Kaolinite

This study is to collect information regarding major metallogenic aspects of Kaolin deposits with certain commercial possibilities in the northeastern part of Bolivar state. This article describes the geological, physicochemical and genesis of kaolin deposits that developed in an economically significant in geological provinces of the Guayana Shield. A portion of these Kaolin deposits have been exploited in the region of Upata and Km 88 in the 1990s for the production of refractory and ceramic products, however, there are many deposits of Kaolin with geo-economic potential that currently do not known geological reserves and commercial quality. It describes the main physicochemical characteristics of kaolin and its most striking applications.

The results on the elemental and mineralogical compositions of clays from Central Uganda differed from those from the volcanic sediments of the Mt. Elgon in Eastern Uganda. Utilisation of the two types of clays should be strict after understanding their structural differences. Whereas elemental, mineralogical, DTA, IR, XRD and pH data on selected clays from Kumi, Nakawa, Seeta, Kajansi, Kawuku, Lwanda, Chodah and Umatengah indicated that they were kaolinites. Similar data on clays from Mutufu, Budadiri, Chelel and Siron indicated that they were largely smectites. The IR data accumulated on Kawuku, Kajansi, Lwada, Seeta, Chodah, Umatengah, Kumi and Nakawa clays revealed they were largely kaolinites yet that on Mutufu, Chelel, Budadiri and Siron clays indicated they were smectite-rich.

Archaeological investigations of burial chambers in the north-central highlands of Peru have contributed valuable information on the mortuary practices of a Recuay agro-pastoral community. This thesis relied on grave goods inventories, osteological analysis, and types of stone architecture in the burial chamber.

ÖZ
Türkiye’de çıkan kırmızı kil yataklarından en önemlilerinden ikisi Nevşehir ilinin Avanos ilçesinde ve
Bilecik ilinin Pazaryeri ilçesine bağlı Kınık Köyünde bulunmaktadır. Avanos ve Kınık killerinin ortak özelliği; bu killerde demir oksit (%Fe2O3) oranının, %7’nin üzerinde olmasıdır. Bu çalışmanın amacı ise, saf kaolinin olmadığı durumlarda, sır reçetesine Avanos ve Kınık kırmızı killerinin eklenmesinin sırda yaratacağı artistik değişikliklerin belirlenmesidir. Bu doğrultuda, Avanos ve Kınık killerinin eklendiği ham sır karışımları, şamotlu kil, kırmızı çömlek kili ve döküm kilinden oluşan tabletlere akıtma yoluyla uygulanmıştır. Ayrıca kıyaslama yapmak amacıyla, Avanos ve Kınık killeri yerine saf Avanos kaolini ham sırlara aynı oranda ilave edilmiş ve aynı yüzeyler üzerine uygulanmıştır. Bunlara ek olarak, demir oksit kaynağı olarak düşünülen Avanos ve Kınık killeri; aventurin, krakle ve parlak transparan sır bileşimlerine ilave edilerek ek denemeler yapılmıştır. 1050 derecede fırınlanan sır kompozisyonlarının bünyeyle uyumu, sırın yüzeye tutunması, renkleri, parlak-matlık özellikleri ve estetik durumu incelenmiştir. Sonuç olarak, saf kaolinin olmadığı durumlarda çömlekçi kili olarak kullanılan Avanos ve Kınık killerinin sır karışımında kaolin görevi görebileceği ve sırda küçük çaplı renk değişimleri ve artistik etkiler yarattığı gözlemlenmiştir.

ABSTRACT
Avanos, as a town located in Nevşehir and Kınık village in Pazaryeri, Bilecik, are among the most prominent well-known red clay deposits in Turkey. The common characteristic specific to these both sites is the fact that the percentage of iron oxide (%Fe2O3) in clays extracted from Avanos and Kınık deposits is above 7 (seven). Within this study, it was aimed to examine the changes and artistic effects occurring after the red clays from Avanos and Kınık deposits were added to glaze as colorant, in the absence of pure kaolin. Along with this aim, Avanos and Kınık clays were added to raw glaze compositions, and this blend was applied to tablets made through the proportioned mixture of chamotte clay (fireclay), red earth pottery clay and casting clay. In addition to that, pure Avanos kaolin was added at the same amount to raw glaze composition instead of Avanos and Kınık clays and this composition
was applied to the tablets as well, produced through the use of same clays in order to obtain comparative results. Furthermore, additional tests were conducted by adding Avanos and Kınık clays as iron-oxide source to the blend of aventurine glaze, glossy crackle glaze and transparent glaze. Glaze compositions applied to tabled were fired at 1050 Celsius degrees, and the effects were examined carefully in terms of glaze fit, compatibility between glaze and clay body, glaze colours, the degree of being matte and glossy and aesthetics. The results indicated that Avanos and Kınık clays, used as the pottery clay in the absence of pure kaolin, could be utilized as substitute of kaolin, and the addition of these clays to glaze compositions lead to small-scale colour changes and artistic effects.

Se estudiaron los resultados experimentales de lixiviación en pilas para el blanqueo del caolín a escala de laboratorio basados en un desarrollo teórico. El objetivo principal fue evaluar la remoción de óxidos de hierro sobre la superficie del caolín, Método con el uso de diferentes concentraciones de ácido oxálico en un tiempo de 48 días. Resultado. El índice de blancura del caolín de alimento fue del 52.1%, con porcentajes de hierro del 0.19%. A partir de los ensayos experimentales, Conclusión los resultados mostraron que para las concentraciones de 0.15M, 0.015M y 0.95M, las remociones de hierro fueron alrededor del 72.2%, 26.7%, 90.8% y los índices de blancura obtenidos fueron de 90.2%, 83.8% y 97% respectivamente.Abstract The experimental results of leaching were studied in batteries for bleaching kaolin scale The experimental results of leaching were studied in batteries for bleaching kaolin scale development based on a theoretical laboratory. The main objective was to evaluate the removal of iron oxides on the surface of kaolin, Methods: the use of different concentrations of oxalic acid drip for 48 days in each heap. Results: The whiteness index of feed Kaolin is 52.1%, with an iron content of 0.19%. Conclusions: The results showed that for acidic concentrations 0.15M, 0.015M and 0.95M, the iron removed was approximately 72.2%, 26.7%, 90.8% and the whiteness index rose to 90.23%, 83.8%, and 97% respectively. Palabras clave: Acido Oxálico, Blanqueo de Caolín, Hidrometalurgia, Lixiviación en pilas, Óxidos de hierro

The aim of the present study is to find out the presence of minerals, raw materials used and the ceramic technology of the past in the selected pottery sample of the period 250BC from the important archeological site Keeladi of Sivagangai district, Tamil Nadu, India. Fourier Transform Infra Red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) techniques have been used for the analysis. Examination of pottery sample under FTIR and SEM is an excellent micro analytical technique used for the study of clay mineral configuration, fabric, texture, growth mechanisms and to estimate firing temperatures. The presence of quartz, feldspar, montmorillonite, kaolinite, mullite in the selected pottery samples has been identified. Firing the pottery samples in the reducing atmosphere technique is also brought out.

Kaolinite surfaces were modified by mechanochemical treatment for periods of time up to 10 h. X-ray diffraction shows a steady decrease in intensity of the d(001) spacing with mechanochemical treatment, resulting in the delamination of the kaolinite and a subsequent decrease in crystallite size with grinding time. Thermogravimetric analyses show the dehydroxylation patterns of kaolinite are significantly modified. Changes in the molecular structure of the kaolinite surface hydroxyls were followed by infrared spectroscopy. Hydroxyls were lost after 10 h of grinding as evidenced by a decrease in intensity of the OH stretching vibrations at 3695 and 3619 cm−1 and the deformation modes at 937 and 915 cm−1. Concomitantly an increase in the hydroxyl stretching vibrations of water is found. The water-bending mode was observed at 1650 cm−1, indicating that water is coordinating to the modified kaolinite surface. Changes in the surface structure of the OSiO units were reflected in the SiO stretching and OSiO bending vibrations. The decrease in intensity of the 1056 and 1034 cm−1 bands attributed to kaolinite SiO stretching vibrations were concomitantly matched by the increase in intensity of additional bands at 1113 and 520 cm−1 ascribed to the new mechanically synthesized kaolinite surface. Mechanochemical treatment of the kaolinite results in a new surface structure.

Nowadays, the energetic efficiency becomes one of the major interests of the global society. Thus, the energetic challenges of the new century enforce the scientific and industrial environment to the development of new efficient materials, which present more than the classical thermal properties, according to the energy storage, energy consumption and other specific needs. In this context, the present work constitutes the third step of the development of a new kind of composite materials (micro-composites and nano-composites), using natural marl (clay) clay and biodegradable polymer, which is the PolyEthylene Glycol 6000 (PEG 6000). This step corresponds to characterization of the variation of the specific heat (denoted Cp) of the materials elaborated. So, in order to estimate the capacity of thermal energy adsorption, we utilized a SHIMATZU-DSC 60 Differential Scanning Calorimeter. The main results present the evolution of the Cp according to the PEG 6000 doping and also the specific melting enthalpy of the polymer within the natural clay matrix; by the way this enthalpy constitutes the specific heat stocked in the materials.

Samples were collected from the argillic alteration zones in Sappes area, Thrace, Northern Greece and were examined for their mineralogical composition. Results showed that the sericite zone is the most widespread type of alteration in the studied area, followed by the transitional sericite–kaolinite zone and finally the pyrophyllite-rich zone. After determination of the spatial distribution of the different argillic alteration zones, selected samples were examined for their technological ceramic properties in order to evaluate their use in ceramic production. Preliminary results showed that after beneficiation processes, the clayey raw material from the alteration zones could be used in the ceramic industry.

Abstract
The late Paleozoic Era was an interval of major tectonic and climatic changes,
including formation of the supercontinent Pangea and the ~60-Myr-long Late
Paleozoic Ice Age (LPIA). Although bauxite formation declined globally from the
Carboniferous to the Permian in conjunction with global cooling, it was an interval of
widespread bauxite formation in China. In South China, (1) the Jiujialu Formation
bauxite deposits in central and northern Guizhou (Zunyi area) are of early-middle
Visean age; (2) the Dazhuyaun Formation bauxite deposits in northern Guizhou
(Wuchuan–Zheng’an–Daozheng area) to southern Chongqing (Nanchuan area) and
southeastern Guizhou (Fuquan–Kaili area) are of Late Pennsylvanian–Early Permian
age; and (3) the Heshan Formation bauxite deposits in western Guangxi to Yunnan are
of Middle–Late Permian age. In North China, the Benxi Formation bauxite deposits
are of Late Mississippian–Middle Pennsylvanian age. The contrasting trends in
bauxite metallogenesis between China and the rest of the world imply different
climatic patterns in the eastern Tethys (high annual humidity with seasonal dryness)
and Pangea (aridification). This hypothesis is further supported by differences in the
chemical index of alteration, or CIA (>80 in the eastern Tethys vs. ~50 in western
Pangea), and in paleotemperatures (mean annual temperature, or MAT = ~20 °C in the
eastern Tethys vs. ~4 °C in western Pangea) determined from Permo-Carboniferous
siliciclastic deposits. Permo-Carboniferous bauxite deposits in South China formed in
coastal plain and coastal karstic depression environments, in which the position of the
groundwater table was related to sea-level changes. During the late Paleozoic,
high-frequency eustatic fluctuations caused by waxing and waning of Gondwana
icesheets controlled sedimentation in these coastal depositional systems, leading to
cyclic accumulation of coal and bauxite deposits and cycles of vadose- and
phreatic-type bauxite formation. The results of the present study show that, during
interglacial stages, lateritization resulted from high pCO2, high sea-level and
groundwater-table elevations, low precipitation, and limited vegetation cover, whereas
during glacial stages, bauxitization of these ferralitic weathering products was
promoted by low pCO2, low sea-level and groundwater-table elevations, high precipitation, and more extensive vegetation cover. Thus, a unique combination of
geographic, climatic, and eustatic factors accounted for widespread formation of
bauxite in South China during the LPIA.

The modification of kaolinite surfaces through mechanochemical treatment has been studied using a combination of mid-IR and near-IR spectroscopy. Kaolinite hydroxyls were lost after 10 h of grinding as evidenced by the decrease in intensity of the OH stretching vibrations at 3695 and 3619 cm−1 and the deformation modes at 937 and 915 cm−1. Concomitantly an increase in the hydroxyl-stretching vibrations of water is observed. The mechanochemical activation (dry grinding) causes destruction in the crystal structure of kaolinite by the rupture of the OH, AlOH, AlOSi and SiO bonds. Evidence of this destruction may be followed using near-IR spectroscopy. Two intense bands are observed in the spectral region of the first overtone of the hydroxyl-stretching vibration at 7065 and 7163 cm−1. These two bands decrease in intensity with mechanochemical treatment and two new bands are observed at 6842 and 6978 cm−1 assigned to the first overtone of the hydroxyl-stretching band of water. Concomitantly the water combination bands observed at 5238 and 5161 cm−1 increase in intensity with mechanochemical treatment. The destruction of the kaolinite surface may be also followed by the loss of intensity of the two hydroxyl combination bands at 4526 and 4623 cm−1. Infrared spectroscopy shows that the kaolinite surface has been modified by the removal of the kaolinite hydroxyls and their replacement with water adsorbed on the kaolinite surface. NIR spectroscopy enables the determination of the optimum time for grinding of the kaolinite. Further NIR allows the possibility of continual on-line analysis of the mechanochemical treatment of kaolinite.

Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging between 14.6 nm and 92.5 nm. The particle size varied with intercalation ratios with methanol intercalated kaolinite > DMSO-kaolinite > urea-kaolinite (KPDMU). Following intercalation, SEM analysis revealed a change of order from thick compact overlapping euhedral pseudohexagonal platelets to irregular booklets which later transformed to vermiform morphology and dispersed euhedral pseudohexagonal platelets. Besides, dispersed euhedral pseudohexagonal platelets were seen to coexist with blocky-ve...

Kaolinite surfaces were modified by grinding kaolinite/quartz mixtures with mole fractions of 0.25 kaolinite and 0.75 quartz for periods of time up to 4 h. X-ray diffraction shows the loss of intensity of the d(001) spacing with mechanical treatment resulting in the delamination of the kaolinite. Thermogravimetric analyses show the kaolinite surface is significantly modified and surface hydroxyls are replaced with water molecules. Changes in the molecular structure of the surface hydroxyls of the kaolinite/quartz mixtures were followed by infrared spectroscopy. Kaolinite hydroxyls were lost after 2 h of grinding as evidenced by the decrease in intensity of the OH stretching vibrations at 3695 and 3619 cm-1 and the deformation modes at 937 and 915 cm-1. Changes in the surface structure of the OSiO units were reflected in the SiO stretching and OSiO bending vibrations. The decrease in intensity of the 1056 and 1034 cm-1 bands attributed to kaolinite SiO stretching vibrations were concomitantly matched by the increase in intensity of additional bands at 1113 and 520 cm-1 ascribed to the new mechanically synthesized kaolinite surface. Mechanochemical treatment of the kaolinite results in a new surface structure.

We developed a predictive model to study how flocculant additives alter the interactions among clay particles in colloidal suspensions, such as industrial mining tailings. Fully atomistic models of kaolinite
nanoplatelets constructed from X-ray crystal structure data feature a highly polarized charge distribution, which defines their solvation, adsorption and association properties. Effective interactions,
in the form of potential of mean force (PMF), between kaolinite platelets in aqueous electrolyte solution are calculated using the three-dimensional reference interaction site model with the Kovalenko-Hirata closure relation (3D-RISM-KH) molecular theory of solvation based on the first
principles of statistical mechanics. This theory is also employed to study the adsorption of ions and flocculant additive building blocks onto kaolinite surfaces. Three main mutual orientations of platelets
are studied in aqueous electrolyte solutions of several polymer building blocks represented by acrylamide, acrylic acid, acrylate and styrene. The results indicate that Na + are predominantly adsorbed
onto the siloxane surface of kaolinite while the chloride and acrylate anions prefer the aluminum hydroxide surface of kaolinite. Weaker preferential adsorption is observed for the neutral monomers.
The PMF between platelets depends nontrivially on the concentration of solvent components and exhibits a complex oscillating behavior with several minima and maxima that correspond to important
solvation and aggregation energy barriers. Among the three studied mutual orientations of the nanoplatelets, the most stable one corresponds to the direct contact of the aluminum hydroxide with
siloxane surfaces. Other highly probable arrangements correspond to nanoplatelets separated by a single layer of solvent. The effect of additives on interparticle interactions is correlated with the
strength of adsorption on kaolinite relative to water, as strongly and weakly adsorbing species cause increase and decrease, respectively, of the PMF at short distances. Moreover, hydrophobic additives
cause a decrease in the local solvent density between nanoparticles and consequently a decrease in the PMF. These results provide valuable insights into the mechanism of interactions of kaolinite nanoplatelets in thermodynamic conditions relevant to clay dispersions, as occurring in tailings produced by the process of hot water extraction of bitumen from oil sands and other mining tailings.

The study of identification methods for clay minerals is very important because of the very fine particle size (less than 2 μm) of these materials, which makes it difficult to recognize them with the naked eye. Because they consist of electrically charged particles, clay minerals exhibit distinct and dynamic behavior. From geotechnical standpoint , clay minerals are present in a wide variety of rocks and soils. Because their behavior is difficult to predict, careful consideration is necessary because they exert great influence on the design and construction of roads, tunnels, foundations, slopes, and many other types of infrastructure. Their characteristics may have a positive effect , e.g., when acting as clay liners, or a negative one, e.g., when their swelling characteristic causes buildings to lose their stability. In this context, the purpose of this work was to compare the reliability of two clay mineral identification methods: combined differential thermal analysis and thermogravimetry (DTA-TG) and the methy-lene blue adsorption test (MBAT). Proportional mixtures of kaolinite and bentonite were prepared in order to investigate the two methods. These two types of clay were chosen due to their distinct behaviors: kaolinite is a 1:1 clay mineral, and bentonite is composed mostly of montmorillonite, a 2:1 clay mineral. The two methods showed a positive and highly significant correlation. Moreover, the MBAT is a lower cost test that requires only ordinary chemistry laboratory equipment. Correlations revealed that the MBAT can provide thermal information related to DTA-TG tests.

This paper is tried to recycling debris in earthen sites with natural clay minerals. It also studies the mechanical and physical properties of different portion of clay minerals in the earthen masonry. Two kind of soil as base of masonry has been selected. One of them is the soil of debris with non plasticity and no good features and the other is a suitable soil with adequate clay content which imported to the site from out. So various quantities of Kaolinite, Bentonite and sand added to the same amount of both kind of soils and different kind of Adobes prepared. After that, those are examined under compressive strength and moisture softening. According to the results, with increasing amount of Bentonite to the debris, cohesion and consequently compressive strength increased. This increase, for Kaolinite takes place in the smaller limit. In fact Kaolinite fills the pores but because it has no plasticity increasing in compressive strength is lesser than Bentonite. In the suitable soi...

The thermal behaviour of kaolinites intercalated with formamide, dimethyl sulphoxide and hydrazine has been studied by simultaneous TG-DTG-DTA-EGA and TG-MS techniques. The complexes can be decomposed completely without dehydroxylating the mineral. It was found that the amount of intercalated guest molecules per inner surface OH-group is close to unity for the formamide and dimethyl sulphoxide intercalates. For the intercalation of

Abstract The study of identification methods for clay minerals is very important because of the very fine particle size (less than 2 μm) of these materials, which makes it difficult to recognize them with the naked eye. Because they consist of electrically charged particles, clay minerals exhibit distinct and dynamic behavior. From geotechnical standpoint, clay minerals are present in a wide variety of rocks and soils. Because their behavior is difficult to predict, careful consideration is necessary because they exert great influence on the design and construction of roads, tunnels, foundations, slopes, and many other types of infrastructure. Their characteristics may have a positive effect, e.g., when acting as clay liners, or a negative one, e.g., when their swelling characteristic causes buildings to lose their stability. In this context, the purpose of this work was to compare the reliability of two clay mineral identification methods: combined differential thermal analysis and thermogravimetry ( DTA-TG ) and the methylene blue adsorption test ( MBAT ). Proportional mixtures of kaolinite and bentonite were prepared in order to investigate the two methods. These two types of clay were chosen due to their distinct behaviors: kaolinite is a 1:1 clay mineral, and bentonite is composed mostly of montmorillonite, a 2:1 clay mineral. The two methods showed a positive and highly significant correlation. Moreover, the MBAT is a lower cost test that requires only ordinary chemistry laboratory equipment. Correlations revealed that the MBAT can provide thermal information related to DTA-TG tests.

Intercalation of an ordered kaolinite with potassium acetate (KCH 3 COO) under a pressure of 20 bars and 220 degrees C, induced new Raman bands at 3590, 3603, and 3609 cm (super -1) in addition to the normal kaolinite bands. These bands are attributed to the inner surface hydroxyls hydrogen bonded to the acetate. It is proposed that the intercalation under 20 bars pressure at 220 degrees C caused the differentiation of the inner surface hydroxyl groups, resulting in the appearance of these additional bands. Diffuse reflectance infrared spectra of the potassium acetate intercalated kaolinite that was formed at 20 bars and at 220 degrees C showed new bands at 3595 and 3605 cm (super -1) . Upon formation of the intercalate at 2 bars and at 120 degrees C additional infrared (IR) bands were found at 3592, 3600, and 3606 cm (super -1) . These IR bands correspond well with the observed Raman spectra. It is proposed that the effect of intercalation of the highly ordered kaolinite under pressure caused the kaolinite to become disordered and this disordering was dependent on the temperature of intercalation. It is suggested that when pressure is applied to the kaolinite crystal in the presence of an intercalating agent, the hydrogen bonds between adjacent layers are broken to create space for the intercalating agent between the layers. A direct result is that the order of the kaolinite crystals shows a decrease resulting in more defect structures. This is evidenced by the additional spectroscopic bands in both the Raman and IR spectra.

The Raman spectra of urea and urea-intercalated kaolinites have been recorded at 77 K using a Renishaw Raman microprobe equipped with liquid nitrogen cooled microscope stage. The NH2 stretching modes of urea were observed as four bands at 3250, 3321, 3355 and 3425 cm−1 at 77 K. These four bands are attributed to a change in conformation upon cooling to liquid nitrogen temperature. Upon intercalation of urea into both low and high defect kaolinites, only two bands were observed near 3390 and 3410 cm−1. This is explained by hydrogen bonding between the amine groups of urea and oxygen atoms of the siloxane layer of kaolinite with only one urea conformation. When the intercalated low defect kaolinite was cooled to 77 K, the bands near 3700 cm−1 attributed to the stretching modes of the inner surface hydroxyls disappeared and a new band was observed at 3615 cm−1. This is explained by the breaking of hydrogen bonds involving OH groups of the gibbsite-like layer and formation of new bonds to the CO group of the intercalated urea. Thus it is suggested that at low temperatures two kinds of hydrogen bonds are formed by urea molecules in urea-intercalated kaolinite.

Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging between 14.6 nm and 92.5 nm. The particle size varied with intercalation ratios with methanol intercalated kaolinite > DMSO-kaolinite > urea-kaolinite (KPDMU). Following intercalation, SEM analysis revealed a change of order from thick compact overlapping euhedral pseudohexagonal platelets to irregular booklets which later transformed to vermiform morphology and dispersed euhedral pseudohexagonal platelets. Besides, dispersed euhedral pseudohexagonal platelets were seen to coexist with blocky-vermicular booklets. In addition, a unique brain-form agglomeration which transformed into roundish particles mart was observed after encapsulation. The nanocomposites decomposed between 48 and 600 ∘ C. Release profiles showed that 100% of urea was released in 97 hours from KPDMU while 87% was released in 150 hours from the encapsulated nanocomposite. The findings established that it is possible to use Pugu kaolinite and gum arabic biopolymer to prepare urea CRF formulations.

Abstract Synthesized rare earth ion-adsorption clays (La, Ce, Nd, Dy and Y, ~ 400 ppm each) were prepared from kaolinite at various basic pH in open-air conditions. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma mass spectrometry (ICP-MS) were used to characterize the effect of pH on the adsorption mechanism of rare earth elements (REEs) on kaolinite. The crystal structure of kaolinite by XRD analysis is not altered after REE adsorption, suggesting that REEs are bound to the surface of kaolinite. Elemental analysis by XPS and ICP-MS show that the surface concentration of REEs on kaolinite is pH dependent, and a local maximum of the surface concentration is achieved at pH 10. Three characteristics of the La 3d5/2 XPS photoemission feature were measured and compared to those of standard La compounds to probe the speciation of REEs, and electrostatically bound hydroxides such as REE(OH)2+ are identified as the primary species on the surface of kaolinite. Compared to the typical ion-adsorption clays with intrinsic acidic pH, clays synthesized at basic pH exhibit similarly high rare earth ion-exchange efficiency with ammonium sulfate (AS), suggesting that rare earth ion-adsorption clays can exist in both acidic and basic environments.

Tortuosity tau is defined as the square of the ratio, phi-range of the effective length of pore channels to the length parallel to the overall direction of the pore channels in a porous medium. It has significance in interpreting the hydraulic and electric proper ties of porous media. In this study, ...

Layered clay systems intercalated with inorganic and organic compounds were analyzed
to highlight how XPS can provide information on the different environments surrounding a particular
atom as well as provide discernments on the size, coordination, and structural and oxidative
transformations of the intercalating/pillaring compounds. XPS data on the intercalation of urea and
K-acetate in low- and high-defect kaolinite revealed the interaction of the intercalating group NH2
with the siloxane functional groups in the interlayer surface. The intercalation of HDTMA in Mt
demonstrated the use of XPS in monitoring the change in conformation assumed by alkylammonium
intercalating compounds in Mt with increasing CEC. Studies on the pillaring of Mt by Al13 and
Ga13 by XPS allowed determination of the coordination of the pillaring compound within the Mt
layer. Lastly, the intercalation of hexacyanoferrate in hydrotalcite demonstrated the capability of
XPS in following changes in the oxidation state of the iron compound. These were gleaned from
interpretation of the shifts in binding energies and presence of multiplet splitting in the XPS of the
component elements of the minerals or the intercalating compounds.

The molecular structures of low defect kaolinite completely intercalated with formamide and formamide–water mixtures have been determined using a combination of X-ray diffraction, thermoanalytical techniques, DRIFT and Raman spectroscopy. Expansion of the kaolinite to 10.09 Å was observed with subtle differences whether the kaolinite was expanded with formamide or formamide–water mixtures. Thermal analysis showed that greater amounts of formamide could be intercalated into the kaolinite in the presence of water. New infrared bands were observed for the formamide intercalated kaolinites at 3648, 3630 and 3606 cm−1. These bands are attributed to the hydroxyl stretching frequencies of the inner surface hydroxyls hydrogen bonded to formamide with water, formamide and interlamellar water. Bands were observed at similar positions in the Raman spectrum. At liquid nitrogen temperature, the 3630 cm−1 Raman band separated into two bands at 3633 and 3625 cm−1. DRIFT spectra showed the hydroxyl deformation mode at 905 cm−1. Changes in the molecular structure of the formamide are observed through both the NH stretching vibrations and the amide 1 and 2 bands. Upon intercalation of kaolinite with formamide, bands are observed at 3460, 3344, 3248 and 3167 cm−1 attributed to the NH stretching vibration of the NH involved with hydrogen bonded to the oxygens of the kaolinite siloxane surface. In the DRIFT spectra of the formamide intercalated kaolinites bands are observed at 1700 and 1671 cm−1 and are attributed to the amide 1 and amide 2 vibrations.

Zeolite Y was synthesized hydrothermally from Elefun kaolinite clay. The raw kaolinite was calcined at 8500C to obtain more reactive clay (metakaolin). The metakaolin was dealuminated using non-heating methods to obtain the optimum dealumination route desired silica to alumina ratio between 3 and 7. The non-heating method proved successful in producing a desired ratio of 4 which was used in producing the aluminosilicate gel. The aluminosilicate gel was aged for 7 days at 950C for 36 hours with varying Na2O/SiO2 ratios of 0.60, 0.65, 0.70, 0.75 and 0.80 to produce zeolite Y. The synthesized zeolites were characterized by X-ray diffraction (XRD) analysis. The effect of NaOH concentration was studied using the XRD patterns of synthesized zeolite Y samples with reference to a standard zeolite Y. The results indicated zeolite Y of low crystallinity accompanied with other impure phases. Furthermore, the concentration of NaOH improved the intensity of the zeolite Y crystal peaks. The Na2O/...

The metakaolin was produced by thermal treatment (calcination) of the starting high-quality kaolin clay from Serbia. The optimal calcination parameters, for which nearly complete dehydroxylation of the material was achieved, are: temperature 650?C and heating time of 90 min. The conversion of the kaolinite to metakaolin was confirmed by XRD and IR analyses of the starting and thermally treated kaolin samples. The pozzolanic activity was determined by Chapelle test. The obtained value 0.65 g Ca(OH)2/g of metakaolin indicates that produced metakaolin may be used as supplementary cementitious material.

Nano-clays are a broad class of naturally occurring inorganic minerals in the form of plate-like alumina-silicate layers with thickness between 1nano-meter to 10micro-meters. Due to the very small sizes of nanoparticle, they provide a large specific surface area which make them to absorb water and fill the voids within the soil particles. The aim of this paper is to investigate the use of nano-clays for modifying the engineering properties of granular soils. This type of soil covers large parts of the land surface and cause many problems for the development of urban areas, infrastructure projects and instability of slopes along the railways and road networks. The mineral composition of the granular soil mainly consists of quartz grains and the soil types are classified as poorlyto well-grade materials. In order to evaluate the effect of micro and nano clay on modification of geotechnical properties of the sand, different percentage of 0.5%, 1%, 2% and 4% of micro-clay and percentage 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 12% and 14% nano-clay. In order to determine the value of its peak were done. Then mixed with the sand and a number of tests such as compaction test, direct shear test are conducted on the samples. The result shows that maximum dry unit weight and maximum optimum moisture content were obtained when 10% nano-clay mixed with the sand. It was also was noted that the increment of nano-clay and micro-clay causes gradual increases and gradual decreases of the shear strength of the sample, respectively.

Raw kaolinite clay collected from Ire-Ekiti, Ekiti State, Nigeria, was used to adsorb some heavy metals (Pb, Cr, Ni and Cu) from their aqueous solution through batch experiments. Adsorption studies were performed at the different temperatures, concentration and time to determine the kinetics, isotherm and thermodynamic properties of the adsorption processes. The adsorption thermodynamic properties showed that sorption of Cu, Cr and Ni on the raw clay was exothermic, while adsorption of Pb was endothermic. The negative values of ∆G for Pb adsorption revealed the feasibility and spontaneity of the adsorption process while the positive ∆G values for Cu, Cr and Ni sorption showed non-spontaneity of the adsorption process. Langmuir, Freundlich and Elovich isotherms were applied to explicate the nature of adsorption process, while Pseudo-first-order (PFO), Pseudo-second-order and Elovich kinetics were applied to literarily determine the adsorbate-adsorbent interaction. Pseudo-second-order...

Kaolinite hydroxyl surfaces have been modified upon intercalation with cesium acetate under a range of conditions. Upon intercalation of both low- and high-defect kaolinites with cesium acetate at 25 °C, additional infrared hydroxyl stretching bands are observed at 3606 and at 3603 cm-1. New infrared hydroxyl deformation modes were observed at 898 and 910 cm-1 upon intercalation with cesium acetate. These changes are attributed to the hydrogen bonding of the acetate ion to the inner surface hydroxyls. The intercalation process involves the incorporation of water into the interlayer structure. When treatment of the kaolinites is carried out under hydrothermal conditions, intercalation is incomplete. The 001 d spacing showed strong asymmetry on the low angle side indicative of some expansion of the kaolinite layers. Changes in both the hydroxyl stretching and deformation regions indicate that water is being incorporated into the kaolinite structure at the elevated temperatures of 120 and 220 °C. Raman spectra of the 25 °C cesium acetate intercalated kaolinites show additional bands at 3606 and 3598 cm-1. These bands are attributed to the inner surface hydroxyls hydrogen bonded to the acetate ions. The Raman spectra also suggest that some structural rearrangements of the kaolinite layers are occurring with consequential alteration in the defect structures.

The thermal behaviour of fully and partially expanded kaolinites intercalated with formamide has been investigated in nitrogen atmosphere under quasi-isothermal heating conditions at a constant, pre-set decomposition rate of 0.20 mg min–1 . With this technique it is possible to distinguish between loosely bonded (surface bonded) and strongly bonded (intercalated) formamide. Loosely bonded formamide is liberated in an equilibrium reaction under quasi-isothermal conditions at 118°C, while the strongly bonded (intercalated) portion is lost in an equilibrium, but non-isothermal process between 130 and 200°C. The presence of water in the intercalation solution can influence the amount of adsorbed formamide, but has no effect on the amount of the intercalated reagent. When the kaolinite is fully expanded, the amount of formamide hydrogen bonded to the inner surface of the mineral is 0.25 mol formamide/mol inner surface OH group. While the amount of surface bonded formamide is decreasing with time, no change can be observed in the amount of the intercalated reagent. With this technique the mass loss stages belonging to adsorbed and intercalated formamide can be resolved thereby providing a complex containing only one type of bonded (intercalated) formamide.

A series of laboratory wave-flume experiments was conducted to investigate the dissipation of monochromatic regular waves on a horizontal muddy bed of commercial kaolinite. The rheological parameters of kaolinite samples with different water content ratios were obtained from controlled shear rate tests using the rheometer. The flow curves of shear stress versus shear rate were found to be essentially Bingham viscoplastic medium for steady unidirectional mud flows of the rheological tests. Assuming Bingham behavior for kaolinite, a wave-mud interaction model was employed to obtain the values of the wave attenuation coefficients. Comparisons between the measured and simulated results show a good agreement.