Wyniki wyszukiwania - Biblioteka Nauki

1

A direct method of studying colloid interactions and adsorption at solid / liquid interfaces

100%

Adamczyk Z. , Szyk L. , Warszyński P.

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1998

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tom Vol. 46, No. 4

425-439

EN

A new cell for direct in situ observations of colloid particle adsorption was developed. The controlled convective transport conditions were created by exploiting the slot impinging jet (SIJ) principle. Numerical solutions of the governing Navier-Stokes equation showed that the flow pattern in the cell can be approximated by the planeparallel stagnation flow with the perpendicular velocity component independent of the lateral distance X. Thus, the solid/liquid interface at distances close to the symmetry plane was found uniformly accessible for particle transport. This flow field was used to derive the mass transport equation which was then numerically solved to obtain the initial flux (adsorption rate) for various transport conditions. These theoretical predictions were verified experimentally using monodisperse polystyrene latex particles. A good agreement between predicted and measured initial flux was found for a broad range of Reynolds number and ionic strength of the particle suspension. This confirmed that the SIJ cell can be used as a useful tool of studying colloid and bioparticle interactions and adsorption under well-defined transport conditions.

2

ATORVASTATIN ADSORPTION STUDIES ON CHITOSANS IN AN in vitro PHARMACEUTICAL MODEL

80%

Meler J. , Grimling B. , Szcześniak M. , Karolewicz B. , Biernat P.

Progress on Chemistry and Application of Chitin and its Derivatives

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2018

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tom 23

140 - 148

EN

During the pharmacological therapy of specific diseases, drugs are used which, with other preparations or foods, can create connections, in many cases changing or even blocking their action. On the other hand, the use of unsuitable polymers as excipients may result in drug-polymer incompatibilities. Interactions consisting mainly of the occurrence of the adsorption phenomenon and on the formation of complex bonds that reduce the effect of the drugs are of particular importance. The aim of the study was to investigate whether the active substance atorvastatin is incompatible with dietary supplements containing chitosan. The phenomenon of the adsorption of the drug was examined using a static model of a pharmaceutical gastrointestinal tract, in the concentration range generally ingested in a single dose. Measurement results of the amount of bound drug were used to determine the average percentage of adsorbed drug dose. The results of the study prove that the anticholinesterase drug is adsorbed on chitosan in the pH ranges used, and that the binding capacity depends on the chitosan variety, which indirectly affects the reaction of the environment. It was observed that the average size of sorption depending on the chitosan variety ranged from 38% to 86%. The fact that the lowest value of adsorption was at pH 6.4 can be explained by the chemical properties of chitosan, which shows a charge only at pH >6.7. Under such conditions, the phenomenon of electrostatic adsorption may occur in relation to the healing substances of weak acids. At a pH above 7.6, corresponding to the intestinal fluid-filled intestine, the mean sorption for the highest dose of chitosan was from 38–86%. The increase in the adsorbed amount of anticholinesterase drugs on the polymer along with the increase in pH from 7.6 to 8.0 can be explained by the chitosan swelling properties, which increase with an increase in the pH. As a result, the specific surface area of the polymer and its sorption capacity increase. Based on the above considerations, it can be concluded that there is an antagonistic interaction between the drug and the polymer studied, which involves the adsorption of a drug from this group on the polymer (chitosan) and a decrease in its bioavailability

3

Modeling of experimental data for the adsorption of methyl orange from aqueous solution using a low cost activated carbon prepared from Prosopis juliflora

80%

Kumar M. , Tamilarasan R.

Polish Journal of Chemical Technology

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2013

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tom 15

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nr 2

29-39

EN

This paper presents the feasibility for the removal of methyl orange (MO) dye from aqueous solution using an activated carbon prepared from Prosopis juliflora bark. Batch adsorption experiments were carried out as a function of pH, contact time, adsorbate concentration, adsorbent dosage and temperature. The commonly applicable isotherms namely Freundlich and Langmuir equations are used for the prediction of isotherm parameters. A comparison of linear least-square method and a trial-and-error non-linear method are examined in Freundlich and Langmuir (Four forms) isotherms. The nature of adsorption isotherm feasibility was evaluated with dimensionless separation factors (RL). The dynamics of adsorption process was analyzed with Lagergren’s Pseudo-first order and Pseudo-second order kinetic equations. Thermodynamic parameters like the change in enthalpy (ΔHo), change in entropy (ΔSo) and change in Gibbs free energy (ΔGo) were evaluated and ΔGo shows a negative value whereas ΔHo shows the positive value indicating that the adsorption process was spontaneous and endothermic in nature. The functional group characterization of the adsorbent was done using Fourier transform infrared spectroscopy (FTIR). The thermal stability of activated carbon was analyzed using Thermo gravimetric analysis (TGA) and Differential thermal analysis (DTA).

4

Activated carbons for the removal of heavy metal ions: A systematic review of recent literature focused on lead and arsenic ions

80%

Deliyanni E. A. , Kyzas G. Z. , Triantafyllidis K. S. , Matis K. A.

Open Chemistry

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2015

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tom 13

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nr 1

EN

This work is a systematic review of the literature over the past decade of the application of activated carbon (microporous or mesoporous) as adsorbents for the removal of heavy metals, focusing especially on lead (Pb) and arsenic (As) ions from the aqueous phase. Classical examples from our lab are also given. Activated carbon is known to provide a high surface area for adsorption. Generally, surface modification is typically required, such as oxidation, treatment with ammonia or even impregnation with ferric ion, etc. and the adsorbent material may originate from various sources. The pristine materials, after modification and those after batch-wise adsorption, were characterized by available techniques (BET analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, thermal analyses, X-ray photoelectron spectroscopy). Adsorption isotherms, thermodynamics and kinetics of the process are also discussed. Selected studies from the literature are examined in comparison with other adsorbents. The role of chemistry in the metals adsorption/removal was investigated.

5

Sorption of the anionic reactive red RB dye in cellulose: Assessment of kinetic, thermodynamic, and equilibrium data

80%

Silva L. S. , Lima L. C. B. , Ferreira F. J. L. , Silva M. S. , Osajima J. A. , Bezerra R. D. S. , Filho E. C. S.

Open Chemistry

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2015

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tom 13

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nr 1

EN

The cellulose matrix was characterized by FTIR, 13C NMR, XRD, TG, SEM and applied in the removal of the reactive red RB dye in an aqueous medium, with a capacity of adsorption at a pH of 2.0, and an adsorption equilibrium time which was reached at around 200 mins. The kinetic study for the system followed the Elovich model. The adsorption isotherms for the system at temperatures of 35°C, 45°C, and 55°C were adjusted to the Langmuir, Freundlich, Sips, and Redlich-Peterson non-linear models, with a capacity of adsorption for adsorbent of 5.97 mg g-1, 5.64 mg g-1, and 4.62 mg g-1, respectively. The adsorption occurred by electrostatic interactions and it was favorable and spontaneous, with the influence of temperature.

6

On the quantitative estimation of surface energetic heterogeneity of adsorbents and catalysts surfaces from TPD spectra based on the statistical rate theory of interfacial transport: variable heating rate as a promising way to establish the values...

80%

Rudziński W. , Borowiecki T. , Dominko A. , Pańczyk T. , Gryglicki J.

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1998

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tom Vol. 72, nr 9

2103-2114

EN

An essential development is presented of our new method of quantitative estimation of the energetic heterogeneity of adsorbent and catalysts surfaces from Temperature Programmed Desorption spectra, based on the Statistical Rate Theory of Interfacial Transport. That method, presented in a series of our recent publications, involved a necessity of estimating, in other than TPD experiments, of certain adsorption parameters which are necessary to calculate the adsorption energy distribution. This was a serious inconvenience of that new method. In this paper, it is shown for the first time, that these parameters can be determined in the same TPD experiment by applying variable heating rate.

7

The influence of aniline radicals concentration in the stationary phase on the retention in gas chromatography

80%

Nasuto R.

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1998

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tom Vol. 72, nr 10

2303-2311

EN

Four adsorbents with chemically bounded aniline radicals on silica gel surface of concentration 2.94; 5.86; 6.47 and 7.81 mymole/m(2) were prepared. On packed chromatographic column with unmodified silica gel Si 100 and obtained adsorbents the retention times of aliphatic (C6-C12) and aromatic (benzene, toluene and m-xylene) hydrocarbons and polar organic compounds (chloroform, ethylene chloride, chlorobenzene, p-chlorotoluene and ethyl benzene) were measured. Retention times, obtained on column with packing of the highest concentration of the bounded phase, were shorter than those on column with unmodified silica gel Si 100. Thus, there exists a possibility of optimization of retention of chemical compounds by change of their phase concentration on the support surface.

8

THE USE OF ACTIVE CARBON IMMOBILISED ON CHITOSAN BEADS FOR RB5 AND BV10 DYE REMOVAL FROM AQUEOUS SOLUTIONS

80%

Filipkowska U. , Jóźwiak T. , Szymczyk P. , Kuczajowska-Zadrożna M.

Progress on Chemistry and Application of Chitin and its Derivatives

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2017

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tom 22

14-26

EN

This paper presents the adsorption of dyes – the anionic Reactive Black 5 (RB5) and cationic Basic Violet 10 (BV10) dyes – on activated carbon (AC) immobilised on chitosan (CHs). The results were compared with the removal efficiency of RB5 and BV10 on the individual sorbents: chitosan beads and activated carbon. In this study, the sorption capacities of the sorbents, sorption pH and the point of zero charge (pHZPC) were determined. For the description of the obtained results, the Freundlich, Langmuir and double Langmuir models were used. The results show that the developed sorbent (CHs-AC) is effective for both types of dye (RB5 or BV10) over a broad pH range 4–10, which makes it a universal sorbent. The maximum sorption capacity of CHs-AC with RB5 was 639.8 mg/g, while for BV10 it was 50.7 mg/g.

9

Oddziaływania adsorpcyjne i ich wpływ na właściwości tribologiczne materiałów ceramicznych

80%

Ozimina D. , Madej M. , Kałdoński T. , Styp-Rekowski M. , Senatorski J.

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2008

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tom Z. 7

127-132

PL

W pracy przedstawiono wyniki pomiarów adsorpcji materiałów ceramicznych o jonowym i kowalencyjnym wiązaniu chemicznym. Określono oddziaływania adsorpcyjne alkiloditiofosforanu cynku - ZDDP na reprezentatywnych powierzchniach ceramicznych - Al2O3 i SiC. Następnym etapem była ocena właściwości tribologicznych ceramiki przy użyciu testera tribologicznego T-01M, pracującego w skojarzeniu kula - tarcza w warunkach tarcia ze smarowaniem modelową bazą olejowową, zawierającą 1% ZDDP. Analiza wpływu adsorpcji na właściwości tribologiczne materiałów ceramicznych pokazała znaczący wpływ rodzaju wiązania zarówno na współczynnik tarcia i zużycie liniowe tak skonfigurowanego węzła tarcia.

EN

The article discusses results of investigations of adsorption of ceramics materials with ion and atomic assimilates. The research on adsorption antiwear additives - ZDDP on ceramic surfaces - Al2O3 and SiC. The next stage of the investigations qualify of the tribological properties were obtained on a T-01M tribological ball-disc tester in during lubrication for model lubricant containing antiwear additive - 1 % ZDDP. The analysis of the adsorption on the tribological properties shows that significant influence in this configured friction junction and their relationship of the kind assimilates on the coefficient of friction and linear wear.

10

IMPACT OF CHITOSAN CROSS-LINKING ON RB 5 DYE ADSORPTION EFFICIENCY

80%

Filipkowska U. , Kuczajowska-Zadrożna M. , Jóźwiak T. , Szymczyk P. , Nierobisz M.

Progress on Chemistry and Application of Chitin and its Derivatives

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2016

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tom 21

46-54

EN

In this work, the effect of cross-linking of chitosan beads on the removal efficiency of dye RB 5 from aqueous solutions was defined. In the studies not crosslinked chitosan as well as chitosan cross-linked with a chemical cross-linking agent - glutaraldehyde and ionic cross-linking agent - pentasodium tripolyphosphate were used. The scope of the research included the determination of pH at which the adsorption process proceeded efficiently, study time, in order to designate the time, after which the reaction equilibrium is reached and to determine the kinetics of the adsorption process and constants in the Langmuir 2 equation. The work sets maximum sorption capacity of the sorbent non-crosslinked and two crosslinked sorbents. Based on these results, it was found that the highest removal efficiency of dye RB 5 was obtained for chitosan crosslinked with ion agent - pentasodium tripolyphosphate. The maximum sorption capacity of the sorbent amounted 1125.7 mg / g d.m. of chitosan.

11

ADSORPTION OF SILVER IONS ON CHITOSAN HYDROGEL BEADS

80%

Sujka W. , Rogacki G. , Modrzejewska Z. , Zarzycki R.

Progress on Chemistry and Application of Chitin and its Derivatives

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2023

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tom 28

166-187

EN

We investigated the adsorption of silver(I) from silver nitrate (AgNO3) and silver sulphate (Ag2SO4). We compared the adsorption ability of chitosan in the form of hydrogel beads with that of chitosan acetate – an initial solution from which the beads were derived. We developed a model of adsorption kinetics, assuming the simultaneous occurrence of the diffusion process and the chemical reaction. We confirmed and described the chemical nature of adsorption based on the Fourier-transform infrared and X-ray photoelectron spectra.

12

IN VITRO STUDIES OF ADSORPTION OF ERYTHROMYCIN ON CHITOSANS FROM DIETARY SUPPLEMENTS

80%

Meler J. , Grimling B. , Szcześniak M. , Biernat P.

Progress on Chemistry and Application of Chitin and its Derivatives

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2014

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tom 19

119-123

EN

In clinical practice, in the treatment of obesity, a plurality of natural high-molecular compounds are used, the activity of which supports weight loss. During the use of dietary supplements containing chitosan, illness sometimes develops and other therapeutic agents are applied as antibiotics The aim of our study was to determine the binding capacity of the antibiotic erythromycin depending on variable physicochemical factors, in the model of the gastrointestinal tract, by chitosans found in slimming dietary supplements Erythromycin adsorption phenomenon was studied by static and dynamic pharmaceutical model (according to the modified method of the Polish Pharmacopoeia) simulating in vitro conditions. The amount of bound drug was used to calculate the average percentage of the adsorbed dose. The results obtained show that erythromycin is adsorbed by chitosans at various pH ranges, and the binding capacity of the environment depends on the pH, viscosity and concentration of the antibiotic, as well as the chitosan and type and additional substances present in the gastrointestinal tract. The average level of the adsorption of erythromycin in the chitosan-nutrients system depends on the pH of the medium. The highest amount of adsorption was noted above pH 7 (chitosan precipitated polymer forming the emulsion-gel system).

13

Experimental investigation of the ecological hybrid refrigeration cycle

80%

Cyklis P. , Kantor R. , Ryncarz T. , Górski B. , Duda R.

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14

Two-Dimensional Structures Composed of Cross-Shaped Molecules Adsorbed on Solid Surfaces – a Computational Model

80%

Kasperski A. , Szabelski P.

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nr 1-2

EN

The ability of simple molecular building blocks to form extended ordered patterns by adsorption and self-assembly on solid substrates is an advantageous property that has been widely used to create nanostructured surfaces. In this contribution we demonstrate how the lattice Monte Carlo simulation method can be used to predict morphology of adsorbed overlayers comprising simple functional cross-shaped molecules resembling phthalocyanines and porphyrins. In particular, we focus on the influence of the distribution of active interaction centers within a model crossshaped molecule on the structure of the resulting molecular networks. Additionally, we investigate how using racemic mixtures of input prochiral molecules affects the chirality and porosity of the corresponding ordered patters. The obtained results show that suitable manipulation of the chemistry of cross-shaped building block allows for the controlled creation of largely diversified molecular porous networks.

15

PHOSPHATE REMOVAL FROM AQUEOUS SOLUTIONS BY CHITIN AND CHITOSAN IN FLAKES

80%

Szymczyk P. , Filipkowska U. , Jóźwiak T. , Kuczajowska-Zadrożna M.

Progress on Chemistry and Application of Chitin and its Derivatives

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2016

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tom 21

192-202

EN

The article presents the effectiveness of phosphate adsorption on the flakes of chitin and chitosan. Studies performed determined adsorption capacity of chitin and chitosan, best among the tested adsorption pH and the equilibrium time. Langmuir model was used to describe the results. The highest removal efficiency of phosphorus compounds using chitin was obtained at pH 3 and with chitosan at pH 4. The study of phosphate equilibrium concentration time obtained for both sorbents was carried out at three concentrations of 1, 5 and 10 mg/dm3. The highest sorption efficiency of the phosphate using chitin was achieved after 20 minutes of the process and at the chitosan after 40 minutes. In the case of chitosan after the equilibrium time the effect of partial P-PO4 release was observed, which could be related to the change in pH of the solution by the sorbent. Studies have shown that chitosan is a more effective absorbent for phosphorus compounds. The maximum adsorption capacity of chitosan with phosphate was 6.65 mg/g, and chitin - 2.09 mg/g.

16

Adsorption of tyrosine on Ag(110) and Ag(111) surfaces

80%

Miłkowska M. , Jurkiewicz-Herbich M.

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1998

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tom Vol. 72, nr 6

1096-1105

EN

The adsorption of tyrosine at Ag(110) and Ag(111) single crystal electrodes has been studied in aqueous solutions of 0.1 M LiClO4. The standard Gibbs energies of adsorption Delta G(0)-ads, at the potential of maximum adsorption and the interaction parameters, A, using Frumkin's isotherm were calculated. The orientation of the adsorbed tyrosine molecules is different on Ag(111) and Ag(110) electrodes. At Ag(111) the molecules adsorb flat with the benzene ring parallel to the electrode, whereas at Ag(110) electrode the orientation is propably vertical with OH group tawards the metal. The origin of that differences is propably the different atomic structure of both electrodes.

17

Characterization of carbon molecular sieves based on nitrogen and carbon dioxide adsorption

80%

Buczek B.

|

2010

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tom Vol. 31, z. 2

217-224

EN

Evaluation of carbon molecular sieves (CMSs) has been based on adsorption of nitrogen at 77 K and carbon dioxide at 273 K. Dubinin and Radushkevich theory of volume filling of micropores was used to interpret adsorption isotherms. The structure of micropores was determined based on nitrogen isotherms. Adsorption of CO2 confirmed the assumed density of adsorbed phase in the subcritical region. Due to diffusional limitations, carbon molecular sieves used for kinetically controlled processes cannot be characterized by nitrogen adsorption at 77 K. Adsorption of CO2 at 273 K has such advantages that low relative pressures are attained at temperatures sufficiently high to which avoid diffusion problems. Micropore volumes were used to predict separation abilities for CO2.CH4 mixture of carbon molecular sieve.

PL

Ocenę węglowych sit molekularnych oparto na adsorpcji azotu w temperaturze 77 K oraz ditlenku węgla w 273 K. Izotermy adsorpcji interpretowano, korzystając z teorii objętościowego zapełniania porów Dubinina i Raduszkiewicza. Analizę struktury mikroporów węglowego sita molekularnego o otwartej porowatości oparto na równowadze adsorpcyjnej azotu. Adsorpcja CO2 posłużyła natomiast do potwierdzenia przyjętej gęstości fazy zaadsorbowanej w obszarze podkrytycznym. Charakterystyka węglowych sit molekularnych używanych w procesach kontrolowanych kinetycznie nie może być oparta na adsorpcji azotu w 77 K z powodu ograniczeń dyfuzyjnych. W tym przypadku adsorpcja ditlenku węgla w 273 K daje widoczne korzyści. Właściwości fizyczne CO2 pozwalają osiągnąć dostatecznie niskie ciśnienie w temperaturze wystarczająco wysokiej, aby uniknąć problemów z dyfuzją. Oznaczona tym sposobem objętość mikroporów została użyta do przewidywania zdolności do rozdzielania sita węglowego mieszaniny CO2.CH4.

18

An innovative ecological hybrid refrigeration cycle for high power refrigeration facility

80%

Cyklis P. , Janisz K.

Chemical and Process Engineering

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2015

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tom 36

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nr 3

321-330

EN

Searching for new refrigerants is one of the most significant scientific problems in refrigeration. There are ecological refrigerants commonly known: H2O and CO2. H2O and CO2 known as natural refrigerants, but they have problems:a high freezing point of H2O and a low triple point of CO2. These problems can be solved by the application of a hybrid sorption-compression refrigeration cycle. The cycle combines the application possibility of H2O in the high temperature sorption stage and the low temperature application of CO2 in the compression stage. This solution gives significant energy savings in comparison with the two-stage compressor cycle and with the one-stage transcritical CO2 cycle. Besides, the sorption cycle may be powered by low temperature waste heat or renewable heat. This is an original idea of the authors. In the paper an analysis of the possible extension of this solution for high capacity industrial refrigeration is presented. The estimated energy savings as well as TEWI (Total Equivalent Warming Impact) index for ecological gains are calculated.

19

Purification of the used palm oil by adsorption

80%

Buczek B. , Chwiałkowski W.

Polish Journal of Chemical Technology

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2008

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tom 10

|

nr 1

19-21

EN

The components of fresh vegetable oils are mainly non-polar. During frying of food, complex and multistage reactions occur in the oil, which produce various polar compounds. Active carbons are characterized by small contents of polar functional groups, which are responsible for adsorbing such polar compounds. Effective purification of the used frying oils must involve the removal of the polar substances. To improve the quality of the used palm oil, an active carbon oxidized by a hydrogen peroxide treatment was used. Such a carbonaceous adsorbent improves the quality of the oil used for frying food by purifying it from colour substances, lipid hydrolysis products, oxidation products and total polar compounds.

20

Stochastic resonance in a realistic model for surface adsorption

80%

Sierra J. , Wio H.

Open Physics

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2012

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tom 10

|

nr 3

625-630

EN

We study a model for a monolayer single adsorbate system used to describe pattern formation on adsorbates with lateral interactions, when it is submitted to pressure oscillations. Through numerical and analytical (based on a two-state approximation) methods to analyze the existence of stochastic resonance in such a bistable system. This is a first step toward the study of resonant phenomena in adsorbate systems with moving fronts and/or with presence of micro-reactors or spots.