freundlich models. It is likely that sorption takes place largely by the physical binding of sorbate molecules to the surface of the activated carbon with intermolecular attraction forces, with a certain proportion of ion exchange as the accompanying mechanism. Research in this doctoral dissertation showed that by simple and affordable methods of chemical and thermal modification of inexpensive and available agro-waste materials sorbents with significantly improved sorption characteristics can be prepared. The developed materials have great potential for the removal of toxic metals and other cationic pollutants from water, as well as organic non-polar and weakly polar compounds, in a wide range of initial concentrations, pH and temperatures. High sorption capacities for investigated pollutants, a short time for achieving sorption equilibrium and a simple and inexpensive procedure for preparation, suggest that biosorbent and activated carbon can be competitive in the market of materials for water purification technologies
- Published
- 2016
19. Razvoj i primena eko-sorbenata na bazi modifikovane ligno-celulozne biomase
- Author
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Nikolić, Goran, Onjia, Antonije, Veljković, Vlada, Bojić, Danijela., Nikolić, Goran, Onjia, Antonije, Veljković, Vlada, and Bojić, Danijela.
- Abstract
The subject of this doctoral dissertation was the development of two new eco-sorbents, biosorbent and activated carbon, based on modified lignocellulosic precursor – shell of Lagenaria vulgaris plant, intended for the removal of cationic, weakly polar and non-polar pollutants from waste and natural polluted water. A literature review showed that there had not been any systematic evaluation of the application of similar sorbent based on L. vulgaris. Also, this plant, more popular because of its healing properties, grows well in a wide area in the whole world, is simple for cultivation and obtained in a high yield. Biosorbent was obtained by the chemical modification of L. vulgaris shell with concentrated sulfuric acid in a process called "cold carbonation". Activated carbon was synthesized in a two-stage thermal modification of the shell of this plant, by the process of thermal carbonization, and then activation by steam at high temperature. Textural analysis of the biosorbent surface showed that this material has, typically, a small specific surface area, which is not of crucial importance for its sorption characteristics. In contrast, activated carbon has very high specific surface area and porosity, because of the efficient activation of the material by the steam. On the surface and in the interior of the activated carbon particles micropores predominate, while the amount of mesopores is relatively small. The morphological analysis of biosorbent by scanning electron microscopy showed the presence of numerous macropores, channels and cavities, plant vessels that provide a large contact surface of biosorbent with the aqueous phase. This is of great importance for the efficient diffusion of sorbate molecules, especially when it comes to high initial concentrations. The same analysis showed that a typical particle of activated carbon also has numerous channels and macro pores, which provide good contact with the aqueous phase and the effective mass exchange. In the ca
- Published
- 2016
20. Factors determining the alpine treeline
- Author
-
Oľhava, Rastislav, Sklenář, Petr, and Treml, Václav
- Subjects
nestrukturní sacharidy ,non-structural cyrbohydrates ,růst-limitující hypotéza ,isotherm ,C-limitující hypotéza ,growth-limitation hypothesis ,izoterma ,Horní hranice lesa ,C-limitation hypothesis ,Alpine treeline - Abstract
The alpine treeline is a global phenomenon which represents sudden change between two significantly different vegetation types: mountain forest and low-stature alpine vegetation. The primary climatic factor that determines its position seems to be the temperature. We summarize the results that describe the relation between temperature and the altitudinal position of the treeline and search for a general formula that would determine its position. There are two hypotheses which try to explain what is the main limiting factor above tre- eline: C-limitation and growth-limitation. The first one claims trees are limited by carbon shortage, while the latter one favours low-temperature limitation of tissue formation al- though the carbon income is sufficient. This thesis provides a summary of the arguments for each of them and describes the state of knowledge on this matter.
- Published
- 2015
21. Uklanjanje arsena iz vode za piće procesom adsorpcije
- Author
-
Stulić, Višnja
- Subjects
uklanjanje arsena ,adsorpcija ,izoterma - Abstract
U ovom radu praćeno je uklanjanje arsena adsorpcijom na Fe(OH)3 i na adsorpcijske mase Bayoxide i Titansorb. Pokusima su određene konstante Freundlichove i Langmuirove izoterme za vodovodnu i destiliranu vodu. Najbolju učinkovitost vezanja arsena imao je Fe(OH)3, a najlošiju adsorpcijska masa Titansorb, a sve tri adsorpcijske mase bolje su uklanjale arsen iz destilirane vode nego iz vodovodne vode. Uklanjanjem arsena propuštanjem otopine kroz kolone s masama Bayoxide i Titansorb postignuto je potpuno uklanjanje arsena iz vode, a zasićenje kolona do pojave arsena u izlaznoj vodi u koncentraciji od 10 µg/L primijećeno je za masu Bayoxide kod volumena mase 1234, a kod mase Titansorb kod volumena mase od 949, po čemu zaključujemo da masa Bayoxide bolje uklanja arsen od mase Titansorb.
- Published
- 2011
22. Izučavanje mehanizama sorpcije teških metala apatitom : mogućnost primene u remedijaciji zagađenog zemljišta i podzemnih voda
- Author
-
Kaluđerović Radoičić, Tatjana, Grbavčić, Željko, Raičević, Slavica, Ristić, Mirjana, and Pejanović, Srđan
- Subjects
izoterma ,model ,sorption ,isotherm ,prirodni apatit ,mechanism ,sintetički apatit ,mehanizam ,soil remediation ,sorpcija ,teški metali ,natural apatite ,ground water remediation ,remedijacija zemljišta ,kinetics ,ion-ion interaction potential ,remedijacija podzemnih voda ,jon-jon interakcioni potencijal ,synthetic apatite ,heavy metals ,kinetika - Abstract
U ovom radu izučavani su mehanizmi sorpcije teških metala korišćenjem dve forme minerala apatita: sintetičkog hidroksiapatita (HAP) i prirodnog apatita iz ležišta Lisina kod Bosilegrada (LA). Karakterizacija materijala je izvršena korišćenjem metode difrakcije x-zraka. Utvrđeno je da je sintetički apatit (HAP) čist hidroksiapatit molekulske formule Ca10(PO4)6(OH)2, dok je prirodni apatit (LA) smeša minerala kvarca, muskovita i fluorapatita. Mehanizmi sorpcije izučavani su korišćenjem teorijskog modela stabilnosti čvrste faze, kao i eksperimentalnim proučavanjem sorpcije olova iz vodenog rastvora. Teorijski matematički model stabilnosti čvrste faze baziran je na izračunavanju jon-jon interakcionih potencijala. Ovaj model upotrebljen je za procenu stabilnosti čvrste faze nastale reakcijom zagađujućih materija sa prirodnim i sintetičkim apatitom. Primenjeni model omogućava preliminarni izbor najpogodnijeg aditiva za imobilizaciju teških metala u zagađenom zemljištu ili podzemnim vodama sa stanovišta stabilnosti novonastale čvrste faze. Detaljno su razmotreni sledeći sistemi: Cd/HAP, Pb/HAP, Pb/prirodni apatiti i As/HAP. Na osnovu prikazanih rezultata predloženi su dominantni mehanizmi u procesima sorpcije zagađujućih materija u ispitivanim sistemima. U radu su izvršena eksperimentalna ispitivanja i modelovanje kinetike sorpcije olova iz vodenih rastvora korišćenjem prirodnog i sintetičkog apatita na tri temperature. Za modelovanje eksperimentalnih podataka korišćeni su kinetički modeli pseudo-prvog i pseudo-drugog reda. Utvrđeno je da model pseudo-drugog reda dobro opisuje kinetiku sorpcije olova u oba ispitivana sistema. Takođe su izvršena eksperimentalna ispitivanja adsorpcionih izotermi olova na hidroksiapatitu i prirodnom apatitu. Za analizu sorpcionih podataka korišćeno je pet modela adsorpcionih izotermi. Na osnovu primene ANOVA statističke analize utvrđeno je da Freundlich-ova adsorpciona izoterma najbolje opisuje eksperimentalne podatke u oba sistema. Analiza svih dobijenih rezultata ukazuje na mogućnost primene prirodnog apatita iz ležišta Lisina, kao jeftine polazne sirovine, za remedijaciju zemljišta i podzemnih voda zagađenih teškim metalima. In this work, the mechanisms of heavy metal sorption by two forms of mineral apatite were studied. The materials used include synthetic hydroxyapatite (HAP) and natural apatite from Lisina ore deposit (LA). The materials were characterized by x-ray diffraction. It was shown that synthetic apatite is pure hydroxyapatite, with molecular formula Ca10(PO4)6(OH)2, while natural apatite is a mixture of three minerals: quartz, muscovite and fluorapatite. The mechanisms were investigated using theoretical model of the solid matrix/impurity system stability as well as by experimental investigations of dissolved Pb sorption by HAP and LA. The theoretical model of the solid matrix/impurity system stability is based on ion-ion interaction potential calculation. This model was used to estimate the stability of the solid phase obtained by the reaction of heavy metals with synthetic and natural apatite. The applied model can be used for pre-selection of the most suitable amendment for heavy metal immobilization in polluted soils and ground water, based on the stability of the newly formed solid phase. The following systems were investigated in detail: Cd/HAP, Pb/HAP, Pb/natural apatites and As/HAP. Based on the results obtained, the dominant mechanisms involved in reactions in the investigated systems were suggested. In this work, experimental investigations and modeling of the kinetics of Pb sorption by natural and synthetic apatites were carried out at three temperatures. Two kinetic models were used: pseudo-first and pseudo-second order model. It was concluded that pseudo-second order model describes the kinetics of the processes in both systems best. Experimental investigations of the sorption isotherms were also carried out. Five sorption isotherms were used to model the experimental results. Using ANOVA statistical analysis it was concluded that Freundlich isotherm model described both systems with the greatest accuracy. Based on the analysis of all the results obtained, it can be concluded that natural apatite from Lisina ore deposit is a promising material for heavy metal remediation in polluted soils and ground water.
- Published
- 2010
23. Study of the mechanisms of heavy metal sorption by mineral apatite: the feasibility of soil and ground water remediation
- Author
-
Kaluđerović-Radoičić, Tatjana, Grbavčić, Željko, Raičević, Slavica, Ristić, Mirjana, and Pejanović, Srđan
- Subjects
izoterma ,sorption ,model ,isotherm ,prirodni apatit ,mechanism ,sintetički apatit ,soil remediation ,mehanizam ,sorpcija ,teški metali ,natural apatite ,ground water remediation ,kinetics ,remedijacija zemljišta ,ion-ion interaction potential ,remedijacija podzemnih voda ,jon-jon interakcioni potencijal ,synthetic apatite ,heavy metals ,kinetika - Abstract
In this work, the mechanisms of heavy metal sorption by two forms of mineral apatite were studied. The materials used include synthetic hydroxyapatite (HAP) and natural apatite from Lisina ore deposit (LA). The materials were characterized by x-ray diffraction. It was shown that synthetic apatite is pure hydroxyapatite, with molecular formula Ca10(PO4)6(OH)2, while natural apatite is a mixture of three minerals: quartz, muscovite and fluorapatite. The mechanisms were investigated using theoretical model of the solid matrix/impurity system stability as well as by experimental investigations of dissolved Pb sorption by HAP and LA. The theoretical model of the solid matrix/impurity system stability is based on ion-ion interaction potential calculation. This model was used to estimate the stability of the solid phase obtained by the reaction of heavy metals with synthetic and natural apatite. The applied model can be used for pre-selection of the most suitable amendment for heavy metal immobilization in polluted soils and ground water, based on the stability of the newly formed solid phase. The following systems were investigated in detail: Cd/HAP, Pb/HAP, Pb/natural apatites and As/HAP. Based on the results obtained, the dominant mechanisms involved in reactions in the investigated systems were suggested. In this work, experimental investigations and modeling of the kinetics of Pb sorption by natural and synthetic apatites were carried out at three temperatures. Two kinetic models were used: pseudo-first and pseudo-second order model. It was concluded that pseudo-second order model describes the kinetics of the processes in both systems best. Experimental investigations of the sorption isotherms were also carried out. Five sorption isotherms were used to model the experimental results. Using ANOVA statistical analysis it was concluded that Freundlich isotherm model described both systems with the greatest accuracy. Based on the analysis of all the results obtained, it can be concluded that natural apatite from Lisina ore deposit is a promising material for heavy metal remediation in polluted soils and ground water. U ovom radu izučavani su mehanizmi sorpcije teških metala korišćenjem dve forme minerala apatita: sintetičkog hidroksiapatita (HAP) i prirodnog apatita iz ležišta Lisina kod Bosilegrada (LA). Karakterizacija materijala je izvršena korišćenjem metode difrakcije x-zraka. Utvrđeno je da je sintetički apatit (HAP) čist hidroksiapatit molekulske formule Ca10(PO4)6(OH)2, dok je prirodni apatit (LA) smeša minerala kvarca, muskovita i fluorapatita. Mehanizmi sorpcije izučavani su korišćenjem teorijskog modela stabilnosti čvrste faze, kao i eksperimentalnim proučavanjem sorpcije olova iz vodenog rastvora. Teorijski matematički model stabilnosti čvrste faze baziran je na izračunavanju jon-jon interakcionih potencijala. Ovaj model upotrebljen je za procenu stabilnosti čvrste faze nastale reakcijom zagađujućih materija sa prirodnim i sintetičkim apatitom. Primenjeni model omogućava preliminarni izbor najpogodnijeg aditiva za imobilizaciju teških metala u zagađenom zemljištu ili podzemnim vodama sa stanovišta stabilnosti novonastale čvrste faze. Detaljno su razmotreni sledeći sistemi: Cd/HAP, Pb/HAP, Pb/prirodni apatiti i As/HAP. Na osnovu prikazanih rezultata predloženi su dominantni mehanizmi u procesima sorpcije zagađujućih materija u ispitivanim sistemima. U radu su izvršena eksperimentalna ispitivanja i modelovanje kinetike sorpcije olova iz vodenih rastvora korišćenjem prirodnog i sintetičkog apatita na tri temperature. Za modelovanje eksperimentalnih podataka korišćeni su kinetički modeli pseudo-prvog i pseudo-drugog reda. Utvrđeno je da model pseudo-drugog reda dobro opisuje kinetiku sorpcije olova u oba ispitivana sistema. Takođe su izvršena eksperimentalna ispitivanja adsorpcionih izotermi olova na hidroksiapatitu i prirodnom apatitu. Za analizu sorpcionih podataka korišćeno je pet modela adsorpcionih izotermi. Na osnovu primene ANOVA statističke analize utvrđeno je da Freundlich-ova adsorpciona izoterma najbolje opisuje eksperimentalne podatke u oba sistema. Analiza svih dobijenih rezultata ukazuje na mogućnost primene prirodnog apatita iz ležišta Lisina, kao jeftine polazne sirovine, za remedijaciju zemljišta i podzemnih voda zagađenih teškim metalima.
- Published
- 2010
24. Izučavanje mehanizama sorpcije teških metala apatitom : mogućnost primene u remedijaciji zagađenog zemljišta i podzemnih voda
- Author
-
Grbavčić, Željko, Raičević, Slavica, Ristić, Mirjana, Pejanović, Srđan, Kaluđerović Radoičić, Tatjana, Grbavčić, Željko, Raičević, Slavica, Ristić, Mirjana, Pejanović, Srđan, and Kaluđerović Radoičić, Tatjana
- Abstract
U ovom radu izučavani su mehanizmi sorpcije teških metala korišćenjem dve forme minerala apatita: sintetičkog hidroksiapatita (HAP) i prirodnog apatita iz ležišta Lisina kod Bosilegrada (LA). Karakterizacija materijala je izvršena korišćenjem metode difrakcije x-zraka. Utvrđeno je da je sintetički apatit (HAP) čist hidroksiapatit molekulske formule Ca10(PO4)6(OH)2, dok je prirodni apatit (LA) smeša minerala kvarca, muskovita i fluorapatita. Mehanizmi sorpcije izučavani su korišćenjem teorijskog modela stabilnosti čvrste faze, kao i eksperimentalnim proučavanjem sorpcije olova iz vodenog rastvora. Teorijski matematički model stabilnosti čvrste faze baziran je na izračunavanju jon-jon interakcionih potencijala. Ovaj model upotrebljen je za procenu stabilnosti čvrste faze nastale reakcijom zagađujućih materija sa prirodnim i sintetičkim apatitom. Primenjeni model omogućava preliminarni izbor najpogodnijeg aditiva za imobilizaciju teških metala u zagađenom zemljištu ili podzemnim vodama sa stanovišta stabilnosti novonastale čvrste faze. Detaljno su razmotreni sledeći sistemi: Cd/HAP, Pb/HAP, Pb/prirodni apatiti i As/HAP. Na osnovu prikazanih rezultata predloženi su dominantni mehanizmi u procesima sorpcije zagađujućih materija u ispitivanim sistemima. U radu su izvršena eksperimentalna ispitivanja i modelovanje kinetike sorpcije olova iz vodenih rastvora korišćenjem prirodnog i sintetičkog apatita na tri temperature. Za modelovanje eksperimentalnih podataka korišćeni su kinetički modeli pseudo-prvog i pseudo-drugog reda. Utvrđeno je da model pseudo-drugog reda dobro opisuje kinetiku sorpcije olova u oba ispitivana sistema. Takođe su izvršena eksperimentalna ispitivanja adsorpcionih izotermi olova na hidroksiapatitu i prirodnom apatitu. Za analizu sorpcionih podataka korišćeno je pet modela adsorpcionih izotermi. Na osnovu primene ANOVA statističke analize utvrđeno je da Freundlich-ova adsorpciona izoterma najbolje opisuje eksperimentalne podatke u oba sistema. Analiza s, In this work, the mechanisms of heavy metal sorption by two forms of mineral apatite were studied. The materials used include synthetic hydroxyapatite (HAP) and natural apatite from Lisina ore deposit (LA). The materials were characterized by x-ray diffraction. It was shown that synthetic apatite is pure hydroxyapatite, with molecular formula Ca10(PO4)6(OH)2, while natural apatite is a mixture of three minerals: quartz, muscovite and fluorapatite. The mechanisms were investigated using theoretical model of the solid matrix/impurity system stability as well as by experimental investigations of dissolved Pb sorption by HAP and LA. The theoretical model of the solid matrix/impurity system stability is based on ion-ion interaction potential calculation. This model was used to estimate the stability of the solid phase obtained by the reaction of heavy metals with synthetic and natural apatite. The applied model can be used for pre-selection of the most suitable amendment for heavy metal immobilization in polluted soils and ground water, based on the stability of the newly formed solid phase. The following systems were investigated in detail: Cd/HAP, Pb/HAP, Pb/natural apatites and As/HAP. Based on the results obtained, the dominant mechanisms involved in reactions in the investigated systems were suggested. In this work, experimental investigations and modeling of the kinetics of Pb sorption by natural and synthetic apatites were carried out at three temperatures. Two kinetic models were used: pseudo-first and pseudo-second order model. It was concluded that pseudo-second order model describes the kinetics of the processes in both systems best. Experimental investigations of the sorption isotherms were also carried out. Five sorption isotherms were used to model the experimental results. Using ANOVA statistical analysis it was concluded that Freundlich isotherm model described both systems with the greatest accuracy. Based on the analysis of all the results obtained, it
- Published
- 2010
25. Study of the mechanisms of heavy metal sorption by mineral apatite: the feasibility of soil and ground water remediation
- Author
-
Grbavčić, Željko, Raičević, Slavica, Ristić, Mirjana, Pejanović, Srđan, Kaluđerović-Radoičić, Tatjana, Grbavčić, Željko, Raičević, Slavica, Ristić, Mirjana, Pejanović, Srđan, and Kaluđerović-Radoičić, Tatjana
- Abstract
In this work, the mechanisms of heavy metal sorption by two forms of mineral apatite were studied. The materials used include synthetic hydroxyapatite (HAP) and natural apatite from Lisina ore deposit (LA). The materials were characterized by x-ray diffraction. It was shown that synthetic apatite is pure hydroxyapatite, with molecular formula Ca10(PO4)6(OH)2, while natural apatite is a mixture of three minerals: quartz, muscovite and fluorapatite. The mechanisms were investigated using theoretical model of the solid matrix/impurity system stability as well as by experimental investigations of dissolved Pb sorption by HAP and LA. The theoretical model of the solid matrix/impurity system stability is based on ion-ion interaction potential calculation. This model was used to estimate the stability of the solid phase obtained by the reaction of heavy metals with synthetic and natural apatite. The applied model can be used for pre-selection of the most suitable amendment for heavy metal immobilization in polluted soils and ground water, based on the stability of the newly formed solid phase. The following systems were investigated in detail: Cd/HAP, Pb/HAP, Pb/natural apatites and As/HAP. Based on the results obtained, the dominant mechanisms involved in reactions in the investigated systems were suggested. In this work, experimental investigations and modeling of the kinetics of Pb sorption by natural and synthetic apatites were carried out at three temperatures. Two kinetic models were used: pseudo-first and pseudo-second order model. It was concluded that pseudo-second order model describes the kinetics of the processes in both systems best. Experimental investigations of the sorption isotherms were also carried out. Five sorption isotherms were used to model the experimental results. Using ANOVA statistical analysis it was concluded that Freundlich isotherm model described both systems with the greatest accuracy. Based on the analysis of all the results obtained, it, U ovom radu izučavani su mehanizmi sorpcije teških metala korišćenjem dve forme minerala apatita: sintetičkog hidroksiapatita (HAP) i prirodnog apatita iz ležišta Lisina kod Bosilegrada (LA). Karakterizacija materijala je izvršena korišćenjem metode difrakcije x-zraka. Utvrđeno je da je sintetički apatit (HAP) čist hidroksiapatit molekulske formule Ca10(PO4)6(OH)2, dok je prirodni apatit (LA) smeša minerala kvarca, muskovita i fluorapatita. Mehanizmi sorpcije izučavani su korišćenjem teorijskog modela stabilnosti čvrste faze, kao i eksperimentalnim proučavanjem sorpcije olova iz vodenog rastvora. Teorijski matematički model stabilnosti čvrste faze baziran je na izračunavanju jon-jon interakcionih potencijala. Ovaj model upotrebljen je za procenu stabilnosti čvrste faze nastale reakcijom zagađujućih materija sa prirodnim i sintetičkim apatitom. Primenjeni model omogućava preliminarni izbor najpogodnijeg aditiva za imobilizaciju teških metala u zagađenom zemljištu ili podzemnim vodama sa stanovišta stabilnosti novonastale čvrste faze. Detaljno su razmotreni sledeći sistemi: Cd/HAP, Pb/HAP, Pb/prirodni apatiti i As/HAP. Na osnovu prikazanih rezultata predloženi su dominantni mehanizmi u procesima sorpcije zagađujućih materija u ispitivanim sistemima. U radu su izvršena eksperimentalna ispitivanja i modelovanje kinetike sorpcije olova iz vodenih rastvora korišćenjem prirodnog i sintetičkog apatita na tri temperature. Za modelovanje eksperimentalnih podataka korišćeni su kinetički modeli pseudo-prvog i pseudo-drugog reda. Utvrđeno je da model pseudo-drugog reda dobro opisuje kinetiku sorpcije olova u oba ispitivana sistema. Takođe su izvršena eksperimentalna ispitivanja adsorpcionih izotermi olova na hidroksiapatitu i prirodnom apatitu. Za analizu sorpcionih podataka korišćeno je pet modela adsorpcionih izotermi. Na osnovu primene ANOVA statističke analize utvrđeno je da Freundlich-ova adsorpciona izoterma najbolje opisuje eksperimentalne podatke u oba sistema. Analiza s
- Published
- 2010
26. Interakce směsi anionických tenzidů s kolgenem
- Author
-
Krejčí, Jiří and Krejčí, Jiří
- Abstract
Byla studována interakce kolagenních vláken kolagenu I s anionickými surfaktanty dodecylbenzensulfonanem sodným (SDBS), dodecylsulfátem sodným (SDS) a jejich směsmi při pH=6, dvou různých iontových silách (I=0,06 mol.l-1a I=0,4 mol.l-1) a laboratorní teplotě. Surfaktanty a jejich směsi byly charakterizovány kritickou micelární koncentrací (c.m.c.), složením směsných micel a interakčním faktorem ? podle Rubingha. Závislost c.m.c. na složení směsi má při vysoké I opačný charakter, což dokumentuje větší vliv přidaného elektrolytu na chování SDS než SDBS. Interakce byla hodnocena vázacími isothermami a stanovením hmotnostního stupně zbotnání ?m. Navázané množství je závislé jednak na složení směsi, jednak na iontové síle. Samotný SDS a směsi s jeho vyšším obsahem se váží více než SDBS (cca 150 % vzhledem k množství SDBS). Zvýšená iontová síla prostředí zvyšuje navázané množství přibližně stejně bez ohledu na složení sorbátu. I složení směsí po interakci s vlákny se výrazněji od původního složení nemění. Zbotnání vláken je ovlivněno složením botnací směsi obdobně jako v případě vázání. Se zvyšujícím se navázaným množstvím surfaktantů se zvyšuje. Zvýšená iontová síla působí proti botnání kolagenu a při dané iontové síle (I=0,4 mol.l-1) dosahuje botnání polovičních hodnot. V obou případech existují charakteristické koncentrace obou surfaktantů a jejich směsí (cs~0,5-1,0 mmol.l-1), které nezpůsobují botnání. Předpokládá se, že toto rozmezí koncentrací odpovídá množství surfaktantů vázaných na kolagen elektrostatickými silami a tedy přechodnému zvýšení hydrofobnosti vláken., Study focused on interaction of collagen fibres of collagen I with anionic surfactants sodium dodecylbenzene sulphonate (SDBS), sodium dodecyl sulphate (SDS) and their mixtures at pH=6, at two ionic strengths (I = 0.06 mol L-1 and I = 0.4 mol L-1) and laboratory temperature. Surfactants and their mixtures were characterised by their critical micelle concentration (c.m.c.), composition of mixed micelles and interaction factor ? according to Rubingh. Dependency of c.m.c. on mixture composition has an opposite tendency at both ionic strengths, which proves the greater influence of added electrolyte on behaviour of SDS than of SDBS. Interaction was evaluated by means of binding isotherms and mass swelling degree ?m. The bound quantity partly depends on mixture composition, partly on ionic strength. SDS and mixtures containing its greater quantities are bound more than SDBS (approx. 150% related to SDBS). Increased ionic strength of the environment increases bound quantity in approximately same manner, heedless of adsorbate composition. Even composition of the mixture after interaction with fibres does not markedly alter from initial composition. Fibre swelling is affected by composition of swelling mixture similarly to binding ? it increases with growing quantity of surfactants. Greater ionic strength acts against collagen swelling, and at given ionic strength (I = 0.4 mol L-1) swelling attains half values compare to swelling at low ionic strength (I=0.06 mol.L-1). There are characteristic concentrations of both surfactants and their mixtures (cs ~ 0.5-1.0 mmol L-1) that do not produce swelling. It is assumed that this range of concentrations corresponds to amount of surfactants bound to collagen through electrostatic forces and thus to temporary increase in fibre hydrophobity.
- Published
- 2007
27. Adsorpcija kadmija(II), olova(II) i bakra(II) iz morske vode na površine stakla, kvarca i nalgena
- Author
-
Cuculić, Vlado
- Subjects
Adsorpcija ,Izoterma ,Morska voda ,Voltammetrija - Abstract
Adsorpcija kadmija(II), olova(II) i bakra(II) iz morske vode na površine stakla, kvarca i nalgena je rađena voltammetrijskim tehnikama s živinom kapi kao radnom elektrodom.
- Published
- 1994
28. Ispitivanje kinetike elektrodnih procesa na aluminiju i kinetike adsorpcije aromatskih amina
- Author
-
Grubač, Zoran, Metikoš-Huković, Mirjana, and Tkalčec, M.
- Subjects
aluminij ,Hg elektroda ,adsorpcija ,izoterma - Abstract
Poznavanje adsorpcijske izoterme i stanja adsorpcijske ravnoteže nužno je pri kvantitativnom proučavanju elektrodnih procesa (inhibicija korozije organskim spojevima). Uspostavljanjem adsorpcijske ravnoteže na kapajućoj Hg elektrodi ispitano je praćenjem kapaciteta dvostrukog sloja metodom ac polarografijom. Nađeno je da 1-naftil amin i 2-naftil amin pokazuju odstupanje od Langmuirove adsorpcijske izoterme kod negativnijih potencijala i viših koncentracija amina.
- Published
- 1991
29. Matematická simulace průběhu teplot v podzákladí a vytvoření modelu odpovídajícího reálnému stavu.
- Author
-
Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, Charvátová, Pavlína, Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, and Charvátová, Pavlína
- Abstract
Stále se zvyšující požadavky na nízké tepelné ztráty a energetickou náročnost budovy ovlivňují energetické výpočty. Jsou kladeny vyšší požadavky na přesnost výpočtů. Důležitou součástí tepelnětechnických výpočtů je stanovení správných okrajových podmínek. Důležitým vstupním faktorem je především vnitřní a vnější prostředí a pro tato prostředí je nejdůležitějším parametrem převážně teplota. Nejedná se vždy pouze o teplotu vnějšího prostředí, ale prostředí, které přiléhá k zemině nebo k nevytápěným či jinak vytápěným prostorům. Možnosti modelování teplot pod objektem jsou popsány v normě ČSN EN ISO 10211. Tato norma stanovuje podrobnosti pro geometrický model pro numerický výpočet tepelných toků ke zhodnocení celkové tepelné ztráty budov nebo její části a také pro odvození lineárních a bodových činitelů prostupu tepla; dále pro výpočet minimálních povrchových teplot ke zhodnocení rizika povrchové kondenzace a stanovení teplotních faktorů povrchu. Jedná se o dva odlišné výpočtové modely. Proto by bylo vhodné tyto výpočty zjednodušit formou zjednodušení okrajových podmínek, a sice v určité úrovni pod terénem vést izotermu, která bude považována za okrajovou podmínku, což vychází také z dlouhodobých zkušeností s "nezámrznou" hloubkou. Tento výpočet by byl jednoznačný, přehledný a jednoduchý., Increasing demands for low heat losses and energy intensity of a building influence energy calculations. Higher demands are placed on the accuracy of the calculations. An important part of the thermal engineering calculations is the determination of the correct boundary conditions. An important input factor is primarily the indoor and outdoor environment, and temperature is the most important parameter for these types of enviromnent. It is not always the temperature of the external environment, but the environment that is adjacent to the soil or to unheated or differently heated spaces. The possibilities of modeling temperatures below the object are described in the standard ČSN EN ISO 10211. This standard specifies details for a geometric model for the numerical calculation of heat flows to assess the total heat loss of buildings or parts thereof, as well as to derive linear and point heat transfer factors. Furthermore, to calculate minimum surface temperatures to assess the risk of surface condensation and to determine the surface temperature factors. These are two different computational models. Therefore, it would be appropriate to simplify these calculations by simplifying the boundary conditions, namely to conduct an isotherm at a certain level below the terrain, which will be considered as a boundary condition, which is also based on long-term experience with "frost-free" depth. This calculation would be unambiguous, clear and simple.
30. Matematická simulace průběhu teplot v podzákladí a vytvoření modelu odpovídajícího reálnému stavu.
- Author
-
Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, Charvátová, Pavlína, Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, and Charvátová, Pavlína
- Abstract
Stále se zvyšující požadavky na nízké tepelné ztráty a energetickou náročnost budovy ovlivňují energetické výpočty. Jsou kladeny vyšší požadavky na přesnost výpočtů. Důležitou součástí tepelnětechnických výpočtů je stanovení správných okrajových podmínek. Důležitým vstupním faktorem je především vnitřní a vnější prostředí a pro tato prostředí je nejdůležitějším parametrem převážně teplota. Nejedná se vždy pouze o teplotu vnějšího prostředí, ale prostředí, které přiléhá k zemině nebo k nevytápěným či jinak vytápěným prostorům. Možnosti modelování teplot pod objektem jsou popsány v normě ČSN EN ISO 10211. Tato norma stanovuje podrobnosti pro geometrický model pro numerický výpočet tepelných toků ke zhodnocení celkové tepelné ztráty budov nebo její části a také pro odvození lineárních a bodových činitelů prostupu tepla; dále pro výpočet minimálních povrchových teplot ke zhodnocení rizika povrchové kondenzace a stanovení teplotních faktorů povrchu. Jedná se o dva odlišné výpočtové modely. Proto by bylo vhodné tyto výpočty zjednodušit formou zjednodušení okrajových podmínek, a sice v určité úrovni pod terénem vést izotermu, která bude považována za okrajovou podmínku, což vychází také z dlouhodobých zkušeností s "nezámrznou" hloubkou. Tento výpočet by byl jednoznačný, přehledný a jednoduchý., Increasing demands for low heat losses and energy intensity of a building influence energy calculations. Higher demands are placed on the accuracy of the calculations. An important part of the thermal engineering calculations is the determination of the correct boundary conditions. An important input factor is primarily the indoor and outdoor environment, and temperature is the most important parameter for these types of enviromnent. It is not always the temperature of the external environment, but the environment that is adjacent to the soil or to unheated or differently heated spaces. The possibilities of modeling temperatures below the object are described in the standard ČSN EN ISO 10211. This standard specifies details for a geometric model for the numerical calculation of heat flows to assess the total heat loss of buildings or parts thereof, as well as to derive linear and point heat transfer factors. Furthermore, to calculate minimum surface temperatures to assess the risk of surface condensation and to determine the surface temperature factors. These are two different computational models. Therefore, it would be appropriate to simplify these calculations by simplifying the boundary conditions, namely to conduct an isotherm at a certain level below the terrain, which will be considered as a boundary condition, which is also based on long-term experience with "frost-free" depth. This calculation would be unambiguous, clear and simple.
31. Matematická simulace průběhu teplot v podzákladí a vytvoření modelu odpovídajícího reálnému stavu.
- Author
-
Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, Charvátová, Pavlína, Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, and Charvátová, Pavlína
- Abstract
Stále se zvyšující požadavky na nízké tepelné ztráty a energetickou náročnost budovy ovlivňují energetické výpočty. Jsou kladeny vyšší požadavky na přesnost výpočtů. Důležitou součástí tepelnětechnických výpočtů je stanovení správných okrajových podmínek. Důležitým vstupním faktorem je především vnitřní a vnější prostředí a pro tato prostředí je nejdůležitějším parametrem převážně teplota. Nejedná se vždy pouze o teplotu vnějšího prostředí, ale prostředí, které přiléhá k zemině nebo k nevytápěným či jinak vytápěným prostorům. Možnosti modelování teplot pod objektem jsou popsány v normě ČSN EN ISO 10211. Tato norma stanovuje podrobnosti pro geometrický model pro numerický výpočet tepelných toků ke zhodnocení celkové tepelné ztráty budov nebo její části a také pro odvození lineárních a bodových činitelů prostupu tepla; dále pro výpočet minimálních povrchových teplot ke zhodnocení rizika povrchové kondenzace a stanovení teplotních faktorů povrchu. Jedná se o dva odlišné výpočtové modely. Proto by bylo vhodné tyto výpočty zjednodušit formou zjednodušení okrajových podmínek, a sice v určité úrovni pod terénem vést izotermu, která bude považována za okrajovou podmínku, což vychází také z dlouhodobých zkušeností s "nezámrznou" hloubkou. Tento výpočet by byl jednoznačný, přehledný a jednoduchý., Increasing demands for low heat losses and energy intensity of a building influence energy calculations. Higher demands are placed on the accuracy of the calculations. An important part of the thermal engineering calculations is the determination of the correct boundary conditions. An important input factor is primarily the indoor and outdoor environment, and temperature is the most important parameter for these types of enviromnent. It is not always the temperature of the external environment, but the environment that is adjacent to the soil or to unheated or differently heated spaces. The possibilities of modeling temperatures below the object are described in the standard ČSN EN ISO 10211. This standard specifies details for a geometric model for the numerical calculation of heat flows to assess the total heat loss of buildings or parts thereof, as well as to derive linear and point heat transfer factors. Furthermore, to calculate minimum surface temperatures to assess the risk of surface condensation and to determine the surface temperature factors. These are two different computational models. Therefore, it would be appropriate to simplify these calculations by simplifying the boundary conditions, namely to conduct an isotherm at a certain level below the terrain, which will be considered as a boundary condition, which is also based on long-term experience with "frost-free" depth. This calculation would be unambiguous, clear and simple.
32. Matematická simulace průběhu teplot v podzákladí a vytvoření modelu odpovídajícího reálnému stavu.
- Author
-
Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, Čupr, Karel, Katunský,, Dušan, and Ostrý, Milan
- Abstract
Stále se zvyšující požadavky na nízké tepelné ztráty a energetickou náročnost budovy ovlivňují energetické výpočty. Jsou kladeny vyšší požadavky na přesnost výpočtů. Důležitou součástí tepelnětechnických výpočtů je stanovení správných okrajových podmínek. Důležitým vstupním faktorem je především vnitřní a vnější prostředí a pro tato prostředí je nejdůležitějším parametrem převážně teplota. Nejedná se vždy pouze o teplotu vnějšího prostředí, ale prostředí, které přiléhá k zemině nebo k nevytápěným či jinak vytápěným prostorům. Možnosti modelování teplot pod objektem jsou popsány v normě ČSN EN ISO 10211. Tato norma stanovuje podrobnosti pro geometrický model pro numerický výpočet tepelných toků ke zhodnocení celkové tepelné ztráty budov nebo její části a také pro odvození lineárních a bodových činitelů prostupu tepla; dále pro výpočet minimálních povrchových teplot ke zhodnocení rizika povrchové kondenzace a stanovení teplotních faktorů povrchu. Jedná se o dva odlišné výpočtové modely. Proto by bylo vhodné tyto výpočty zjednodušit formou zjednodušení okrajových podmínek, a sice v určité úrovni pod terénem vést izotermu, která bude považována za okrajovou podmínku, což vychází také z dlouhodobých zkušeností s "nezámrznou" hloubkou. Tento výpočet by byl jednoznačný, přehledný a jednoduchý., Increasing demands for low heat losses and energy intensity of a building influence energy calculations. Higher demands are placed on the accuracy of the calculations. An important part of the thermal engineering calculations is the determination of the correct boundary conditions. An important input factor is primarily the indoor and outdoor environment, and temperature is the most important parameter for these types of enviromnent. It is not always the temperature of the external environment, but the environment that is adjacent to the soil or to unheated or differently heated spaces. The possibilities of modeling temperatures below the object are described in the standard ČSN EN ISO 10211. This standard specifies details for a geometric model for the numerical calculation of heat flows to assess the total heat loss of buildings or parts thereof, as well as to derive linear and point heat transfer factors. Furthermore, to calculate minimum surface temperatures to assess the risk of surface condensation and to determine the surface temperature factors. These are two different computational models. Therefore, it would be appropriate to simplify these calculations by simplifying the boundary conditions, namely to conduct an isotherm at a certain level below the terrain, which will be considered as a boundary condition, which is also based on long-term experience with "frost-free" depth. This calculation would be unambiguous, clear and simple.
33. Matematická simulace průběhu teplot v podzákladí a vytvoření modelu odpovídajícího reálnému stavu.
- Author
-
Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, Čupr, Karel, Katunský,, Dušan, and Ostrý, Milan
- Abstract
Stále se zvyšující požadavky na nízké tepelné ztráty a energetickou náročnost budovy ovlivňují energetické výpočty. Jsou kladeny vyšší požadavky na přesnost výpočtů. Důležitou součástí tepelnětechnických výpočtů je stanovení správných okrajových podmínek. Důležitým vstupním faktorem je především vnitřní a vnější prostředí a pro tato prostředí je nejdůležitějším parametrem převážně teplota. Nejedná se vždy pouze o teplotu vnějšího prostředí, ale prostředí, které přiléhá k zemině nebo k nevytápěným či jinak vytápěným prostorům. Možnosti modelování teplot pod objektem jsou popsány v normě ČSN EN ISO 10211. Tato norma stanovuje podrobnosti pro geometrický model pro numerický výpočet tepelných toků ke zhodnocení celkové tepelné ztráty budov nebo její části a také pro odvození lineárních a bodových činitelů prostupu tepla; dále pro výpočet minimálních povrchových teplot ke zhodnocení rizika povrchové kondenzace a stanovení teplotních faktorů povrchu. Jedná se o dva odlišné výpočtové modely. Proto by bylo vhodné tyto výpočty zjednodušit formou zjednodušení okrajových podmínek, a sice v určité úrovni pod terénem vést izotermu, která bude považována za okrajovou podmínku, což vychází také z dlouhodobých zkušeností s "nezámrznou" hloubkou. Tento výpočet by byl jednoznačný, přehledný a jednoduchý., Increasing demands for low heat losses and energy intensity of a building influence energy calculations. Higher demands are placed on the accuracy of the calculations. An important part of the thermal engineering calculations is the determination of the correct boundary conditions. An important input factor is primarily the indoor and outdoor environment, and temperature is the most important parameter for these types of enviromnent. It is not always the temperature of the external environment, but the environment that is adjacent to the soil or to unheated or differently heated spaces. The possibilities of modeling temperatures below the object are described in the standard ČSN EN ISO 10211. This standard specifies details for a geometric model for the numerical calculation of heat flows to assess the total heat loss of buildings or parts thereof, as well as to derive linear and point heat transfer factors. Furthermore, to calculate minimum surface temperatures to assess the risk of surface condensation and to determine the surface temperature factors. These are two different computational models. Therefore, it would be appropriate to simplify these calculations by simplifying the boundary conditions, namely to conduct an isotherm at a certain level below the terrain, which will be considered as a boundary condition, which is also based on long-term experience with "frost-free" depth. This calculation would be unambiguous, clear and simple.
34. Matematická simulace průběhu teplot v podzákladí a vytvoření modelu odpovídajícího reálnému stavu.
- Author
-
Čupr, Karel, Katunský,, Dušan, Ostrý, Milan, Čupr, Karel, Katunský,, Dušan, and Ostrý, Milan
- Abstract
Stále se zvyšující požadavky na nízké tepelné ztráty a energetickou náročnost budovy ovlivňují energetické výpočty. Jsou kladeny vyšší požadavky na přesnost výpočtů. Důležitou součástí tepelnětechnických výpočtů je stanovení správných okrajových podmínek. Důležitým vstupním faktorem je především vnitřní a vnější prostředí a pro tato prostředí je nejdůležitějším parametrem převážně teplota. Nejedná se vždy pouze o teplotu vnějšího prostředí, ale prostředí, které přiléhá k zemině nebo k nevytápěným či jinak vytápěným prostorům. Možnosti modelování teplot pod objektem jsou popsány v normě ČSN EN ISO 10211. Tato norma stanovuje podrobnosti pro geometrický model pro numerický výpočet tepelných toků ke zhodnocení celkové tepelné ztráty budov nebo její části a také pro odvození lineárních a bodových činitelů prostupu tepla; dále pro výpočet minimálních povrchových teplot ke zhodnocení rizika povrchové kondenzace a stanovení teplotních faktorů povrchu. Jedná se o dva odlišné výpočtové modely. Proto by bylo vhodné tyto výpočty zjednodušit formou zjednodušení okrajových podmínek, a sice v určité úrovni pod terénem vést izotermu, která bude považována za okrajovou podmínku, což vychází také z dlouhodobých zkušeností s "nezámrznou" hloubkou. Tento výpočet by byl jednoznačný, přehledný a jednoduchý., Increasing demands for low heat losses and energy intensity of a building influence energy calculations. Higher demands are placed on the accuracy of the calculations. An important part of the thermal engineering calculations is the determination of the correct boundary conditions. An important input factor is primarily the indoor and outdoor environment, and temperature is the most important parameter for these types of enviromnent. It is not always the temperature of the external environment, but the environment that is adjacent to the soil or to unheated or differently heated spaces. The possibilities of modeling temperatures below the object are described in the standard ČSN EN ISO 10211. This standard specifies details for a geometric model for the numerical calculation of heat flows to assess the total heat loss of buildings or parts thereof, as well as to derive linear and point heat transfer factors. Furthermore, to calculate minimum surface temperatures to assess the risk of surface condensation and to determine the surface temperature factors. These are two different computational models. Therefore, it would be appropriate to simplify these calculations by simplifying the boundary conditions, namely to conduct an isotherm at a certain level below the terrain, which will be considered as a boundary condition, which is also based on long-term experience with "frost-free" depth. This calculation would be unambiguous, clear and simple.
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