Wyniki wyszukiwania - Biblioteka Nauki

1

Characteristic curves for gases at supercritical temperatures. Adsorption equilibria of methane and nitrogen on molecular-sieve carbon

100%

Warmuziński K. , Zielińska I. , Śmigasiewicz S.

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tom T. 20, z. 4

613-627

EN

The evaluation of some of the principal correlations that describe adsorption equilibria for gases at supercritical temperatures is carried out. Based on the experimental data for the adsorption of methane and nitrogen on a carbon molecular sieve 5A (Takeda) it is found that the four-parameter characteristic curve of Amankwah and Schwarz seems to be superior to the three-parameter Dubinin-Astakhov equation. It is also demonstrated that, since the parameters visibly depend upon both the type of equation and the accuracy of the experimental data and regression procedures employed, caution should be exercised in ascribing any specific physical significance to the values of these parameters.

PL

Dokonano przeglądu podstawowych korelacji opisujących równowagi adsorpcyjne gazów powyżej temperatury krytycznej. Opierając się na danych równowagowych dla metanu i azotu na węglowym sicie molekularnym 5A (Takeda) stwierdzono, że czteroparametrowa krzywa charakterystyczna Amankwaha i Schwarza lepiej koreluje punkty eksperymentalne niż trójparametrowe równanie typu Dubnina-Astachowa. Stwierdzono jednak, że wobec wyraźnej zależności parametrów od rodzaju korelacji oraz dokładności danych eksperymentalnych ( a nawet typu stosowanych metod regresyjnych), należy zachować ostrożność w przypisywaniu wartościom tych parametrów jednoznacznego sensu fizycznego.

2

Badanie równowagi procesu adsorpcji mocznika na wymieniaczu jonowym Wofatit KPS

80%

Robak A. , Piotrowski J.

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2000

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tom Vol. 7, nr 1-2

79-85

PL

Wyznaczono równowagę procesu adsorpcji mocznika z roztworów wodnych na wymieniaczu jonowym Wofatit KPS w zakresie temperatury 298-323 K oraz stężeń mocznika 0,8-10 g/dm3. Rezultaty badań przedstawiono w postaci izoterm Langmuira, Freundlicha i Dubinina-Raduszkiewicza. Podano izosteryczne ciepło adsorpcji mocznika. Wykazano fizykalny charakter procesu sorpcji mocznika na kwaśnym wymieniaczu jonowym.

EN

The equilibrium of the urea adsorption process from its aqueous solutions on ion-exchange regin Wofatit KPS in the range 298-323K and urea concentration 0,8-10 g/dm3 has been studed. Results were presented in the form of Langmuir, Freundlich and Dubinin-Raduszkiewicz isotherms. The isosteric heat of urea adsorption was determined. Physical character of the urea adsorption on acid form ion-exchanger was proved.

3

Methods of Dyes Removal from Aqueous Environment

80%

Bożęcka A. , Orlof-Naturalna M. , Kopeć M.

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tom Vol. 22, nr 9

111--118

EN

In this paper, selected methods of dyes removal from water environment were discussed, with particular attention to the adsorption method. A literature review of the latest scientific research on colour impurities removal with the use of various types of adsorbents was presented. The efficiency of the methylene blue removal process, with use of selected natural sorbents and activated carbons, was tested. The competitiveness of natural sorbents was shown. It was confirmed that these materials are efficient in removing coloured compounds from aqueous solutions.

4

Adsorption of Naproxen Sodium from Aqueous Solutions on Commercial Activated Carbons

80%

Lach J. , Szymonik A.

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tom Vol. 20, nr 10

241--251

EN

The pollution of surface and drinking water with pharmaceuticals is one of the growing problems. One of the groups used in large quantities involves nonsteroidal anti-inflammatory drugs which can be bought without a prescription. This group includes naproxen, which was identified in wastewater, surface water and even drinking water all over the world. The aim of the study was to assess the opportunities for the removal of naproxen sodium from water using carbon sorbents. The measurements were carried out for three commercial microporous (WG-12 and F-300) and micro-mesoporous (ROW 08 Supra) activated carbons. The kinetics and statics of adsorption were studied. The adsorption from solutions with pH from 6 to 10 and temperature from 20°C to 40°C was analysed. It was found that the higher the pH, the lower the adsorption and the higher the temperature, the greater the adsorption of naproxen sodium. The highest adsorption of naproxen sodium was obtained for the F-300 activated carbon, whereas the lowest – for the ROW 08 Supra activated carbon. It was found that the adsorption results depend on many factors, the most important of which include hydrogen bonds between carboxyl groups of naproxen sodium and phenolic groups on the surface of activated carbons and electrostatic repulsion between the anions of naproxen sodium and negatively charged the surface of the activated carbon. The results of adsorption kinetics were described with the following models: pseudo-first order and pseudo-second order, intraparticle diffusion, and Elovich. The highest values of correlation coefficient R2 were obtained for the pseudo-second order and Elovich model. The results of adsorption statics were described using the Freundlich, Langmuir, and Temkin models. A good match between isotherms and the obtained results was obtained for the Freundlich and Temkin equations. It was found based on the adsorption intensity 1/n and distribution coefficient RL that this process was beneficial for all the considered activated carbons and the investigated adsorption conditions.

5

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

6

Layered Double Hydroxide/Chitosan Composite (Mg-Al/CT) as a Selective Adsorbent in Congo Red Adsorption from Aqueous Solution

80%

Mohadi R. , Siregar P. M. S. B. N. , Palapa N. R. , Taher T. , Lesbani A.

Ecological Engineering & Environmental Technology

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2022

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tom Vol. 23, iss. 2

144--152

EN

Layered double hydroxide (LDH) can be used as an adsorbent to remove pollutants from aqueous solutions, but it drawbacks where the structure is easily damaged so that it cannot be reused in the adsorption process and has a low adsorption capacity. This can be overcome through the development of layered double hydroxide material composited with chitosan support material. In addition to untilizing waste, chitosan is selected as supporting material in the layered double hydroxide modification process, because it is cheap, has high selectivity, and is biodegradable. In this study, the adsorbent was applied in the process of removing Congo Red (CR). The LDH modification process using chitosan was successfully carried out, as seen from XRD analysis which resembled the base material (Mg-Al) and support (CT), the BET analysis which showed an increase in surface area, as well as from the large adsorption capacity value and the regeneration process which tends to be stable after compositing is done.

7

Binding features of N-hexadecanoylglycine on two terminations of fluorapatite (001) surface and their effect on fluorapatite flotation

80%

Zou H. , Liu D. , Cao Q. , Chen X.

Physicochemical Problems of Mineral Processing

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2020

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tom Vol. 56, iss. 5

949--959

EN

N-hexadecanoylglycine (C16Gly) is a newly synthesized collector, which can be used as an efficient collector for fluorapatite (FA) rather than for dolomite. To extend our knowledge regarding the C16Gly collector, the contact angle method was employed to understand the flotation selectivity of C16Gly in the FA and dolomite system. On the other hand, the possible binding models of C16Gly anion on Ca-rich and PO4-rich terminations of FA (001) surface were investigated with density functional theory calculations to reveal the interaction between the C16Gly and the FA surface. Results showed that C16Gly anion could interact with these two terminations to generate 12 low-energy configurations, including bidentate, tridentate and chelating binding models. The C16Gly anion preferred to adsorb onto the Ca-rich termination, which is caused by the weaker electrostatic repulsion force between the C16Gly anion and the PO4 groups on this termination. The adsorption of C16Gly on these terminations was more stable than that on the dolomite (104) surface, which is one of the reasons for the preferential flotation of FA from dolomite using C16Gly as a collector. These findings provide further insights into the selectivity of C16Gly during the flotation of FA and dolomite.

8

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.

9

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.

10

Adsorption and desorption characteristics of rare earth ions on halloysite surfaces

80%

Long Q. , Yan H. , Zhou X. , Qiu S. , Qiu T.

Physicochemical Problems of Mineral Processing

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2024

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tom Vol. 60, iss. 1

art. no. 185763

EN

Rare earths (REs) are primarily adsorbed in ionic form on the surface of clay minerals such as halloysite in ionic rare earth ores. As a result, understanding the adsorption and desorption behaviors of RE ions on the surface of the halloysite may contribute to clarifying the mineralization process of ionic rare earth ores and provide a theoretical framework for the optimization of the extraction process. The adsorption and desorption characteristics of light (Nd3+), medium (Eu3+), and heavy (Lu3+) RE ions on the surface of halloysite-10 Å were comprehensively examined in this study. Because REs are more inclined to form an outer layer and inner layer adsorption when halloysite is protonated and deprotonated with the range of pH, respectively, pH has a significant impact on how halloysite adsorbs and desorbs. The experiment findings indicate that RE concentration, duration, and pH all increased the adsorption capacity of light, medium, and heavy REEs, and exhibited some selectivity for heavy REEs. Nd3+, Eu3+ and Lu3+ ions adsorption processes on the surface of Halloysite-10 Å are consistent with the Langmuir isothermal adsorption model and pseudo-second-order kinetic equations. The desorption efficiency of Lu3+ decreases dramatically with increasing pH due to hydrolysis and more inner layer adsorption than that of Nd3+ and Eu3+.

11

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.

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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.

12

Assessment of Modified Rice Husks for Removal of Aniline in Batch Adsorption Process: Optimization and Isotherm Study

80%

Dakhil I. H. , Naser G. F. , Ali A. H.

Journal of Ecological Engineering

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2021

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tom Vol. 22, nr 7

179--189

EN

The present work is aimed at investigating the capability of chemically modified rice husks (MRH) for the reduction of aniline ions from industrial wastewater. The experiments have been conducted to examine the influence of four operating parameters in the batch adsorption technique. The effect of initial concentrations of aniline (10–100) mg•L-1, MRH dose (0.1–1) g/100 ml, pH (3–9), and contact time (10–90) min has been studied. The selected range of operating factors was designed using the response surface method to establish a mathematical model that describes the adsorption process. The optimum parameters were 25 mg•L-1 initial concentration of aniline, 0.68 g MRH dose, 6.6 pH, and 70 min contact time. The point of zero charge was found equal to 6.8. The maximum removal efficiency of 84.97% was found under optimum conditions. The consistency of the mathematical model has been examined and the equilibrium results confirmed with the standard adsorption isotherm models, Langmuir and Freundlich, with a high correlation coefficient.

13

Using Sawdust to Treat Synthetic Municipal Wastewater and Its Consequent Transformation Into Biogas

80%

Abudi Z. N.

Journal of Ecological Engineering

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2018

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tom Vol. 19, nr 5

10--18

EN

Sawdust, as an agricultural waste which is highly efficient, readily available, and relatively inexpensive, has the potential to be an applicable alternative adsorbent for the total organic carbon (TOC) removal from synthetic domestic wastewater. This study aims firstly to investigate the feasibility of sawdust as a new adsorbent and understand its adsorption mechanism for TOC. The impact of particle size, pH, contact time, and temperature has been evaluated as the controlling factors on the adsorption process. The results presented that the removal efficiency rose with the decrease of particle size, pH, and temperature, as well as the increase of the contact time. The maximum adsorption was obtained at particle size of 0.05 mm, pH of 1, contact time of 1.5 h, and temperature of 15°C, respectively. The second aim of this study is to utilize the sawdust that is used in the adsorption process as biomass in batch anaerobic digestion (AD) to produce methane. Spent sawdust was characterized by the methane production which was 5.9 times greater than in the case of raw sawdust. Four operating parameters were checked, Carbon/Nitrogen ratio (C/N), inoculation, particle size, and total solid (TS) content. The batch results indicated that the optimum parameters were: 20%, 30%, 2 mm, and 15%, respectively.

14

Two-stage membrane separation process for biohydrogen recovery

80%

Búcsú D. , Bélafi-Bakó K. , Pientka Z.

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tom Vol. 31, nr 3-4

33-38

EN

Porous and non-porous gas separation membranes were used for concentration of biohydrogen produced by a heterotrophic hyper-thermophilic, anaerobic micro-organisms. A laboratory-scale integrated system was designed and built based on a liquid seal system and more than 70% hydrogen concentration was achieved from the initial gaseous mixture containing hydrogen, carbon dioxide and nitrogen. Liquid absorption and desorption of the carbon dioxide were also studied.

15

Removal of heavy metal ions: copper, zinc and chromium from water on chitosan beads

80%

Jaros K. , Kamiński W. , Albińska J. , Nowak U.

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tom Vol. 31, nr 3-4

153-162

EN

The paper deals with the application of chitosan in the form of beads to the removal of copper, zinc and chromium ions from water. The main element of the experimental equipment was a glass column, 5 cm in diameter and 30 cm high. The column was filled with chitosan beads. The research was car-ried out in one-, two- and three-component solutions, at the initial concentrations c0 ranging from 50 to 70 mg/dm3.In the description of metal sorption kinetics, the second-order equation was used. It well describes experimental data (its correlation coefficient ranged from 0.94 to 0.99).

16

A Review on the Adsorption of Phenol Derivatives from Wastewater

80%

Benaddi R. , Osmane A. , Zidan K. , El Harfi K. , Ouazzani N.

Ecological Engineering & Environmental Technology

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2023

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tom Vol. 24, iss. 4

35--43

EN

Several environmental companies consider phenols compounds to be very dangerous pollutants because they are highly toxic and non-biodegradable, notably their high toxicity in water. For this reason, several processes have been studied by researchers to understand the mechanisms of elimination of phenolic compounds. Adsorption remains the best technique due to its characteristics, in fact, it is non-destructive and simple to use as well as have more other advantages, such as practicality and efficiency and low cost, Therefore, these methods need to be widely developed on an industrial scale to remove phenol derivatives and achieve wastewater quality in accordance with standards. On the other hand, the development of these adsorption methods is highly dependent on new research on materials from abundant natural resources, namely apatites or biomaterials.

17

Enhanced adsorption of Direct Orange 26 dye in aqueous solutions by modified halloysite

80%

Kuśmierek K. , Świątkowski A. , Wierzbicka E. , Legocka I.

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tom Vol. 56, iss. 4

693--701

EN

The usefulness of untreated (H-NM) as well as modified by sodium benzoate (H-SB) and sulfuric acid (H-SA1 and H-SA2) halloysites as low-cost adsorbent for the removal of Direct Orange 26 azo dye from aqueous solutions was investigated. The kinetic data were evaluated in terms of the pseudo-first order and pseudo-second order kinetic models, while the equilibrium adsorption data were analyzed by the Freundlich and Langmuir isotherm equations. The data follows the pseudo-second order kinetic and Langmuir adsorption models. The DO26 adsorption capacities were 64.93, 74.07, 303.0, and 384.4 μmol/g for the H-NM, H-SB, H-SA1, and H-SA2, respectively. Adsorption of the dye was strongly pH dependent; no effect of ionic strength was observed. The study revealed that halloysites, especially acid-activated halloysites, could be used as an effective and low-cost adsorbents.

18

Removal of Ni2+from Aqueous Solutions by Adsorption Onto Magnetic Multiwalled Carbon Nanotube Nanocomposite

80%

Konicki W. , Pełech I. , Mijowska E.

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nr 2

87-94

EN

The removal of Ni2+ from aqueous solution by magnetic multiwalled carbon nanotube nanocomposite (MMWCNTs-C) was investigated. MMWCNTs-C was characterized by X-ray Diffraction method (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), surface area (BET), and Fourier Transform-Infrared Spectroscopy (FTIR). The effects of initial concentration, contact time, solution pH, and temperature on the Ni2+ adsorption onto MMWCNTs-C were studied. The Langmuir and Freundlich isotherm models were applied to fit the adsorption data. The results showed that the adsorption isotherm data were fitted well to the Langmuir isotherm model with the maximum monolayer adsorption capacity of 2.11 mg g–1. The adsorption kinetics was best described by the pseudo-second-order model. The thermodynamic parameters, such as ΔHo, ΔGo and ΔSo, were also determined and evaluated. The adsorption of Ni2+ is generally spontaneous and thermodynamically favorable. The values of ΔHo and ΔGo indicate that the adsorption of Ni2+ onto MMWCNTs-C was a physisorption process.

19

Influence of hydrated Ca2+ and Mg2+ complexes on the sulfidization of smithsonite : density functional based tight binding (DFTB+) study

80%

Wu Z. , Tang X. , Chen J. , Chen Y.

Physicochemical Problems of Mineral Processing

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2022

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tom Vol. 58, iss. 6

art. no. 156040

EN

Ca2+ and Mg2+ are the most dominating unavoidable ions in the smithsonite flotation. In this paper, the effect of Ca2+ (Mg2+) on the surface of smithsonite sulfidization in a system where water molecules are present was investigated using density functional based tight binding (DFTB+) simulations for the first time. The results indicated that the adsorption of hydrated Ca2+ complexes is stronger than that of hydrated Mg2+ complexes on the hydrated smithsonite (101) surface. In addition, at low concentrations of sodium sulfide, there is no adsorption of HS- on the surface pre-adsorbed with hydrated Ca2+ complexes, but only on the surface pre-adsorbed with hydrated Mg2+ complexes. At high concentrations of Na2S, S2- weakens the adsorption of hydrated Ca2+ complexes due to competitive adsorption, but the presence of S2- could desorb hydrated Mg2+ complexes from the surface. The results compared the differences in effects of Ca2+ and Mg2+ on smithsonite sulfidization, which could provide an atomic scale basis for researching the surface sulfidization of oxide minerals.

20

Adsorption of humic acid on mesoporous carbons prepared from poly- (ethylene terephthalate) templated with magnesium compounds

80%

Karolczyk J. , Mozia S. , Morawski A. W. , Przepiórski J.

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nr 4

95-99

EN

Porous carbons obtained from poly(ethylene terephtalate) contained in a mixture with either MgCO3 or Mg(OH)2 were examined as adsorbents for removal of humic acid from water. Adsorption of the model contaminants is discussed in relation to the textural parameters of the obtained carbon materials. Pore structure parameters of the carbonaceous materials were strongly influenced by preparation conditions including temperature and relative amounts of the inorganics used during preparations as template. Porous carbons prepared revealed a potential to purify water from the model contaminant of high molecular weight. The results presented confirmed a key role of mesoporosity in the adsorption of humic acid. Fluorescence spectroscopy was confirmed to be an useful method to evaluate concentration of humic acid in water.