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Preparation of amphoteric modified bentonite from calcium-based bentonite for adsorption of anionic dye. The importance of sodium-modification pretreatment

Yin Hang, Ren Zijie, Gao Huimin, Han Weiyi, Guan Junfang

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 1

1--17

EN

To understand the influence of sodium-modification pretreatment on the adsorption of anionic dye by amphoteric modified bentonite, three kinds of adsorbent materials, including sodium-modified bentonite, amphoteric modified calcium-based bentonite and amphoteric modified bentonite pretreated by sodium modification, were firstly synthesized and characterized, and afterwards their adsorption performance and mechanism for a form of anionic dye, Acid Yellow 11, were investigated comparatively. The crystalline phases, hydration property, surface charge characteristic and functional groups of prepared modified bentonite were characterized and evaluated by X-ray diffraction swelling volume, Zeta potential and Fourier transform infrared spectroscopy, respectively. The sodium modification expanded the interlayer space of montmorillonite, released the internal surface area and improved the hydration performance of bentonite. Due to the replacement of Na+ for Ca2+, the probability of interlayer cations overflowing from the interlayer space and exchanging with the amphoteric modifier increases. Therefore, the content of interlaminar organic material in amphoteric modified bentonite pretreated with sodium-modification pretreatment was higher than that in unpretreated amphoteric modified bentonite. The hydration and dispersibility were significantly stronger, and the adsorption capacity of acid dye was also better. The findings of this investigation suggest that sodium modification pretreatment is very positive and necessary in the process from sodium–amphoteric modification.

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Adsorpcja barwników z roztworów wodnych na węglach aktywnych

Choma J., Czubaszek M., Jaroniec M.

Ochrona Środowiska

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2015

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Vol. 37, nr 3

3--14

PL

W pracy przedstawiono przegląd najnowszej literatury poświęconej porównaniu metod biologicznych, fizycznych i chemicznych stosowanych do usuwania syntetycznych barwników organicznych z roztworów wodnych. Szczególną uwagę zwrócono na zastosowanie w tym celu procesów adsorpcyjnych na węglach aktywnych. Skupiono się na analizie procesu adsorpcji barwników kationowych i anionowych na różnych materiałach węglowych, w tym na adsorbentach uzyskanych z prekursorów odpadowych. Przytoczono przykłady handlowych węgli aktywnych, które są stosowane do skutecznego usuwania barwników z roztworów wodnych. Podano parametry ich struktury porowatej, a także zdolności adsorpcyjne względem wybranych barwników. Opisano czynniki wpływające na proces adsorpcji barwników z roztworów wodnych (masa i rodzaj użytego adsorbentu, stężenie początkowe i klasa użytego barwnika, czas, intensywność mieszania, temperatura i pH roztworu). Na tej podstawie wykazano, że proces adsorpcji na węglach aktywnych jest jednym z najważniejszych sposobów skutecznego usuwania barwników z roztworów wodnych.

EN

This work represents an overview of the newest literature on comparison of biological, physical and chemical methods applied to removal of synthetic organic dyes from water. A special attention is given to dye adsorption processes on activated carbons. The main focus is on the adsorption process of cationic and anionic dyes on different activated carbon materials, including adsorbents from waste precursors. Numerous examples of commercial activated carbons applied for effective removal of dyes from water solutions are presented. Parameters of their porous structure, as well as adsorption abilities of selected dyes are provided. Factors affecting the process of dye adsorption from water solutions are described (adsorbent mass and type, initial concentration and class of dye, adsorption time, mixing intensity, temperature and solution pH). In conclusion, it is demonstrated that the process of dye adsorption on activated carbons is one of the most important ways of effective dye removal from water solutions.

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Preparation of activated carbons with enhanced adsorption of cationic and anionic dyes from Chinese Hickory husk using the Taguchi method

Cao Y., Pawłowski A., Zhang J.

Environment Protection Engineering

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2010

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Vol. 36, nr 3

69-86

EN

Waste Chinese Hickory husk biomass was used as a precursor in the preparation of low-cost activated carbon by ZnCl2 activation. The activated carbon was to be used for the removal of both cationic and anionic dyes - methylene blue (MB) and methyl orange (MO). The preparation parameters, including impregnation ratio (the mass ratio of ZnCl2 to the precursor), the activation temperature, the activation time and the impregnation time, were evaluated. The Taguchi method, in combination with analysis of variance (ANOVA), was used to determine the effects of the preparation parameters on the dye adsorptive capacities of the activated carbon, and to optimize preparation conditions with the goal of maximizing its adsorptive capacities. The optimized conditions were an impregnation ratio of 2.0 g/g, an activation temperature of 550 oC and an activation time of 60 min. In such an optimal combination of parameters, the adsorption of MB and MO was expected to reach approximately 400 mg/g and 900 mg/g, respectively. The activation temperature had the most significant effect on the carbon capacity to adsorb MB and MO. The impregnation ratio had a significant effect on the adsorption of both dyes with the trend towards higher adsorption at higher impregnation ratio, while the activation time and the impregnation time were found to be insignificant.