http://library.um.ac.id/free-contents/downloadpdf.php/buku/complexation-reactions-in-aquatic-systems-an-analytical-approach-j-buffle-translators-s-p-kounaves-a-kounaves-and-r-s-altman-12623.pdf

Complexation reactions in aquatic systems : an analytical approach / J. Buffle, translators S.P. Kounaves, A. Kounaves and R.S. Altman

Aquatic surface chemistry: Edited by Werner Stumm. Wiley, New York. 1987. $69.95 (ISBN 0471822951)

Graphene oxide-supported polyaniline (PANI@GO) composites were synthesized by chemical oxidation and were characterized by SEM, Raman and FT-IR spectroscopy, TGA, potentiometric titrations, and XPS. The characterization indicated that PANI can be grafted onto the surface of GO nanosheets successfully. The sorption of U(VI), Eu(III), Sr(II), and Cs(I) from aqueous solutions as a function of pH and initial concentration on the PANI@GO composites was investigated. The maximum sorption capacities of U(VI), Eu(III), Sr(II), and Cs(I) on the PANI@GO composites at pH 3.0 and T = 298 K calculated from the Langmuir model were 1.03, 1.65, 1.68, and 1.39 mmol·g–1, respectively. According to the XPS analysis of the PANI@GO composites before and after Eu(III) desorption, nitrogen- and oxygen-containing functional groups on the surface of PANI@GO composites were responsible for radionuclide sorption, and that radionuclides can hardly be extracted from the nitrogen-containing functional groups. Therefore, the chemical a...

Highly efficient enrichment of radionuclides on graphene oxide-supported polyaniline

The interaction mechanism between Eu(II) and graphene oxide nanosheets (GONS) was investigated by batch and extended X-ray absorption fine structure (EXAFS) spectroscopy and by modeling techniques. The effects of pH, ionic strength, and temperature on Eu(III) adsorption on GONS were evaluated. The results indicated that ionic strength had no effect on Eu(III) adsorption on GONS. The maximum adsorption capacity of Eu(III) on GONS at pH 6.0 and T = 298 K was calculated to be 175.44 mg.g(-1), much higher than any currently reported. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Eu(III) adsorption on GONS was an endothermic and spontaneous process. Results of EXAFS spectral analysis indicated that Eu(III) was bound to similar to 6-7 O atoms at a bond distance of similar to 2.44 angstrom in the first coordination shell. The value of Eu C bond distance confirmed the formation of inner-sphere surface complexes on GONS. Surface complexation modeling gave an excellent fit with the predominant mononuclear monodentate >SOEu2+ and binuclear bidentate (>SO)(2)Eu-2(OH)(2)(2+) complexes. This paper highlights the application of GONS as a suitable material for the preconcentration and removal of trivalent lanthanides and actinides from aqueous solutions in environmental pollution management.

http://ir.hfcas.ac.cn:8080/bitstream/334002/5625/1/Interaction%20between%20Eu%28III%29%20and%20Graphene%20Oxide%20Nanosheets%20Investigated%20by%20Batch%20and%20Extended%20X-ray%20Absorption%20Fine%20Structure%20Spectroscopy%20and%20by%20Modeling%20Techniques.pdf

Interaction between Eu(III) and Graphene Oxide Nanosheets Investigated by Batch and Extended X-ray Absorption Fine Structure Spectroscopy and by Modeling Techniques

Sorption of lanthanides on smectite and kaolinite

The present paper describes the surface complexation behaviour of trivalent metal ions, Am(III) and Eu(III), on well characterised γ-alumina. Experiments are conducted at different pH (4-8) and ionic strength (0.001 - 0.1 M NaClO4) either in the presence or absence of CO2. By varying the metal ion concentration from 10-9 to 10-4 mol/L, the sorption isotherm is established under each given experimental condition. Different surface complexation models are applied to the experimental results to interpret and appraise the surface sorption processes under different experimental conditions. A comparison of the present results is made with the Eu(III) sorption onto the hematite mineral surface investigated previously. It has been shown that sorption properties of hematite and γ-alumina seem to be quite similar. For both systems, a good agreement is found between experimental data and modelling, once using the two site surface complexation model and the same complexation constants for the respective monodentate surface complex. The Eu(III) sorption reaction is additionally studied in-situ by time resolved laser fluorescence spectroscopy (TRLFS). Formation of inner-sphere complexes can be deduced from the emission spectra. The continuous increase of the fluorescence life time with increasing pH starting from pH = 5.0 indicates that surface complexation is accompanied by a decreasing number of hydration water in the first coordination sphere.

Sorption of Am(III) and Eu(III) onto γ-alumina: experiment and modelling

The solid/water interface reaction is investigated for the sorption of the Eu3+ ion onto a well-characterized natural hematite at pH </=6 in 0.1 mol/L NaClO4. Sorption isotherms are determined at different pH. The sorption of Eu3+ onto hematite at coverages <1% of the surface hydroxyl groups follows the ideal Nernst behavior and can be interpreted in terms of the surface complexation by the following equilibrium reaction: tXOH + Eu3+ if tXOEu2+ + H+ (log Kintx = 2.50 +/- 0.19). Complexation constants are calculated by either graphically interpretating the sorption isotherms or fitting the data using the code FITEQL. At higher surface coverages a deviation from the Nernst behavior is observed which can be described satisfactorily by a two-site surface complexation model, taking into account the lateral electrostatic interaction of surface-bound Eu(III): tYOH + Eu3+ if tYOEu2+ + H+ (log Kinty = -0.82 +/- 0.11). The experimental results are compared with data published in the literature, and the interpretation of sorption isotherms with regard to the sorption mechanisms is critically discussed. Copyright 1998 Academic Press.

Sorption of Eu(III) on a Natural Hematite: Application of a Surface Complexation Model.

The influence of smectite colloids on the migration behaviour of U(VI), Th(IV), Pu([V), Am(III), Np(V), Sr(II) and Cs(I) is investigated within the Colloid and Radionuclide Retardation experiment (CRR). Two in situ experiments in a well-characterized granitic fracture zone are carried out in presence and absence of bentonite colloids. Radionuclide retardation observed in the field studies increases in the sequence Np(V) ∼ U(VI) < Sr(II) < Cs(I), where a small fraction of colloid borne breakthrough is only stated for Cs(I) in presence of bentonite colloids. Arn(III) and Th/Pu(IV) mainly migrate as colloids without retardation in the presence and absence of smectitic colloids. The radionuclide migration behaviour is discussed on the basis of results obtained in laboratory batch sorption experiments and spectroscopic studies. Consistent with the field observation, laboratory derived K d values increase in the order Np(V) ∼ U(VI) < Sr(II) < Cs(I). Significant kinetic hindrance for the sorption to fault gauge minerals is observed for Sr(II) and Cs(I), but notably for Am(III) and Pu(IV). The slow sorption reaction of tri-and tetravalent actinide ions is explained by their kinetically hindered dissociation from colloidal species. In order to explain the colloidal behaviour of tri- and tetravalent actinides even in absence of bentonite colloids, ultracentrifugation and spectroscopic experiments are performed. It is found that up to 60% of Pu(IV) and Am(III) species can be centrifuged off. Adding Cm(III) (5 x 10 - 8 molL - 1 ) into both injection solutions instead of Am(III) allows for a spectroscopic study by using the time resolved laser fluorescence spectroscopy (TRLFS). Peak position and fluorescence lifetimes (λ = 604 nm, T = 110-114 μs) together with the fact that Cm(III) can be widely separated by ultracentrifugation, suggest the existence of inner-sphere surface complexes on groundwater and bentonite colloids. Carbon K-edge XANES analysis of the bentonite colloids reveal the presence of natural organic constituents. They are mainly of aliphatic nature containing high fractions of carboxylate groups. A contribution of these organic species towards the bentonite colloid stability and sorption of actinides is assumed to be likely.

Results of the colloid and radionuclide retention experiment (crr) at the grimsel test site (gts), switzerland - impact of reaction kinetics and speciation on radionuclide migration

Sorption of Cm(III) onto γ-alumina coated with humic acid (HA) is studied by the Time Resolved Laser Fluorescence Spectroscopy (TRLFS). The experiments are performed at 0.1 M NaClO 4 , 0.44 g/L γ-Al 2 O 3 , 10 mg/L HA and ata metal ion concentration of 2 × 10 - 7 mol/L. At the investigated pH range (4 to 10) HA is completely sorbed to γ-Al 2 O 3 . The excitation spectrum of Cm(III) bound to HA/γ-Al 2 O 3 in the wavelength range 370-400 nm exhibits broad flat bands very different from those obtained for the Cm(III) aquo ion and the Cm(III)-γ-Al 2 O 3 surface complex, respectively. The spectrum, lacking distinctive structure due to intramolecular energy transfer processes, points to the predominant binding of the Cm(III) to surface-bound HA. TRLFS experiments performed at two different excitation wavelengths (λ e x =355 and 396.6 nm) allow for a differentiation of humic-bound and non-humic-bound Cm(III). Differences in fluorescence spectra obtained at the different excitation wavelengths are found at pH Al-O-Cm(III)(HA).

Effect of humic acid on the sorption of Cm(III) onto γ-Al2O3 studied by the time-resolved laser fluorescence spectroscopy

Known data on the solubility of Am(OH) 3 (s) and the hydrolysis of Am(III) and Cm(III), additional information from an extensive solubility study with Nd(OH) 3 (s) in NaCl, MgCl 2 , and CaCl 2 media of various ionic strengths and spectroscopic (time-resolved laser fluorescence spectroscopy, TRLFS) data for Cm(III) in alkaline CaCl 2 solutions are used to evaluate a comprehensive set of standard-state equilibrium constants and ion interaction parameters for the specific ion interaction theory (SIT) and Pitzer equations at 25 °C. The thermo dynamic model takes into account the analogous solubility and hydrolysis behavior of trivalent actinides and Nd(III) and covers the entire pH range in dilute to concentrated NaCl, MgCl 2 , and CaCl 2 solutions. In alkali chloride/hydroxide solutions, the formation of the tetrahydroxide complex M(OH) 4 - requires OH - concentration above 3 mol l -1 , whereas in alkaline CaCl 2 solutions (at pH c < 12) M(III) complexes with four and six hydroxide ligands are formed. Similar as the recently detected ternary Ca-M(IV)-OH complexes Ca 3 (Zr(OH) 6 ) 4+ and Ca 4 (Th(OH) 8 ) 4+ , these complexes are stabilized by the association of Ca 2+ ions. The solubility and hydrolysis of Am(III), Cm(III), and Nd(III) in both Ca-free and -containing solutions is consistently described with a model including the ternary Ca-M(III)-OH complexes Ca(M(OH) 3 ) 2+ , Ca 2 (M(OH) 4 ) 3+ , and Ca 3 (M(OH) 6 ) 3+ .

Thomas Rabung

Papers

Sorption of Am(III) and Eu(III) onto γ-alumina: experiment and modelling

Sorption of Eu(III) on a Natural Hematite: Application of a Surface Complexation Model.

Results of the colloid and radionuclide retention experiment (crr) at the grimsel test site (gts), switzerland - impact of reaction kinetics and speciation on radionuclide migration

Effect of humic acid on the sorption of Cm(III) onto γ-Al2O3 studied by the time-resolved laser fluorescence spectroscopy

Thermodynamics of trivalent actinides and neodymium in NaCl, MgCl 2 , and CaCl 2 solutions: Solubility, hydrolysis, and ternary Ca-M(III)-OH complexes