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1

Phosphoric Acid Treated Oil Palm Trunk Waste for Removal of Malachite Green – Kinetics and Isotherm Investigations

Zainon Abidin Zarifah Aisyah, Al-Amrani Waheeba Ahmed, Mohd Suah Faiz Bukhari, Ibrahim Shariff, Megat Hanafiah Megat Ahmad Kamal

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 6

33--43

EN

Dyeing operations in industries like textiles, paper, and leather are significant contributors to environmental pollution due to the release of harmful dyes. The current study aimed to examine the use of oil palm trunk (OPT) treated with phosphoric acid (PAOPT) to remove malachite green (MG) dye from aqueous solutions through batch adsorption experiments. Spectroscopic and quantitative tests were used to characterise the PAOPT adsorbent. The effects of initial solution pH (3–6), PAOPT dosage (0.02–0.10 g), and adsorption duration (0–120 min) were studied. The adsorption rate of MG followed a pseudo-second-order kinetic model with a high regression correlation (R2 ) and a low chi-squared value (χ2 ). The single-layer adsorption of PAOPT for MG was determined to be 217.23 mg/g at a pH of 6, 0.02 g PAOPT mass, 20 min contact time, and 298 K. The percentage of MG desorption from the loaded PAOPT using distilled water and 0.01 M HCl was 0% and 19.65%, respectively, indicating the possible involvement of electrostatic interactions between the dye and PAOPT, π-π interaction and hydrogen bonding. The experimental results of the current study and the assessment with other stated adsorbents indicate that PAOPT could be used as a cost-effective alternative adsorbent for MG removal.

2

The behaviour of tannic acid adsorption on fluorite surface: isotherm, kinetic and thermodynamic studies

Tangarfa Mariam, Semlali Aouragh Hassan Naoul

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 1

77--87

EN

Fluorite is an important mineral to produce hydrofluoric acid. As fluorite resources contain calcite as a gangue mineral, the separation between these two calcium containing minerals is difficult. Tannic acid is the most commonly used reagent as a depressant to separate fluorite from calcite by flotation. To enhance this separation, it is so primordial to understand tannic acid physicochemical reactivity via these minerals. Therefore, the aim of this work is to investigate the mechanism of tannic acid adsorption on the fluorite surface by experimental study using isotherm, kinetic and thermodynamic. Adsorption isotherm modelling results showed that the adsorption process is well described by Sips model. On the other hand, the kinetic and thermodynamic require firstly the adsorption study as a function of three main reactional parameters including initial tannic acid concentration, solution pH and temperature. This study showed that acidic pH as well as initial tannic acid concentration increase and temperature decrease promote the studied adsorption. These finding were then exploited to determine the adsorption mechanism by pseudo n order kinetic model adjustment to experimental kinetic data using nonlinear regression method. Obtained high correlation coefficient and low mean absolute error at 95 % confidence level showed good agreement of experimental kinetic data with the tested model. These results revealed that the mechanism of tannic acid adsorption onto fluorite was attributed to a chemical reaction. In addition, the thermodynamic study showed that the studied adsorption process was exothermic.

3

Use of Eichhornia Crassipes as a Bioadsorbent for the Removal of Methyl Orange and Methylene Blue Present in Residual Solutions

Hernández-Origel Carlos David, Patiño-Saldivar Laura, Salazar-Hernández Mercedes, Ardila Alba Nelly, Talavera-López Alfonso, Hernánez-Soto Rosa, Hernández José Alfredo

Journal of Ecological Engineering

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2022

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Vol. 23, nr 9

193--211

EN

The textile industry is very important because its products are widely used by society, however, this activity has a great contribution to the contamination of water resources due to its effluents that contain large amounts of colorants, among which is the blue of methylene (MB) and methyl orange (MO) that can cause damage to the health of living being. For this reason the present study concerned the removal of these dyes by adsorption using Eichhornia Crassipes (Water lily) with different treatments. The results show that the chemisorption removal process using two sites per dye molecule having an exothermic nature for the water-treated lily and for the NaOH-treated lily is endothermic. The maximum adsorption capacities of 228.9 mg/g for MB (60 °C) and 155.38 mg/g (30 °C) for MO with the NaOH treatment were achieved. The SEM analysis shows that there are significant changes in the surface due to the treatments. The XRD patterns indicate that with the pretreatment with NaOH the crystallinity of WL increases while the treatment with water maintains the presence of amorphous cellulose. In the FTIR spectra, the bands corresponding to different functional groups such as lignin, cellulose and hemicellulose that participate in the adsorption of both dyes are observed.

4

The formation of Si-aluminide coating formed by plasma spraying and subsequent diffusion annealing on Ti-Al-7Nb intermetallic alloy

Góral M., Monteiro P.C., Sosnowy C., Woźniak M., Kubaszek T., Kościelniak B.

Archives of Materials Science and Engineering

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2022

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Vol. 117, nr 2

49--56

EN

Purpose: In the article, the kinetic growth phenomena of aluminide coating formed by plasma spraying pure Al-Si powder and subsequent diffusion annealing on TiAl intermetallic alloy in inert atmosphere were investigated. Design/methodology/approach: The Al-Si powder was thermal sprayed (APS) on TiAl7Nb intermetallic alloy and annealed in Ar atmosphere during 5, 15, 30, 60, 240 and 480 min. The kinetic growth of the coating was observed using the scanning electron microscopy method (SEM), and chemical composition was analysed using the EDS method. Findings: The Kirkendall Effects pores formation, as well as titanium silicides on the grain boundary of TiAl3, was found. Research limitations/implications: The oxidation resistance of the developed coating might be analysed in further work. Practical implications: The developed coating might be used for the production of protective aluminide coatings on TiAl intermetallic alloys. Originality/value: The description of aluminide coating formation in a new technological process.

5

Mechanism of the oxidation of nitric oxide with oxygen

Głowiński Józef, Hoffmann Józef, Wilk Marcin

Polish Journal of Chemical Technology

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2021

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Vol. 23, nr 1

31--36

EN

Very fast reactions of forming higher nitrogen oxides set out an equilibrium framework for the course of the reaction of nitrogen monoxide oxidation. The slow course of reaction of nitrogen monoxide with oxygen permanently violates the created equilibria. In particular, the equilibrium of the oxidation reaction of nitrogen monoxide with nitrogen dioxide. The contribution of this reaction to the transformation of nitrogen monoxide in the conditions of nitrogen trioxide removal from the gas phase was estimated.

6

Oxalate Intercalated Mg/Cr Layered Double Hydroxide as Adsorbent of Methyl Red and Methyl Orange from Aqueous Solution

Badri Arini Fousty, Juleanti Novie, Palapa Neza Rahayu, Hanifah Yuliza, Mohadi Risfidian, Mardiyanto, Lesbani Aldes

Ecological Engineering & Environmental Technology

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2021

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Vol. 22, iss. 3

71--81

EN

Mg/Cr layered double hydroxide (LDH) has been successfully synthesized by means of the coprecipitation method followed by the intercalation process using oxalate to form Mg/Cr-oxalate. The materials were characterized using XRD, BET, and FTIR and then applied as an adsorbent of anionic dyes i.e. methyl red (MR) and methyl orange (MO). MR and MO adsorption was studied through variations of adsorption time, concentration, temperature, desorption process, and adsorbent regeneration. The XRD characterization results showed an increase in the interlayer distance from 7.62 Å to 11.35 Å after the intercalation process. The increase of interlayer space of Mg/Cr-oxalate is also equal to the BET data, which shows an increase in surface area from 21.511 m2/g to 49.270 m2/g. The kinetics and isotherm parameters of MR and MO adsorption using Mg/Cr LDH and Mg/Cr-oxalate showed the same results following the PFO kinetics model and Langmuir isotherm model with R2 close to one. Mg/Cr LDH has the adsorption capacity for MR and MO up to 61.728 mg/g 54.645 mg/g, respectively. In turn, the highest adsorption capacity is achieved by Mg/Cr-oxalate for MR adsorption at 81.235 mg/g and MO at 71.429 mg/g. The thermodynamic parameters of MR and MO adsorption using Mg/Cr LDH and Mg/Cr-oxalate indicate that the adsorption process is endothermic and spontaneous.

7

Dissolution kinetics of malachite in ethylene diamine phosphate solutions

Shen Peilun, Liu Ruizeng, Liu Dianwen, Zhan Xiaolin, Jia Xiaodong, Song Kaiwei

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 4

1039--1048

EN

Ethylene diamine phosphate (EDP), as a synthetic organic reagent, was used for the first time to leach malachite, and a new method of using organic amine to leach copper oxide ore was developed. The effects of stirring speed, particle size, reagent concentration, and reaction temperature on EDP-dissolution malachite were investigated. Results showed that malachite rapidly dissolved in EDP solution. The malachite-dissolving rate also increased with increased reagent concentration, increased reaction temperature, and decreased particle size. Stirring speed exhibited nearly no effect on EDP-induced malachite dissolution. The leaching kinetics was found to follow the shrinking-core model, and dissolution was controlled by surface chemical reaction with an activation energy of 52.63kJ×mol−1. A semiempirical rate equation was obtained to describe the dissolution process expressed as 1-(1-XCu)1/3=0.0149(CEDP)0.7814 × (Pmalachite)−0.7982×exp(−6.3308/T) ×t.

8

The Influence of Steric Stabilization on Process of Au, Pt Nanoparticles Formation

Luty-Błocho M.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

55--63

EN

Nanoparticles are very fascinating area of science not only due to their unique properties but also possibility of producing new more complex materials, which may find an application in modern chemistry, engineering and medicine. In process of nanoparticles formation very important aspect is a rate of individual stage i.e. reduction, nucleation and autocatalytic growth, because this knowledge allows for proper materials design, morphology manipulation, stability. The last one aspect can be realized using proper electrostatic, steric and electrosteric stabilization. However until now nobody reports and measures kinetic rates of all stages during process of particles formation in the presence of steric stabilizers. Thus, the main contribution of this paper is determination of individual rate constants for nanoparticles formation in the presence of steric stabilizers and their comparison to the system without stabilizer. For this purpose, an aqueous solution of Au(III) and Pt(IV) ions were mixed with steric stabilizers like PVA and PVP, and reduced using L-ascorbic acid as a mild and sodium borohydride as a strong reductant. As a results stable nanoparticles were formed and process of their formation was registered spectrophotometrically. From obtained kinetic curves the values of observed rate constants for reduction metal ions, slow nucleation and fast autocatalytic growth were determined using Watzky-Finke model. It was found that the addition of polymer affects the rate of the individual stages. The addition of steric stabilizers to gold ions reduced with L-ascorbic acid causes that the process of nucleation and autocatalytic growth slows down and the value of observed rate constants for nucleation changes from 3.79·10-3 (without polymer) to 7.15·10-5 s-1 (with PVA) and for growth changes from 1.15·103 (without polymer) to 0.48·102 s-1 M-1 (with PVA). However, the rate of the reduction reaction of Au(III) ions is practically unchanged. In case of using strong reductant the addition of polymer effects on the shape of kinetic curve for reduction of Au(III) and it suggests that mechanism is changed. In case of Pt(IV) ions reduction with L-ascorbic acid, the process speeds up a little when PVA was added. Determined values of observed rate constants for nucleation and growth platinum nanoparticles decrease twice comparing to the system without polymer. The reduction of Pt(IV) ions with sodium borohydride accelerates when PVP was added and slows down when PVA was used. Moreover, the size of obtained colloidal gold and platinum was also analysed using DLS method. Obtained results (rate constants) may be useful in the process of nanomaterials synthesis, in particular in microflow.

9

The effect of particle size on coal flotation kinetics: A review

Sokolović J. M., Miskovic S.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 4

1172--1190

EN

Coal flotation is a complex multiphase process governed by different sub-processes and interphase interactions. The coal cleaning efficiency by flotation is largely affected by many different physical and chemical factors that can be roughly classified into three main group: coal feed properties, pulp chemical and rheological properties, and machine and operational properties. A great number of flotation kinetic model have been proposed in literature but a vast majority uses three parameters to describe the flotation kinetics, which are the ultimate recovery, the flotation rate constant, and flotation time. The models expand on the classical theory of flotation proposed by Zuniga (1935) that is based on the assumption that the particle–bubble collision rate is first-order with respect to the number of particles in the system, while bubble concentration remains constant. The flotation rate constant is directly proportional to available bubble surface area and probability of flotation, which is strongly dependent on particle size. Therefore, particle size is one of the most important parameters in coal flotation because it affects gas bubble mineralization and froth stability, bubble size distribution and air holdup, bubble-particle collision, attachment, and detachment rates, and reagent adsorption. Numerous researchers have studied the effect of particle size on flotation kinetics over years. This paper provides a comprehensive review of coal flotation kinetics models with a special focus on the effect of particle size on coal kinetic rate, recovery, and product quality. A particular emphasis will be put on research findings reported over the last three decades.

10

Adsorption of penicillin by decaffeinated tea waste

Gharbani P., Mehrizad A., Jafarpour I.

Polish Journal of Chemical Technology

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2015

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Vol. 17, nr 3

95--99

EN

Removal of penicillin has been investigated using decaffeinated tea waste (DCTW). Decaffeination of tea waste was investigated using different methods. Results indicate that ozonation was the most effective process for removal of penicillin. Batch adsorption experiments were completed at various temperatures (20, 30, and 40°C), DCTW dosages (2, 4, 6, 8, and 10 g per 250 mL), penicillin concentrations (4, 10, and 14 mg/L), and pH (3, 7, and 10) conditions. Studies showed that adsorption reaches equilibrium within 40 min. The main factor affecting adsorption of penicillin was the solution pH, with maximum adsorption occurring at pH 3. Higher adsorbent dosages and lower penicillin concentrations also resulted in higher percentages of penicillin removal. Results show that data obeyed the pseudo-first-order kinetic and Freundlich isotherm models. This process proves that low-cost DCTW could be used as a high performance adsorbent for removing penicillin from aqueous solutions.

11

Synthesis Of Magnesium-Aluminum Layered Double Hydroxides By Mechanochemical Method And Its Solid State Reaction Kinetics

Hongbo Y., Meiling C., Xiuhui W., Hong G.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1455--1457

EN

A mechanochemical method is developed in preparing magnesium-aluminum-layered double hydroxides (MgAl-LDHs). This approach includes activation process and diffusion process. In order to verify the LDHs structure and study the reaction kinetics, X-ray diffraction (XRD) patterns, inductively coupled plasma(ICP) and physical adsorption instrument were characterized. The results show that activation time can change the surface of particles and affect the reaction grade. During the diffusion process, reaction time is the most important factor. The reaction energy (ΔQ) was calculated that is 6kJ/mol.

12

Mechanizm zgazowania ditlenkiem w aspekcie równań kinetycznych

Mianowski A., Radko T., Siudyga T.

Karbo

|

2014

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Nr 4

181--187

PL

Przeprowadzono analizę kinetyczną reakcji Boudouarda-Bella (B-B) przebiegającą w złożu stałym czynnika zgazowywanego w strumieniu przepływającego CO2 w warunkach izotermicznych. Analiza dotyczyła fazy gazowej, do której w przeciwieństwie do klasycznej teorii Erguna przypisano udział produktu pośredniego. Rozwiązując układ liniowych równań kinetycznych (z wykorzystaniem transformacji Laplace’a) wykazano, że dla czasu zmierzającego do nieskończoności zależność opisująca udział molowy CO od czasu, posiada charakter asymptotyczny. W wyniku prac doświadczalnych otrzymuje się również zależności udziału molowego CO vs. czas wykazujące maksimum. Stosowne równanie uzyskuje się po modyfikacjach przyjętych ścieżek reakcji, jednakże mało prawdopodobnych ze względu na mechanizm zgazowania z udziałem aktywnych centrów reakcji. Uzyskane rozwiązania umożliwiły wyprowadzenie jednego dwuczłonowego równania (68), które obejmuje trzy charakterystyczne przypadki tj. charakter asymptotyczny [CO]∞ < 1 lub [CO]∞ = 1 oraz zależności wykazujące maksimum względem czasu. Propozycja wynika z założenia, że przebieg reakcji/procesu B-B jest wynikiem szybszej, mimo że odwracalnej, reakcji chemicznej w stosunku do wolniejszego procesu degradacji kompleksu tlenowego i desorpcji.

EN

Kinetic analysis of Boudouard-Bell reaction (BB) was performed for fixed bed in CO2 stream under isothermal conditions. The analysis was performed for gaseous phase and participation of the intermediate product in this phase was assigned in contrast to the classical Ergun theory. It was proved by solving a set of linear kinetic equations (using the Laplace transforms) that for the time tending to infinity relation describing of CO mole fraction with time is asymptotic. Relations of CO mole fraction vs. time exhibiting maximum were also obtained during experiments. Appropriate equation is obtained after modification of adopted reaction paths, however unlikely because of gasification mechanism with participation of active sites of reaction. Obtained solutions allowed derivation of the single, double-element equation (68) which covers three specific cases i.e. asymptotic form [CO]∞ < 1 or [CO]∞ = 1 and relations exhibiting maximum vs. time. This proposal results from the assumption that course of B-B reaction/process is result of faster, although reversible chemical reaction in relation to slower process of degradation of oxygen complex and desorption.

13

Badania kinetyki reakcji hydrokonwersji triglicerydów

Jęczmionek Ł.

Przemysł Chemiczny

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2013

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T. 92, nr 10

1941-1945

PL

Wstępnie uwodorniony olej z orzechów laskowych w mieszaninie z parafiną ciekłą poddawano hydrokonwersji za pomocą komercyjnego katalizatora NiMo w reaktorze przepływowym (9–20 h-1), pod ciśnieniem 3 MPa, w zakresie temp. 320–340°C, w celu zbadania kinetyki reakcji otrzymywania węglowodorów. Przedstawiono dyskusję uzyskanych wyników w odniesieniu do mechanizmu reakcji.

EN

Hydrorefined hazel-nut oil was mixed with liq. paraffin and hydrogenated at 320–340°C under 3 MPa in a flow reactor (9–20 h-1) over a com. NiMo catalyst to det. the kinetics of hydrocarbon formation. Mechanism of the reaction was discussed.

14

Modelowanie kinetyki fotoprzewodnictwa półizolującego GaAs

Suproniuk M., Pawłowski M., Kamiński P., Kozłowski R.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 9

165-168

PL

Rozwój energetyki w dużej mierze zależy od właściwości materiałów półprzewodnikowych, z których wytwarzane są elementy układów przekształtników energoelektronicznych. Stosowane dotychczas elementy na bazie krzemu są obecnie wypierane przez elementy produkowane na bazie arsenku galu. Parametry nowego typu przyrządów silnie zależne są jednak od właściwości i koncentracji defektów punktowych sieci krystalicznej w tym materiale, które badane są metodą niestacjonarnej spektroskopii fotoprądowej. W artykule zaproponowano model i przeprowadzono analizę wpływu szybkości generacji par elektron-dziura na szybkość narastania koncentracji nadmiarowych nośników ładunku dla założonych właściwości i wartości koncentracji centrów defektowych w półizolującym GaAs.

EN

Energy development largely depends on the properties of semiconductor materials, which are used for fabrication of power converters system components. Used so far silicon-based components are now being replaced by elements of made of gallium arsenide. The parameters of the new type of devices, however, are strongly dependent on the properties and concentrations of lattice point defects in this material. The photoinduced transient spectroscopy is a powerful method for studying defect centers in semi-insulating (SI) GaAs. A model is proposed and the analysis of the effect of the electron-hole pairs generation rate on the rise of the excess charge carriers concentrations in semi-insulating GaAs for the assumed properties and concentrations of defect centers has been performed.

15

The metastable eutectic growth

Trepczyńska-Łent M.

Journal of Polish CIMAC

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2012

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Vol. 7, no 3

347-352

EN

The paper presents adaptation problem of metastable growth of eutectic. In the case of rapid solidification the ledeburite eutectic structure in Fe-C system is become. This cementite eutectic is one from the most commercial eutectic of quasiregular eutectics group.

16

The kinetics of the thermal decomposition of the willow wood (Salix viminalis L.) exposed to the torrefaction process

Walkowiak M., Bartkowiak M.

Drewno : prace naukowe, doniesienia, komunikaty

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2012

|

vol. 55, nr 187

37-49

EN

The aim of the study was to analyze the kinetic parameters (activation energy Ea, pre-exponential coefficient A, rate constant k) of thermolysis in torrefied and raw willow wood (Salix viminalis L.), as well as to determine the effect of thermal modification conditions on the kinetics of this process. Samples of raw and torrefied willow wood in a steam atmosphere were analysed. The samples were subjected to thermogravimetric analysis under isothermal conditions. Analyses were conducted in an atmosphere of helium at 270–330 C degree. TG and DTG curves were recorded. The thermal characteristics of the samples were based on thermogravimetric analysis under dynamic conditions at a temperature of up to 600 C degree. On the basis of the data obtained from the TGA analyses, the kinetic parameters were calculated and statistical and mathematical analyses of the results were performed.

PL

Celem pracy było obliczenie parametrów kinetycznych (energii aktywacji Ea, współczynnika przedwykładniczego A, stałej szybkości k) procesu termolizy prażonego i surowego drewna wierzby konopianki (Salix viminalis L.) oraz określenie wpływu warunków modyfikacji termicznej na kinetykę tego procesu. Stosowano próbki wikliny surowej oraz prażonej w następujących warunkach: temperatura procesu 200 stopni C, czas prażenia: 6 godzin (W-200-6-H2O), 12 godzin (W-200-12-H2O) oraz 24 godziny (W-200-24-H2O). Proces był prowadzony w atmosferze pary wodnej, działającej przez 6 godzin w początkowym okresie modyfikacji. Surowce poddano analizie termograwimetrycznej w warunkach izotermicznych. Analizy były prowadzone w atmosferze helu w temperaturach 270 stopni C, 285 stopni C, 300 stopni C, 330 stopni C. Rejestrowano krzywe TG i DTG. Charakterystykę termiczną wikliny oparto na analizie termograwimetrycznej w warunkach dynamicznych, w temperaturze do 600°C. Na podstawie danych otrzymanych z wykonanych analiz obliczono parametry kinetyczne (Ea, A, k) i przeprowadzono analizę statystyczno- matematyczną wyników. Wartość energii aktywacji procesu termolizy wikliny zawierała się w przedziale 138,1– –227,3 kJ/mol. Największą wartość Ea (227,3 kJ/mol) uzyskano w przypadku wikliny prażonej w temperaturze 200 stopni C, w czasie 24 godzin (W-200-24-H2O). Surowiec ten również okazał się najbardziej odporny termicznie. W celu ustalenia funkcji g(.), która najlepiej opisuje proces termicznego rozkładu surowego i prażonego drewna wierzby konopianki wybrano trzy modele kinetyczne: F1, D3, R3. Modelem, który najlepiej opisywał dane doświadczalne był model D3, odnoszący się do procesu dyfuzji trójwymiarowej.

17

CFD analysis of mixing intensity in jet stirred reactors

Gil I., Mocek P.

Chemical and Process Engineering

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2012

|

Vol. 33, nr 3

397-410

EN

The homogeneous stirred reactor designed for kinetic studies of the combustion of hydrocarbons with intensive internal recirculation in high temperature combustion chamber is described. The originality of our reactor lies in its construction which allows to intensively mix fuel and flue gases, measure gas temperature as well as obtain samples which can be used to investigate diffusion flames. The cylindrical construction enables to use the reactor in laboratory cylindrical electrically heated ovens. The CFD analysis of the reactors, the mixing parameters (turbulent Peclet number and mixing level) and the volume average temperature in the reactors were elaborated on the basis of the typical dimensions of classical reactors to kinetics research as well as the own reactor design. The results of the analysis allow to reveal advantages of our construction.

18

Utilization of agricultural and industrial wastes for metal removal from aqueous solutions

Biegańska M., Cierpiszewski R.

Polish Journal of Chemical Technology

|

2011

|

Vol. 13, nr 1

20-22

EN

In this study a possibility of obtaining sorbents from basketry wastes has been investigated. Therefore, adsorption of cadmium ions on wicker bark of Salix americana has been studied. The obtained experimental results were described by the Freundlich equation and adsorption kinetics by the pseudo-second order equation. The effect of pH on cadmium ions adsorption by S. americana was also investigated. It has been found that for the pH values ranging from 2 to 7 cadmium removal from the solution was held at almost constant level.

19

Adsorption behavior of Pb(II) onto xanthated rubber (Hevea brasiliensis) leaf powder

Khalir W.K.A.W.M., Hanafiah M.A.K.M., So’ad S.Z.M., Ngah W.S.W.

Polish Journal of Chemical Technology

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2011

|

Vol. 13, nr 4

82-88

EN

A plant waste, rubber (Hevea brasiliensis) leaf powder was modified with carbon disulfide (xanthation) for the purpose of introducing sulfur groups, and the adsorbent performance in removing Pb(II) ion was evaluated. Pb(II) adsorption was confirmed by spectroscopic analysis, which involved Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The amount of Pb(II) adsorbed increased with increasing pH, contact time and concentration but slightly decreased with increasing ionic strength. Adsorption equilibrium was achieved in less than 60 min and followed the pseudo-second order model. The isotherm data indicated that Pb(II) adsorption on xanthated rubber leaf (XRL) fitted well with Langmuir isotherm model. The maximum adsorption capacity computed from the Langmuir isotherm model was 166.7 mg/g. Pb(II) adsorption occurred via ion-exchange and complexation mechanisms.

20

Wspólne oddziaływanie dodatku popiołu lotnego i domieszki napowietrzającej na kinetykę hydratacji kompozytów cementowych

Ezerskiy V., Lelusz M.

Budownictwo i Inżynieria Środowiska

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2011

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Vol. 2, no. 2

129-135

PL

W pracy przedstawiono wyniki eksperymentu laboratoryjnego wpływu ilości popiołu lotnego i domieszki napowietrzającej, współczynnika wodno-cementowego oraz czasu dojrzewania na wytrzymałość na ściskanie (odpowiedź Y) próbek zaprawy cementowej. W eksperymencie rozpatrywano następujący zakres zmienności czynników: czynnik X1 (Pl/C) – od 0 do 0,33; czynnik X2 (d/C) – od 0 do 0,003; X3 (W/C) – od 0,5 do 0,6; czynnik X4 (czas dojrzewania) – od 28 do 180 dni. Na podstawie wyników opracowano model matematyczny zależności Y = f(X1, X2, X3, X4) oraz przeanalizowano charakter i stopień wpływu poszczególnych czynników. Przestrzeń czynnikową zbadano na występowanie ekstremum. Ustalono, że maksymalne wartości wytrzymałości na ściskanie uzyskuje się przy następujących wartościach czynników: X1= +1; X2= -1; X3= -0,1; X4= 0,9, tj. przy ilości popiołu Pl/C=0,33; bez domieszki napowietrzającej; dla W/C=0,54 z oraz po 169 dniach dojrzewania.

EN

The results of laboratory investigation concerning the influence of: the amount of fly ash and air-entraining admixture, the W/C ratio, and the time of curing is presented in the paper. The range of changeability factors was determined: X1 factor (the amount of fly ash) – from 0 to 33%; X2 factor (the amount of air-entraining admixture) – from 0 to 0,3%; X3 factor (W/C ratio) from 0.5 to 0.6; X4 factor (the time of curing) – from 28 to 180 days. On the basis of the results a mathematical model was elaborated Y = f(X1, X2, X3, X4), and the character and the grade of influence of each factor were analysed. The factor space was examined for occurrence of extrema. The optimum factor values assuring maximum compressive strength were given. They are for the following factor values: X1 = +1; X2 = –1; X3 = –0.1; X4 = 0.9, i.e.: with the amount of fly ash Pl/C = 0.33; without the airentraining admixture; with W/C = 0.54 and after 169 days of curing.