Synthesis and Adsorption Properties of Chelating Resins Containing Sulfoxide and Heterocyclic Functional Groups

Chelating resins containing heterocyclic functional groups and sulfoxide show high affinity for heavy and noble metal ions, so many attempts are under way to anchore such groups onto solid supports1-3. The earlier studies were on the resins containing het…     

Synthesis and Adsorption Properties of Polystyrene-supported Chelating Resins Containing Heterocyclic Functional Groups

A series of new chelating resins with incorporating heterocyclic functional groups： pyridine, thiadizole, benzothizole into macroporous chloromethylated polystyrene were synthesized via hydrophilic spacer arm of polyethylene glycol containing sulfur. These chelating resins were found to show high adsorption capacities for Ag^＋, Hg^2＋, Au^3＋ and Pd^2＋, and the presence of spacer arm can enhance adsorption ability due to increase the hydrophilicity of the chelating resins.     

Sorption of Lead(II) on Two Chelating Resins: From the Exchange Coefficient to the Intrinsic Complexation Constant

The sorption of inorganic lead(II) on two cationic resins containing different complexing groups, the iminodiacetic Chelex 100 and the carboxylic Amberlite CG-50, was investigated. The Gibbs-Donnan model was used to describe and predict the sorption through the determination of the intrinsic complexation constants. These quantities, even though non-thermodynamic, characterize the sorption as being independent of experimental conditions. The sorption mechanism for metals on complexing resins was also studied by adding a competitive soluble ligand that shifts the sorption curves to higher pH. The ligand competes with the resin for complexation with the metal ion. Lead(II) is strongly sorbed on Chelex 100 through the formation of two complexes in the resin phase: MHL with log ₁₀ β _111i =−0.3 and ML with log ₁₀ β _111i =−3.7. The presence of the competitive ligand in solution allows for the determination of a third complex. Furthermore, on Amberlite CG-50 the sorption is rather strong and involves the formation of the complex ML, in more acidic solution, with log ₁₀ β _110i =−2.0. In the presence of the ligand PyDA, the ML(OH) complex was characterized by log ₁₀ β _11−1i =−5.6. In all the experiments the hydrolysis reactions in the aqueous phase are considered quantitatively.     

Analysis of the Pore Structure of Ion-Exchange Resins and the Adsorption Equilibrium of Fe3+/Cl− Complex Ions

The microstructure of ion-exchange resins has been investigated to understand more clearly the ion-exchange mechanism. Nine types of resins with different pore structures were used: all of the polystyrene family crosslinked with divinylbenzene and anionic resins, with mesh sizes ranging from 100 to 200, except for one (20–50 mesh). Various pore volumes of each resin were determined by measurements of intrusion of some chemical species (H₂O, Nd³⁺, and Hg) into the resin. The results are analyzed on the basis that an ion-exchange resin particle consists of four regions. They are: 1) the mercury intrusion region, 2) the region where coions (such as Nd³⁺) can intrude but mercury cannot, 3) the region where water or counterions can intrude but coions cannot, and 4) the polymer matrix region occupied by the polymer skeleton. The former two regions are not influenced by the resin-fixed ionic groups. While it used to be thought that specific adsorption of counterions may occur in the entire exchange resin particle, it is appropriate to consider that specific adsorption takes place only in the latter two regions. According to this point of view, the adsorption equilibrium of the Fe³⁺/Cl^? complex ions could be explained more satisfactorily.     

Quantum-Chemical Simulation of the Adsorption of OH– Ions on Au(111)

Russian Journal of Electrochemistry - Based on the cluster model of the metal surface, the OH– ion interaction with the gold surface is studied by the density functional method. The...     

Adsorption of Ions on Zirconium Oxide Surfaces from Aqueous Solutions at High Temperatures

Surface titrations were carried out on suspensions of monoclinic ZrO₂ from 25 to 290 °C slightly above saturation vapor pressure at ionic strengths of 0.03, 0.1 and 1.0 mol⋅kg⁻¹(NaCl). A typical increase in surface charge was observed with increasing temperature. There was no correlation between the radius of the cations, Li⁺, Na⁺, K⁺ and (CH₃)₄N⁺, and the magnitude of their association with the surface. The combined results were treated with a 1-pK_a MUSIC model, which yielded association constants for the cations (and chloride ion at low pH) at each temperature. The pH of zero-point-charge, pH_zpc, decreased with increasing temperature as found for other metal oxides, reaching an apparent minimum value of 4.1 by 250 °C. Batch experiments were performed to monitor the concentration of LiOH in solutions containing suspended ZrO₂ particles from 200 to 360 °C. At 350 and 360 °C, Li⁺ and OH⁻ ions were almost totally adsorbed when the pressure was lowered to near saturation vapor pressure. This reversible trend has implications not only to pressure-water reactor, PWR, operations, but is also of general scientific and other applied interest. Additional experiments probed the feasibility that boric acid/borate ions adsorb reversibly onto ZrO₂ surfaces at near-neutral pH conditions as indicated in earlier publications. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.     

Bi-, TRI- and Penta-Nuclear Complexes of Chelating Schiff Bases Derived from o-Acetoacetylphenol and Amine Complexes, [Ni(1,2-pn)2Cl2]·3H2O and [Cu(1,2-pn)2]SO4·2H2O

Two novel macroacylic Schiff base ligands were prepared by condensation of two diamine metal complexes, [Ni(1,2-pn)₂Cl₂]·3H₂O and [Cu(1,2-pn)₂]SO₄·2H₂O with o-acetoacetylphenol. The ligands MH₆L(M = Ni or Cu) are hexabasic and contain two O₄ coordination sites. They act as ligands towards transition metal ions yielding homo- and heteronuclear complexes of the type [NiH₄ LCu(H₂O)₂]·4H₂O, [MH₂LM' ₂(H₂O)₆], [MLM' ₄(H₂O)₈], [MH₂ LCe₂(NO>₃)₂(H₂O)₂] and [NiLTh₂(NO₃)₂(H₂O)₂] (M = Ni or Cu; M' = Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ce(III), Th(IV) and UO₂ (VI)). The complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), IR, visible and ESR spectra, magnetic susceptibility measurements and mass spectrometry. Magnetic moments were altered by the introduction of metal cations besides the one already present in the complex ligands. The M' cations were linked to two ketonic oxygen atoms and two phenyl oxygen atoms in [NiH₆ L(H₂O)₂] and [CuH₆ L] complex ligands. All homo- and hetero-, bi- and tri-nuclear complexes show antiferromagnetic interactions which are attributed to inter- or intramolecular interactions of the metal cations. Mass spectra of the complex ligands and selected homo- and heteronuclear complexes support the formula weights of these complexes. Visible and ESR spectra as well as magnetic moments indicated that the parent mononuclear complex ligands [MH₆ L] have an octahedral geometry for Ni(II) and a square-planar geometry distorted towards tetrahedral for Cu(II). The metal cations in bi-, tri- and pentanuclear complexes are octahedral or square-planar. The octahedral configuration is completed by chloride anions and/or solvent molecules.     

Effects of Temperature and Common Ions on Binding of Puerarin to BSA

The effects of temperature and common ions on binding of puerarin to bovine serum albumin (BSA) are investigated. The binding constants (K _a) between puerarin and BSA are 1.13×10⁴ L⋅mol⁻¹ (20 °C) and 1.54×10⁴ L⋅mol⁻¹ (30 °C), and the number of binding sites (n) is (0.95±0.02). However, at a higher temperature (40 °C) the stability of the puerarin–BSA system decreases, which results in a lower binding constant (1.58×10³ L⋅mol⁻¹) and number of binding sites (n=0.73) of the puerarin–BSA system. However, the presence of Cu²⁺ and Fe³⁺ ions increases the binding constants and the number of binding sites in the puerarin–BSA complex.     

Thermodynamic Approach of Uranium(VI) Extraction by N,N-(2–ethylhexyl)Isobutyramide

The study of extraction of U(VI) from LiNO3 media by N,N-(2-ethylhexyl)isobutyramide (DEHiBA) in dodecane has been performed at 25.00 °C using isothermal titration microcalorimetry. The raw heat measured is a sum of contributions. To obtain the net extraction enthalpy variation, different heats have to be evaluated as the dilution of amide into dodecane phase which has been measured and subtracted. The microcalorimetric extraction results are then compared to data obtained by Van’t Hoff classical method. The extraction enthalpies obtained by both methods are similar. This first study allowed to define the experimental calorimetric conditions and will be followed by determination with other actinides and amides.     

Adsorption and decomposition of cyclohexanone (C6H10O) on Pt(111) and the (2 × 2) and (√3 × √3)r30°-Sn/Pt(111) surface alloys

Adsorption and decomposition of cyclohexanone (C(6)H(10)O) on Pt(111) and on two ordered Pt-Sn surface alloys, (2 × 2)-Sn/Pt(111) and (√3 × √3)R30°-Sn/Pt(111), formed by vapor deposition of Sn on the Pt(111) single crystal surface were studied with TPD, HREELS, AES, LEED, and DFT calculations with vibrational analyses. Saturation coverage of C(6)H(10)O was found to be 0.25 ML, independent of the Sn surface concentration. The Pt(111) surface was reactive toward cyclohexanone, with the adsorption in the monolayer being about 70% irreversible. C(6)H(10)O decomposed to yield CO, H(2)O, H(2), and CH(4). Some C-O bond breaking occurred, yielding H(2)O and leaving some carbon on the surface after TPD. HREELS data showed that cyclohexanone decomposition in the monolayer began by 200 K. Intermediates from cyclohexanone decomposition were also relatively unstable on Pt(111), since coadsorbed CO and H were formed below 250 K. Surface Sn allowed for some cyclohexanone to adsorb reversibly. C(6)H(10)O dissociated on the (2 × 2) surface to form CO and H(2)O at low coverages, and methane and H(2) in smaller amounts than on Pt(111). Adsorption of cyclohexanone on (√3 × √3)R30°-Sn/Pt(111) at 90 K was mostly reversible. DFT calculations suggest that C(6)H(10)O adsorbs on Pt(111) in two configurations: by bonding weakly through oxygen to an atop Pt site and more strongly through simultaneously oxygen and carbon of the carbonyl to a bridged Pt-Pt site. In contrast, on alloy surfaces, C(6)H(10)O bonds preferentially to Sn. The presence of Sn, furthermore, is predicted to make the formation of the strongly bound C(6)H(10)O species bonding through O and C, which is a likely decomposition precursor, thermodynamically unfavorable. Alloying with Sn, thus, is shown to moderate adsorptive and reactive activity of Pt(111).     

HREELS Studies on Adsorption and Decomposition of ~(15)NO on Mo(100)-c(2×2)N Surface

MolybdenumnitridesascatalystsexhibituniquecataIyticactivitiesforawidevarietyofreactions,particularlyforthehydrodenitrogenationintherefineryprocessingofcrudesl.However,thefundamentalunderstandingconcerningthereactionmechanismsovermolybdenumnitrideisnotasweIlestablishedasthatontheMosurface.APplicationofpowerfulsurfacesciencespectroscopiesonwell-characterizednitrideoverlayersshouldprovideimPortantinsightsintothesurfacestrllctureandreactivityofsuchimportantcatalyticmaterials.Inthepresentwork,ahi…     

Structure of Oxygen and CO Adsorption on Ru(0001) Electrode

It is important to understand the chemisorption of oxygen and CO on Ru(0001) surface. CO oxidation at oxygen precovered Ru(0001) surface at low oxygen coverages gave an extremely low CO oxidation rate, and it was also observed that, with a nominal oxygen coverage exceeding ca. 3 mL, rather high CO/CO2 conversion probabilities were achieved1. In the case of coadsorption of CO and oxygen on Ru(0001) surface under UHV conditions, a model comprising two CO molecules in an (22)-O unit cel…     

Adsorption of chlorobenzene and benzene on γ-Al2O3/atl>

Adsorption of chlorobenzene and benzene on -Al₂O₃ was investigated in the 413--572 K temperature region at an adsorbate partial pressure ranging from 2 to 1000 Pa. The adsorption isotherms were measured and the isosteric heats and the entropy characteristics of adsorption were determined. The experimentally found and theoretically calculated entropy changes upon adsorption were compared. The mobility of the molecules of both adsorbates in the adsorption layer was limited with respect to that predicted by the ideal two-dimensional gas model. The mechanism of adsorption of benzene and chlorobenzene is discussed.     

Study of H2O and HOCH2CH2OH Adsorption on the Relaxation Surface of β-Si3N4(0001) by Density Functional Theory

Density functional theory (DFT) B3LYP method is used to theoretically investigate the adsorption conformations of H2O and glycol on the relaxation surface of β-Si3N4(0001) with cluster models. For H2O, the most stable structure is that adsorbed through the H atom lying above a N(3) site of the relaxation surface of β-Si3N4(0001); while for glycol, it is the one adsorbed via the H atom lying above the center of Si(2) and N(3) of the same relaxation surface. The adsorption energy, adsorption bond and transfer electrons of the two adsorbed substances prove that glycol is easy to be adsorbed on the relaxation surface of β-Si3N4(0001).     

Hetero-heptanuclear (Fe–Na) complexes of salicylaldehydes: crystal and molecular structure of [Fe2(3-OCH3-salo)8 · Νa5] · 3OH · 8H2Ο

The reaction of Fe(III) with the substituted salicylaldehydes [X-saloH, where X = 3-OCH₃ (L ¹ ), 5-CH₃ (L ² ), 5-Cl (L ³ ), 5-NO₂ (L ⁴ )] led to the formation of four new iron(III) hetero-heptanuclear complexes (Fe–Na) under the general formula [Fe₂(X-salo)₈Νa₅] · 3OH · zH₂Ο. The two different coordination modes of the ligand, as well as the geometry around the metal ions were deduced by X-ray structure analysis of compound 1, [Fe₂(3-OCH₃-salo)₈Νa₅] · 3OH · 8H₂Ο. The complexes have also been characterized by physicochemical and spectroscopic (IR, UV–Vis, Mössbauer) methods.     

Adsorption and Reaction of CO on Mo(100)-c(2×2)-N Surface Studied by HREELS

Molybdenum nitrides have attracted significant attention recently due to their uniquephysical and chemical properties. Many studies have shown that Mo,N is an activecatalyst for CO hydrogenation. The fundamental understanding concerning the reactionmechanisms over Mo=N. however, is not well established. The powerful surface sciencetechniques may provide an insight into the surface structure and properties of such animportant catalytic material. In previous paper', we described the results o…     

Investigation on the Adsorption and Corrosion Inhibition Behavior of Gum Acacia and Synergistic Surfactants Additives on Mild Steel in 0.1 M H2SO4

Adsorption and corrosion inhibition effect of gum acacia alone and in presence of surfactants sodium dodecyl benzene sulphonate and cetyltrimethyl ammonium bromide on mild steel in 0.1 M H₂SO₄ in temperature range of 30 to 60°C was investigated using weight loss method, chemical analysis of solution, scanning electron microscopy, atomic force microscopy and determination of thermodynamic parameters. Inhibiting action of gum acacia is synergistically enhanced on addition of small amount of surfactants. SEM and AFM results confirmed the existence of an adsorbed protective film on the mild steel surface. Thermodynamic parameters reveal that adsorption process is spontaneous and obey Freundlich adsorption isotherm.