Wyniki wyszukiwania - Biblioteka Nauki

1

Dye removal using keggin polyoxometalates assisted ultrafi ltration: characterization and UV visible study

100%

Kahloul M. , Chekir J. , Hafiane A.

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tom Vol. 45, no. 4

30--39

EN

To improve dye retention, there is a concurrent interest in the development and optimization of an alternative and promising method for the dye recovery in aqueous solutions. In this regard, considerable attention was paid to the polyoxometalates (POMs) assisted ultrafiltration (POMAUF). The aim of the present study is to eliminate toluidine blue (TB) dye by ultrafiltration membrane using keggin polyoxometalates (POMs) as complexing agents. In the first step, the keggin polyoxometalates K3[PW12O40]∙6H2O (PW12) and K7 [PW11O39]∙14H2O (PW11) were prepared. Then, the obtained powders were characterized by X-ray diffraction and infrared spectroscopies. Afterwards, the removal of toluidine blue (TB) using polyoxometalates assisted ultrafiltration (POMAUF) was studied. Factors affecting the retention of dye and permeate flux such as transmembrane pressure, operating time, polyoxometalates concentration, ionic strength, surfactant and pH were investigated. All results of both compounds have been presented and discussed. The results reveal that the addition of POMs leads to an increase in dye retention from 11 to 95% for the PW12 and to 98% for the PW11. The results of this work have thus suggested the promising enhancement of ultrafiltration membrane selectivity for the dye removal using new complexing agents such as POMs in place of polyelectrolytes and surfactants.

2

The effect of external mass transfer resistance on the adsorption rate in a liquid phase

86%

Piątkowska S. , Gwadera M.

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2018

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tom Vol. 115, iss. 3

79--90

EN

The paper presents the results of studies on the adsorption of a dye from a water solution on activated carbon. An activated carbon with the best adsorption properties for the dye used in the studies was selected experimentally. The equilibrium and kinetic measurements for the selected system were conducted. Constants of linear, Langmuir and Freundlich isotherms were determined. The obtained results have shown that increasing the flow rate of the solution in an adsorber results in increasing the adsorption rate.

PL

W pracy zaprezentowano wyniki badań adsorpcji barwnika z roztworu wodnego na węglu aktywnym. Dokonano eksperymentalnego doboru węgla aktywnego o najlepszych właściwościach adsorpcyjnych dla stosowanego w badaniach barwnika. Wykonano badania równowagi i kinetyki adsorpcji dla badanego układu. Wyznaczono stałe w równaniu izotermy liniowej, Langmuira i Freundlicha. Otrzymane wyniki wskazują, że zwiększenie natężenia przepływu roztworu w adsorberze skutkuje zwiększeniem szybkości adsorpcji.

3

Fabrication of heterojunction MnTiO3–TiO2-decorated carbon nanofibers via electrospinning as an effective multifunctional photocatalyst

86%

Yousef A.

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tom Vol. 40, No. 2

289--305

EN

In this paper, we successfully synthesized heterojunction manganese titanate/titanate nanoparticles (MnTiO3–TiO2 NPs)-decorated carbon nanofibers (CNFs) employing the electrospinning process. The morphology, crystallinity, and chemical composition of the MnTiO3–TiO2-decorated CNFs is characterized via SEM, FESEM, STEM, TEM EDX, and XRD techniques. The synthesized nanocomposite exhibits good performance for photodegradation of methylene blue (MB) dye and hydrolysis of ammonia–borane complex for hydrogen releasing experiment in a batch reactor under visible light. A mathematical model was developed to predict the photocatalytic activity of the produced nanocomposite with various parameters. The operational parameters include the effect of the initial concentration, catalyst dosage, light intensity, and reaction temperature, which are studied to validate the mathematical model. The reaction rate constant of MB photodegradation is found to be 0.0153 min−1 for an initial MB concentration of 5 mg·L−1 with a catalytic dosage of 200 mg·L−1 at a reaction temperature of 25°C under a light intensity of 25 W·m−2. Similarly, the H2 generation employing TiO2@CNFs and MnTiO3–TiO2@CNFs under visible light irradiation is observed to be 0.31 mol and 2.95 mol, respectively, corresponding to an exposure of 10 min. We also demonstrated that the yield of hydrogen employing MnTiO3–TiO2@CNFs under visible light increases to 2.95 mol compared with 1.51 mol in darkness. Finally, comparisons were made between the experimental and model-predicted values of the reaction rate constant and final concentrations. Theoretical and experimental data of photocatalytic activity are found to be in good agreement for MnTiO3–TiO2@CNFs.

4

Dye removal efficiency of virgin activated carbon and activated carbon regenerated with Fenton's reagent

58%

Dąbek L. , Ozimina E. , Picheta-Oleś A.

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tom Vol. 38, nr 1

5-13

EN

The effectiveness of virgin and regenerated activated carbons was established for crystal violet removed from aqueous solutions. Granular activated carbon, WDex, saturated with the dye was regenerated using classic or modified Fenton's reagent, Fe2+/H2O2 and Fe2+/Ox, respectively. The application of modified Fenton's reagent resulted in the formation of hydrogen peroxide directly in the regeneration solution. The study was conducted under static and dynamic conditions. The sorptive capacities of virgin and regenerated WDex activated carbons for crystal violet were reported to be similar (approximately 42 mg/g). The results of the dynamic sorption show that under the predetermined conditions the regenerated activated carbons were better sorbents. The amount of dynamic sorption was approx. 17.6 g/dm3. The longest breakthrough time (3970 min) and the longest saturation time (11 600 min) were observed for the carbon bed regenerated with modified Fenton's reagent.