The effect of microwave irradiation and conventional acid activation on the textural properties of smectite: Comparative study

Abstract Crude kaolinite-glauconite clay was active with hydrochloric acid for various times under variable microwave irradiation power. The influence of activation parameters (power and/or time) on the structural and textural properties of the treated samples has been studied. The modifications were evaluated by XRD, FTIR, XRF, SEM, BET, grain size and zettametry. The XRD and IR results show that acid activation reveals only weak changes on crystallinity of samples. However, HCl activation of clay assisted by microwave modifies morphology and size of grains with a little variation of the specific surface area values. The adsorbing power of the raw and activated clay was tested with methyl orange dye and the adsorption isotherms were modeled using Langmuir and Freundlich models. This study showed that the maximum adsorbed quantity of dye passes from 3.21mg/g for the untreated raw clay to 4.29mg/g for the activated clay irradiated 2 min under microwave at a power of 900W and that the Langmuir model is the most adequate to describe the adsorption process.

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Characterization and catalytic properties of a saponite clay modified by acid activation

Clay Minerals ◽

10.1180/claymin.1997.032.4.13 ◽

1997 ◽

Vol 32 (4) ◽

pp. 633-643 ◽

Cited By ~ 38

Author(s):

F. Kooli ◽

W. Jones

Keyword(s):

Infrared Spectroscopy ◽

Room Temperature ◽

Textural Properties ◽

Acid Sites ◽

Single Type ◽

Activation Process ◽

Acid Activation ◽

Strongly Correlated ◽

Lewis Site ◽

Adsorbed Pyridine

AbstractA natural saponite was acid activated at room temperature or 90°C with different acid/clay ratios and the products were characterized by powder X-ray diffraction, infrared spectroscopy and thermogravimetry. The leaching of Mg from the octahedral sheets is enhanced by an increase in the acid/clay ratio and by an increase in temperature of activation. Textural properties are reported, and it appears that they are strongly correlated to the presence of a noncrystalline silica phase which is formed during the acid activation process. The desorption of cyclohexylamine indicates that for samples activated at 90°C the number of acid sites in the acidactivated saponites decreases following severe acid treatment. Infrared spectroscopy of adsorbed pyridine on samples after calcination at 500°C suggests that acid activation at 90°C produces a single type of Bronsted site but two types of Lewis sites whereas activation at room temperature results in only one type of Lewis site in addition to a Brønsted site. The two Lewis sites are suggested to originate from residual Al in the clay structure and to AI exsolved from the layers during activation. The dehydration of pentan-1-ol has been used as a further probe to measure acidity by monitoring the degree of conversion and selectivity for the different samples.

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Production of Porous Materials by Dealumination of Alumina-Rich Zeolites

MRS Proceedings ◽

10.1557/proc-371-123 ◽

1994 ◽

Vol 371 ◽

Cited By ~ 5

Author(s):

R. Le Van Mao ◽

G. Denes ◽

N.T.C. Vo ◽

J.A. Lavigne ◽

S.T. Le

Keyword(s):

Comparative Study ◽

Pore Size Distribution ◽

Mesoporous Materials ◽

Acid Leaching ◽

Textural Properties ◽

Zeolite A ◽

New Materials ◽

Ammonium Hexafluorosilicate ◽

Void Volumes ◽

Exchange Properties

AbstractA comparative study of chemical and textural properties for materials obtained by three different methods of dealumination of alumina-rich parent Ca-A zeolite showed that the method using ammonium hexafluorosilicate (AFS) resulted in the most interesting developments of mesoporous materials, with much higher void volumes and cation exchange properties than obtained by acid leaching or hydrothermal treatment. AFS treatment on both the Na and Ca forms of zeolite A resulted in materials with 12 nm sized mesopores, whereas smaller mesopores of about 4 nm were obtained when using the higher Si/Al ratio parent zeolite Na-X. Pore size distribution profiles obtained for these new materials are fairly narrow, indicating homogeneous mesopore sized solids.

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Investigation of activated Al-pillared clay efficiency in vegetable oil purification

Acta periodica technologica ◽

10.2298/apt0435031l ◽

2004 ◽

pp. 31-36 ◽

Cited By ~ 3

Author(s):

Gizela Lomic ◽

Erne Kis ◽

Etelka Dimic ◽

Ranko Romanic

Keyword(s):

Surface Area ◽

Vegetable Oil ◽

Total Pore Volume ◽

Textural Properties ◽

Sample Surface ◽

Pillared Clay ◽

Acid Activation ◽

Micropore Surface Area ◽

Natural Clays ◽

Oil Purification

This paper represents a contribution to the applicability of natural clays and their derivates as adsorbents in the process of purification of vegetable oil. Investigation of textural properties of raw and purified clay samples reveals that during acid activation and Al-pillaring, BET and micropore surface area increases significantly. However, bleaching capacity of clay and its derivates is not determined by using sample surface area, but rather sample total pore volume. Surface area, especially micropore surface area contributes to removal of smaller molecules. This was confirmed by successful elimination of moisture and volatile materials by samples with an appropriate micropore structure. Used samples of clay and its derivates do not significantly influence acid and peroxide values of raw sunflower oil during its treatment.

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