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1.
Reduced and intermediate S species (sulfide, thiosulfate, sulfite) were determined in 26 thermal water samples from the granitic massifs of south-west Bulgaria. Analysis of these S species was performed in the field, using a potentiometric-titration technique. Reduced and intermediate S species were found to enhance the solubility of Cu, Zn and Pb to an appreciable extent. According to thermodynamic equilibrium calculations, the prevailing complexes for sulfide-containing waters are CuS(HS)−, Zn(OH)(HS)0, ZnS(HS)− and PbS(HS)−. For waters which do not contain sulfide S, Cu(S2O3)−, Cu(SO3)−, Zn(OH)+, Zn(OH)20, HZnO2−, ZnCO30, ZnSO40, Zn2+ and PbCO30 are the important species. Whereas Cu and Pb are found to be controlled by their respective endmember sulfide phases, Zn appears to be controlled by formation of an FeZnS solid solution.  相似文献   

2.
The adsorption behavior of Zn2+ ions onto the surface of amorphous aluminosilicates was studied using both potentiometric and spectroscopic methods (XANES: X-ray Absorption Near-Edge Structure). The aluminosilicates were prepared with different Al/Si ratios in order to compare the reactivities of surface aluminol and silanol groups toward Zn2+ ions. Potentiometric experiments were performed by maintaining the reacting suspensions at constant pH, ionic strength, and solid concentration, while Zn concentration was increased by stepwise addition. Our results showed that the surface aluminol and silanol groups possess significantly different reactivities toward Zn2+ ions. The reaction of Zn2+ ions with aluminol groups occurs through three processes: (i) surface complexation, (ii) dissolution, and (iii) re-sorption. A stoichiometric relationship was confirmed for the surface complexation between the aluminol groups and Zn2+ ions: two moles of H+ ions were released for one mole of Zn2+ ion adsorption. Following the surface complexation process, measurable amounts of zinc and aluminum ions were found to be mobilized from the surface of the solid to the liquid phase; subsequently, these ions precipitated on the solid surface, and possibly formed a co-precipitate with the hydrotalcite-type structure. On the other hand, a stoichiometric relationship was not obtained for the sorption of Zn2+ ions on silanol groups, and therefore, it was concluded that Zn2+ ions are retained on the surface of amorphous aluminosilicates by two different reactions. One reaction involves the surface complexation between Zn2+ ions and surface aluminol groups, which proceeds rapidly. The other reaction is the slow retention of Zn2+ ions onto silanol and/or aluminol groups, which could be the surface precipitation of Zn(OH)2 or the co-precipitation of Zn2+-Al3+ hydroxides. It can be suggested that the total sorption behavior of Zn2+ ions on amorphous aluminosilicates with different Al/Si ratios can be represented as the sum of the individual reactions of Zn2+ ions toward the aluminol and silanol groups. The potentiometric results were confirmed by XANES data. It was clearly evident that only the aluminol groups were responsible for surface complexation of Zn2+ ions. An equilibrium constant was calculated for this reaction.  相似文献   

3.
Polarized infrared absorption spectra of thin single-crystal slabs parallel to (010) and (001) of a staurolite from Pizzo Forno, Ticino, with analyzed composition (Fe2.9Mg0.9Zn0.1Mn0.1)Al17.5Ti0.1(Si7.7Al0.3)O48H3 have been measured in the range of 3000–4000 cm?1. From the pleochroitic behaviour of the OH-vibrations three groups of bands can be distinguished: the bands of group I, a strong band at 3445 cm?1 plus a weak shoulder at 3358 cm?1, and the bands of group II, a weak band centered at 3677 cm?1 plus a shoulder at 3635 cm?1, are assigned to the H1 and H2 protons, respectively. The bands of group III, a weak band at 3577 cm?1 plus a shoulder, cannot be interpreted on the basis of the proton positions known so far. We assign them to an additional proton H3, which is bonded to O1 and shows a bifurcated hydrogen bridge to two O5 in a vacant T2 site.  相似文献   

4.
Over 60 minerals, including native elements, intermetallic compounds, haloids, sulfides, sulfates, arsenides, oxides and hydroxides, silicates, borosilicates, wolframates, phosphates and REE phosphates, were established in Triassic siliceous rocks of Sikhote Alin. Allothigenic and authigenic minerals in the carbonaceous silicites were formed over a long period through several stages. Judging from morphology, chemical composition, and structural position, K-feldspar (K-Fsp), illite, kaolinite, metahalloysite, monazite, xenotime, zircon, rutile, or its polymorphs are the disintegration products of sialic rocks of continental crust. Authigenic sulfides are dominated by diagenetic pyrite (fine-crystalline, microglobular, framboidal, as well as those developed after biogenic siliceous and carbonate fragments), which has been formed prior to precipitation of siliceous cement and lithification of siliceous rocks. Most of other sulfides (sphalerite, galena, chalcopyrite, pyrrhotite, argentite, pentlandite, antimonite, ulmanite, and bravoite), arsenides and sulfoarsenides (arsenopyrite, nickeline, skutterudite, cobaltite, glaucodot, and gersdorffite), wolframates (scheelite and wolframite), intermetallides (Cu2Zn, Cu3Zn2, Cu3Zn, Cu4Zn, CuSn, Cu4Sn, Cu8Sn, Cu4Zn2Ni, Ni2Cu2Zn, Ni4Cd), and native elements (Au, Pd, Ag, Cu, Fe, W, Ni, Se) were crystallized later (during catagenesis after the lithification and brecciation of siliceous beds) from metals involved in the easily mobile fractions of bitumens. Supergene mineral formation was mainly expressed in the sulfide oxidation and replacement of diagenetic pyrite by jarosite and iron hydroxides.  相似文献   

5.
The investigation of hydrous boro(alumino)silicate melts and glasses with near infrared (NIR) spectroscopy revealed an important effect of boron on the water speciation. In the NIR spectra of B-bearing glasses new hydroxyl-related bands develop at the high frequency side of the 4500 cm−1 peak. In NaAlSi3O8 + B2O3 glasses this new peak is present as a shoulder at 4650 cm−1, and in NaAlSi3O8-NaBSi3O8 (Ab-Rd) glasses it appears as a resolved peak at 4710 cm−1. These bands increase with increasing boron concentration, suggesting that they are due to B-OH complexes. Furthermore, the variations in the NIR spectra indicate that with increasing B-content, but constant total water concentration, the amount of structurally bonded hydroxyl groups increases at the expense of molecular H2O. For example, at a total water concentration of 4 wt.%, pure Rd-glass contains ∼50% more water as hydroxyl groups than pure Ab-glass.In-situ NIR spectroscopy at high P and T using a hydrothermal diamond-anvil cell was used to gain information about the temperature dependence of the water speciation in NaBSi3O8 melts. The data demonstrate the conversion of molecular H2O to hydroxyl groups with increasing temperature. However, a fully quantitative evaluation of the high T spectra was hampered by problems with defining the correct baseline in the spectra. As an alternative approach annealing experiments on a Rd-glass containing 2.8 wt.% water were performed. The results confirm the conversion of H2O to OH groups with increasing T, but also suggest that the OH groups represented by the 4710 cm−1 peak (B-OH) participate much less in the conversion reaction compared to X-OH, represented by the 4500 cm−1 peak.  相似文献   

6.
We measured the adsorption of Cu(II) onto goethite (α-FeOOH), hematite (α-Fe2O3) and lepidocrocite (γ-FeOOH) from pH 2-7. EXAFS spectra show that Cu(II) adsorbs as (CuO4Hn)n−6 and binuclear (Cu2O6Hn)n−8 complexes. These form inner-sphere complexes with the iron (hydr)oxide surfaces by corner-sharing with two or three edge-sharing Fe(O,OH)6 polyhedra. Our interpretation of the EXAFS data is supported by ab initio (density functional theory) geometries of analogue Fe2(OH)2(H2O)8Cu(OH)4and Fe3(OH)4(H2O)10Cu2(OH)6 clusters. We find no evidence for surface complexes resulting from either monodentate corner-sharing or bidentate edge-sharing between (CuO4Hn)n−6 and Fe(O,OH)6 polyhedra. Sorption isotherms and EXAFS spectra show that surface precipitates have not formed even though we are supersaturated with respect to CuO and Cu(OH)2. Having identified the bidentate (FeOH)2Cu(OH)20 and tridentate (Fe3O(OH)2)Cu2(OH)30 surface complexes, we are able to fit the experimental copper(II) adsorption data to the reactions
  相似文献   

7.
Infrared and Raman spectra of the basic copper salts malachite, Cu2(OH)2CO3, and brochantite, Cu4(OH)6SO4, as well as of deuterated and 13C substituted samples are presented and discussed in terms of group theory and the hydrogen bonds present. The main results are that (i) the hydrogen donor strengths of the OH? ions are strongly increased due to the very great synergetic effect of the copper ions, (ii) the acceptor strengths of the H-bond acceptor groups (SO4 2-, CO3 2-, and OH? ions) are significantly modified by the linkage and coordination of the acceptor atoms — this complicates true assignment of the OH bands observed to the two and six different OH? ions present in malachite and brochantite, respectively -, and (iii) the Cu — O stretching modes at 430–590 cm?1 and 420–520 cm?1 for malachite and brochantite, respectively, exhibit strong, partially covalent Cu — O bonding.  相似文献   

8.
The crystal structure of the rare secondary mineral cualstibite-1M (formerly cyanophyllite), originally reported to have the chemical formula 10CuO·2Al2O3·3Sb2O3·25H2O and orthorhombic symmetry, was solved from single-crystal intensity data (Mo-Kα X-radiation, CCD area detector, 293 K, 2θmax?=?80) collected on a twinned crystal containing very minor Mg. The mineral is monoclinic, P21/c (no. 14), with a?=?9.938(1), b?=?8.890(1), c?=?5.493(1) Å, β?=?102.90(1)°, V?=?473.05(11) Å3; R1(F)?=?0.0326. All crystals investigated turned out to be non-merohedric twins. The atomic arrangement has a distinctly layered character. Brucite-like sheets composed of two [4?+?2]-coordinated (Cu,Al,Mg) sites are linked by weak hydrogen-bonding (O···O?~?2.80 Å) to isolated regular Sb(OH)6 octahedra (<Sb-O>?=?1.975 Å). The layered, pseudotrigonal character explains the perfect cleavage and the proneness to twinning. The Sb site is fully occupied and the two (Cu,Al,Mg) sites have occupancies of Cu0.79Al0.17Mg0.04 and Cu0.72Al0.23Mg0.05. The Cu-richer site shows a slightly stronger Jahn-Teller-distortion. The resulting empirical formula, which necessitates a H2O-for-OH substitution to obtain charge balance, is (Cu2.23Al0.63Mg0.14)(OH)5.63(H2O)0.37[Sb5+(OH)6]. The ideal chemical formula is (Cu,Al)3(OH)6[Sb5+(OH)6], with Cu:Al = 2:1. The structure is closely related to those of trigonal cualstibite-1T [Cu2AlSb(OH)12, P-3, with ordered Cu-Al distribution in the brucite sheets], and its Zn analogue zincalstibite-1T [Zn2AlSb(OH)12]. Cualstibite-1M and cualstibite-1T are polytypes and, together with zincalstibite-1T, zincalstibite-9R and omsite, belong to the cualstibite group within the hydrotalcite supergroup, which comprises all natural members of the large family of layered double hydroxides (LDH).  相似文献   

9.
《Applied Geochemistry》1998,13(5):643-650
Minerals coating brass ammunition shells that rested at the bottom of Halifax Harbour, Nova Scotia, for 52 a have been identified by X-ray diffraction and analytical scanning electron microscopy. The admiralty brass shells, partially buried in anoxic muds, straddle a strong Eh gradient ranging from 0 mV to values characteristic of oxygenated seawater. Whereas the brass surface in contact with the sediment has been preserved, parts of the shells exposed to seawater have corroded throughout their thickness. The corrosion products identified include metallic Cu, djurleite (Cu1.96S), cuprite (Cu2O), atacamite (Cu2Cl(OH)3), spertiniite (Cu(OH)2) and hydrozincite (Zn5(CO3)2(OH)6). These products are those predicted thermodynamically on the basis of ambient Eh and pH. However, this study also revealed the presence of a mineral not previously known to exist and tentatively identified as Cu14Zn14Cl5(SO4)5(OH)41.H2O. This “new” mineral seems to have a stability field in Eh–pH diagrams similar to that of connellite (Cu19Cl4SO4(OH)32.2H2O).  相似文献   

10.
We measured the adsorption of Cu(II) onto kaolinite from pH 3-7 at constant ionic strength. EXAFS spectra show that Cu(II) adsorbs as (CuO4Hn)n−6 and binuclear (Cu2O6Hn)n−8 inner-sphere complexes on variable-charge ≡AlOH sites and as Cu2+ on ion exchangeable ≡X--H+ sites. Sorption isotherms and EXAFS spectra show that surface precipitates have not formed at least up to pH 6.5. Inner-sphere complexes are bound to the kaolinite surface by corner-sharing with two or three edge-sharing Al(O,OH)6 polyhedra. Our interpretation of the EXAFS data are supported by ab initio (density functional theory) geometries of analog clusters simulating Cu complexes on the {110} and {010} crystal edges and at the ditrigonal cavity sites on the {001}. Having identified the bidentate (≡AlOH)2Cu(OH)20, tridentate (≡Al3O(OH)2)Cu2(OH)30 and ≡X--Cu2+ surface complexes, the experimental copper(II) adsorption data can be fit to the reactions
  相似文献   

11.
The crystal chemistry of paratacamite has been re-evaluated by studying a crystal from the holotype specimen BM86958 of composition Cu3.71Zn0.29(OH)6Cl2 using single-crystal X-ray diffraction at 100, 200, 300, 353, 393 and 423 K. At 300 K paratacamite has space group $R\bar{3}$ with unit-cell parameters a 13.644 and c 14.035 Å and exhibits a pronounced subcell, a′ = ½a and c′ = c, analogous to that of the closely related mineral herbertsmithite, Cu3Zn(OH)6Cl2. Between 353 and 393 K, paratacamite undergoes a reversible phase transformation to the herbertsmithite-like substructure, space group $R\bar{3}m$ , unit-cell parameters a 6.839 and c 14.072 Å (393 K). The transformation is characterised by a gradual reduction in intensity of superlattice reflections, which are absent at 393 and 443 K. On cooling from 443 to 300 K at ~10 K min?1, the superlattice reflections reappear and the refined structures ( $R\bar{3}$ ) of the initial and recovered 300 K states are almost identical. The complete reversibility of the transformation establishes that paratacamite of composition Cu3.71Zn0.29(OH)6Cl2 is thermodynamically stable at ambient temperatures. The nature of the rhombic distortion of the M(2)O6 octahedron is discussed by considering two possibilities that are dependent upon the nature of cation substitution in the interlayer sites.  相似文献   

12.
Zinccopperite (tentatively named) is a rare native alloy mineral discovered in quartz monzonite-porphyry in the Xifanping area, Yanyuan County, Sichuan Province. It is a new variety of zinc-copper alloy mineral found for the first time in the porphyry-copper deposit in China. Its intergrown minerals are K-feldspar (mainly perthite), albite-oligoclase, quartz and biotite; and the associated minerals include pyrite and chalcopyrite. It is characterized by a golden reflection colour, being isotropic (isometric), with the grain size ranging from 10 to 50 μm, microhardness VHN10= 190 kg/mm2, and reflectance RVis= 67.97%. Electron microprobe (Model JXA-733) analysis shows Cu = 59.15%-62.55% and Zn= 36.32%-39.85%. The crystallochemical formula is Cu6.27-7.0Zn4.0, simplified as Cu7Zn4.  相似文献   

13.
《Geochimica et cosmochimica acta》1999,63(19-20):3159-3169
Using zinc sulfide as an example, we demonstrate a plausible stepwise process for the formation of minerals from low temperature aqueous solutions. The process occurs with the formation of soluble complexes that aggregate into soluble rings and clusters. The final moiety in solution has a structure similar to the moiety in the first formed solid, which is a restatement of the Ostwald step rule. Titrations of aqueous Zn(II) with bisulfide indicate that sulfide clusters form at concentrations of 20 μM (or less) of metal and bisulfide. Precipitation does not occur according to voltammetric measurements using a mercury electrode and UV-VIS (ultra-violet to visible) spectroscopic data. UV-VIS data and filtration experiments indicate that the material passes through 0.1 μm Nuclepore and 1000 dalton filters. The complexes form rapidly (kf > 108 Ms−1), are kinetically inert to dissociation and thermodynamically strong. Although a neutral complex of 1:1 (ZnS) empirical stoichiometry initially forms, an anionic complex with an empirical 2 Zn:3 S stoichiometry results with continued addition of sulfide. Gel electrophoresis confirms the existence of a cluster that is negatively charged with a molecular mass between 350 and 750 daltons. On the basis of known mineral and thiol complex structures for these systems, a tetrameric cluster unit of Zn4S6(H2O)44− is likely. Molecular mechanic calculations show that this cluster is structurally analogous to ZnS minerals (particularly sphalerite) and is a viable precursor to mineral formation and a product of mineral dissolution.The formation of Zn4S6(H2O)44− can occur from condensation of Zn3S3(H2O)6 rings, which are neutral molecular clusters. The Zn atoms on one Zn3S3(H2O)6 ring combine with the S atoms on another Zn3S3(H2O)6, to lead to higher order clusters with loss of water. The Zn4S64− species form by the cross-linking of two neutral Zn3S3 rings by added sulfide; thus a Zn–S–Zn bridge forms across the rings with subsequent rearrangement and condensation to Zn4S64−; this combination results in a sphalerite-like cluster. If the rings condense without additional sulfide, a wurtzite-like structure could form. All condensations result in sulfide displacement of water from Zn to form Zn–S bonds. Water loss is an example of an entropy-driven process, which leads to a more favorable thermodynamic process. These clusters would be resistant to oxidation by O2. Voltammetric experiments indicate neutral and anionic clusters for Zn and agree with ion chromatographic data from the sulfidic waters of the Black Sea.  相似文献   

14.
A comprehensive approach to studying the nature of interaction between heavy-metal ions and the organic–mineral matrix of soils involves application of modern physical analytical techniques and chemical methods of extractive fractionation. XANES was used to obtain the first data on the near-edge fine structure of X-ray spectra for a number of heavy-metal species in ordinary chernozem. Data on the structure of soil samples saturated with Zn2+ and Cu2+ obtained by XANES (X-ray absorption near-edge structure) make it possible to elucidate the interaction mechanisms of the metals and the types of chemical bonds formed thereby. As contamination doze of with Cu and Zn is increased (from 2000 to 10 000 mg/kg soil), particularly if the metals are introduced in the form of readily solubility salts, bonding between the metals and soil components weakens. Data of extractive fractionation of metal compounds from samples saturated with Cu and Zn compounds testify that the Cu2+ ion is preferably retained in the organic matter of the soil, whereas the Zn2+ ion is bound mostly to silicates, carbonates, and Fe and Mn (hydro)oxides.  相似文献   

15.
Infrared and electron microprobe analysis of natural tourmalines from the dravite-schorl and elbaite-schorl series were carried out. The infrared study differentiates between OH groups located at the centre of hexagonal rings and those which are placed between hexagonal pillars and are coordinated to two Al ions. The correlation of infrared spectra with chemical composition of tourmalines made possible the assignment of different OH stretching bands to the more frequent octahedral cation associations. The study of the thermal dehydroxylation of tourmalines in air indentified the IR bands corresponding to OH bonded to Fe+2 ions in AlAlFe, AlFeLi or FeFeFe environments. The change in intensity of the OH absorption lines with the sample orientation has permitted the identification of several orientations of the OH bond axes. Electron microprobe analysis of zoned coloured samples has shown that the Fe, Mn distribution is partially ordered in some samples of the elbaite-schorl series.  相似文献   

16.
The chemical composition of pyrite in coal can be used to investigate its geological and mineralogical origin. In this paper, high-resolution time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to study the chemical composition of various pyrite forms in the No. 9 coal seam (St,d=3.46%) from the Wuda Coalfield, Inner Mongolia, northern China. These include bacteriogenic, framboidal, massive, cell-filling, fracture-filling, and nodular pyrites. In addition to Fe+ (54Fe+, 56Fe+, 57Fe+), other fragment ions were detected in bacteriogenic pyrites, such as 27Al+, Si+ (28Si+, 29Si+, 30Si+), 40Ca+, Cu+ (63Cu+, 65Cu+), Zn+ (64Zn+, 66Zn+, 67Zn+, 68Zn+), Ni+ (58Ni+, 60Ni+, 62Ni+), and C3H7+. TOF-SIMS images show bacteriogenic pyrites are relatively rich in Cu, Zn, and Ni, suggesting that bacteria probably play an important role in the enrichment of Cu, Zn, and Ni during their formation. Intense positive secondary ion fragments from framboidal aggregates, such as 27Al+, 28Si+, 29Si+, AlO+, CH2+, C3H3+, C3H5+, and C4H7+, indicate that formation of the framboidal aggregates may have occurred together with clay mineral and organic matter, which probably serve as the binding substance. The intense ions of 28Si+ and 27Al+ from massive pyrites also suggest that their pores incorporated clay minerals during crystallization. Together with the lowest 28Si+/23Na+ value, the intense organic positive secondary ion peaks from cell-filling pyrites, such as C3H3+, C3H5+, C3H7+, and C4H7+, indicate that pyrite formation may have accompanied dissolution or disintegration of the cell. The intense P+ peak was observed only in the fracture-filling pyrite and the highest 28Si+/23Na+ value of fracture-filling pyrite reflects its epigenetic origin. Together with XRD and REEs data, the stronger 40Ca+ in nodular pyrite than other pyrite forms shows seawater influence during its formation.  相似文献   

17.
The theoretical infrared (IR) and Raman spectra of bayerite (β-Al(OH)3) are computed in the density functional theory framework, using the linear response theory. The results are consistent with the occurrence of six non-equivalent OH groups in a bayerite structure with space group P21/n. Similar to gibbsite, the transmission powder IR spectrum of bayerite in the region of the OH stretching bands is found to depend on the shape of particles. In particular, the broadening of the strong band observed at about 3,460 cm−1 in the spectrum of Al hydroxides is related to the electrostatic charges occurring at the surface of the polarized dielectric particles. The experimental correlation observed between the shape of this band and morphological parameters has therefore a physical, instead of chemical, origin.  相似文献   

18.
Health hazards from heavy metal pollution in water systems are a global environmental problem. Of similar concern is sludge that results from wastewater treatment due to unsatisfactory sludge management technology. Therefore, the effectiveness of using Mg–Al-layered double hydroxide in the removal of heavy metals from mine wastewater was tested and compared with that of calcium hydroxide [Ca(OH)2], which is a common treatment method for heavy metal removal. Initially, the mine wastewater contained cations of the heavy metals iron (Fe), zinc (Zn), copper (Cu), and lead (Pb). The Mg–Al-layered double hydroxides were able to remove 371, 7.2, 121, and 0.4 mg/L of these pollutants, respectively, using the co-precipitation method. The removal of these metals is most effective using 0.5 g Mg–Al-layered double hydroxide (Mg/Al molar ratio 4) and 20 min of shaking. Zn was removed by the formation of Zn(NO3)(OH)·H2O and Zn5(NO3)2(OH)8 when LDH, Mg/Al molar ratios of 4 and 2, respectively, were used. Similarly, Fe, Cu, and Pb were removed by the formation of Fe–Al-layered double hydroxide, Cu2(OH)3·NO3 and Pb4(OH)4(NO3)4, respectively. While Ca(OH)2 is also capable of reducing the heavy metal concentrations below the Japanese recommended values, this analysis shows that using 0.5 g Mg–Al-layered double hydroxide is a better treatment condition for mine wastewater, because it generates lower sludge volumes than 0.1 g of Ca(OH)2. The measured sludge volume was 1.5 mL for Mg–Al-layered double hydroxide and 2.5 mL for Ca(OH)2, a nearly twofold further reduction.  相似文献   

19.
Isothermal solid state experiments on the diffusion of Cu, Fe, Zn and In and related effects have been carried out in sphalerite single crystals. The driving force for the diffusion and corresponding reactions are chemical potential gradients which are established by differences in sulfur fugacity, oxygen fugacity and the chemical activity between sulfide powders as metal sources and receptor crystals.Studies in the system ZnS-CuInS2 show replacement rims in sphalerite produced by the formation of solid solutions between ZnS and CuInS2. These differences reflect the extent of mutual solid solution. The composition profiles of these rims at different temperatures and sulfur fugacities are calculated to diffusion coefficients for the coupled substitution of Cu+ + In3+ versus 2 Zn2+. The interdiffusion coefficients of (Cu + In) in Fe-free sphalerite at the Fe/FeS sulfur fugacity of the sources obey to the relation:  相似文献   

20.
Readily dispersible clay is the part of the clay fraction in soils that potentially disperses in water when a small amount of mechanical energy is applied to soil. Column and batch experiments were conducted to identify the effect of readily dispersible clay on the mobility of some metal ions in a disturbed soil sample. The clay fraction (<0.002 mm) was separated from an alkaline Vertisol from the Nile River Delta. X-ray diffraction technique was used to identify minerals present in the clay fraction. Clay suspensions and deionized H2O solutions of Cd2+, Cu2+, and Zn2+ were prepared and used as influents in soil columns. Adsorption capability of the studied soil among the three metal ions was investigated. The results showed high adsorption capacity of Cd2+, Cu2+, but not Zn2+ for the studied soil. Cu2+ was the highest adsorbed metal by soil and its sorption increased at small equilibrium concentrations compared with Cd2+ and Zn2+. For the three studied metal ions, Langmuir model represented the best fit to the adsorption data. The concentration of Zn2+ and Cd2+ in leachates increased as the leaching solution volume increased, while Cu2+ showed a homogeneous distribution throughout the soil column. According to DTPA extractable metals, Zn2+ was appeared at greater depths than Cd2+, while Cu2+ had homogeneous distribution through the soil column.  相似文献   

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