Modification of bentonite clay & its applications: a review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Debasis Borah ◽  
Harshajit Nath ◽  
Hemaprobha Saikia
Keyword(s):  
Surface Area ◽  
Chemical Properties ◽  
Bentonite Clay ◽  
Total Surface Area ◽  
Efficient Catalyst ◽  
Swelling Properties ◽  
Arenesulfonic Acid ◽  
Organophilic Clay ◽  
Ancient Times ◽  
Physical And Chemical

Abstract Bentonite clay is one of the oldest clays that humankind has been using from ancient times as traditional habits and remedies. In recent years researchers have found many applications of bentonite clay due to its various physio-chemical properties. In the present work, various physical and chemical properties of bentonite such as surface area, adsorption, swelling properties, cation exchange properties, etc. have been studied. This study also includes various procedures of modification of bentonite clay into Chitosan/Ag-bentonite composite, Fe-Modified bentonite, Hydroxyl-Fe-pillared-bentonite, Organo Bentonite, Organophilic clay, Arenesulfonic Acid-Functionalized Bentonite, Bentonite clay modified with Nb2O5. The study reveals that bentonite clay has large surface area due to similar structure with montmorillonite and it is found that the functionality of bentonite can be increased by increasing total surface area of the clay. Due to high cation exchangeability of bentonite, various cations can be incorporated into it. After purification and modification, the absorbent aluminum phyllosilicate bentonite clay can be used as an efficient catalyst in various types of catalytic reactions. Moreover, bentonite clay can be applied in various field like drilling, civil engineering, agriculture and water treatment.

Cottonseed oil bleaching by acid-activated montmorillonite

Clay Minerals ◽  
1999 ◽  
Vol 34 (2) ◽  
pp. 221-232 ◽  
Author(s):  
P. Falaras ◽  
I. Kovanis ◽  
F. Lezou ◽  
G. Seiragakis
Keyword(s):  
Surface Area ◽  
Chemical Properties ◽  
Acid Value ◽  
Cottonseed Oil ◽  
Total Surface Area ◽  
Acid Activation ◽  
Bleaching Efficiency ◽  
Bleaching Procedure ◽  
Physical And Chemical

AbstractA progressive decrease in cation exchange capcity (CEC) values was observed by treating Ca-montmorillonite with sulphuric acid solutions and this can be understood in terms of the layered structure of the clay. Elemental analysis showed that moderate activation occurred and only 25–30% of the octahedral cations were removed. At the same time the total surface area and the clay acidity increase. X-ray and FTIR data confirmed that acid activation affects both the octahedral and the tetrahedral sheets. The efficiency of acid-activated montmorillonite for the bleaching of cottonseed oil was investigated. The differences in bleaching efficiency appeared to be due to differences in the physical and chemical properties of the bleaching media. The oil acid value was not affected by the bleaching procedure but a slight shift in the absorption maximum of the bleached cottonseed oil was observed. Medium activation of the clay (treatment of Ca-montmorillonite with 4 N H2SO4) was the most effective in bleaching the cottonseed oil, resulting in the best colour index and the lowest peroxide value. A linear dependence of the bleaching efficiency on the clay surface area and acidity was observed. The role of the increased Bronsted acidity is also discussed.

scholarly journals Influence of the Calcination Temperature on the properties of The Alumina as Catalyst Support for Catalysis

Paliva ◽  
2020 ◽  
pp. 155-161
Author(s):  
Tomáš Hlinčík ◽  
Veronika Šnajdrová ◽  
Veronika Kyselová
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Catalyst Support ◽  
Chemical Properties ◽  
Total Pore Volume ◽  
Temperature Range ◽  
Calcination Temperatures ◽  
Physical And Chemical

Alumina is commonly used in industrial practice as a catalyst support and it is made from boehmite. Depending on the calcination temperature, this mineral is transformed into various crystalline modifications which have different physical and chemical properties. For this reason, the following parameters were determined at different calcination temperatures: length, width, material hardness, specific surface area and total pore volume. The results show that with increasing calcination temperature there have been significant changes which may be important when using the material as a catalyst support, e.g. in the preparation of catalysts or in the design of cat-alytic reactors. The specific surface area, which decreases in the temperature range 450–800 °C, is an important parameter for the preparation of catalysts, so it is appropriate to choose a temperature of 600 °C, when the specific surface area is above 200 m2·g-1. The effect of calcination temperature on the structural transitions of boehmite was also monitored. The results showed that γ-Al2O3 has the most suitable properties as a catalyst sup-port in the temperature range 450–800 °C.

Analytical Methodology from Lavoisier to Mendeleev

2014 ◽  
Author(s):  
Marco Fontani ◽  
Mariagrazia Costa ◽  
Mary Virginia Orna
Keyword(s):  
Chemical Change ◽  
Chemical Properties ◽  
Professional Activity ◽  
Analytical Methodology ◽  
Long Run ◽  
Similar Chemical ◽  
Experimental Errors ◽  
Ancient Times ◽  
Almost All ◽  
Physical And Chemical

Within the period covered by Part II, 1789–1869, 37 true elements, almost all of them metals, were discovered. Prior to this time, about 14 metals had been discovered, excluding those that had been known from ancient times. The discovery of the elements during this period of interest is intimately related to the analytical methodologies available to chemists, as well as to a growing consciousness of just what an element is. Because these methods were also available to the less competent who may have lacked the skills to use them or the knowledge to interpret their results, their use also led to as many, if not more, erroneous discoveries in the same period. One can number among the major sources of error faulty interpretation of experimental data, the “rediscovery” of an already known element, sample impurities, very similar chemical properties (as in the case of the rare earths), the presence of an element in nature in very scarce or trace amounts, gross experimental errors, confusion of oxides and earths with their metals, and baseless dogmatic pronouncements by known “authorities” in the field. Antoine Laurent Lavoisier’s conceptualization of what constitutes an element was a radical break from the principles of alchemy. His stipulation that an element is a substance that cannot be further decomposed conferred an operational, pragmatic, concrete definition on what had previously been a more abstract concept. At the other end of the spectrum was the intuition of Dmitri Mendeleev who, contrary to the prevailing acceptance of Lavoisier’s concept, stressed the importance of retaining a more abstract, more fundamental sense of an element—an idea that in the long run enabled the development of the periodic table. What both men had in common is that they defined and named individual elements as those components of substances that could survive chemical change and whose presence in compounds could explain their physical and chemical properties. Mendeleev’s table has been immortalized in every chemistry classroom—and also concretely in Saint Petersburg, the city that saw most of his professional activity, by a spectacular building-sized model The analytical chemist depends on both of these concepts and indeed, analytical practice preceded Lavoisier’s concept by at least a century.

Some Physical, Chemical and Mineralogical Properties of Some Canadian Fly Ashes

1986 ◽  
Vol 86 ◽  
Author(s):  
R. C. Joshi ◽  
B. K. Marsh
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Chemical Properties ◽  
Water Soluble ◽  
Pozzolanic Activity ◽  
Unburned Carbon ◽  
Magnetic Fraction ◽  
Fly Ashes ◽  
Physical And Chemical

ABSTRACTThis paper gives physical and chemical properties of some Canadian fly ashes. Specific surface area, magnetic fraction, water soluble fraction and fraction finer than 45 μm were determined as part of the physical tests. Thermo-gravimetric analyses (TGA) in oxygen and nitrogen were conducted on raw ash samples. The change of pH with time in suspensions of the different ashes in water was also determined. Pozzolanic activity of the ashes with lime for all the ashes was evaluated to measure ash reactivity.The ash activity seems to be related to fineness of the ash measured by the Blaine air permeability method, but not to the fineness measured by nitrogen sorption. Generally the greater the specific surface area, the higher the reactivity of the ash. The correlation was, however, not strong and no other physical or chemical parameter measured in this investigation seems to be related to pozzolanic activity.The results of pH and TGA tests indicated that the ashes differ in many respects from each other. The TGA data suggest that loss on-ignition in many of the ashes is not entirely due to the presence of unburned carbon. Specific surface area determined by various methods seems to provide different values. No characterization parameter was found that was uniquely related to coal type.

scholarly journals Reactivity of fly ashes milled in different milling devices

2019 ◽  
Vol 58 (1) ◽  
pp. 179-188 ◽  
Author(s):  
Yong-Sik Chu ◽  
Batmunkh Davaabal ◽  
Dae-Sung Kim ◽  
Sung-Kwan Seo ◽  
Yoo Kim ◽  
...  
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Surface Area ◽  
Thermal Power ◽  
Chemical Properties ◽  
Particle Size Reduction ◽  
Attrition Mill ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Physical And Chemical

Abstract The effect of two different milling devices, namely attrition mill versus vibration mill, on the reactivity of fly ash was studied. High calcium fly ash from 4th Thermal power station of Ulaanbaatar (Mongolia) was used for the experiments. The raw and processed samples were characterized by XRD, SEM, Particle size distribution, BET, Blaine surface area and density measurements. The efficiency of 1 hour milling was evaluated with the Blaine surface area set to be more than 5000 cm2/g. The physical and chemical properties of the attrition milled fly ash changed not much compared to the vibration milled samples. For example the d50 particle size became reduced from 29 µm to 6 µm by attrition milling and in vibration milled fly ash it was reduced to 7 µm. The density increased from 2.44 g/cm3 of raw fly ash to 2.84 g/cm3 and 2.79 g/cm3 in attrition and vibration milled samples, respectively. Mechanical milling revealed not only a particle size reduction but also the formation of a denser microstructure. As a result the vibration milled fly ash showed a weaker interaction with the alkaline solution (8 M NaOH used here) compared to the attrition milled fly ash. Consequently, compressive strength of the binder prepared using the attrition milled fly ash was higher, 61 MPa, while for vibration milled fly ash it was 49 MPa. For comparison unmilled fly ash, it was 21 MPa.

scholarly journals Characterization of Samarium Doped Ceria Powders Having High Specific Surface Area Synthesized by Carbon-Assisted Spray Pyrolysis

2011 ◽  
Vol 485 ◽  
pp. 137-140 ◽  
Author(s):  
Kenichi Myoujin ◽  
Hiroki Ichiboshi ◽  
Takayuki Kodera ◽  
Takashi Ogihara
Keyword(s):  
Specific Surface ◽  
Relative Density ◽  
Spray Pyrolysis ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Sources ◽  
Chemical Properties ◽  
High Specific Surface Area ◽  
Doped Ceria ◽  
Physical And Chemical

Spherical samarium doped ceria (Ce0.8Sm0.2O1.9, SDC) powders having high specific surface area (SSA) were successfully synthesized by carbon-assisted spray pyrolysis (CASP). Saccharides, such as monosaccharides and disaccharides, or organic acids were used as carbon sources. The physical and chemical properties of these powders were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Thermo gravimetry-Differential Thermal Analysis (TG-DTA), and BET. Decarbonized powders obtained by this method exhibit spherical morphologies and nano- and submicron-sizes. The SSA of SDC obtained from CASP was more than seven times higher than that obtained from conventional spray pyrolysis (CSP). The SSA of the decarbonized SDC powders obtained by calcination at 900 °C was estimated to be approximately 70 m2/g by using the BET method. The relative density of SDC obtained from CASP was higher than that obtained from CSP. The relative density of the SDC pellet was highest (96 %) when it was sintered at 1400 °C.

Introduction

1995 ◽  
Author(s):  
K. O. Emery ◽  
David Neev
Keyword(s):  
Oil And Gas ◽  
Chemical Properties ◽  
Dead Sea ◽  
Water Well ◽  
Ancient Times ◽  
Diapiric Structure ◽  
The Dead ◽  
Natural Result ◽  
Physical And Chemical

The thrilling biblical saga of Sodom and Gomorrah leaves a deep impression on the spirit of its readers, especially the young. Basic ethical concepts such as right and wrong were dramatically portrayed by that simple and cruel, yet humane, story. Memories of even more ancient disastrous geological events apparently were interwoven into the saga. A geologist cannot remain indifferent when investigating the Dead Sea region and observing stratigraphical and structural evidence of past and continuing similar events. Forceful dynamics indicated by vertically tilted beds of rocksalt layers that have penetrated upward through the ground and by later processes that have shaped some beds into pillars trigger association with the ancient story. Such features are abundant and clearly recognizable along the foot of the diapiric structure of Mount Sedom (Arabic Jebel Usdum). A gas blowout during the drilling of a water well near the Amazyahu fault in 1957 only by good luck failed to produce a gush of fire and smoke. Such an event could have happened in ancient times as a natural result of faulting. Knowledge of the regional geological background permits translation of the biblical descriptions into scientific terms, which suggests that the sagas of Sodom, Gomorrah, and Jericho described real events that occurred during ancient times before much was known about geology. Thirty-five years of the authors' professional experience in the Dead Sea region encompasses many geological aspects of the basin: deep and shallow stratigraphy, structural history, seismology, sedimentological processes, and the physical and chemical properties of the water. Archaeological studies in the region are reviewed. Although most of these studies are applicable to exploration for oil and gas or extraction of salts from brines, their results illuminate the role of changing paleogeography and paleolimnology on human environments. Climate changes and lake-level fluctuations have occurred since Mid-Pleistocene, especially during the past 50,000 years. Studies of sediments from shallow core holes delimit coastal areas that when exposed by drops in the level of the Dead Sea, quickly developed soils that could be used for agriculture.

scholarly journals Internal Porosity of Mineral Coating Supports Microbial Activity in Rapid Sand Filters for Groundwater Treatment

2014 ◽  
Vol 80 (22) ◽  
pp. 7010-7020 ◽  
Author(s):  
Arda Gülay ◽  
Karolina Tatari ◽  
Sanin Musovic ◽  
Ramona V. Mateiu ◽  
Hans-Jørgen Albrechtsen ◽  
...  
Keyword(s):  
Surface Area ◽  
Removal Rate ◽  
Chemical Properties ◽  
Filter Material ◽  
Microbial Colonization ◽  
Bacterial Cells ◽  
Electron Microscopic ◽  
Sand Filters ◽  
Internal Porosity ◽  
Physical And Chemical

ABSTRACTA mineral coating develops on the filter grain surface when groundwater is treated via rapid sand filtration in drinking water production. The coating changes the physical and chemical properties of the filter material, but little is known about its effect on the activity, colonization, diversity, and abundance of microbiota. This study reveals that a mineral coating can positively affect the colonization and activity of microbial communities in rapid sand filters. To understand this effect, we investigated the abundance, spatial distribution, colonization, and diversity of all and of nitrifying prokaryotes in filter material with various degrees of mineral coating. We also examined the physical and chemical characteristics of the mineral coating. The amount of mineral coating correlated positively with the internal porosity, the packed bulk density, and the biologically available surface area of the filter material. The volumetric NH4+removal rate also increased with the degree of mineral coating. Consistently, bacterial 16S rRNA andamoAabundances positively correlated with increased mineral coating levels. Microbial colonization could be visualized mainly within the outer periphery (60.6 ± 35.6 μm) of the mineral coating, which had a thickness of up to 600 ± 51 μm. Environmental scanning electron microscopic (E-SEM) observations suggested an extracellular polymeric substance-rich matrix and submicron-sized bacterial cells. Nitrifier diversity profiles were similar irrespective of the degree of mineral coating, as indicated by pyrosequencing analysis. Overall, our results demonstrate that mineral coating positively affects microbial colonization and activity in rapid sand filters, most likely due to increased volumetric cell abundances facilitated by the large surface area of internal mineral porosity accessible for microbial colonization.

scholarly journals Pt Nanoparticles Supported on Nitrogen doped Carbon as an Efficient Catalyst for Decalin Dehydrogenation

2020 ◽  
Vol 194 ◽  
pp. 02025
Author(s):  
Huiru Yun ◽  
Zhuo Li ◽  
Shiguang Fan ◽  
Jian Wang ◽  
He Liu
Keyword(s):  
Chemical Properties ◽  
Pt Nanoparticles ◽  
Mesoporous Structure ◽  
Catalytic Performance ◽  
High Specific Surface Area ◽  
Efficient Catalyst ◽  
Transmission Electron ◽  
Mean Size ◽  
Nitrogen Doped Carbon ◽  
Physical And Chemical

A novel Pt/CN catalyst was synthesized by sodium borohydride treatment. The physical and chemical properties of Pt/CN catalyst were characterized by X-ray diffraction (XRD), brunner-emmet-teller (BET), transmission electron microscope (TEM) and High-resolution transmission electron microscopy (HRTEM). The characterized results showed that the catalyst has a high specific surface area, mesoporous structure and the mean size of Pt nanoparticles is 2.59 nm. Subsequently, the catalytic performance of Pt/CN catalyst for decline dehydrogenation was studied. Pt/CN catalyst exhibited excellent performance in decalin dehydrogenation with the conversion of decalin was 30.70%, and the selectivity of naphthalene was 90.86% at 200 ℃ for 150 minutes. When the reaction temperature increased to 210 ℃, the conversion of catalyst increased to 52.02%, and the selectivity of naphthalene reduced to 90.21%. The possible reason may be attributed to the difficulty in converting decalin to tetralin. This paper would provide a novel method for the synthesis of efficient dehydrogenation catalyst of decalin..

Relationship Between Particle Size Distribution and Specific Surface Area of Urban Roadway Stormwater Solids

1997 ◽  
Vol 1601 (1) ◽  
pp. 95-108 ◽  
Author(s):  
John J. Sansalone ◽  
Steven G. Buchberger ◽  
Joseph M. Koran ◽  
Joseph A. Smithson
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Particle Surface ◽  
Chemical Properties ◽  
Spherical Particles ◽  
Particle Surface Area ◽  
Surface Areas ◽  
Physical And Chemical ◽  
And Chemical Properties

Surface area is a primary factor in determining many physical and chemical properties of solids, especially particles. In urban and highway runoff, solids can mediate the partitioning between the dissolved and particulate-bound phases of metal elements and organic compounds. Solids are also capable of adversely affecting roadway drainage appurtenances through sedimentation and clogging. Solids characteristics of primary importance for both solute adsorption and clogging and sedimentation are particle size distributions (PSDs), specific surface areas (SSAs), and mass loadings. PSD and SSA results are presented for rainfall and snowmelt solids from a heavily traveled urban roadway in Cincinnati. Integration of the PSD and SSA results indicates that particle surface area is greatest for the midrange (> 100 μm) to the coarser end (<2000 μm) of the gradation. SSA results determined using the assumption of smooth spherical particles are indicated to grossly underestimate actual SSA values.

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