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  • 21
    Electronic Resource
    Electronic Resource
    The Ionic Strength Dependence of Rare Earth and Yttrium Fluoride Complexation at 25°C (2000)
    Springer
    Journal of solution chemistry 29 (2000), S. 1089-1099 
    Details
    ISSN: 1572-8927
    Keywords: Rare earth elements ; fluoride complexation ; stability constants ; sodium perchlorate ; ionic strength ; lanthanide ; yttrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Formation constants for the complexation of yttrium and rare earth elements(YREE) by fluoride ions have been measured at 25°C. The ionic strength (μ)dependence of YREE formation constants in perchlorate solution for ionicstrengths between 0 and 6 molar can be expressed aslogFβ1 (M, μ) =logFβ1 o (M) −3.066 μ0.5/(1 + 1.769 μ0.5)+ 0.1645 μwhere logFβ1 o(M) represents MF2+formation constants at zero ionic strength.The logFβ1 o(M) results obtained inthis work are: Y(4.46), La(3.62), Ce(3.86),Pr(3.84), Nd(3.82), Sm(4.15), Eu(4.27), Gd(4.24), Tb(4.37), Dy(4.39), Ho(4.28),Er(4.27), Tm(4.29), Yb(4.39), and Lu(4.25). The relative magnitudes of YREEformation constants are independent of ionic strength. The pattern oflogFβ1(M,μ),formation constants obtained in this work [relative magnitudes oflogFβ1 o (M)],exhibits a shallow minimum between Dy and Yb. In contrast to the smoothpattern of stability constants expected if fluoride were to interact with bare ions(with monotonically decreasing crystal radii between La and Lu), theinteractionof F− with YREEs, which have extensive hydration spheres[M(H2O)8–9 3+] resultsin a relatively complex pattern of lanthanide stability constants. The fluoridecomplexation behavior of yttrium differs distinctly from the behavior of any rareearth. Although the crystal radius of Y3;pl is approximately equalto that of Ho3+,differences in the covalence/ionicity of Y3+ relative to therare earths leads to aYF2+ stability constant that exceeds that of any rare earthelement (REE).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005186932126
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  • 22
    Electronic Resource
    Electronic Resource
    Comparative Coprecipitation of Phosphate and Arsenate with Yttrium and the Rare Earths: The Influence of Solution Complexation (1997)
    Springer
    Journal of solution chemistry 26 (1997), S. 1187-1198 
    Details
    ISSN: 1572-8927
    Keywords: Coprecipitation ; rare earths ; lanthanides ; yttrium ; phosphate ; arsenate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Coprecipitation of yttrium (Y) and rare earth elements (REEs) with phosphate and arsenate removes these elements from solution in variable proportions. During both phosphate and arsenate Coprecipitation, middle REEs (Sm and Eu) are progressively depleted in solution relative to heavier and lighter elements. Solution complexation by oxalate (Ox 2-) influences Y and REE removal patterns by strongly enhancing the retention of Y and the heaviest REEs in solution. The extent of this enhancement is well described by a quantitative account of the comparative solution complexation of Y and REEs as M(Ox)+ and M(Ox) $$_{\text{2}}^ - $$ . The comparative behavior of phosphate and arsenate coprecipitation exhibits both similarities and differences. During arsenate coprecipitation the light REEs are retained in solution, relative to the heavy REEs, to a greater extent than is the case for phosphate coprecipitation. Notable irregularities are observed in the comparative coprecipitation behavior of nearest-neighbor elements (e.g., Eu–Gd–Tb and Tm–Yb–Lu). Such irregularities are very similar for phosphate and arsenate coprecipitation in the absence and in the presence of solution complexation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022933224074
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  • 23
    Electronic Resource
    Electronic Resource
    The hydrolysis and fluoride complexation behavior of Fe(III) at 25°C and 0.68 molal ionic strength (1996)
    Springer
    Journal of solution chemistry 25 (1996), S. 773-785 
    Details
    ISSN: 1572-8927
    Keywords: Iron(III) ; ferric ; hydrolysis ; fluoride ; complexation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Fe(III) hydrolysis and fluoride complexation behavior was examined in 0.68 molal sodium perchlorate at 25°C. Our assessment of the complexation of Fe(III) by fluoride ions produced the following results: logFβ1 = 5.155, logFβ2 = 9.107, logFβ3 = 11.96, logFβ4 = 13.75, where logFβn = 5.155=[FeF n (3-n)+ ][Fe3+]−1[F−]−n. The stepwise fluoride complexation constants,FK n+1, obtained in our work (where logF K n+1 =logFβn) indicate that K n+1/K n =0.072±0.01. Formation constants for equilibria, Fe3++nH2O⇌Fe(OH) n (3−n)+ +nH+, expressed in the form β n * [Fe(OH) n (3-n)+ ][H+]n ,[Fe 3+]-1, were estimated as β 1 * = −2.754, and β 2 * ≤ −7. Our study indicates that the results of previous hydrolysis investigations include very large overestimates of Fe(OH) 2 + formation constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00973784
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  • 24
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    Unknown
    They Lived the Faith. (Thomas P. Neill) (Book Review). (1951)
    Washington : Periodicals Archive Online (PAO)
    Catholic historical review. 37:3 (1951:Oct.) 319 
    Details
    ISSN: 0008-8080
    Topics: History , Theology and Religious Studies
    Notes: BOOK REVIEWS
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:1053-1951-037-03-000026
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  • 25
    Electronic Resource
    Electronic Resource
    Water column dissolution of aragonite in the Pacific Ocean (1984)
    [s.l.] : Nature Publishing Group
    Nature 312 (1984), S. 321-326 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Pelagic pteropods are an important component of the oceanic CO2 system. Their shells appear to be a principal source of excess alkalinity in the upper water column of the North Pacific Ocean. Dissolution of aragonite must therefore be taken account of in generating models of the oceanic ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/312321a0
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  • 26
    Electronic Resource
    Electronic Resource
    Ionic Strength Dependence of Rare Earth – NTA Stability Constants at 25°C (1997)
    Springer
    Aquatic geochemistry 3 (1997), S. 99-115 
    Details
    ISSN: 1573-1421
    Keywords: rare earth elements ; copper ; complexation ; ionic strength effects ; nitrilotriacetic acid ; lanthanide ; yttrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Observations of competitive complexation of NTA by Cu2+ and rare earth element (REE) ions are used to determine REE-NTA stability constants at ionic strengths between 0.1 and 5.0 molar. Although REE stability constants change markedly with ionic strength, differences in the ionic strength dependence of REE-NTA stability constants across the rare earth element series are small. The ionic strength dependence of logβ1 for Y and REEs with NTA at 25 °C can be described as: logβ1(M) = logβ1(M)0 - 9.198 I1/2/(1+B I1/2)+C I + D I3/2, where β1(M) = [MNTA°][M3+]-1[NTA3-]-1, I is ionic strength, B = 1.732, C = 0.1596, D = 0.0816, and logβ1(M)° is the metal-NTA stability constant at zero ionic strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009643409154
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  • 27
    Electronic Resource
    Electronic Resource
    The solubility control of rare earth elements in natural terrestrial waters and the significance of PO 4 3− and CO 3 2− in limiting dissolved rare earth concentrations: A review of recent information (1995)
    Springer
    Aquatic geochemistry 1 (1995), S. 157-173 
    Details
    ISSN: 1573-1421
    Keywords: rare earth elements ; lakes ; groundwaters ; activity products ; solubility products ; solubility controls ; complexation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Rare earth element (REE) concentrations in alkaline lakes, circumneutral pH groundwaters, and an acidic freshwater lake were determined along with the free carbonate, free phosphate, and free sulfate ion concentrations. These parameters were used to evaluate the saturation state of these waters with respect to REE phosphate and carbonate precipitates. Our activity product estimates indicate that the alkaline lake waters and groundwaters are approximately saturated with respect to the REE phosphate precipitates but are significantly undersaturated with respect to REE carbonate and sulfate precipitates. On the other hand, the acidic lake waters are undersaturated with respect to REE sulfate, carbonate, and phosphate precipitates. Although carbonate complexes tend to dominate the speciation of the REEs in neutral and alkaline waters, our results indicate that REE phosphate precipitates are also important in controlling REE behavior. More specifically, elevated carbonate ion concentrations in neutral to alkaline natural waters tend to enhance dissolved REE concentrations through the formation of stable REE-carbonate complexes whereas phosphate ions tend to lead to the removal of the REEs from solution in these waters by the formation of REE-phosphate salts. Removal of REEs by precipitation as phosphate phases in the acid lake (pH=3.6) is inconsequential, however, due to extremely low [PO 4 3− ] F concentrations (i.e., ∼ 10−23 mol/kg).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702889
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  • 28
    Electronic Resource
    Electronic Resource
    Interaction of B $$(OH)_3^0 $$ and $$HCO_3^ - $$ in Seawater: Formation of B $$(OH)_2 CO_3^ - $$ (1997)
    Springer
    Aquatic geochemistry 3 (1997), S. 345-356 
    Details
    ISSN: 1573-1421
    Keywords: boron ; boric acid ; carbonate ; CO2 system ; complexation ; spectrophotometric pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Boron is known to interact with a wide variety of protonated ligands(HL) creating complexes of the form B(OH)2L-.Investigation of the interaction of boric acid and bicarbonate in aqueoussolution can be interpreted in terms of the equilibrium $$B(OH)_3^0 + HCO_3^ - \rightleftharpoons B(OH)_2 CO_3^ - + H_2 O$$ The formation constant for this reaction at 25 °C and 0.7 molkg-1 ionic strength is $$K_{BC} = \left[ {B(OH)_2 CO_3^ - } \right]\left[ {B(OH)_3^0 } \right]^{ - 1} \left[ {HCO_3^ - } \right]^{ - 1} = 2.6 \pm 1.7$$ where brackets represent the total concentration of each indicatedspecies. This formation constant indicates that theB(OH)2 $$CO_3^ - $$ concentration inseawater at 25 °C is on the order of 2 μmol kg-1. Dueto the presence of B(OH)2 $$CO_3^ - $$ , theboric acid dissociation constant ( $$K\prime _B $$ ) in natural seawaterdiffers from $$K\prime _B $$ determined in the absence of bicarbonate byapproximately 0.5%. Similarly, the dissociation constants of carbonicacid and bicarbonate in natural seawater differ from dissociation constantsdetermined in the absence of boric acid by about 0.1%. Thesedifferences, although small, are systematic and exert observable influenceson equilibrium predictions relating CO2 fugacity, pH, totalcarbon and alkalinity in seawater.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009633804274
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  • 29
    Electronic Resource
    Electronic Resource
    A Coupled Riverine-Marine Fractionation Model for Dissolved Rare Earths and Yttrium (1998)
    Springer
    Aquatic geochemistry 4 (1998), S. 103-121 
    Details
    ISSN: 1573-1421
    Keywords: Rare earth ; Rare earth ; fractionation ; model ; riverine ; oceanic ; estuarine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Fractionation of yttrium (Y) and the rare earth elements (REEs) begins in riverine systems and continues in estuaries and the ocean. Models of yttrium and rare earth (YREE) distributions in seawater must therefore consider the fractionation of these elements in both marine and riverine systems. In this work we develop a coupled riverine/marine fractionation model for dissolved rare earths and yttrium, and apply this model to calculations of marine YREE fractionation for a simple two-box (riverine/marine) geochemical system. Shale-normalized YREE concentrations in seawater can be expressed in terms of fractionation factors (λ ij ) appropriate to riverine environments ( $$\lambda _{ij}^{river}$$ ) and seawater ( $$\lambda _{ij}^{ocean}$$ ): $$\log \frac{{\left( {M_i } \right)_T^{ocean} }}{{\left( Y \right)_T^{ocean} }} = log\;\lambda _{ij}^{ocean} + ((\lambda _{ij}^{river} )^{ - 1} - 1)\;log\frac{{[Y]_T^{river} }}{{[Y^0 ]_T^{river} }}$$ where $$\left( {M_i } \right)_T^{ocean}$$ and $$\left( Y \right)_T^{ocean}$$ are input-normalized total metal concentrations in seawater and $$[Y]_T^{river} /[Y^0 ]_T^{river}$$ is the ratio of total dissolved Y in riverwater before $$([Y^0 ]_T^{river} )$$ and after $$([Y]_T^{river} )$$ commencement of riverine metal scavenging processes. The fractionation factors (λ ij ) are calculated relative to the reference element, yttrium, and reflect a balance between solution and surface complexation of the rare earths and yttrium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009651919911
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  • 30
    Electronic Resource
    Electronic Resource
    Metal complexes of 2-mercaptobenzothiazole (1982)
    Springer
    Transition metal chemistry 7 (1982), S. 5-10 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Metal complexes of 2-mercaptobenzothiazole (LH) have been prepared and investigated. The metal complexes obtained were of the types ML2 (M = Ni, Pd, Pt, Zn, Cd), CuL.LH, and AgL. The copper complex has been shown to contain copper(I). Evidence from the i.r. spectra shows that in all the complexes the ligand is coordinatedvia the thiazole nitrogen and the exocyclic sulfur atom. Adducts of both the nickel and cadmium complexes were obtained with several nitrogen heterocycles. The complex CdL2py2 (py = pyridine) is isostructural with the six-coordinate NiL2py2 and CoL2py2 which possess acis configuration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00623797
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