Synthesis Of Clay Minerals Research Articles

Soil Genesis of Four Alfisols Established in Oak Hickory Forests along Drainages into the Mississippi River in Southeastern Missouri, USA

Alfisols in USA taxonomy are “deciduous forest” soils having an argillic horizon with a base saturation in the control section greater than 35%. Alfisols are geographically extensive and support productive agriculture and deciduous forest ecosystems. Understanding Alfisol genesis, including the presence and intensity of the dominant soil processes, facilitates best management practices that provide stewardship for these soil resources and improves forest and agriculture productivity. Four Alfisols, presently having mature forest settings and located in the central United States along the Mississippi River, were selected for soil and landscape description, classification, and delineation of the dominant soil forming processes. Excavated soils were described and routinely sampled for subsequent physical, chemical, and mineralogical analysis. An aqua regia digestion protocol provided elemental analysis for identifying and inferring the intensity of soil forming processes. The dominant soil forming factors include 1) organic matter accumulation, 2) clay eluviation-illuviation, 3) acidification, 4) base cation accumulation in the A horizons by the forest vegetation, 5) Fe-oxyhydroxide formation, and 6) clay mineral synthesis. Two soils were developed entirely in Peoria loess and two soils were developed in Peoria Loess overlying Ordovician limestone residuum. Ecological site descriptions provide land managers information for evaluating land suitability and the capability to implement different management activities without ecosystem disturbance. Best management practices for the described landforms and based on their Ecological Site Descriptions are presented.

Iron-rich clay mineral synthesis using design of experiments approach

The precipitation of iron-rich clay minerals has been reported in various geologic environments. However, large quantities of these minerals are not widely accessible to study their thermodynamic properties and thus improve our understanding of these particular geological systems. To obtain sufficient amount of iron-rich minerals, their synthesis can be foreseen. A design of experiments and surface response methodology was used in this study to find optimum synthesis conditions for these clay minerals. Three parameters were considered: quantity of OH−, synthesis time and temperature. The quantity of OH− had the largest influence on the synthesis result. The amount of 2:1 type clay mineral with respect to 1:1 type clay mineral increased with OH/Fe molar ratio. Time and temperature had less significant impact on the synthesis outcome, yet the formation of 2:1 type phase was favored at short synthesis time (1 day) and high temperature (160 °C). The findings suggested that the kinetic of 2:1 type clay mineral phase formation with respect to 1:1 type phase was faster, yet the precipitation was strongly dependent on the availability of the reactants.

Synthesis of nontronite and other Fe-rich smectites: a critical review

AbstractThe synthesis of clay minerals has been studied for decades in an attempt to better understand their formation in natural environments and more recently to obtain clay minerals with controlled compositions and properties. Even though nontronite has been synthesized successfully since 1935, the process is not a straightforward and has been poorly documented. In the present review concerning the synthesis of nontronite and other Fe-rich smectites, the experiments attempted in the past are discussed critically in light of the most recent data. Most notably, the application of relationships established recently, thanks to synthetic smectitic series, have allowed us to refine the chemical compositions of some nontronites synthesized previously.

Reflections on the material science of clay minerals

Possible new applications of clay minerals are explored continuously. Three such areas are clay-polymer nanocomposites, clay mineral films and clay mineral catalysts. Advances in these areas must come from the increase of fundamental knowledge of the clay minerals, especially the expanding clay minerals or smectites. Examples of fundamental research areas are: the mechanical properties of single clay layers and the change of these mechanical properties with the number of layers in a clay mineral particle; control of the organization of clay mineral layers and of molecules in the interlayer space for the production of functional films; and the distribution of pillars and of metal nanoparticles in the interlayer space for application as catalysts. Natural clay minerals suffer from several disadvantages, such as the presence of impurities and inhomogeneities in sizes and shapes of particles and in charge distribution. Synthesis of clay minerals with well-defined sizes and shapes of the particles and with homogeneous charge distribution is imperative to obtain significant advancement of knowledge.

Hydrothermal Synthesis of Clay Minerals from Kanemite

Hydrothermal Synthesis of Clay Minerals from Kanemite

Does the preferential microbial colonisation of ferromagnesian minerals affect mineral weathering in soil?

Fungal activity is thought to play a direct and effective role in the breakdown and dissolution of primary minerals and in the synthesis of clay minerals in soil environments, with important consequences for plant growth and ecosystem functioning. We have studied primary mineral weathering in volcanic soils developed on trachydacite in southern Tuscany using a combination of qualitative and quantitative mineralogical and microbiological techniques. Specifically, we characterized the weathering and microbiological colonization of the magnetically separated ferromagnesian minerals (biotite and orthopyroxene) and non-ferromagnesian constituents (K-feldspar and volcanic glass) of the coarse sand fraction (250-1,000 microm). Our results show that in the basal horizons of the soils, the ferromagnesian minerals are much more intensively colonized by microorganisms than K-feldspar and glass, but that the composition of the microbial communities living on the two mineral fractions is similar. Moreover, X-ray diffraction, optical and scanning electron microscope observations show that although the ferromagnesian minerals are preferentially associated with an embryonic form of the clay mineral halloysite, they are still relatively fresh. We interpret our results as indicating that in this instance microbial activity, and particularly fungal activity, has not been an effective agent of mineral weathering, that the association with clay minerals is indirect, and that fungal weathering of primary minerals may not be as important a source of plant nutrients as previously claimed.

Hydrothermal synthesis of clay minerals from burned sludge

Hydrothermal synthesis of clay minerals from burned sludge

Synthetic organo- and polymer–clays: preparation, characterization, and materials applications

We have over the years developed and patented a general technique for the hydrothermal synthesis of clay minerals in the presence of organic, organometallic, and polymeric intercalants. This review will summarize the details for crystallization of modified hectorites along with their characterization and materials applications. Among the several potential uses of these synthetic materials, there are two important applications concerning catalysis and composites. The fate of the template dictates which of these applications is pertinent. First, if the organic molecule or polymer is used with the intention of acting as templates of pore structure, then the organic template is removed after the modified clay has been crystallized. Upon template removal, the now porous materials are examined for their use as potential catalysts and catalyst supports. We have recently proven a correlation between catalyst pore size in the mesoporous range and the size and concentration of a polymeric template that is used. Preliminary hydrodesulfurization catalytic results have been obtained using these materials. If, on the other hand, intercalants are allowed to remain as a part of the structure, then a distinctive class of organic–inorganic composites becomes possible. When polymeric intercalants are used, especially at high concentrations, the materials have relevance to nanocomposite applications. Work in this area has focused on incorporating polymers at higher than 85 wt.% of the nanocomposite.

Material property changes in granitic rock during long-term immersion in hot water

To study the effects of temperature and time on hydro-mechanical properties of crystalline rocks, a laboratory weathering test was carried out, in which twenty-five cylindrical specimens of biotite granite were immersed in 90°C water for 2000 days. During the test, various measurements were made, in parallel, to investigate the long term changes in the specimens' physical properties such as permeability, porosity, longitudinal wave velocity and so on. Growth of microcracks and synthesis of clay minerals were also investigated to supply fundamental data for the analysis. The experimental results indicate that a discontinuous increase in permeability takes place around 1030 days of immersion, although only a slight increase occurs up to 670 days. This occurs because microcracks become dense because of chemical and physical weathering, and thus become fully interconnected to form large-scale flow paths. Halloysite and smectite were synthesized as weathering products of plagioclase in the laboratory weathering tests. A stably produced clay mineral changes from halloysite to smectite at around 1030 days. This can be explained in terms of the selection of stably produced clay minerals dependent on the chemical condition of the solution. It can be said that chemical weathering, i.e., hydration forming clay minerals, is a key factor when considering the safety and integrity of structures constructed in underground rock masses and subjected to circulation of subsurface waters for a long period of time.

Mineral genesis in ironstones: a model based upon laboratory experiments and petrographic observations

Summary Although mineral assemblages of ironstones vary widely, with hematite and goethite being the main components of red deposits and berthierine and siderite predominating in green deposits, the bulk major and minor elemental chemical compositions for both types of deposits are very similar. This indicates that the source material and physico — chemical conditions at the site of deposition must have been almost identical and that the different mineral associations probably developed during early diagenesis. Data from experimental studies including iron clay mineral synthesis throw light upon the post-depositional processes. It is demonstrated that berthierine can be synthesized from iron hydroxides in solution with initial SiO 2 concentrations of 5–9ppm, low concentrations of Mg and K, and with ferrous iron dominant. Decay of organic matter causes changes of Eh towards reducing conditions, which destabilizes the iron-rich particles and leads to both increased concentration of ferrous ions in the pore solution and the release of silicic acid ions. pH and concentration of silicic and carbonic acid controls whether berthierine or siderite is formed. In red deposits the concentration of organic material is low, suggesting that the presence and amount of organic material is a controlling influence.

粘土鉱物の合成

粘土鉱物の合成

Current and future trends in clay mineralogy—a review

AbstractProgress in science is not a linear function of time but resembles more closely a sigmoidal process in which new trends depend on the nucleation of new ideas and the re-activation of older studies. New and improved instruments, particularly electron microscopes and microprobes, infrared spectrometers and atomic absorption analysers have been the nucleating agents for many new lines of investigation. The interdisciplinary nature of clay mineralogy makes communication between different areas of study very important and the clay mineral societies have an important part to play in this respect.In the future, renewed efforts to obtain a convenient and reliable method of quantitative mineral analysis are likely to be made. Crystal structure analysis will be directed increasingly towards the study of order and disorder in cation distributions, layer charges, and layer stacking arrangements. Studies of domain structures in layer silicates will continue, and further refinements in mixed-layer structure analysis can be expected. Infrared spectroscopic analysis will increasingly become a major tool. The study of clay mineral synthesis and alteration in nature and in the laboratory shows signs of important re-activation. Clay-organic studies are developing in many directions.

Nontronite synthesis at low temperatures

The low-temperature synthesis of clay minerals is possible through the aging of freshly prepared hydroxide—silica precipitates. The rapid synthesis of nontronite is only possible at surface temperatures under reducing conditions. Under oxidizing conditions, pure Fe(III)- or pure Al-smectite minerals could not be synthesized at low temperatures. It is only from Fe(II)-containing solutions that nontronite and lembergite, the di-[Fe(III)] and tri-[Fe(II)] octahedral three-layer silicates, are built up in several days at low temperatures. The presence of Fe(II) enables an octahedral layer of the brucite—gibbsite type to be formed. These are necessary for the bidimensional orientation of SiO 4 tetrahedrons, leading to clay-mineral formation. The Fe 2+ and/or Mg 2+ ions are necessary for the formation of the Al 3+- and Fe 3+-containing three-layer silicate minerals. Under reducing diagenetic conditions, the Fe contents in recent sediments are sufficient to build up Al-rich three-layer minerals under both fresh-water and salt-water conditions.

The role of magnesium in the formation of smectite minerals

The synthesis of clay minerals at elevated temperatures has been studied in many papers but only very few investigations have been made of the synthesis of clay minerals at surface conditions. It has been shown that amorphous hydroxides of Al, Fe, Mg, etc. are capable of co-precipitating silica even from very dilute surface solutions. By aging of these X-ray amorphous hydroxide—silica precipitates under certain conditions clay minerals can be synthesized at low temperatures. The presence of magnesium particularly favours the formation of smectite minerals. From Mg-hydroxide silica precipitates montmorillonite and talc could be synthesized under basic conditions at low temperatures. From pure Al-hydroxide—silica precipitates framework silicate (quartz and feldspar) and bayerite was formed, while the synthesis of pure Al-clay minerals at low temperatures seems to be more difficult. From Mg-containing Al-hydroxide silica precipitates tri- and di-octahedral smectite could be synthesized. The following conditions favour the formation of montmorillonite at low temperatures. 1. (1) Low silica concentration in solution. Formation of clay minerals and other minerals (quartz, feldspar, etc.) takes place at low temperatures (20° and 3° C) only in those precipitates that are in contact with solutions undersaturated with SiO 2 (in respect to amorphous silica). If the SiO 2 concentration in the solution has higher values the hydroxide—silica precipitates stay amorphous. It seems that polymerisation of the silicic acid inhibits the formation of clay minerals. 2. (2) Composition of precipitates. The concentration of silica and the other elements in these hydroxide silica precipitates should be similar to the composition of naturally occurring smectite minerals. 3. (3) Magnesium content in solution and precipitates. The hydrogen ion-concentration effects the precipitation and co-precipitation of magnesium. Under basic conditions (pH 10) only 10 p.p.m. Mg are necessary in the solution for the formation of smectite minerals. Under neutral conditions it is possible to co-precipitate Mg with Al-hydroxide, the Mg-content of such Al-hydroxide—silica precipitates depends on the Mg concentration in the solution and the pH during precipitation. The formation of smectite minerals is only possible when the precipitates contain at least 6% of MgO. The precipitates stay amorphous if the magnesium content is lower. The magnesium seems to favor the formation of all three-layer silicates.

Clay Mineral Genesis of Some New York Spodosols

AbstractSome Spodosols in northern New York previously shown to have well crystallized montmorillonite in the albic horizon but only amorphous clay sized material in the spodic horizon were studied to determine the source or genesis of the montmorillonite. The soils used to test several hypotheses of the clay mineral genesis represented Orthods, Humods, and Aquods. These soils were also shown to be deficient in mica and chlorite in the sand, silt, and clay fractions. This allowed a test of the hypothesis that montmorillonite in albic horizons weathers from mica, a process which previously has been reported to be active. The presence of only traces of mica and chlorite in the sand and silt fractions would indicate that weathering of sand and silt sized minerals directly to clay sized minerals should not be important. However, the small amount (generally less than 3%) of clay sized materials in the pedons makes this assumption inconclusive.Soil solution studies, coupled with equilibrium diagrams, provide evidence that clay mineral synthesis from ions does not occur in these soils.The well crystallized clay sized minerals detected in the upper solum of the pedons studied may have (i) weathered directly from sand and silt sized minerals, (ii) been added as dust, or (iii) weathered from minerals added as dust. There is recent evidence that appreciable amounts of montmorillonite, illite, vermiculite, and kaolinite are deposited as dust throughout the northern United States. If projected figures are valid, dust could account for most of the montmorillonite in the albic horizons studied. Concomitant additions of chlorite and mica are not detected. Chlorite and mica added as dust, as well as any traces of these minerals present as sand or silt, must be weathered to some other species in the clay fraction, because they are not detected in the clays.It is proposed that in the Spodosols studied (i) any chlorite in the albic horizon is weathered to amorphous aluminosilicates and translocated to the spodic horizon, and (ii) mica is weathered to montmorillonite in the albic horizon, to vermiculite in the Bh horizon, and to “chloritized” vermiculite in the Bir horizon.

On the evolution of subsurface brines in Israel

Subsurface brines occurring in Israel at depths of 1,000–3,400 m in Early Cambrian-Early Cretaceous formations are classified into four groups. 1. (1) A group identical in composition and salinity with present-day ocean water, except for its higher Ca 2+ and lower Mg 2+-content, a change attributed to dolomitization. 2. (2) The oilfield waters in Early Cretaceous formations of the coastal plain, still similar to ocean water, but twice to three times more saline; they have lost most of their sulphates through reduction to H 2S, and are enriched in Br and I, both derived from organic sources. The relative Mg-depletion of these brines is attributed to the uptake of Mg 2+ by the regrading and synthesis of clay minerals. Waters near the Jurassic-Lower Cretaceous unconformity show a pronounced salinity minimum, which is attributed to dilution by meteoric water during a shortlived emersion. 3. (3) Brines from Jurassic to Early Cambrian source units. Within this section, salinities as well as the Ca/Na- and Br/I-ratios increase progressively with depth while the Na/K, HCO 3 Cl and Cl/Br-ratios decrease. The brines change from sodium-chloride to typical calcium-chloride types. It is assumed that the lowermost Palaeozoic brines were formed by surface evaporation during Infracambrian to Early Cambrian time and were later modified by differential ultrafiltration. 4. (4) A most peculiar group is represented by highly saline brines at the depth in the Rift Valley. Sub-group A, found in marine sediments or continental clastic fill, is chemically similar to the Early Palaeozoic brines, but even more differentiated. These waters are assumed to be of Early Palaeozoic age and to have entered the Rift Valley after its last important phase of subsidence in the Plio-Pleistocene. Sub-group B shows salinities of around 300,000 p.p.m., the r Na K-value is 1–2 and the CaCl 2-character is extreme. These waters are believed to be old Palaeozoic brines that have undergone a new cycle of surface concentration in Pleistocene Rift Valley lakes, the precursors of the Dead Sea.

The Octahedral Layer

AbstractIn the first part of this paper the formation processes of pure octahedral hydroxides are investigated. Conditions of synthesis of aluminum, magnesium, iron and mixed Al-Mg, Al-Ca, Al-Fe systems are successively reviewed. In every case crystal growth in deionized medium allows one to figure out genetic conditions.The second part deals with the conditions required for the development of the octahedral layer in the presence of silica, i.e. the clay mineral synthesis. Experimental conditions remain always as nearly as possible to those observed naturally.Trioctahedral minerals are rather easily obtained at ordinary temperature and pressure. The evolution of the magnesium-silica system is described. Synthesis of dioctahedral layer lattices, such as those of the kaolin minerals, appears more difficult to perform under the same conditions. Initial organization of the starting materials plays an important role in this case and procedures are described.Finally, interactions of octahedral and silica layers are studied. The study of infrared spectra in the 9–11μ region permits such observations. Characteristic changes in the spectral region of Si-O stretching allows one either to follow the octahedral destruction (by acid attack or dehydroxylation) or the octahedral layer formation in kaolinite synthesis.

Synthesis of Clay Minerals at Low Temperatures

AbstractNumerous attempts have shown that it seems to be impossible to crystallize co-precipitates of silica and hydroxides; we therefore attempted to prepare clay minerals starting from solutions of their constituents. By allowing these dilute solutions (tenths of milligrams per liter) to pass slowly into a flask containing distilled water, it has been possible to prepare substances similar to clay minerals. These have been identified by x-rays, chemical analysis, dehydration curves, and electron micrographs.Using as cations Mg, Fe2+, Fe3+, and Ni, minerals of the montmorillonite type have been prepared for various pH values (generally greater than 7). Below this, value, depending on the cations; oxides, hydroxides, or amorphous materials are obtained.Under certain conditions in the absence of silica the glass vessel was attacked, and anti-gorites of Mg and Ni were then obtained. Always when the supply of silica was small, and with the cation introduced in the form of a very dilute solution, the process gave rise to montmorillonite. In the presence of K, illites were sometimes formed.The method seems to be of very general application. Only the purely aluminum minerals offer difficulties of preparation. The significance of these results is discussed.

A Study of the Synthesis of Clay Minerals

A Study of the Synthesis of Clay Minerals