Showing papers on "Vermiculite published in 1997"

Properties and Catalytic Activity of Acid-Modified Montmorillonite and Vermiculite

Abstract: The acidic properties of acid-modified montmorillonite and vermiculite were determined by pyridine and ammonia adsorption to correlate with the alkylating and dehydrating activity of the activated samples. Treatment of the minerals with different concentrations of hydrochloric acid results in the variation of overall acidity and density of acidic sites. Infrared (IR) spectral and differential scanning calorimetric analyses have revealed the presence of Bronsted and Lewis acid sites on the activated samples. The catalytic activity towards the above reaction has been correlated to the acid strength and density of Lewis acid sites. Treatment of montmorillonite with hydrochloric acid in the range of 0.1 and 0.3 M and vermiculite with 0.2 to 0.3 M seemed to be suitable for the conversion of methanol into olefin-rich hydrocarbons. Acid-activated montmorillonite catalyzed the isopropylation of benzene to a maximum extent of 16%, whereas acid-activated vermiculite gave a maximum conversion of only 4%.

Sequential structure transformation of illite-smectite-vermiculite during diagenesis of Upper Jurassic shales from the North Sea and Denmark

Abstract: For mixed-layer clay fractions from the North Sea and Denmark, X-ray diffractograms have been recorded for specimens saturated with Mg, Ca, Na and NH 4 , both airdry and intercalated with ethylene glycol, and the patterns have been computer-simulated with a multicomponent program. The mixed-layer fractions consist of an illite-smectite-vermiculite (I-S-V) phase constituting approximately 90% of the fraction and a kaolinite-illite-vermiculite (K-I-V) phase. For each I-S-V, the degree of swelling in swelling interlayers depends on both interlayer cation and glycolation, whereas the amount of non-swelling illite and swelling interlayers and the interstratification parameters are constant. Based on structural characteristics and the degree of diagenetic transformation, the samples investigated can be divided into three groups. The I-S-V of group one is predominantly detrital and has 0.69-0.73 illite. 0.26-0.20 smectite and 0.04-0.07 vermiculite interlayers, the illite, smectite and vermiculite interlayers being segregated. The I-S-V of group two has been diagenetically transformed and has 0.80 illite, 0.12 smectite and 0.08 vermiculite interlayers, the vermiculite interlayers being segregated whereas the illite and smectite have the maximum ordering possible for R = 1. The I-S-V of group three has been further transformed during diagenesis and has 0.84 illite, 0.08 smectite and 0.08 vermiculite interlayers. Statistical calculations demonstrate that the I-S-V transformation can be described as a single interlayer transformation (SIT) within the crystallites.

Weathering of chlorite to a low-charge expandable mineral in a spodosol on the apennine mountains, Italy

Abstract: The clay fraction of a Spodosol and its parent rock in the Apennlne mountains of central Italy were studied by powder X-ray diffraction (XRD) and infrared (IR) spectroscopy, to evaluate the possibility of transformation of chlorite into low-charge expandable minerals. Results indicated that the main phyl- losilicate in the rock was a slightly weathered trioctahedral chlorite, rich in both Mg and Fe. together with dioctahedral mica and minor amounts of kaolinite. In the BC horizon, chlorite has undergone partial transformation into 2 vermiculitic components, in 1 of which the interlayer could be removed by hot Na-citrate treatment: the presence of a regular interstratified mineral (high-charge corrensite) was also observed. Further changes in the structure of chlorite were detected in the Bsl horizon, becoming more evident towards the soil surface. The first stage of weathering of chlorite involved Fe oxidation and partial expulsion of Mg from the hydroxide sheet, followed by deposition of A1 in the interlayer space. Iron is also removed from the interlayer sheet, possibly remaining, in the oxidized state, in the 2:1 octahedral sheet, and so contributing to the lowering of layer charge and transformation to a dioctahedral structure. When approaching the surface, A1 removal from the interlayers is enhanced by complexing agents, and further charge reduction leads to the formation of 2:1 minerals with a smectite nature. Illite. because ot its low content in the soil clay fraction, contributes marginally to this weathering sequence, forming the high charged expandable component observed in the Bhs horizon. At the soil surface, a randomly inter- stratified vermiculite/illite was detected, which probably originated from K fixation by the higher-charged expandable minerals. This study of weathering in a natural soil strongly supports the hypothesis, previ- ously ascertained by laboratory experiments, that chlorite can transform into a low-charge expandable mineral.

Iodide, caesium and strontium adsorption by organophilic vermiculite

Abstract: A B S T R A C T: Distribution coefficients and isotherms for the adsorption of radioiodide, caesium and strontium ions (125I-, 134Cs+ and 85Sr2+) were determined in untreated vermiculite and in vermiculite treated with the chloride salt of hexadecylpyridinium (HDPy+). Experimental data reveal that some of the alkylammonium ions were incorporated as HDPyCI ion pairs into the vermiculite. The fraction of ion pairs adsorbed is reflected by an increase in distribution coefficients with increasing saturation levels. Consequently, a considerable part of the iodide adsorption could be attributed to an anion exchange process. At smaller amounts of Cs § and Sr z+ adsorbed, distribution coefficients of the modified clay mineral are significantly reduced in comparison with the original material. These differences are less pronounced when greater amounts of cations are adsorbed. Generally, larger distribution coefficients were found for the Cs + compared with the Sr z§ ion in the untreated and modified samples. Soils represent an important filter and buffer system for many cations and anions. Generally, their sorption properties are determined by the contents and compositions of clay minerals and humic substances. A great part of the soil organic matter is associated with clay minerals forming organomineral complexes (Greenland, 1965) which are of pronounced importance with respect to element transport and/or retention and to aggregate stability. Clay minerals also interact with organic cations. The replacement of inorganic cations by alkylammonium ions causes considerable modification in the hydration and swelling properties of the clays. Research in this area has significantly increased the

Equilibrium and Kinetic Study of Ammonium Adsorption and Fixation in Sodium-Treated Vermiculite

Abstract: Ammonium fixation in vermiculite affects the movement of N in many soils. The effects of particle size, solution concentration, pH, and associated anions on NH 4 + fixation in vermiculite are also important information for reducing N leaching from soils. In this study, the retention of NH 4 + on the exchangeable and nonexchangeable sites of Montana vermiculite was determined in batch experiments. In the NH 4 + -K + exchange isotherm, the exchangeable sites of the vermiculite exhibited a preference for K + to NH 4 + , while the nonexchangeable sites preferred NH 4 + to K + . The nonexchangeable sites of the sand fraction had a higher preference for NH 4 + at lower solution NH 4 + concentration and a lower preference at higher NH 4 + concentration. An opposite case was observed for the NH 4 + concentration effect on the preference of nonexchangeable sites in the clay fraction. The retention isotherm of total NH 4 + in the vermiculite exhibited S-shape curves that can be described by the two-surface Langmuir-Freundlich equation. In the kinetic study, the clay fraction adsorbed the largest amount of exchangeable NH 4 + , but the silt fraction fixed the most NH 4 + on its nonexchangeable sites. The retention of NH 4 + in vermiculite increased with solution NH 4 + concentration. Ammonium adsorption on the exchangeable sites increased at low solution pH, while NH 4 + fixation was unaffected by pH change. The effect of associated anions was insignificant, except they caused a pH difference in solution.

Release of Al by hydroxy-interlayered vermiculite and hydroxy-interlayered smectite during determination of cation exchange capacity in fine earth and rock fragments fractions

Abstract: Summary The fine earth ( 2 mm) fractions of two soils derived from Oligocene sandstone have been examined to assess the origin of the discrepancies between cation exchange capacity (CEC) and effective CEC (ECEC). The soils differ in terms of acidity: soil A is more acid than soil B. When the A samples are treated with BaCl2, the solution became sufficiently acid (pH < 4·5) to dissolve and to maintain Al in solution. From these samples more Al is released than base cations. Aluminium was continuously replenished even after 192 h, so that the ECEC was always larger than the CEC. Samples from soil B contain less H and Al ions, and the BaCl2 solution could not lower the pH below 5·0. In these samples little Al is released, and the base cations dominate the exchangeable pool of ions. This Al can be considered to be exchangeable, and a good agreement exists between the ECEC and the CEC. The source of non-exchangeable Al in the A samples is the OH-Al polymers of the hydroxy-interlayered vermiculite (HIV) and hydroxy-interlayered smectite (HIS) that tend to dissolve during the BaCl2 treatments. In the less acid B samples the Al polymers are not affected by BaCl2 treatment. Different results were obtained when the clays, extracted from an Na-dispersed suspension, were treated with BaCl2 solution. Because the clays are no longer acid, no H+ is released, and the OH-Al polymers are not dissolved. Therefore, the saturating ions play an important role in the dissolution of the OH-Al polymers and cause differences between the CEC and ECEC. We discount organic matter and specifically Al-organo complexes as a source of non-exchangeable Al. Both A and B soils contain very similar pyrophosphate-extractable Al, but show substantial differences in the amount of exchangeable Al.

Dehydration and rehydration of vermiculites; III, Phlogopitic Sr- and Ba-vermiculite

Abstract: A B S T RA C T: Dehydration and rehydration of a phlogopitic vermiculite saturated with either Sr 2+ or Ba 2§ were studied by thermoanalysis (TG, DSC, DTA) and by in situ X-ray powder diffractometry. A detailed analysis of the relationship between temperature and state of hydration of the vermiculites close to equilibrium at atmospheric pressure was rendered possible by use of low heating rates in combination with a fast recording position-sensitive detector. For Sr-vermiculite, the results reveal the existence of a number of distinct states of hydration characterized by basal spacings of 1.54, 1.51, 1.49, 1.23, 1.21 and 0.96 nm. The Ba-vermiculite failed to develop a two-layer hydrate even in contact with water. Its one-layer hydrate (1.24 nm) was reversibly transformed into an incompletely dehydrated ordered 'mica-structure' (1.00-0.99 urn), before an irreversibly dehydrated structure was attained at temperatures exceeding 700~ The formation of regular 1:1 interstratification was confirmed for all transformations characterized by a change in the number of water layers. The concluding compilation summarizes basal spacings, stacking orders, layer translations and specific water contents for all discrete states of hydration observed in our experiments at saturation of vermiculite with different alkaline earth cations. The hydration/dehydration characteristics of vermiculites saturated with different species of alkaline earth cations reflect the effects of size and hydration energy of interlayer cations upon the stability of different states of hydration that can be identified by X-ray diffractometry during low-rate temperature variations and can be related to the

Accumulation of pb, Cd and Zn from contaminated soil to various plants and evaluation of soil remediation with indicator plant (Plantago lanceolata L.)

Abstract: The accumulation of cadmium, lead, and zinc by different major cultivated plants from soils contaminated with heavy metals, is presented. The vegetables, crops, and the indicator plant narrow leaf plantain (Plantago lanceolata L.) were used in a field experiment including 3 areas with different levels of pollution. The highest concentrations of heavy metals were observed in edible green parts of vegetables (endive, spinach, lettuce) and roots (carrot, red beet, radish). The heavy metal content in leguminous plants (pods and seeds) was very low compared to high soil concentrations. Wheat and maize showed lower concentrations in grains and kernels than in green parts. Lime and vermiculite were used for reduction of Cd availability to plants in polluted soil. The Cd concentration decreased in the narrow leaf plantain in the presence of both lime and vermiculite in acid soil. In the higher-pH soil the Cd availability to spinach was greatly reduced in the presence of vermiculite.

Specific adsorption of copper and zinc by some soil minerals

Abstract: Specific adsorption of copper and zinc by some mineral soil constituents has been studied. The parameters of the Langmuir adsorption equations were determined. Trioctahedral montmorillonite, vermiculite, chlorite, and biotite exhibited the highest affinity for copper and zinc. Dioctahedral minerals (kaolinite and muscovite) are characterized by a significantly lower adsorbing capacity and by strong bonding to sorbed ions. Experiments on the adsorption of copper and zinc by minerals revealed the reaction sites of different selectivities for copper and zinc at the surface of mineral particles.

Growth and nutrition of geraniums grown in media developed from waste tire components

Abstract: Two cultivars of zonal geraniums (Pelargonium xhortorum Bailey), 'Danielle' and 'Kim', were grown in media containing three grind sizes of rubber (2.4, 6, or 10 mm) and fiber from the fabric belting processed from waste tires in three proportions: 1 rubber or fiber: 1 peat; 1 rubber or fiber: 1 vermiculite: 2 peat; and 2 rubber or fiber: 1 vermiculite: 1 peat (by volume). Two control media were also included: 1 vermiculite: 1 peat, and 1 rockwool: 1 peat (by volume). Geranium plants were grown in media cuntaining up to 25% waste tire products along with traditional medium components without reducing plant quality. Plant growth was best and flower count was highest in the vermiculite and peat medium, plants were smallest and flower count was lowest in media containing the rubber grinds at 2.4 or 6 mm, making up 50% of the media. The medium 1 rubber: 1 vermiculite: 2 peat, regardless of grind or fiber, produced plants equal to the rockwool and peat moss medium. All plants grown in media containing rubber byproducts had elevated Zn and Cu in the foliage; however, Zn and Cu were highest in media containing 50% rubber. Foliar P: Zn ratios were less for plants grown in media containing 50% rubber and also were lower in plants grown in media with smaller rubber grind sizes.

THE EFFECT OF ADDED POLYMERS ON n-BUTYLAMMONIUM VERMICULITE SWELLING

Abstract: Abstraet--A 4-component clay-polymer-salt-water system was studied by neutron scattering. The claysait-water system consisted of n-butylammonium vermiculite, n-butylammonium chloride and heavy water, and the volume fraction of clay in the system was held constant, at r = 0.01. Three polymers in the molecular weight range 10,000 to 30,000 were studied, poly(vinyl methyl ether) (PVME), poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA), at a polymer volume fraction of v = 0.01. The addition of PAA suppressed the clay swelling, irrespective of the salt concentration, c. The addition of the neutral polymers had no effect on the phase transition temperature, To, between the gel and tactoid phases of the system, its value remaining at 14 ~ for c = 0.1 M and 30 ~ c = 0.01 M. At c = 0.01 M, the neutral polymers also had a negligible effect on the lattice constant d along the swelling axis of the clay colloid, but at c = 0.1 M, the d-value was significantly lower than in the system without added polymer. For a PVME sample of molecular weight 18,000, both d and T c were measured as a function of v, for volume fractions between 0 and 0.04. The addition of polymer, up to v = 0.04, had no effect on T c. However, even for v values as low as 0.001, the vermiculite layers in the gel phase were more parallel and more regularly spaced than in the system without added polymer. In the gel phase, d decreased exponentially as a function of v, from 12 nm at v = 0 to 8 nm at v = 0.04. In the tactoid phase, at T > 14 ~ the dvalue in the crystalline regions was equal to 1.94 nm at v = 0 and v = 0.04, showing that the spacing between the vermiculite layers is not affected by the added polymer when they are collapsed by an increase in temperature. The addition of a PVME sample of molecular weight 110,000, at v = 0.001, had no noticeable effect on either d or To.

Clay Mineral Status of Paddy Soils from the Tai Lake Region of China in Relation to High Paddy-Rice Productivity

Abstract: Soil samples which were collected in the Tai Lake region of China during the tour organized after the 14th International Congress of Soil Science in 1990 were analyzed for the determination of the concentration of rare earth elements, particle-size distribution, and clay mineralogical composition. Paddy soils distributed in the plain and polder areas were derived from Xiashu loess. The concentration ratios of Ce/Eu and Eu/Sm of these paddy soils were similar to one another but different from those of the soils in surrounding mountainous and hilly areas. The paddy soils contained large amounts of silt and clay. Discontinuity of the particle-size distribution in the profile was related to the man-made overburdening of mud from a neighboring canal. Mica and, its weathering products were predominant clay minerals. Weathering products of mica consisted of smectite and vermiculite. Smectite was found to occur as mixed-layer minerals of mica/smectite and mica/vermiculite/smectite rich in smectite. Inter...

Isotope substitution of interfacial fluids in vermiculite clays

Abstract: We are using neutron diffraction to investigate the interlayer structure of alkyl-ammonium substituted vermiculite clays. In the case of propyl- and butyl-ammonium these clays exhibit macroscopic expansion to form 1D colloidal gels with interlayer spacings of up to 1000 A. Experiments in conjunction with isotope substitution were used to compare the position and orientation of counterions and water molecules confined between the clay surfaces in methyl-ammonium and butyl-ammonium vermiculite.

Mat for raising seedling of paddy rice

Abstract: PROBLEM TO BE SOLVED: To obtain a mat for raising seedling of paddy-rice plant, by forming vermiculite into a tabular state and supporting a fertilizer of manuring effect control type on the vermiculite, being attached to the fertilizer to a nursery box and used, having improved quality, root rise and root spread, excellent in water retention and shape retention SOLUTION: Vermiculite is formed into a tabular state A fertilizer of manuring effect control type in an amount required for culture of paddy rice plant is supported on the vermiculite to give the objective mat for raising seedling of paddy-rice plant, which is attached to a nursery box at the beginning of raising seedling and used Bentonite as a binder in an amount of 1-10vol% is added the mat The mat is preferably mixed with a non-biodegradable fibrous substance such as glass fiber, metal fiber, polyamide fiber, etc, as a reinforcing material

New phyllosilicate and production thereof

Abstract: PROBLEM TO BE SOLVED: To produce a structurally new phyllosilicate assuming a mixed layer structure of a micaceous structural part and a talcous structural part by specifying production conditions when exchanging Na and Li ions in a swellable phyllosilicate prepared by carrying out a thermal reaction of talc with an alkali silicofluoride as main raw materials and heating the resultant product. SOLUTION: This phyllosilicate comprises an alkali metal of Na or Li, Mg, Si, O, H and F as main constituent elements and assumes a mixed layer structure of a micaceous structural part and a talcous structural part. The phyllosilicate assumes a 2:1 structure; however, the phyllosilicate does not belong to any of mica, vermiculite and smectite of the mineralogical classification in relation to the assumed mixed layer structure of the micaceous structural part and the talcous structural part. The amount of exchanged Na and Li ions in the swellable phyllosilicate with the Mg ions is preferably 10-90% based on the cation exchange capacity of the ions present between layers. The adhesive moisture of the swellable phyllosilicate after the ion exchange is dehydrated at <=100 deg.C and heat-treated at 200-1000 deg.C.

Clay transformations following a leaching experiment on an acid brown soil

Abstract: The chemical and mineralogical properties of the Al and B horizons of an acid brown soil (typic Dystrochrept) were compared before and after a 20 month column leaching experiment. At the end of the leaching period, the organic carbon content of the Al horizon had decreased by approximately 20% compared with the original horizon. In the leached Al horizon, the vermiculite layers of both the vermiculite and interstratified minerals were transformed into high-charge expanding layers, with the charge mainly located in the octahedral sheet. The inhibition of expansion properties by pretreatment with dithionite-citrate-bicarbonate (DCB) was explained by an increase in total layer charge induced by Fe reduction. In the B horizon, leaching resulted in a loss of sesquioxide materials, especially in the interlayers of vermiculites. In both horizons, the amounts of Al extracted by Na citrate and the amounts of Fe extracted by DCB decreased. Analysis of solution composition showed that Al mobilization was closely associated with NO (super -) 3 leaching.

Dissolution Kinetics and Alteration Products of Micas and Epidote in Acidic Solutions at Room Temperature

Abstract: The reaction kinetics of the weathering of several phyllosilicates and one sorosilicate were stud ied experimentally. The alteration products were characterised by various methods in clud ing XRD, HRTEM, SEM, FTIR, NMR and Mossbauer spectroscopy. Weathering of silicates is of particular concern to our knowledge of several areas in low temperature geochemistry, such as el e ment cy cling, ground water chemistry and soil formation. The importance of these processes ex tends to the long-term nutrient supply to forest ecosystems and control of soil and water acidity, es pe cial ly in Scandinavia. Several soil models designed to predict the impact of acid rain on the soil chemistry rely on kinetic data of mineral weathering. The reaction kinetics for minerals are used in such models to predict chang es in soil chem is try. This enables calculation of the effect of acid rain (i. e. critical load) in a 100-year per spec tive. For some minerals relatively little knowledge is available for the reaction kinetics. There fore the dissolution kinetics of muscovite, biotite, phlogopite, vermiculite and epi dote were studied over the pH range 1 to 6.5 at room temperature using flow-through reactors. Silica release rates based on specific surface area are about the same for as divers silicates as epidote (sorosilicate), K-feldspar (tectosilicate) and phlogopite (phyllosilicate). At pH 3 log R = -15.41, -15.5 and -15.46 respectively for these min er als. However, the framework of Si and Al is likely to determine with what ease cations positioned in between the conformation of Si and Al tetrahedra are re leased. For example, K in micas have transportation channels due to the layer struc ture and ought there fore to be released easier than in K-feldspar. In most cases Si is the most slowly released element in silicates, but in epidote, Si and Ca are the fastest released elements from the structure, while Al and Fe are retained. Leaching of inter framework cations creates strain and charge im bal ance in the silicate structure, causing Si to be more readily released in base cation containing silicates than in quartz. Released Si may repolymerise directly at the surface of silicates or interlayers. Amor phous silica gel has been detected, as a weathering product between packages of 2:1 layers in bi otite, using AEM. Iron(hydr)oxides have been found as the end-product of biotite weathering. Re sid u al layer calculations based on the solution composition show that Al and Fe form an enriched layer with a thickness of 1-2 nm at the surface of epidote. Biotite and phlogopite probably alter to trioctahedral vermiculite from the edges and inwards. Mossbauer spectroscopy shows that weathering of biotite as well as ver micu lite is accompanied by oxidation. Al-hydroxy polymers are introduced in the in ter lay er during weathering of phlogopite and vermiculite, which is supported by both XRD and 27Al MAS-NMR analyses. Additions of KCl and AlCl3 to the reactant solutions show that release rates, exfoliation and oxidation processes decrease with increased concentrations for both biotite and phlogopite. Leaching of interlayer cat i ons seems thus to initiate oxidation of ferrous iron.

Clay mineralogy of some alluvial soils of Assam under long -term paddy cultivation

Abstract: Clay mineralogy assemblage of paddy and non-paddy soils from two major valleys viz. Brahmaputra valley and Barak valley of Assam were investigated. In most of the soils, mica is dominant mineral (44-69%) followed by kaolinite (22-33%) and feldspars (4-9%). The content of smectite, ver­ miculite and chlorite are low (3-13%). The content of K- feldspars is less than that of plagioclases. The mica is dominated by its dioctahedral counterpart. Paddy cultivation accelerated weathering of mica leading to formation of smectite and vermiculite through chlorite intergrade. The mica content decreased by 22 to 50% in surface horizon of paddy soils. There was, however, greater stability of smectite and vermiculite in poorly drained paddy soils. Additional keywords: Brahmaputra valley, Barak valley, Paddy soils.

Interaction of aminotriazole with montmorillonite and Mg-vermiculite at pH 4

Abstract: The interaction of aminotriazole (AMT) at pH 4 on Wyoming montmorillonite (mainly with Na ions) and Mg-vermiculite has been studied by X-ray diffraction and infrared spectroscopy The AMT is adsorbed on montmorillonite in the cationic form by cation exchange The amount of pesticide adsorbed was 71 mEq/100 g, which comprises approximately 91% of the CEC of this sample (782 mEq/100 g) Saturation was reached in 24 h giving rise to a complex with basal spacing 125 Aa Vermiculite adsorbs 167 mEq/100 g, almost 20% greater than the CEC (141 mEq/100 g), and the basal spacing was stabilized at 1368 Aa after five weeks of treatment with AMT A part of the AMT is adsorbed in cationic form displacing a great part of the exchangeable Mg (super 2+) cations The rest is adsorbed in molecular form by coordination to the Mg (super 2+) cations which remain in the interlamellar space, removing a great amount of water, and remaining in the interlamellar space of vermiculite after washing with water, probably because of a steric hindrance from the AMT cations adsorbed

Process for producing non-combustible moulded article, especially building panel

Abstract: This article relates to a method of manufacturing a noncombustible molded expanded vermiculite member, wherein the particulate material is expanded vermiculite inorganic adhesive coating, and then pressed. Exfoliated vermiculite particles with an inorganic material coating the adhesive solution, coating the prepressing vermiculite particulate material and cut into a desired shape member, the cutting member at least at room temperature, preferably a temperature of at least 100 deg.] C and at least 0.3N / mm

장항 제련소 지역 토양의 중금속 오염에 대한 환경광물학적 연구

Abstract: 【The Janghang smelter is the first lead, zinc and copper smelting facility in Korea which was operated for a half century from 1936 to 1989. The clay minerals and their heavy metal association in the soil profile around the smelter have been studied using XRD, EPMA, SEM-EDS, TEM, EPR and sequential extraction techniques. The soils in A horizon are highly acidic showing pH 4.45. The pH is going up with increasing depth. They have residual water contents of 1.18-1.51 wt%, loss on ignition of 6.32-7.79 wt%, and carbon contents of 0.08-0.88 wt%. Soils consist of quartz, feldspar, muscovite, kaolinite, vermiculite, biotite, chlorite, goethite and hematite in the decreasing abundance. The contents of clay minerals, especially vermiculite and chlorite, decrease with increasing depth. Sequential extraction experiments for the profile samples show that heavy metals (Zn, Cu, Pb, Cd) are highly concentrated in the A horizon of the soil profile as water-extractable (mostly amorphous), MgCl2-extractable (exchangeable in clay minerals), and organic phases. The heavy metal contents decrease with increasing depth. It suggests that the heavy metals are mainly associate with clay minerlas in an exchangeable state. It is also noted that heavy metals are highly concentrated in the manganese and iron oxide phases.】

Interaction of aminotriazole with montmorillonite and Mg-vermiculite at pH 4

Abstract: AB ST R ACT : The interaction of aminotriazole (AMT) at pH 4 on Wyoming montmorillonite (mainly with Na ions) and Mg-vermiculite has been studied by X-ray diffraction and infrared spectroscopy. The AMT is adsorbed on montmorillonite in the cationic form by cation exchange. The amount of pesticide adsorbed was 71 mEq/100 g, which comprises *91% of the CEC of this sample (78.2 mEq/100 g). Saturation was reached in 24 h, giving rise to a complex with basal spacing 12.5 A ˚ . Vermiculite adsorbs 167 mEq/100 g, almost 20% greater than the CEC (141 mEq/100 g), and the