Infrared study of the thermal treatment of sepiolite and palygorskite saturated with organic amines

Shuali, Uri; Bram, L.; Steinberg, M.; Yariv, S.

doi:10.1016/0040-6031(89)85246-3

Cited by 48 publications

(24 citation statements)

References 19 publications

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“…This induces a relatively low adsorption capacity, as shown in Fig 5. For this reason, in order to increase the adsorption capacity, the surface of natural zeolite was modified with a typical quaternary amine surfactant (HTAB) which not only makes the zeolite surface more hydrophobic but also neutralizes the negative charges. 42,43 The zeta potential of modified zeolite shown in Fig 6 reveals that the surface acquires positive charges and consequently becomes receptive to the uptake of negatively charged dye anions through electrostatic attraction. , the isotherms then show a much steeper linear rise in Region II followed by a reversal towards the adsorption density axis, Region III.…”

Section: Effect Of Mixing Timementioning

confidence: 99%

The removal of reactive azo dyes by natural and modified zeolites

Armağan¹,

Özdemir²,

Turan³

et al. 2003

J of Chemical Tech & Biotech

123

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The adsorption mechanism of three reactive dyes by zeolite has been examined with the aim of identifying the ability of zeolite to remove textile dyes from aqueous solutions. Towards this aim, a series of batch adsorption experiments was carried out, along with determination of the electrokinetic properties of both natural and modified zeolites. The adsorbent in this study is a clinoptilolite from the Gördes region of Turkey. The reactive dyes CI Reactive Black 5, Red 239 and Yellow 176 are typical azo dyes extensively used in textile dyeing. Adsorption tests were carried out as a function of mixing time, solids concentration, dye concentration and pH. The adsorption results indicate that the natural zeolite has a limited adsorption capacity for reactive dyes but is substantially improved upon modifying its surfaces with quaternary amines. An electrostatic adsorption mechanism involving the formation of a bilayer of amine molecules on the clinoptilolite surface onto which anionic dye molecules adsorb, depending on their polarities, is proposed. The results are also supported by electrokinetic measurements. The adsorption data were fitted to the Langmuir isotherm and it was found that the modified sepiolite yields adsorption capacities (q e ) of 111, 89 and 61 mg g −1 for Red, Yellow and Black, respectively. These results are comparable to a popular adsorbent, activated carbon.

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Section: Effect Of Mixing Timementioning

confidence: 99%

The removal of reactive azo dyes by natural and modified zeolites

Armağan¹,

Özdemir²,

Turan³

et al. 2003

J of Chemical Tech & Biotech

123

View full text Add to dashboard Cite

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“…A number of investigators have studied the interaction of water and various organic reagents with sepiolite. These include the adsorption of dilute thiram, an active carbon, as a function of temperature (3), the interaction of amines on sepiolite and polygorskite by infrared measurements (4), and the removal of aromatic amines from aqueous solutions by activated sepiolite (1). Among others, the adsorption properties of water-sepiolite system (5), the uptake of ammonia (6), the access of cationic dye (methylene blue) into the structural micropores of sepiolite (7), the adsorption mechanism of organic and inorganic ions by sepiolite (8), and the removal of ammonia by natural clay minerals (9) are some of the examples pertinent to our studies.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Pyridine Derivatives with Sepiolite

Sabah

Çelik

2002

Journal of Colloid and Interface Science

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“…Sepiolite from Vallecas, Spain, and palygorskite from Quincy, Florida, have already been described (Shuali et al, 1989(Shuali et al, , 1990.…”

Section: Methodsmentioning

confidence: 99%

“…This relatively high evolution temperature of Py compared to its boiling point (115~ may result from its being bonded to zeolitic water in the pores (Shuali et al, 1989). Small amounts of ammonia are evolved, beginning at 80~ up to 435~ with peaks at 140, 255 and 295~ in this sub-region (Fig.…”

Section: (Calc ] "mentioning

confidence: 99%

“…The IR spectra showed the formation of weak hydrogen bonds between Py and Bronsted acid sites which were developed as a result of the thermal treatment. Shuali et al (1989) identified, by IR spectroscopy, several associations which are formed between palygorskite or sepiolite and Py. During the adsorption process, the base penetrates into the channels replacing part of the zeolitic water and forming hydrogen 9 1991 The Mineralogical Society bonds with the rest.…”

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confidence: 99%

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Thermal analysis of pyridine-treated sepiolite and palygorskite

et al. 1991

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A B S T R A C T:The thermal behaviour of sepiolite and palygorskite treated with pyridine (Py) was investigated by DTA, TG, DTG and EGA (by MS) under a flow of air and inert gases (N 2 or Ar). The thermal analysis showed that the organic base was adsorbed by the clays, penetrating into the clay pores and replacing zeolitic and bound water. Its presence in the pores shifted the dehydroxylation peak to temperatures higher than the corresponding peak in the untreated clays. Under N2 and Ar, thermal desorption of Py from sepiolite was observed at 260 and 650~ whereas for palygorskite only traces of Py were detected in the evolved gases. In addition to desorption, reactions of pyrolysis and condensation to coke were detected by the evolution of ammonia, methane and hydrogen, respectively. In air, oxidation of the organic matter led to the appearance of exothermic peaks. The profile of the DTA curve and the temperatures of the most intense exothermic peaks were determined by the rate of the carbon oxidation.In a previous publication (Shuali etal., 1990) we described the thermal behaviour, under air or N2 flow, of the porous clays sepiolite and palygorskite treated with n-butylamine (BA). Under N 2 flow, in addition to thermal desorption of the aliphatic base, reactions of pyrolysis and condensation to coke were detected. In air, oxidation of the sorbed organic matter led to the appearance of exothermic peaks. The temperatures of the most intense exothermic peaks are governed by the rate of carbon oxidation, but the shape of the DTA curves and the temperatures of exothermic shoulders are governed by the rate at which the hydrogen from the organic molecules combine with oxygen from the air.In the present investigation, the thermal behaviour of sepiolite and palygorskite treated with pyridine (Py), both in air and inert atmosphere (N2 or Ar) was studied. There are several publications on the sorption of Py by sepiolite and palygorskite. According to RuizHitzky et al. (1985), the sorption of Py on the external surfaces of these clays takes place in two well-defined steps. In the first step a monolayer is formed with the Py molecules lying with their planes parallel to the (001) plane of the clay crystal; in the second step a bilayer coverage is formed. Blanco et al. (1988) studied the surface acidity of palygorskite by infrared (IR) spectroscopy. After evacuating for 2 h at 150~ the thermally treated clay was saturated with Py. The IR spectra showed the formation of weak hydrogen bonds between Py and Bronsted acid sites which were developed as a result of the thermal treatment. Shuali et al. (1989) identified, by IR spectroscopy, several associations which are formed between palygorskite or sepiolite and Py. During the adsorption process, the base penetrates into the channels replacing part of the zeolitic water and forming hydrogen 9 1991 The Mineralogical Society

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Infrared study of the thermal treatment of sepiolite and palygorskite saturated with organic amines

Cited by 48 publications

References 19 publications

The removal of reactive azo dyes by natural and modified zeolites

The removal of reactive azo dyes by natural and modified zeolites

Interaction of Pyridine Derivatives with Sepiolite

Thermal analysis of pyridine-treated sepiolite and palygorskite

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