Local Cuban bentonite clay: composition, structure and textural characterization

The Cuban bentonite clays have a specific surface area of 79.9098 m2.g-1, a pore volume of about 0.077612 cm3.g-1 and both isotherms exhibited a hysteresis loop of IV type. X-ray diffractogram of raw bentonite shows that the main mineralogical component is montmorillonite (> 90%). The mineral object study presents the first endothermic peak, characteristic of montmorillonite, in 48.11 ºC and others less accentuated (80.81, 94.01, 119.81 ºC) characteristic of calcium montmorillonite, that corresponds to the loss of water, and can be extended up to 250 ºC. The FTIR spectra showed the existence of Si-OH, Al-Al-OH, Al-Fe-OH, Al-Mg-OH and Si-O-Si functional groups in all clay samples, confirmed the presence of hydrated aluminosilicate in the clay, bands between 1120 and 461 cm-1 correspond to phyllosilicate structures and OH stretching vibrations were observed. The pH at the point of zero charge (pHPZC) obtained has a value of 8.1, which allows montmorillonite to be classified as basic. The structural formula for one-layer unit of montmorillonite was determined as (Na3.99Al0.01)(Al1.11Fe3+0.49Mg0.18Ti0.07)(Ca0.24Na0.15K0.01)O10(OH)2, indicate the location of the different cations in metal oxide octahedrons or tetrahedrons, respectively. From the results obtained by different methods and the analysis of the calculated structural formula, it can be concluded that the bentonite under study is a calcium montmorillonite, with a low specific surface area and little porosity.

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Properties of Mechanical Activation Combustion Synthesied High α-Content Silicon Nitride Powders and Sintered Bulk Ceramics after Iteration Reactions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.368-372.862 ◽

2008 ◽

Vol 368-372 ◽

pp. 862-864 ◽

Cited By ~ 1

Author(s):

Ke Gang Ren ◽

Ke Xin Chen ◽

He Ping Zhou ◽

Hai Bo Jin ◽

Ji Dong Zhong ◽

...

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Silicon Nitride ◽

Specific Surface ◽

Mechanical Activation ◽

Relative Density ◽

Combustion Synthesis ◽

Surface Area ◽

Specific Surface Area ◽

A Value

Effect of iteration times on mechanically-activated combustion synthesis of high α-content Si3N4 powders was investigated. Properties of the as-synthesized powders such as α-content (Cα) as well as specific surface area (As) were examined. Results showed that both of Cα and As became higher after iteration reactions. The mechanical properties of the sintered bulk ceramics from as-synthesized powders were also tested to reveal the sinterability of the powders. Results showed that relative density of all the sintered bulk ceramics were higher than 97%. Furthermore, fracture toughness had a trend of becoming higher, which reached a value of 10.2 MPam0.5. Correspondingly, bending strenth became a bit lower.

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Sorption of Ni(II) on surface of bed grains used in iron and manganese removal filters

Water Science & Technology Water Supply ◽

10.2166/ws.2018.127 ◽

2018 ◽

Vol 19 (3) ◽

pp. 815-822

Author(s):

Marta Tytkowska ◽

Magdalena M. Michel ◽

Lidia Reczek ◽

Tadeusz Siwiec

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Manganese Oxides ◽

Point Of Zero Charge ◽

Manganese Removal ◽

Sorption Efficiency ◽

Initial Ph ◽

Bed Materials ◽

Iron And Manganese

Abstract This paper reports the results of determinations of crystalline phase type, specific surface area, point of zero charge pH (pHpzc), and Ni(II) sorption capacities of beds for groundwater treatment. Bed materials from iron and manganese removal filters (FeRF, MnRF) as well as a catalytic bed (G1) were investigated. The reference material was MnO2-coated quartz sand (MnQS). The efficiency of Ni(II) sorption was investigated as a function of pH. It was found that the naturally formed coating on FeRF was characterised by the highest sorption efficiency (80–88%) in the wide pH range (4–9) of the solution. Sorption on MnRF was weaker (35–45%). G1 and MnQS, which contained only manganese oxides, were characterised by a very low sorption efficiency of 0–6% and 3–8%, respectively. A lower Ni(II) removal efficiency was observed at an initial pH close to the pHpzc values. During Ni(II) sorption, the pH of the solution was not constant and tended towards the value of pHpzc for all tested materials. The slightly pH-dependent sorption of Ni(II) indicates that its removal depends more on the chemical composition and the specific surface area of the oxide coatings covering the bed materials.

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ACID ACTIVATION OF PRRENJAS CLAY MINERAL

JOURNAL OF ENGINEERING & PROCESSING MANAGEMENT ◽

10.7251/jepmen1507037m ◽

2018 ◽

Vol 4 (7) ◽

Author(s):

Altin Mele ◽

Krenaida Taraj ◽

Arjan Korpa

Keyword(s):

Specific Surface ◽

Surface Area ◽

Clay Mineral ◽

Specific Surface Area ◽

Pore Volume ◽

Gas Adsorption ◽

Exchange Capacity ◽

Acid Activation ◽

Composition Structure ◽

Adsorption Desorption

Prrenjas clay mineral is found in southeast Albania and has a high content on bentonite. Theinfluence of the sulphuric acid activation on the composition, structure and surface properties ofPrrenjas clay mineral is investigated in this study by means of elemental chemical analysis, X-RayDiffractometry, IR Spectroscopy and gas adsorption-desorption measurement. H2SO4concentrations of 0.143 M, 0.232 M, 0.371 M, 0.537 M, 0.734 M, 0.927 M and 1.456 M were used inthe treatment of samples. The treatment by increasing the acid concentration brings the leaching ofAl3+, Fe2+, Mg2+ from the clay structure. The specific surface area and the pore volume of the claysamples increases respectively from 83 m2/g and 0.069 cm3/g for the untreated clay to 420 m2/g and0.384 cm3/g for the clay mineral treated with 1.456 M H2SO4 solution. New mesopores were createdduring the acid activation mainly in the range of 2 – 8 nm. For the samples treated with 0.927 Mand 1.456 M solutions the increase in specific surface area and pore volume is very high. Thecationic exchange capacity decreases steadily with the concentration of H2SO4 used for thetreatment.

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Rapid and accurate measurement of the specific surface area of snow using infrared reflectance at 1310 and 1550 nm

The Cryosphere Discussions ◽

10.5194/tcd-3-33-2009 ◽

2009 ◽

Vol 3 (1) ◽

pp. 33-75 ◽

Cited By ~ 2

Author(s):

J.-C. Gallet ◽

F. Domine ◽

C. S. Zender ◽

G. Picard

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Atmospheric Chemistry ◽

Integrating Sphere ◽

Dual Frequency ◽

Climatic Impact ◽

Area Index ◽

A Value ◽

Few Data

Abstract. Even though the specific surface area (SSA) of snow is a crucial variable to determine the chemical and climatic impact of the snow cover, few data are available on snow SSA because current measurement methods are not simple to use in the field or do not have a sufficient accuracy. We propose here a novel determination method based on the measurement of the hemispherical reflectance of snow in the infrared using the DUFISSS instrument (DUal Frequency Integrating Sphere for Snow SSA measurement). DUFISSS uses 1310 and 1550 nm radiation provided by laser diodes, an integrating sphere 15 cm in diameter, and InGaAs photodiodes. For SSA<60 m2 kg−1, we use the 1310 nm radiation, reflectance is in the range 15 to 50% and the accuracy is 10%. For SSA>60 m2 kg−1, snow is usually of low to very low density (typically 30 to 100 kg m−3) and this produces artifacts caused by the e-folding length of light in snow being too long. We therefore use 1550 nm radiation for SSA>60 m2 kg−1. Reflectance is then in the range 5 to 12%, and the accuracy is 12%. No effect of crystal shape on reflectance was detected. We propose empirical equations to determine SSA from reflectance at both wavelengths, with that for 1310 nm taking into account the snow density. DUFISSS has been tested in the Alps to measure the snow area index (SAI) of the Alpine snowpack in a south facing area at 2100 m elevation. This was done by measuring the SSA, thickness and density of the seven main layers of the snowpack in just 30 min, and a value of 5350 was found, significantly greater than in Arctic and subarctic regions. DUFISSS can now be used to help study issues related to polar and Alpine atmospheric chemistry and climate.

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The Influence of Acid Treatment on the Nanostructure and Textural Properties of Bentonite Clays

Materials Science Forum ◽

10.4028/www.scientific.net/msf.494.339 ◽

2005 ◽

Vol 494 ◽

pp. 339-344 ◽

Cited By ~ 18

Author(s):

Z. Vuković ◽

A. Milutinović-Nikolić ◽

J. Krstić ◽

A. Abu-Rabi ◽

T. Novaković ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Acid Concentration ◽

Pore Volume ◽

Acid Treatment ◽

Textural Properties ◽

Nitrogen Adsorption ◽

Acid Activation ◽

Bentonite Clays

The nanostructure and textural properties of acid-activated bentonite clays from the Bogovina coalmine were investigated. The acid activation was performed with HCl in the concentration range 1.5-7.5 M. The atomic force microscopy followed by image analysis was used in order to establish the influence of the acid treatment on the size of bentonite particles. Nitrogen adsorption-desorption isotherms at -196 °C were used to estimate the specific surface area, pore volume and pore size distribution. The acid treatment reduces the size of bentonite particles and increases the specific surface area and pore volume of the investigated bentonites. These effects are improved by increasing the acid concentration up to 4.5 M HCl. Further increase in acid concentration does not result in development of new porous structure.

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The influence of modification on structural, textural and adsorption properties of bentonite

Hemijska industrija ◽

10.2298/hemind0803131j ◽

2008 ◽

Vol 62 (3) ◽

pp. 131-137 ◽

Cited By ~ 1

Author(s):

Natasa Jovic-Jovicic ◽

Aleksandra Milutinovic-Nikolic ◽

Ivan Grzetic ◽

Predrag Bankovic ◽

Branislav Markovic ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Interplanar Spacing ◽

Bentonite Clay ◽

Textural Properties ◽

Exchangeable Cations ◽

Adsorption Properties ◽

Microporous Material ◽

X Ray

Natural bentonite clay from the Bogovina locality in Serbia was Na-exchanged and modified using hexadecyll-trimethylammonium bromide as surfactant and organobentonite was obtained. The influence of modifications on the structural, textural and sorption properties of bentonite was investigated. It was estimated that modifications solely replace exchangeable cations in smectite layers, whereas other admixture minerals (quartz, calcite, feldspar) in bentonite remain unaffected. According to X-ray results the modification lead to changes in the smectite structure by either decreasing, for Na-bentonite, or increasing, for organobentonite, the interplanar spacing, JQOI- The appearance of three new bands in IR spectra of HDTMA-bentonite comparing to those of raw and Na-bentonite assigned to the methylene vibrations confirmed the embedding of aliphatic cations into smectite structure. In organobentonite a significant change in textural properties was observed. In particular, specific surface area dramatically decreased while originally meso and microporous material became almost completely non-porous. Despite almost insignificant specific surface area the synthesized organobentonite due to gained organophyllity of its surface exhibits exquisite adsorption properties toward investigated textile dyes having adsorption capacity approx. 2 times higher than activated carbon.

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