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1

Decolorization of Cationic Dye from Aqueous Solution by Multiwalled Carbon Nanotubes

Ahmed Salwa H., Rasheed Ekehwanh A., Rasheed Luma A., Abdulrahim Firas R.

Journal of Ecological Engineering

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2024

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Vol. 25, nr 2

72--84

EN

Methylene blue is a synthetic and cationic dye that finds utility in different fields including pharmaceutical, paper, textile, printing, carpet, and photography industries. Adsorption is a very effective technique to decolorize contaminated wastewater. This study aimed to determine the efficacy of Multiwalled Carbon Nanotubes (MWCNTs) as an adsorbent for decolorization of MB dye from aqueous solutions. The study examined various characteristics affecting adsorption, including concentration of dye, pH value, dosage of MWCNTs, and contact time. The results that growing the adsorbent dosage from (25 to 120) mg increased the dye efficiency rate from 62% to 98%, respectively, were shown. The study also evaluated pH, which is among the most critical factors influencing removal efficiency. The best pH for the removal efficiency was 6 at an initial concentration of MB dye 20 mgL-1, a contact time 60 min, and an MWCNT dosage 100 mg. Langmuir, Freundlich, and Temkin isotherms were used to describe the adsorption equilibrium. The Langmuir isotherm with an R2 value of 0.9968 and a maximum capacity for adsorption of 19.6 mgg-1 provided a suitable fit for the data of the experiment. In comparison between the suitability of kinetic models pseudo-first-order, pseudo-second order, and Weber–Morris, the kinetics model’s correlation value was shown to be greater than that of the pseudo-second order kinetic model with an R2 value of 0.9982.

2

The Effect of Wetting and Drying Cycles on Potassium Release in Three Soil Orders

Al-Silevany Baybeen Saeed Hasen, Mehmedany Lazkeen Ahmed Merween

Journal of Ecological Engineering

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2023

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Vol. 24, nr 1

218--226

EN

This research was conducted to study the potassium release under ten wetting and drying cycles in three soil orders (Mollisols, Vertisols, and Aridisols) collected from three different locations (Sharya, Semeel, and Kanishrin) in Dohuk governorate in Iraqi-Kurdistan region by using Ca-resin capsules, and K+ desorption (Kd) fitted to four model equations to choose the best equation to describe K+. The results of the experiments showed that flocculated water content wetting and drying cycles increased cumulative K-release from Ca-resin capsules until a tenth of the wetting-drying cycle. Potassium desorption according to the kinetic approach showed a significant effect of time on potassium desorption, and potassium desorption conformed to parabolic diffusion equations kinetics was the best equation to describe the Kd of potassium by using Ca-resin with a high coefficient of determination (R2) and low standard error and the order of the equation in terms of their preference in describing the desorption process is as follows: 1 – Parabolic diffusion, 2 – Power function, 3 – Elovich equation, 4 – First-order. The apparent desorption rate coefficient for the parabolic diffusion equation ranged from 0.1084–0.0877–0.1040 cmol kg-1∙day -1 from Mollisols, Vertisols, and Aridisols respectively. The rate coefficient K+ desorption according to the parabolic diffusion equation had a significant and positive correlation with SO42-, K+, T-CaCO3, HCO3, CEC, and Ca2+ but negatively significant correlated with EC and active CaCO3.

3

Funnel and Gate Permeable Reactive Barrier Permeable Reactive Barrier Configuration for Contaminated Groundwater Remediation – Designing, Installation, and Modeling: A Review

Mokif Layla Abdulkareem, Faisal Ayad A. H.

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 9

15--33

EN

Groundwater is a valuable resource whose purity is necessary for human survival. It serves as a significant source of water for household, industrial, and agricultural purposes. Traditional groundwater pollution remediation technologies include pump & treat, phase extraction, aeration gas of groundwater, bioremediation, and chemical oxidation. Permeable reactive barrier (PRB) is one of the most key technology being developed as alternatives to the pump and manage method for the remedying contaminated groundwater. An overview on the groundwater significant as important sources for water, sources of groundwater contamination, transport of contaminants, and groundwater remediation technologies have been discussed in this paper. In addition to reactive media, the design and installation of PRBs of funnel-gate configurations and their application as a remediation technique have been covered in this review. Finally reaction mechanisms in groundwater, contaminant transport governing equation, isotherms sorption models, kinetic sorption models, breakthrough curves modeling have been presented in this review. PRB technique provides financial benefits while also encouraging waste material reuse, so contributing to environmental sustainability. Funnel and gate PRB can offer one or more dense treatment areas for maximizing groundwater pollution plume capture. Funnel-gate PRB is characterized by smaller reaction area, ease in replacement and removal during the blocking of the reactive barrier by fine soil particles and reactive sediments.

4

The Critical Conditions and Kinetics Required for Dynamic Recrystallization in a High-Carbon Tool Steel

Zhang Yong-Ji, Wu Guang-Lian, Wu Shang-Wen

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 1

119--125

EN

A hot compression test was conducted on a Gleeble-3500 thermo-simulation machine to study the critical conditions and kinetics of dynamic recrystallization in a high-carbon tool steel. The critical conditions for the initiation of dynamic recrystallization were determined using the working-hardening theory. The quantitative relationship between the critical characteristics of dynamic recrystallization and the hot deformation parameters were elucidated based on two different methods: the apparent method and physically based method. It was found that the two methods both have high applicability for the investigated steel, but the physically-based method needs less parameters and makes it possible to study the effect of different factors. A dynamic recrystallization kinetics model was used to calculate the recrystallization volume fraction under different conditions. The calculation results matched well with the data obtained from the flow curves.

5

Adaptacja metod analizy kinetyki reakcji w fazie stałej do weryfikacji i modyfikacji modelu procesu starzenia papieru

Gonera Henryk, Dąbrowski Józef

Przegląd Papierniczy

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2019

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R. 75, nr 12

761--766

PL

Wyjaśniono rolę wilgotności powietrza w procesie termicznie przyśpieszonego starzenia się papieru, wykorzystując przekształcenie wcześniej opracowanego modelu (ZFT) fizykochemicznego mechanizmu spadku retencji oporu przedarcia papieru (YFT) w model jego kinetyki (Z FT - ln(t)). Weryfikacji i modyfikacji tego modelu dokonano kierując się zarówno zasadami badań kinetyki przemian fizykochemicznych w ciele stałym i posługując się statystycznymi metodami analizy regresji wielu zmiennych zastosowanymi do danych literaturowych - opublikowanych przez NBS i CCI - z wynikami badań starzenia papierów w atmosferze opisywanej za pomocą temperatury i wilgotności. Stwierdzono, że para wodna przyśpiesza proces starzenia papieru głównie jako nośnik energii. Model nie ma charakteru uniwersalnego ale może służyć do praktycznego szacowania trwałości określonej partii papieru jako produktu technicznego przeznaczonego do trwałego zachowania, a nie jako materiału wzorcowego.

EN

The role of air humidity in the process of thermally accelerated paper ageing is explained using the transformation of the previously developed model (ZFT) of the physicochemical mechanism for decrease in retention of its tear resistance (YFT) into the model of its kinetics (ZFT - ln(t)). The verification of this model was carried out using both the reaction kinetics function occurring in a solid under the influence of thermal stimulation and following statistical methods of regression analysis of many variables applied to literature data - published by NBS and CCI - presenting the results of ageing tests in the atmosphere described by temperature and humidity. It was found that water vapour accelerates the ageing process of paper mainly as an energy carrier. The model is not universal, but it can be used for practical estimation of the durability of a specific batch of paper as a technical product intended for permanent preservation, and not as a reference material.

6

Uncertainty analysis of the kinetic model of natural gas combustion in IC Engine

Mansha M., Naqvi J. H.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 1

1-4

EN

The purpose of this analysis is to determine the uncertainties originating due to the kinetic parameters of the rate of a reaction proposed kinetic model. A kinetic model consisting of 208 reaction steps and 73 species was adopted for analysis. In the required uncertainty analysis, the accuracy of approximate models, generated by the Chemkin 4.1.1 for pollutant species, is determined. The reactions which contribute the uncertainty in the output concentrations of the pollutnats species formed in the combustion chamber were identifi ed. The percentage contribution to the uncertainty in the output concentrations of pollutants were also determined.

7

Analysis of kinetics models of batch flotation

Brożek M., Młynarczykowska A.

Physicochemical Problems of Mineral Processing

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2007

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Vol. 41

51-65

EN

Flotation as a kinetic and thermodynamic phenomenon is a random process. The random variable determining the number of particles in flotation, attached permanently to the bubble surface, and consequently also the recovery, depend on time. Numerous models of flotation kinetics have been worked out to describe this dependence. Each of these models covers in fact a separate aspect of the problem but they complement each other. The paper presents a detailed analysis of the models based on the kinetics of chemical reactions and on the model of chemical absorption. It results from analysis of these models that in the case of flotation of the feed which is non-homogeneous with respect to flotation properties in the initial moments of the process, the particles undergoing flotation have the highest flotation properties according to the equation of zero order and, next, according to the equation of 1\2 order. With time, the particles of decreasing ability to flotation undergo flotation and, simultaneously, the order of flotation kinetics increases. Narrow size-and-density coal fractions of intermediate floatabilty (type 33 of Polish classification) float according to the first order kinetic equation. From the theoretical point of view they can be assumed to be a homogenous material with respect to flotation properties.

PL

Flotacja jako zjawisko kinetyczne i termodynamiczne jest procesem losowym. Zmienna losowa oznaczająca liczbę ziaren flotujących, przyczepionych trwale do powierzchni pęcherzyka, a w konsekwencji i uzysk, są zależne od czasu. Dla opisu tej zależności opracowano szereg modeli kinetyki flotacji. Każdy z tych modeli ujmuje wprawdzie inny aspekt zagadnienia, lecz modele te się wzajemnie uzupełniają. W tym artykule podano szczegółową analizę modelu opartego na kinetyce reakcji chemicznej oraz na modelu absorpcji chemicznej. Z analizy równań tych modeli wynika, że w przypadku flotacji nadawy niejednorodnej pod względem własności flotacyjnych, w początkowych chwilach trwania procesu flotują ziarna o najwyższych własnościach flotacyjnych według równania rzędu zerowego a następnie według równania rzędu 1. W miarę upływu czasu flotują ziarna o coraz niższych własnościach flotacyjnych i zwiększa się zarazem rząd kinetyki flotacji. Wąskie klaso-frakcje węgla o średnich własnościach flotacyjnych (typ 33) flotują według równania kinetyki rzędu I. Można więc z teoretycznego punktu widzenia uznać je za materiał jednorodny pod względem własności flotacyjnych.

8

Kinetic of Methanol Decomposition on Cu/ZnO/ZrO2 Catalysts

Grabowski R., Kozłowska A.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 2

287-298

EN

Interaction of methanol with Cu/ZnO/ZrO2 (with different copper content) has been investigated by gravimetric and TPD methods. The TPD measurements of methanol adsorption on these catalysts show that it forms the complexes of two types. The first complex (I) decomposes at low temperature (453 K) yielding H2 and CO2and second (II) decomposes at the temperature (573 K) giving CO andH2. In the process of the decomposition of the complex (I) takes part water which is adsorbed on the surface of the catalyst and the decomposition of the complexes (II) occurs without participation of adsorbed water. Gravimetric measurements of methanol adsorption show that Cu facilitates adsorption of methanol and that an increase of copper content leads to the changes in the kinetics of methanol adsorption and its decomposition. On the basis of gravimetric measurements a model of methanol adsorption and decomposition on Cu/ZnO/ZrO2 catalyst has been proposed and the rate constants of methanol adsorption (ka) and decomposition with and without participation of water (k1 and k2) have been determined.

9

Model kinetyki zmian porowatości betonów samozagęszczalnych (SCC)

Łaźniewska B.

Zeszyty Naukowe. Budownictwo / Politechnika Śląska

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2003

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z. 101

239-246

PL

W referacie podjęto problematykę badania zmian porowatości SCC. Wykorzystano model numeryczny kinetyki zmian porowatości, który bazuje na teorii homogenizacji tworzywa [18, 19, 20]. W wyniku procesu samozagęszczania w tworzywie występuje pewna ilość porów powietrznych. Z punktu widzenia odporności mrozowej stwardniałego tworzywa powinno się ono charakteryzować optymalną zawartością porów powietrznych. Wielkość porów oraz ich rozstaw również decyduje o mrozoodporności SCC, o czym będzie mowa w niniejszym referacie. Postawiono tezę, że istnieje związek między kinetyką zmian porowatości mieszanki a odpornością mrozową stwardniałego tworzywa.

EN

This report brings closer problem of investigation of SCC porosity changes. Numeric model kinetics of porosity changes is bases on theory of homogenisation with guarantees suitable quantity of aerial pores witch doubtlessly enlarges frost resistance of concrete.

10

Potassium Effects on Kinetics of Propane Oxydehydrogenation on Vanadia-Titania Catalyst

Grabowski R., Samson K.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 4

459-470

EN

Oxidative dehydrogenation of propane (ODH) over V2O5/TiO2 and V2O5/TiO2 doped with K was carried out by measuring conversions and selectivities for various feed compositions, contact times and temperatures. The results obtained for both catalysts were interpreted on the basis of the mechanism, in which propene is formed through Eley-Rideal sequence of steps, i.e. without participation of the adsorbed propane species. Kinetic constants (activation energies, pre-exponential factors) for the model ofODHreaction of propane on these catalysts, obtained on the basis of steady-state results, are given. Addition of K to vanadia-titania catalysts leads to the decrease of total combustion of propane and consecutive combustion of propene. It has been found that the direct propane total oxidation is 5_9 times lower than that of the consecutive propene oxidation and is almost temperature independent for potassium doped catalyst, whereas it quickly decreases with temperature for a non-doped catalyst. Secondly, the addition of K to a vanadia-titania catalyst decreases the activation energies for propene formation (k1), parallel formation of COx (k3) and reoxidation of the catalyst (kOS). Potassium exhibits a stronger inhibitory effect on the secondary propene combustion, what reflects the lower acidity of V+5 cations modified by the strongly basic alkali oxide species.