Ion Exchange In Aqueous Solution Research Articles

Cochineal carmine adsorbed on layered zinc hydroxide salt applied on mortadella to improve color stability

The pink/reddish color meat products characteristic of cured meat without the curing salts is a meat industry demand to serve consumers who are looking for healthy foods with the usual sensory characteristics. This study aimed to obtain and characterize a hybrid dye and use it as a replacer for curing salt in the production of pink/red color in mortadella stored for 40 days. A layered zinc hydroxide salt (ZHN) was obtained by alkaline precipitation to immobilize and increase cochineal carmine stability, obtaining the hybrid dye (ZHN-carmine) by ion exchange in aqueous solution. The ZHN-carmine was subjected to ultrasound to increase color intensity and reduce the amount of application. ZHN, cochineal carmine and ZHN-carmine were characterized by X-Ray Diffraction, Fourier-Transform Infrared Spectroscopy, Thermogravimetric Analysis and Differential Scanning Calorimetry. The ZHN-carmine was used in the mortadella elaboration traditionally prepared with nitrite/nitrate and/or carmine. In the characterization it was observed that carmine dye was adsorbed on the lamellar compound surface and over the mortadella storage, it ensures a more stable pink/reddish color than the others product formulations. A more intense color with lower L* and higher a* values was observed for mortadella added of ZHN-carmine ultrasound-assisted. Therefore, the lamellar matrix adsorbed with cochineal carmine may a suitable and useful alternative to obtain the pink/reddish color characteristic of cooked meat products by applying a natural hybrid dye.

New micronutrient biocomponents based on blackcurrant seeds pomace – Bench-scale kinetic studies

In the present work new universal bench-scale plant for biosorption, useful in production of new micronutrient biocomponents, was described. The new installation enabling working in a fixed bed or stirred tank batch mode. Reactors may also be used in serial or parallel mode, which gives many application possibilities. Copper ions were selected as a sorbate for kinetic modelling. The results of the adsorption capacities of Cu(II) were 13.9 mg/g for fixed bed and 12.8 mg/g for stirred tank. During biosorption of Cu(II) ions from aqueous solution ion exchange and release of Ca(II), K(I), Mg(II), and Na(I) were observed. For kinetics description of stirred tank process pseudo-1st-and pseudo-2nd order models were used. For fixed bed process the Thomas, Yoon-Nelson, Adams-Bohart and Wolborska models were used. The use of blackcurrant seed residues as biosorbents enables the generation of new products from waste biomass, which can become an alternative to the traditional fertilizers with microelements. The presented technology is an attempt to reduce environmental impact of the conventional micronutrient fertilizers, which contain toxic chelators such as EDTA. Minimization of waste and maximization of product output makes it an efficient tool supporting cleaner production.

Selective Catalytic Reduction of NOxwith Ammonia over Copper Ion Exchanged SAPO‐47 Zeolites in a Wide Temperature Range

AbstractCopper‐exchanged H‐SAPO‐47 zeolites were synthesized by an aqueous solution ion exchange method and applied in the selective catalytic reduction of NO with NH3(SCR). The microporous chabazite (CHA) structure of the catalysts was characterized and confirmed using synchrotron X‐ray diffraction and nitrogen adsorption–desorption experiments. The synthesized Cux‐SAPO‐47 catalysts exhibited excellent SCR activity and nearly 100 % N2selectivity in a wide temperature range. The Cu0.1‐SAPO‐47 sample exhibited higher activity than the other samples below 250 °C. The weak Lewis acid sites originating from the introduction of Cu2+were more active than the Brønsted acid sites of the zeolites framework at low temperature. Two types of isolated Cu2+species with different coordination surroundings were found, namely, Cu2+cations bonded with the six‐membered rings and those bonded in the CHA cages. The former species exhibited good stability and activity at high temperature, whereas the latter ones were more active at low temperature. The Cu0.1‐SAPO‐47 catalyst provided a considerable amount of isolated Cu2+bonded in the CHA cages. These results indicated that active Lewis acid sites and isolated Cu2+species are responsible for their excellent SCR activity.

Clarification of copper species over Cu-SAPO-34 catalyst by DRIFTS and DFT study of CO adsorption

In this work, the nature, location and evolution of Cu+ ions in Cu-SAPO-34 are investigated by diffuse reflectance infrared Fourier transform spectrum (DRIFTS) of CO adsorption and density functional theory (DFT) calculation. By combination with DFT results, characteristic Cu+–CO bands located at 2154 and 2136 cm−1 are attributed to CO adsorbed on Cu+ ions located at sites I (in the plane of six-membered ring connected to the large cages) and site II (in the eight-membered ring cages near the tilted four membered ring) in the framework of H-SAPO-34 zeolite. Subsequently, both the influences of Cu loading and preparation method are considered and discussed. By varying the Cu loading, the site-occupation preference of Cu+ ions on site I is confirmed, especially at low Cu loadings. Through elevating the desorption temperature, migration of Cu+ ions is revealed because of the adsorption-induced effect. Furthermore, a facile and more efficient approach to introduce Cu+ ions into CHA zeolite, compared with solid-state ion exchange with CuCl and conventional ion exchange in aqueous solution, and the different preparation methods also result in different occupations of Cu+ ions.

Towards environmentally friendly Na-ion batteries: Moisture and water stability of Na2Ti3O7

We report here on the moisture and water stability of the promising Na-ion anode material Na2Ti3O7. Spontaneous Na+/H+ exchange is detected by PXRD after air exposure, forming solid solution compounds of the form Na2−xHxTi3O7 (0 < x < 2). By controlled ion exchange in aqueous solution two mixed compositions are prepared and their composition and structure are characterized with a panel of techniques. Both mixed compositions crystallize in C2/m space group like H2Ti3O7, and therefore Na+/H+ exchange is found to involve a structural transition from AA stacking of [TiO6] layers to AB stacking sequence. The electrochemical behaviour of the mixed compositions vs. Na+/Na is studied as well as that of an electrode of pure Na2Ti3O7 prepared in water media. The water-processed electrode is shown to exhibit a superior cycling stability and therefore the results obtained highlight the potential of Na2Ti3O7 as a green, low cost anode material for NIBs.

Bioactive and Antibacterial Glass Powders Doped with Copper by Ion-Exchange in Aqueous Solutions.

In this work, two bioactive glass powders (SBA2 and SBA3) were doped with Cu by means of the ion-exchange technique in aqueous solution. SBA2 glass was subjected to the ion-exchange process by using different Cu salts (copper(II) nitrate, chloride, acetate, and sulphate) and concentrations. Structural (X-ray diffraction-XRD), morphological (Scanning Electron Microscopy-SEM), and compositional (Energy Dispersion Spectrometry-EDS) analyses evidenced the formation of crystalline phases for glasses ion-exchanged in copper(II) nitrate and chloride solutions; while the ion-exchange in copper(II) acetate solutions lead to the incorporation of higher Cu amount than the ion-exchange in copper(II) sulphate solutions. For this reason, the antibacterial test (inhibition halo towards S. aureus) was performed on SBA2 powders ion-exchanged in copper(II) acetate solutions and evidenced a limited antibacterial effect. A second glass composition (SBA3) was developed to allow a greater incorporation of Cu in the glass surface; SBA3 powders were ion-exchanged in copper(II) acetate solutions (0.01 M and 0.05 M). Cu-doped SBA3 powders showed an amorphous structure; morphological analysis evidenced a rougher surface for Cu-doped powders in comparison to the undoped glass. EDS and X-ray photoelectron spectroscopy (XPS) confirmed the Cu introduction as Cu(II) ions. Bioactivity test in simulated body fluid (SBF) showed that Cu introduction did not alter the bioactive behaviour of the glass. Finally, inhibition halo test towards S. aureus evidenced a good antimicrobial effect for glass powders ion-exchanged in copper(II) acetate solutions 0.05 M.

Iron Loading Effects in Fe/SSZ-13 NH3-SCR Catalysts: Nature of the Fe Ions and Structure–Function Relationships

Using a traditional aqueous solution ion exchange method under a protecting atmosphere of N2, a series of Fe/SSZ-13 catalysts with various Fe loadings were synthesized. UV–vis, EPR, and Mossbauer spectroscopic methods, coupled with temperature-programmed reduction and desorption techniques, were used to probe the nature of the Fe sites. The major Fe species are extraframework Fe(III) species: [Fe(OH)2]+ (monomeric) and [HO–Fe–O–Fe–OH]2+ (dimeric). Larger oligomers with unknown nuclearity, poorly crystallized Fe oxide particles, together with isolated Fe2+ ions, are minor Fe-containing moieties. Reaction rate and Fe loading correlations, and temperature and Fe loading effects on SCR selectivities, suggest that isolated Fe3+ ions are the active sites for low-temperature standard SCR, and dimeric sites provide the majority of reactivity at higher temperatures. For NO oxidation, dimeric sites are the active centers. NH3 oxidation, on the other hand, is catalyzed by sites with higher nuclearity.

Identification of active sites and reaction mechanism on low-temperature SCR activity over Cu-SSZ-13 catalysts prepared by different methods

Cu-SSZ-13 catalysts with similar Si/Al and Cu/Al ratios were prepared by aqueous solution ion-exchange (Cu-SSZ-13-I) and one-pot synthesis (Cu-SSZ-13-O) methods.

Ion exchange synthesis of lanthanum zirconate

We have studied the formation of lanthanum zirconate through ion exchange in aqueous solutions of lanthanum and zirconyl chlorides and the AV-17-8 anion exchanger. The results demonstrate that the ion exchange leads to the formation of hydrosol of an amorphous lanthanum zirconium compound in the form of spherical particles about 4 nm in diameter. Heat treatment of the hydrosol at 700°C leads to crystallization of lanthanum zirconate with the fluorite structure, which transforms into the pyrochlore structure at higher temperatures.

Improvements of Pd/C Catalyst Support Characteristics by Various Physical Dispersion Methods.

Pd/C catalysts were prepared by ion exchange in aqueous solution. Physical dispersion methods including sonication, high share mixer and stirrer were used for though high dispersion of carbon. The physical properties of the prepared Pd/C particles were investigated by BET, XRD, and FE-TEM. The dispersion of Pd nanoparticles on carbon was measured on the basis of CO adsorption capacity using a pulse technique. FE-TEM micrographs showed that Pd nano particles possessed a spherical morphology with a narrow size distribution, with particles sizes ranging from 2-25 nm. The Pd particles prepared using sonication and high share mixer are well dispersed compared to the stirrer method. In addition, metal dispersions as calculated by CO uptake were 11.3, 20.4, and 25.0% for the stirrer, sonication and high share mixer methods, respectively.

Synthesis and Evaluation of Cu-SAPO-34 Catalysts for Ammonia Selective Catalytic Reduction. 1. Aqueous Solution Ion Exchange

SAPO-34 molecular sieves are synthesized using various structure directing agents (SDAs). Cu-SAPO-34 catalysts are prepared via aqueous solution ion exchange (IE). Catalysts are characterized with surface area/pore volume measurements, temperature programmed reduction (TPR), electron paramagnetic resonance (EPR), and nuclear magnetic resonance (NMR) spectroscopies. Catalytic properties are examined using standard ammonia selective catalytic reduction (NH3–SCR) and ammonia oxidation reactions. During solution IE, different SAPO-34 samples undergo different extent of structural damage via irreversible hydrolysis. Si content within the samples (i.e., Al–O–Si bond density) and framework stress are key factors that affect irreversible hydrolysis. Even using very dilute Cu acetate solutions, it is not possible to generate Cu-SAPO-34 samples with only isolated Cu2+ ions. Small amounts of CuOx species always coexist with isolated Cu2+ ions. Highly active and selective Cu-SAPO-34 catalysts for NH3-SCR are readily ...

Structure–activity relationships in NH3-SCR over Cu-SSZ-13 as probed by reaction kinetics and EPR studies

Cu-SSZ-13 catalysts with various Cu loadings were prepared via aqueous solution ion-exchange. The hydrated samples were characterized with Electron Paramagnetic Resonance (EPR). Cu2+ ion coordination numbers were obtained by analyzing the hyperfine structures, while Cu–Cu distances were estimated from line broadening of the EPR features. By examining EPR and temperature-programmed reduction (TPR) results, two Cu2+ ion locations are suggested. Standard NH3-SCR, as well as non-selective NH3 oxidation reaction with O2, were carried out over these catalysts at high-space velocities. For the SCR reaction, intra-particle diffusion limitations are found. The kinetic data allow for reactant diffusivities to be estimated. However, clear structure–activity relationships for the SCR reaction cannot be derived due to this diffusion limitation. The slower NH3 oxidation reaction, on the other hand, is kinetically limited at low temperatures, and, therefore allows for a correlation between Cu2+ ion location and reaction kinetics to be made.

Synthesis of Rare Earth (Oxo)nitridocarbonates by Employment of Supercritical Carbon Dioxide, Single‐source Precursor, Solid‐State, and Ion Exchange Reactions

AbstractNovel synthetic approaches to rare earth nitrido‐ and oxonitridocarbonates are described. Dioxy mono‐carbodiimides (Ln2O2CN2) from the second half of the lanthanide series are accessible by insertion of supercritical CO2 into lanthanide amido compounds (e.g. [(Cp2ErNH2)2]), forming single‐source precursors. Ammonolyses of amorphous carbamate compounds afford phase pure Ln2O2CN2, which are also accessible via the crystalline carbamate compound [Ln2{μ‐η1:η2‐OC(OtBu)NH}Cp4] (Ln = Y, Ho, Er, Yb). Urea complexes and homoleptic cyanates of europium and strontium were synthesized by solid‐state reaction of urea with the respective metals. Subsequent thermal treatment (160–240 °C) results in formation of solvent‐free homoleptic cyanates. The Eu2+‐doped compounds [Sr(OCN)2(urea)]:Eu2+ and Sr(OCN)2:Eu2+ as well as the respective pure europium compounds exhibit strong broad band emissions due to 4f65d1–4f7 transitions in the bluish green region. Furthermore, rare earth dicyanamides Ln[N(CN)2]3·2H2O as well as Ln[N(CN)2]3 (with Ln = Eu, Tb, and Gd) were prepared by ion exchange in aqueous solution, followed by evaporation of the solvent at room temperature. Condensed nitridocarbonates such as rare earth tricyanomelaminates [NH4]Ln[HC6N9]2[H2O]7·H2O (Ln = La–Nd, Sm–Dy) were obtained through ion exchange reactions. The luminescence properties of the europium and terbium dicyanamides as well as the tricyanomelaminates have been explored in detail.

Influence of pyridine ligand nature and the corresponding ruthenium(ii) dye molecular structure on the performance of dye-sensitized solar cells

cis-[Ru(bpy)(2)(L(n))]Cl(2) (n = 1, L(1) = 4-carboxy-2-(2'-pyridyl)quinoline (); n = 2, L(2) = 2,2'-pyridine-4,4'-dicarboxylic acid ()); and cis-[Ru(bpy)(2)(L')(2))]Cl(2) (L' = 4-pyridinecarboxylic acid ()) complexes, with surface anchoring groups, are prepared from the reaction of cis-[Ru(bpy)(2)Cl(2)] () with the appropriate ligand (L(1), L(2), L'). Ion exchange in aqueous solution with NH(4)PF(6) gives the corresponding bis(hexafluorophosphate) derivatives cis-[Ru(bpy)(2)(L(1))](PF(6))(2) (), cis-[Ru(bpy)(2)(L(2))](PF(6))(2) () and cis-[Ru(bpy)(2)(L')(2)](PF(6))(2) (), respectively. The photo-electrochemical properties of the dyes () are investigated and the efficiency of the corresponding dye sensitized solar cells is compared to a N719 sensitized device, under similar fabrication and testing conditions.

Zeolite an efficient catalyst for the Biginelli condensation reaction

A zeolite catalyzed, single step and environmentally friendly process for synthesis of classical Biginelli reaction was investigated. For this reaction Transition metal/Y zeolites were prepared by microwave solid-state and aqueous solution ion-exchange methods. The yield of reactions was increased in order of CuY > CoY > NiY > MnY ≈ FeY > VY > CrY > ZnY for the solid-state zeolite ion-exchange and CuY > CoY > NiY > MnY > CrY > VY > ZnY > FeY for the aqueous solution ion-exchange. The solid-state ion-exchange zeolite by microwave irradiation showed higher activity compared to the aqueous solution exchange. The yield of the product in the present of CuY zeolite was in order of 22–50%.

Conversion of acids to benzimidazoles with transition metal/zeolites

Transition metal/Y zeolites were prepared using microwave solid state and aqueous solution ion exchange methods. The activity of these zeolites was investigated in a conversion of acids to benzimidazoles reaction between 4-methyl-1, 2-phenylenediamine and 3-nitrobenzoic acid. The yield of these reactions increased in order of CuY < Fe2+Y < NiY < CoY < NaY < CrY < MnY < ZnY for both methods. The solid state ion-exchanged zeolites showed higher activity in comparison to the aqueous solution exchange. Yields of products in the presence of the ZnY zeolite were of the order of 69–83%. It seems that the Lewis sites are better sites compared to the Bronsted sites for this reaction.

Synthesis of cerium dioxide sols by an ion exchange method

Finely dispersed CeO2 hydrosol is synthesized through ion exchange in aqueous solutions of cerium chloride in the presence of anionite AV-17-8.

Synthesis and Characterization of Tb[N(CN)2]3×2H2O and Eu[N(CN)2]3×2H2O: Two New Luminescent Rare‐Earth Dicyanamides.

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Synthesis and Characterization of Tb[N(CN)2]3·2H2O and Eu[N(CN)2]3·2H2O: Two New Luminescent Rare-Earth Dicyanamides

Two new rare-earth dicyanamides, namely, Tb[N(CN)2]3·2H2O and Eu[N(CN)2]3·2H2O, have been prepared by ion exchange in aqueous solution, followed by evaporation of the solvent at room temperature. The structures of both compounds have been solved and refined from single-crystal and powder X-ray diffraction data, respectively. The two compounds are isostructural and are built up from irregular quadratic antiprismatic LnN6O2 polyhedra connected to each other by three crystallographically independent dicyanamide ([N(CN)2]3-) ions (Tb[N(CN)2]3·2H2O, P21/n, Z = 4, a = 7.4632(15) A, b = 11.523(2) A, c = 13.944(3) A, β = 94.06(3)°, V = 1196.2(4) A3; Eu[N(CN)2]3·2H2O, P21/n, Z = 4, a = 7.4780(3) A, b = 11.5429(5) A, c = 13.9756(7) A, β = 93.998(4)°, V = 1203.41(10) A3). Annealing of the hydrated phases of Ln[N(CN)2]3·2H2O (Ln = Eu, Tb) at 150 °C under an argon atmosphere leads to the formation of nonhydrated Ln[N(CN)2]3 (Ln = Eu, Tb). Both the hydrated (Eu[N(CN)2]3·2H2O) and nonhydrated (Eu[N(CN)2]3) europium(III)...

Synthesis, Crystal Structure and Thermal Behavior of Gadolinium Dicyanamide Dihydrate Gd[N(CN)2]3 · 2 H2O

AbstractGadolinium dicyanamide dihydrate Gd[N(CN)2]3 · 2 H2O was prepared by ion exchange in aqueous solution followed by evaporation of the solvent at room temperature. Gd[N(CN)2]3 · 2 H2O was characterized by single‐crystal structure analysis, FTIR spectroscopy and DSC analysis. In the crystal there are three crystallographically independent [N(CN)2]− ions and Gd3+ which are coordinated by six N atoms from six different [N(CN)2]− ions and two O atoms from two water molecules forming an irregular quadratic antiprism. Four H bonds have been identified in the structure of Gd[N(CN)2]3 · 2 H2O, two of them running to terminal N atoms and two to the bridging N atoms of dicyanamide ions (Gd[N(CN)2]3 · 2 H2O: P21/n (no. 14), a = 7.4845(15) Å, b = 11.529(2) Å, c = 13.941(3) Å, β = 93.98(3)°, Z = 4, 1948 reflections, 175 parameters, R1 = 0.0493). The DSC analysis indicates that Gd[N(CN)2]3 · 2 H2O looses the crystal water at temperatures around 130 – 140 °C forming anhydrous Gd[N(CN)2]3, the structure of which has been refined by the Rietveld method based on X‐ray powder diffraction data. Gd[N(CN)2]3 was found to be isotypic with Ln[N(CN)2]3 (Ln = La, Ce, Pr, Nd, Sm and Eu) which previously have been described in the literature.