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Bentonite is an aluminum phyllosilicate, a clay consisting mainly of nanocrystalin particles of montmorillonite adsorbent. In this study, the physiochemical analyses of cation exchange capacity (CEC) measurements, methylene blue index (MBI), and characterization of bentonites for separation applications are examined. Some characterizations of bentonite particles such as surface properties were examined by scanning electron microscopy (SEM), x-ray diffraction (XRD), x-ray fluorescence (XRF), and Barret-Johner-Halenda (BJH) pore size distribution measurements. The adsorption of Fe(III) from a 0.01 N solution using bentonites has also been studied. The result showed that the amount of clay minerals (motmorillonite) is very high in sample A2 (from deposits of Toroud, Semnan Province of Iran). Results also show the MBI and CEC along with montmorillonite content were effective parameters on Fe(III) separation. Iron separation with removal efficiency of 52% for sample A1 (from deposits of Toroud, Semnan Province of Iran) is due to the difference in surface active doners (like O), silica entities with more homogeneous surface negative charge, interaction forces, and CEC. [ABSTRACT FROM AUTHOR]

Bentonite particles are widely used for different applications such as drilling fluid, bleaching earth, catalyst, nanoclays, etc. Bentonite is rich in Montmorillonite, which is a nanostructured and nanoporous clay mineral. To characterize bentonite it is important to distinguish different components of clay mineral admixtures from each other and to obtain information regarding their structure, composition, and structural changes. In this research, bentonites are first screened and purified using sedimentation through dispersing 13% concentrations of bentonites in deionized water. FTIR spectroscopy along with other characterizing method such as x-ray diffraction and x-ray fluorescence is used for characterization of bentonites. Adsorption peaks at 524, 466, and 917 cm−1 confirm the presence of montmorillonite. The broadness of 3623 cm−1 peak shows the isomorphic substitution of octahedral Al3+ by Fe2+ or Mg2+ cations which affects the type and properties of studied bentonites. For samples S3 and G1, most of the quartz (793 cm−1) is settled in U.F.2 (underflow 2). The amount of montmorillonite decreases in U.F.2. The decrease in quartz is observed in O.F.1 (overflow 1) and especially in all O.F.2 (overflow 2) samples. This result is in agreement with XRD patterns. This research aims at using FTIR technique along with other complementary methods in the characterization of bentonites. [ABSTRACT FROM AUTHOR]

Bentonite is rich in montmorillonite, which is a nanostructured and nanoporous member of smectite group. Mineralogical and physicochemical properties of bentonites play a key role in choosing appropriate bentonites for different applications. Scanning electron microscopy (SEM) reveals the morphological form and size of mineral phase of the studied bentonite samples. X-ray diffraction (XRD) analysis showed that the studied bentonites predominantly consist of montmorillonites accompanying other impurities such as quartz, calcite, and plagio feldspar. The amount of organic components CHNO (carbon, hydrogen, nitrogen, and oxygen) in the samples was so low that it had no significant effect on the result of XRF analyses. X-ray fluorescence (XRF) analysis showed that there was a large amount of Al2O3 in sample ES3 and this large amount of Al2O3 indicates a greater amount of montmorillonite in this sample compared to that in sample GH1. Due to a larger amount of CaO, the type of GH1 montmorillonite is Ca-montmorillonite and due to a lower amount of CaO compared to that of Na2O the type of ES3 montmorillonite is Na-montmorillonite. This study aims at examining a novel insight to characterize bentonites to find out the mineralogical and physicochemical properties of studied samples. [ABSTRACT FROM AUTHOR]

Swelling and non-swelling properties of bentonite particles play an important role in their performance as well as their applications. Swelling bentonites, containing montmorillonite as the main constituent, are mainly used in drilling fluids, bonding sands in foundry molds, iron ore palletizing, and environmental sealing, while non-swelling ones are primarily used as adsorbents in bleaching earth and heavy metal removal. Experimental studies on 10 natural bentonite samples, namely S1 to S10, were conducted to identify the swelling behavior of the samples. XRD studies showed the presence of nanoporous and nanostructured montmorillonite species along with some other clay and non-clay mineral impurities. XRF studies through the measurement of CaO and Na2O weight percents provided a good measure to determine swelling or non-swelling properties of bentonites. XRD and XRF analyses demonstrated that Na2O in samples S5 to S8 belongs to montmorillonite, which is a clay mineral. The first main peak of montmorillonite in its XRD pattern was another guide in assigning the type of the bentonites. BET surface area measurement was employed to verify the former observations. A higher surface area was measured for swelling bentonites, while the highest surface area of 78 m2/g was obtained for the swelling S8 bentonite. The studies showed that samples S9 and S10 are non-swelling, samples S4, S7, and S8 are swelling, samples S2, S5, and S6 are swelling/non-swelling, and sample S3 is a non-swelling/swelling bentonite. [ABSTRACT FROM AUTHOR]