Sample records for aqueous solution cation

  1. Magnetic susceptibilities of actinide cations in aqueous solution

    Paramagnetic cations serve as a useful and efficient NMR probes of coordination environment and can also give insight into dynamics on the millisecond timescale. In an effort to extend the powerful analytical techniques employed with the lanthanide series, some studies to characterize the actinide paramagnetic behavior have been undertaken in our labs under the auspices of the European ACTINET Integrated Infrastructure Initiative and the DOE, NEUP program. We will present a series of magnetic susceptibility measurements spanning all of the readily accessible actinide cations. Variable temperature data has been collected to gather information on the ground electronic state of the cations. The effects of the counter anion in solution are also discussed as they relate to 'softness' and the apparent reduction in free electron character on the metal. Comparisons with first-order Van Vleck and Russell-Saunders predictions will also be shown. (authors)

  2. From solution to oxide. Cations condensation in aqueous solution. Surface chemistry of oxides

    How is formed a solid from a solution? What are the properties of a dispersion of particles? The aim of this book is to answer to these questions. From an overview of the condensation processes of the cations in aqueous solution and the revealing of the structural relationships between species in solution and the formed solids, this book gives a logic in the phenomenon of oxides precipitation. The relationship that is established between the solutions chemistry and the solid chemistry allows to rationalize the behaviour of cations and to discuss the various factors whose structure, morphology and particles size are depending. It is from basic concepts relative to the oxide - aqueous solution interface that is presented the surface chemistry of oxides nano-particles. This one establishes the properties and the behaviour of the dispersions. Different phenomena bound to adsorption (arranged aggregation, control of particles size, interfacial electronic transfer, magnetic interactions between particles...) are studied. This book develops some aspects of the chemistry of metallic cations which is very important in a fundamental and technological point of view (synthesis of nano-materials, ceramics powders, catalysts, geochemical processes, biological phenomena, sol-gel techniques...). It is intended for university or engineers students and industrial searchers. (O.M.)

  3. Americium and samarium determination in aqueous solutions after separation by cation-exchange

    The concentration of trivalent americium and samarium in aqueous samples has been determined by means of alpha-radiometry and UV-Vis photometry, respectively, after chemical separation and pre-concentration of the elements by cation-exchange using Chelex-100 resin. Method calibration was performed using americium (241Am) and samarium standard solutions and resulted in a high chemical recovery for cation-exchange. Regarding, the effect of physicochemical parameters (e.g. pH, salinity, competitive cations and colloidal species) on the separation recovery of the trivalent elements from aqueous solutions by cation-exchange has also been investigated. The investigation was performed to evaluate the applicability of cation-exchange as separation and pre-concentration method prior to the quantitative analysis of trivalent f-elements in water samples, and has shown that the method could be successfully applied to waters with relatively low dissolved solid content. (author)

  4. Micellization properties of cationic gemini surfactants in aqueous solution

    Łudzik, K., E-mail: [Department of Physical Chemistry, University of Łódź, Pomorska 165, 90-236 Łódź (Poland); Piekarski, H.; Kubalczyk, K.; Wasiak, M. [Department of Physical Chemistry, University of Łódź, Pomorska 165, 90-236 Łódź (Poland)


    Highlights: ► We measured the d and c{sub p} of for the aqueous solutions of 8-6-8 and 8-12-8 surfactants. ► We analyzed the α{sub T} = f (m), V{sub ϕ} = f (m), c{sub p} = f (m) and C{sub p,ϕ} = f (m). ► The inflection point in the curves of the C{sub p,ϕ} = f (m) corresponds to the c.m.c. ► We analyzed thermodynamics parameters of the micellization for the surfactants. - Abstract: The main goal of this work was to investigate the self-assembly process for water solutions of two gemini surfactants, which differ in spacer chain length, at wide range of temperatures. For this reason the aqueous solutions of hexylene-1,6-bis(dimethyl-octylammonium bromide) and dodecylene-1,12-bis(dimethyloctylammonium bromide) have been examined by the calorimetric (DSC) and densimetric methods within the 293–323 K and 288–323 K temperature range, respectively. The analysis of c{sub p} values obtained for the examined systems allowed to propose an alternative way to estimate the region where micellization process can occur. The observed temperature dependence of the c.m.c. for surfactants investigated shows a typical shape for ionic gemini surfactants. This behavior was explained as a resultant of two competing effect: decrease in the hydrophilic properties of the surfactant molecule and decrease in the hydrophobic hydration of the alkyl chain along with the temperature increase. The enthalpy of micellization ΔH{sub mic} and other thermodynamics parameters associated with the micellization process: ΔG{sub mic}, ΔS{sub mic} and ΔC{sub p} {sub mic} were calculated on the base of the pseudo-phase separation model. As expected, more exothermic enthalpies of micellization are observed with increasing temperature for both the surfactants investigated in this work.

  5. Uptake of Cationic Dyes from Aqueous Solution by Biosorption Using Granulized Annona squmosa Seed

    Santhi, T.; S. Manonmani


    A new, low cost, locally available biomaterial was tested for its ability to remove cationic dyes from aqueous solution. A sample of granulized Annona squmosa seeds had been utilized as a sorbent for uptake of three cationic dyes, methylene blue (MB), methylene red (MR) and malachite green (MG). The effects of various experimental parameters (e.g., contact time, dye concentration, adsorbent dose and pH) were investigated and optimal experimental conditions were ascertained. Above the value of...

  6. Flocculation performance of a cationic biopolymer derived from a cellulosic source in mild aqueous solution.

    Liimatainen, Henrikki; Sirviö, Juho; Sundman, Ola; Visanko, Miikka; Hormi, Osmo; Niinimäki, Jouko


    The flocculation behavior of cationic, quaternary ammonium groups containing cellulosic biopolymers, CDACs, synthesized by cationizing dialdehyde cellulose in mild aqueous solution was studied in a kaolin suspension. In particular, the role of CDAC dosage and solution pH, NaCl concentration, and temperature were clarified. In addition, the initial apparent charge densities (CDs), particle sizes, ζ-potential, and stability of CDs were determined. CDACs possessed a high flocculation activity in neutral and acidic solutions, but a significant decrease was observed in alkaline solutions (pH >9). This was also seen as a decline in the apparent CD and particle size of the CDACs in alkaline conditions. The measurements also indicated that the apparent CD decreased to a constant level of 3 mmol/g in aqueous solutions. However, no notable decrease in flocculation performance was obtained after several days of storage. Moreover, the variation of NaCl concentration and temperature did not affect the flocculation activity. PMID:21862324


    Yufeng Wang; Kefu Chen; Lihuan Mo; Huiren Hu,


    A cationic polyacrylamide (CPAM) dispersion, the copolymer of acrylamide (AM) and acryloyloxyethyltrimethyl ammonium chloride (DAC), has been synthesized through dispersion polymerization in aqueous ammonium sulfate ((NH4)2SO4) solution. The polymerization was initiated by tert-butyl hydroperoxide (TBHP) and ferrisulfas (FeSO4) using poly(dimethyl diallyl ammonium chloride) (PDMDAAC) as the stabilizer. At the optimal reaction conditions, the relative molecular weight of the CPAM dispersion wa...

  8. Selective separation of actinyl(V,VI) cations from aqueous solutions by Chelex-100

    Kiliari, T.; Pashalidis, I. [Cyprus Univ., Nicosia (Cyprus). Chemistry Dept.


    Experimental studies on the selectivity of Chelex-100 resin for the separation of actinide cations at different oxidation states (III, IV, V and VI) from aqueous solution have shown that Chelex-100 presents increased selectivity for actinyl cations at near neutral pH (pH {proportional_to} 4.5). The effect of salinity on the chemical recovery indicates that the increased selectivity could be attributed to the formation of complexes with specific interactions and the pH area, in which the formation of the respective complexes is favored, indicates the occurrence of guest-host interactions. The specific interaction of Chelex-100 with actinyl cations could be of particular interest not only for the separation and preconcentration of uranium from natural waters prior its analysis but also for the recovery of uranium from seawater on a large scale. (orig.)

  9. Ozonation of Cationic Red X-GRL in aqueous solution: degradation and mechanism.

    Zhao, Weirong; Shi, Huixiang; Wang, Dahui


    Ozonation of the azo dye Cationic Red X-GRL was investigated in a bubble column reactor at varying operating parameters such as oxygen flow rate, temperature, initial Cationic Red X-GRL concentration, and pH. The conversion of dye increased with the increasing of pH and oxygen flow rate. As the reaction rate constant and the volumetric mass transfer coefficient increase while the ozone equilibrium concentration decreases with the temperature, there is a minimum conversion of dye at 25 degrees C. The increasing of initial dye concentration leads to a decreasing conversion of dye while the ozonation rate increases. The formation of intermediates and the variation of pH, TOC, and nitrate ion during ozonation were investigated by the use of some analytical instruments such as GC/MS, GC, and IC. The intermediates of weak organic acids lower the pH value of the solution. The probable degradation mechanism of the Cationic Red X-GRL in aqueous solution was deliberated with the aid of Molecular Orbital calculations. The N(12)-C(13) site in Cationic Red X-GRL, instead of the N(6)-N(7) site, is found to be the principal site for ozone cycloaddition in the degradation processes. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one is converted into an amine compound, and the remaining four are transformed into two molecules of nitrogen. PMID:15504479

  10. Association of ionic liquids with cationic dyes in aqueous solution: A thermodynamic study

    Highlights: ► Precipitate was formed between cationic dye and ionic liquid in aqueous solution. ► Precipitates are 1:1 formed by cation of the dyes and anion of the ionic liquids. ► Association constants decrease with increasing temperature. ► The associates can be used as active materials of ion-selective electrode. - Abstract: In this paper, the interactions between cationic dyes and the ionic liquids (ILs) have been studied by 31P nuclear magnetic resonance (NMR), UV–Vis spectroscopy and conductometric measurements at different temperatures. It was shown that a decrease in the measured specific conductance of the (dye + IL) mixtures was caused by the formation of non-conducting or less conducting (dye + IL) associates. The associates were formed by 1:1 ratio of cation of the cationic dyes and anion of the ILs by using the 31P NMR and UV–Vis spectroscopy methods. The association constants were calculated by theoretical model based on the deviation from linear behavior, and the association constants were as high as 106 (L · mol−1)2. Thermodynamic results imply that the formation process of association was exothermic nature. It is expected that the associates reported here would have promising application as active materials for the preparation of ion-selective electrode used in the determination of ILs concentrations.

  11. The interactions between cationic cellulose and Gemini surfactant in aqueous solution.

    Zhao, Shaojing; Cheng, Fa; Chen, Yu; Wei, Yuping


    Due to the extensive application of cationic cellulose in cosmetic, drug delivery and gene therapy, combining the improvement effect of surfactant-cellulose complexes, to investigate the properties of cellulose in aqueous solution is an important topic from both scientific and technical views. In this study, the phase behavior, solution properties and microstructure of Gemini surfactant sodium 5-nonyl-2-(4-(4-nonyl-2-sulfonatophenoxy)butoxy)phenyl sulfite (9-4-9)/cationic cellulose (JR400, the ammonium groups are directly bonded to the hydroxyethyl substituent with a degree substitution of 0.37) mixture was investigated using turbidity, fluorescence spectrophotometer and shear rheology techniques. As a control, the interaction of corresponding monovalent surfactant, sodium 2-ethoxy-5-nonylbenzenesulfonate (9-2) with JR400 in aqueous solution was also studied. Experimental results showed that 9-4-9/JR400 mixture has lower critical aggregation concentration (CAC) and critical micelle concentration (CMC) (about one order of magnitude) than 9-2/JR400 mixture. A low concentration of Gemini surfactant 9-4-9 appeared to induce an obvious micropolarity and viscosity value variation of the mixture, while these effects required a high concentration of corresponding monovalent one. Furthermore, dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements illuminated the formation and collapse procedure of network structure of the 9-4-9/JR400 mixture, which resulted in the increase and decrease of viscosity. These results suggest that the molecular structure of the surfactant has a great effect on its interaction with cationic cellulose. Moreover, the Gemini surfactant/cationic cellulose mixture may be used as a potencial stimuli-responsive drug delivery vector which not only load hydrophilic drugs, but also deliver hydrophobic substances. PMID:26876997

  12. Micelle-mediated preconcentration using cationic surfactants for the spectrophotometric determination of uranium in aqueous solutions

    A sensitive cloud point extraction method was developed for uranium(VI) preconcentration and determination in aqueous solutions. The method is based on uranium( VI) complexation with eriochrome cyanine R and extraction of the complex into the cationic surfactant CTAB at pH 5.5. The optimal extraction and reaction conditions were evaluated and optimized. Under optimum conditions, linearity was obtained for uranium(VI) concentration range of 10-200 ng mL-1 and the limits of detection and quantification were 0.70 and 2.33 ng mL-1 respectively. The interference effect of some anions and cations was evaluated. The method was successfully applied for uranium(VI) spectrophotometric determination in water samples. (author)

  13. Gum karaya based hydrogel nanocomposites for the effective removal of cationic dyes from aqueous solutions

    Mittal, Hemant; Maity, Arjun; Ray, Suprakas Sinha


    Biodegradable hydrogel nanocomposites (HNC) of gum karaya (GK) grafted with poly(acrylic acid) (PAA) incorporated silicon carbide nanoparticles (SiC NPs) were synthesized using the in situ graft copolymerization method and tested for the adsorption of cationic dyes from aqueous solution. The structure and morphology of the HNC were characterized using different spectroscopic and microscopic techniques. The results showed that the surface area and porosity of the hydrogel polymer significantly increased after nanocomposite formation with SiC NPs. The HNC was employed for the removal of cationic dyes, i.e., malachite green (MG) and rhodamine B (RhB) from the aqueous solution. The HNC was found to remove 91% (MG) and 86% (RhB) of dyes with a polymer dose of 0.5 and 0.6 g l-1 in neutral medium, respectively. The adsorption process was found to be highly pH dependent and followed the pseudo-second-order rate model. The adsorption isotherm data fitted well with the Langmuir adsorption isotherm with a maximum adsorption capacity of 757.57 and 497.51 mg g-1 for MG and RhB, respectively. Furthermore, the HNC was demonstrated as a versatile adsorbent for the removal of both cationic and anionic dyes from the simulated wastewater. The HNC showed excellent regeneration capacity and was successfully used for the three cycles of adsorption-desorption. In summary, the HNC has shown its potential as an environment friendly and efficient adsorbent for the adsorption of cationic dyes from contaminated water.

  14. Application of bifunctional magnetic adsorbent to adsorb metal cations and anionic dyes in aqueous solution

    Lin, Ya-Fen [Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 260, Taiwan (China); Chen, Hua-Wei [Department of Cosmetic Application and Management, St. Mary' s Medicine Nursing and Management College, I-Lan, Taiwan (China); Chien, Poh-Sun [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China); Chiou, Chyow-San, E-mail: [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China); Liu, Cheng-Chung [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China)


    A magnetic adsorbent, amine-functionalized silica magnetite (NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4}), has been synthesized to behave as an anionic or cationic adsorbent by adjusting the pH value of the aqueous solution to make amino groups protonic or neutral. NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4} were used to adsorb copper ions (metal cation) and Reactive Black 5 (RB5, anionic dye) in an aqueous solution in a batch system, and the maximum adsorption were found to occur at pH 5.5 and 3.0, respectively. The adsorption equilibrium data were all fitted the Langmuir isotherm equation reasonably well, with a maximum adsorption capacity of 10.41 mg g{sup -1} for copper ions and of 217 mg g{sup -1} for RB5. A pseudo-second-order model also could best describe the adsorption kinetics, and the derived activation energy for copper ions and RB5 were 26.92 kJ mol{sup -1} and 12.06 kJ mol{sup -1}, respectively. The optimum conditions to desorb cationic and anionic adsorbates from NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4} were provided by a solution with 0.1 M HNO{sub 3} for copper ions and with 0.05 M NaOH for RB5.

  15. Interactions of cationic trimeric, gemini and monomeric surfactants with trianionic curcumin in aqueous solution.

    Wang, Meina; Wu, Chunxian; Tang, Yongqiang; Fan, Yaxun; Han, Yuchun; Wang, Yilin


    Interactions of trianionic curcumin (Cur(3-)) with a series of cationic surfactants, monomeric surfactant dodecyl trimethylammonium bromide (DTAB), dimeric surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and trimeric surfactant tri(dodecyldimethylammonioacetoxy)diethyltriamine trichloride (DTAD), have been investigated in aqueous solution of pH 13.0. Surface tension and spectral measurements indicate that the cationic surfactants display a similar surfactant concentration dependent interaction process with Cur(3-), involving three interaction stages. At first the three cationic surfactants electrostatically bind on Cur(3-) to form the surfactant-Cur(3-) complex. Then the bound and unbound cationic surfactants with Cur(3-) aggregate into surfactant-Cur(3-) mixed micelles through hydrophobic interactions above the critical micelle concentration of the surfactants (CMCC) in the presence of Cur(3-). Finally excess unbound surfactants self-assemble into micelles like those without Cur(3-). For all the three surfactants, the addition of Cur(3-) only decreases the critical micelle concentration of 12-6-12 but does not affect the critical micelle concentration of DTAB and DTAD. As the oligomeric degree of surfactants increases, the intermolecular interaction of the cationic surfactants with Cur(3-) increases and the surfactant amount needed for Cur(3-) encapsulation decreases. Compared with 12-6-12, either the weaker interaction of DTAB with Cur(3-) or stronger interaction of DTAD with Cur(3-) limits the stability or solubility of Cur(3-) in surfactant micelles. Therefore, gemini surfactant 12-6-12 is the best choice to effectively suppress Cur(3-) degradation at very low concentrations. Isothermal titration microcalorimetry, surface tension and (1)H NMR results reveal that 12-6-12 and Cur(3-) form a (12-6-12)2-Cur(3-) complex and start to form micelles at extremely decreased concentrations, where either 12-6-12 or Cur(3-) works as a bridge


    Yufeng Wang


    Full Text Available A cationic polyacrylamide (CPAM dispersion, the copolymer of acrylamide (AM and acryloyloxyethyltrimethyl ammonium chloride (DAC, has been synthesized through dispersion polymerization in aqueous ammonium sulfate ((NH42SO4 solution. The polymerization was initiated by tert-butyl hydroperoxide (TBHP and ferrisulfas (FeSO4 using poly(dimethyl diallyl ammonium chloride (PDMDAAC as the stabilizer. At the optimal reaction conditions, the relative molecular weight of the CPAM dispersion was 4.2×106, its charge density was 2.2 mmol•g-1, its average particle size was 6.01 μm, and its stability and dissolvability were both excellent. The CPAM dispersion was characterized using Fourier-transform infrared (FTIR spectroscopy, nuclear magnetic resonance (NMR spectroscopy, and differential scanning calorimeter (DSC. Results indicated that the copolymerization was successful.

  17. Correlation between the Increasing Conductivity of Aqueous Solutions of Cation Chlorides with Time and the “Salting-Out” Properties of the Cations

    Nada Verdel


    Full Text Available The time-dependent role of cations was investigated by ageing four different aqueous solutions of cation chlorides. A linear correlation was found between the cations’ Setchenov coefficient for the salting-out of benzene and the increase in the conductivity with time. The conductivity of the structure-breaking cations or the chaotropes increased more significantly with time than the conductivity of the kosmotropes. Since larger water clusters accelerate the proton or hydroxyl hopping mechanism, we propose that the structuring of the hydration shells of the chaotropes might be spontaneously enhanced over time.

  18. Study of lanthanide tri-cations in aqueous solution by molecular dynamic

    This is essentially a lanthanide tri-cation hydration study by means of classical molecular dynamics (CLMD) simulations using explicit polarization. Explicit polarization is calculated with a Car-Parrinello type of dynamics on induced dipoles, which decreases the CPU time as compared to the self-consistent resolution. Several pair interaction potentials are parametrized from ab initio calculations (MP2) and tested for the La3+-OH2 interaction. The best results are obtained with an exponential-6 Buckingham potential. Next, the La3+-OH2 interaction potential parameters are extrapolated to the other Ln3+-OH2 interactions, only by using the ionic radii. The CLMD results reproduce the reliable experimental data (EXAFS distances), and the sigmoidal variation of the coordination number (with S shape), from 9 for La3+ to 8 for Lu3+. This variation is explained by the linear variation of DrG0 (9,298) vs. atomic number. Insights are also given on the Co2+ hydration, CPMD simulations, reconstruction of EXAFS signal from MD simulations, and OH- complexation of La3+ in aqueous solution. (author)

  19. Coacervation and aggregate transitions of a cationic ammonium gemini surfactant with sodium benzoate in aqueous solution.

    Wang, Ruijuan; Tian, Maozhang; Wang, Yilin


    Coacervation in an aqueous solution of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (C12C6C12Br2) with sodium benzoate (NaBz) has been investigated at 25 °C by turbidity titration, light microscopy, dynamic light scattering, cryogenic temperature transmission electron microscopy (Cryo-TEM), scanning electron microscopy (SEM), isothermal titration calorimetry, ζ potential and (1)H NMR measurements. There is a critical NaBz concentration of 0.10 M, only above which coacervation can take place. However, if the NaBz concentration is too large, coacervation also becomes difficult. Coacervation takes place at a very low concentration of C12C6C12Br2 and exists in a very wide concentration region of C12C6C12Br2. The phase behavior in the NaBz concentration from 0.15 to 0.50 M includes spherical micelles, threadlike micelles, coacervation, and precipitation. With increasing NaBz concentration, the phase boundaries of coacervation shift to higher C12C6C12Br2 concentration. Moreover, the C12C6C12Br2-NaBz aggregates in the coacervate are found to be close to charge neutralized. The Cryo-TEM and SEM images of the coacervate shows a layer-layer stacking structure consisting of a three-dimensional network formed by the assembly of threadlike micelles. Long, dense and almost uncharged threadlike micelles are the precursors of coacervation in the system. PMID:24651935

  20. Photocontrolled selective isolation of uranyl cation from aqueous solution onto a photo-responsive Langmuir-Blodgett film

    We applied a photo-responsive Langmuir-Blodgett (LB) film to selective isolation of uranyl cation from aqueous solutions. Uranyl cation was isolated onto a quartz plate covered with 5-octadecyloxy-2-(2-pyridylazo)phenol (PARC18) LB film which possesses the potential to form a complex with transition metal cations. The isolation process could be switched on by photoillumination. On the other hand, lanthanides (La, Ce, Nd, Gd, Er and Yb) were hardly isolated onto this film. Therefore, it was suggested that uranyl can selectively be collected from mixed solutions containing uranyl and lanthanides and that this process can be controlled by photoillumination. Detection limit of uranyl concentration in this system was also determined to be about 1.5 ppb. (author)

  1. A procedure for preferential trapping of cesium cations from aqueous solutions and their separation from other inorganic cations

    The title procedure is as follows. Deltahedral heteroborane anions are added to the aqueous solution containing cesium ions, precipitate (if any) is separated off, and the cesium salts involving the deltahedral heteroborane anions are trapped on activated carbon. The cobaltocarborane anion [3-Co-(1,2-C2B9H11)2] and/or its substitution derivatives are particularly well suited to this purpose. The process can find use in the separation of radionuclides present in waste solutions arising from spent nuclear fuel treatment. (P.A.). 1 fig

  2. Removal of cationic dyes by poly(acrylamide-co-acrylic acid) hydrogels in aqueous solutions

    Poly(acrylamide-co-acrylic acid (poly(AAm-co-AAc)) hydrogels prepared by irradiating with γ-radiation were used in experiments on swelling, diffusion, and uptake of some cationic dyes such as Safranine-O (SO) and Magenta (M). Poly(AAm-co-AAc) hydrogels irradiated at 8.0 kGy have been used for swelling and diffusion studies in water and cationic dye solutions. The maximum swellings in water, and SO, and M solutions observed are 2700%, 3500%, and 4000%, respectively. Diffusions of water and cationic dyes within hydrogels have been found to be non-Fickian in character. Adsorption of the cationic dyes onto poly(AAm-co-AAc) hydrogels is studied by the batch adsorption technique. The adsorption type was found Langmuir type in the Giles classification system. The moles of adsorbed dye for SO and M per repeating unit in hydrogel (binding ratio, r) have been calculated as 3834x10-6 and 1323x10-6, respectively. These results show that poly(AAm-co-AAc) hydrogels can be used as adsorbent for water pollutants such as cationic dyes

  3. Soft X-ray absorption spectra of aqueous salt solutions with highly charged cations in liquid microjets

    Schwartz, Craig P.; Uejio, Janel S.; Duffin, Andrew M.; Drisdell, Walter S.; Smith, Jared D.; Saykally, Richard J.


    X-ray absorption spectra of 1M aqueous solutions of indium (III) chloride, yttrium (III) bromide, lanthanum (III) chloride, tin (IV) chloride and chromium (III) chloride have been measured at the oxygen K-edge. Relatively minor changes are observed in the spectra compared to that of pure water. SnCl{sub 4} and CrCl{sub 3} exhibit a new onset feature which is attributed to formation of hydroxide or other complex molecules in the solution. At higher energy, only relatively minor, but salt-specific changes in the spectra occur. The small magnitude of the observed spectral changes is ascribed to offsetting perturbations by the cations and anions.

  4. Effect of plasticizer on surface of free films prepared from aqueous solutions of salts of cationic polymers with different plasticizers

    Bajdik, János; Fehér, Máté; Pintye-Hódi, Klára


    Acquisition of a more detailed understanding of all technological processes is currently a relevant tendency in pharmaceutical technology and hence in industry. A knowledge of film formation from dispersion of polymers is very important during the coating of solid dosage forms. This process and the structure of the film can be influenced by different additives. In the present study, taste-masking films were prepared from aqueous citric acid solutions of a cationic polymer (Eudragit ® E PO) with various hydrophilic plasticizers (glycerol, propylene glycol and different poly(ethylene glycols)). The mechanical properties, film thickness, wetting properties and surface free energy of the free films were studied. The aim was to evaluate the properties of surface of free films to predict the arrangement of macromolecules in films formed from aqueous solutions of salts of cationic polymers. A high molecular weight of the plasticizer decreased the work of deformation. The surface free energy and the polarity were highest for the film without plasticizer; the hydrophilic additives decreased these parameters. The direction of the change in polarity (a hydrophilic component caused a decrease in the polarity) was unexpected. It can be explained by the change in orientation of the macromolecules, a hydrophobic surface being formed. Examination of the mechanical properties and film thickness can furnish additional results towards a knowledge of film formation by this not frequently applied type of polymer from aqueous solution.

  5. Removal of cationic dyes from aqueous solution using magnetic multi-wall carbon nanotube nanocomposite as adsorbent

    A magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and was used as an adsorbent for removal of cationic dyes from aqueous solutions. The MMWCNT nanocomposite was composed of commercial multi-wall carbon nanotubes and iron oxide nanoparticles. The properties of this magnetic adsorbent were characterized by scanning electron microscopy, X-ray diffraction and BET surface area measurements. Adsorption characteristics of the MMWCNT nanocomposite adsorbent were examined using methylene blue, neutral red and brilliant cresyl blue as adsorbates. Experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of adsorption dosage and solution pH values on the removal of cationic dyes. Kinetic data were well fitted by a pseudo second-order model. Freundlich model was used to study the adsorption isotherms. The prepared MMWCNT adsorbent displayed the main advantage of separation convenience compared to the present adsorption treatment.

  6. Considerable Enhancement of Emission Yields of [Au(CN)2(-)] Oligomers in Aqueous Solutions by Coexisting Cations.

    Wakabayashi, Ryo; Maeba, Junichi; Nozaki, Koichi; Iwamura, Munetaka


    The photophysical properties of [Au(CN)2(-)] oligomers in aqueous solutions were investigated as functions of coexisting cations as well as the viscosity and temperature of solutions. A solution of [Au(CN)2(-)] in the concentration range of 0.03-0.2 mol/dm(3) exhibited emission peaks at 460-480 nm because of the presence of oligomers larger than trimers. Although the emission yields (ϕem) of K[Au(CN)2] solutions were wavelength regions were very short and independent of the viscosity of the solutions and coexisting cations (dimer, ∼25 ps; trimer, ∼2 ns). These results indicated that the deactivation of the excited-state [Au(CN)2(-)]n oligomers (n ≥ 4) was dominated by the dissociation of the oligomers to a shorter species (dimer or trimer). The hydrophobic interactions between tetraalkylammonium cations and CN ligands remarkably stabilized the larger oligomers and suppressed the dissociation of the excited-state oligomers, which enhanced the emission yield of the oligomers. This work provides a new method of "exciplex tuning" by changing the environment of excited-state [Au(CN)2(-)]n oligomers. PMID:27391559

  7. Silica gel modified with ethylenediamine and succinic acid-adsorption and calorimetry of cations in aqueous solution

    Highlights: ► Succinic acid-modified silica acted as an adsorbent for Cu (II), Ni (II), and Co (II) from aqueous solutions. ► Modified silica adsorbed metallic cations in the order Cu2+ > Co2+ > Ni2+. ► Succinic acid-modified silica could be employed as low-cost material for the removal of cations from aqueous solution. ► Thermodynamic data for these systems are favorable at the solid/liquid interface. - Abstract: Ethylenediamine molecules were covalently immobilized onto silica gel previously functionalized with 3-chlorosilylpropyltrimethoxysilane (Sil–Cl), producing a Sil–N surface. The Sil–N surface reacted with succinic acid, yielding a Sil–NSuc surface. This new synthesized silica gel surface was used to adsorb divalent cations from aqueous solutions at room temperature. The adsorption isotherms were fit to a modified Langmuir equation using the data obtained by suspending the solid in MCl2 (M = Cu, Ni, and Co) aqueous solutions, yielding the maximum number of moles adsorbed as 1.04 ± 0.01, 1.89 ± 0.02 and 1.85 ± 0.02 mmol g−1 for divalent copper, nickel and cobalt, respectively. The metal-basic center ratio for complexes on the surfaces varied with the nature of the metal. The spontaneity of these systems was reflected in the negative values of the Gibbs free energy calculated using calorimetric data. The net thermal effects obtained from the calorimetric titration measurements were adjusted to a modified Langmuir equation, and the calculation of the enthalpies of the interaction for the complexation with Sil–NSuc yielded the following exothermic values: 2.81 ± 0.08, 0.35 ± 0.04 ± and 0.69 ± 0.05 kJ mol−1 for Cu2+, Co2+ and Ni2+, respectively. Based on these values, the metals are preferentially adsorbed in the order Cu2+ > Co2+ > Ni2+. The other thermodynamic data for these systems are favorable at the solid/liquid interface, suggesting the efficacy of this modified silica for cation removal from solution

  8. Electrogenerated chemiluminescence of a cationic cyclometalated iridium complex–Nafion modified electrode in neutral aqueous solution

    Electrogenerated chemiluminescence (ECL) of a cationic cyclometalated iridium complex, [(pqcm)2Ir(bpy)](PF6) (1, pqcmH=2-phenyl-quinoline-4-carboxylic acid methyl ester, bpy=2,2′-bipyridine), was investigated at a bare glassy carbon electrode in CH3CN solution and 4 ECL peaks were observed. Then, the ECL of the iridium complex was studied in neutral phosphate buffer solution (PBS) by immobilizing it on a glassy carbon electrode. Two closely located ECL peaks were obtained at 1.07 and 1.40 V when the potential was scanned from −3.00 V to 2.20 V, while only one broad ECL peak located around −2.0 V was obtained when the potential was scanned from 2.20 V to −3.00 V. In the presence of oxalate, one ECL peak located around 1.22 V could be obtained except the broad ECL peak located at −2.00 V. The ECL peak at positive potential range was enhanced more than one magnitude in the presence of Nafion and was nearly 5-times higher than that of Ru(bpy)32+–Nafion modified electrode, suggesting that the synthesized iridium complex has great application potential in ECL detection. The ECL spectra of iridium complex were identical to its photoluminescence spectrum, indicating the same metal-to-ligand charge transfer (MLCT) excited states. The mechanisms of ECL were proposed based on the experimental results. The present ECL sensor gave a linear response for the oxalate concentration from 1.0×10−6 to 1.0×10−4 mol L−1 with a detection limit (S/N=3) of 9.1×10−7 mol L−1. -- Graphical abstract: Electrochemiluminescence (ECL) of immobilized novel cationic cyclometalated iridium complex in neutral phosphate buffer solution is reported for the first time. The intensity of iridium complex ECL is 5-times higher than that of Ru(bpy)32+ ECL. Highlights: ► Cationic cyclometalated iridium complex was modified on a bare electrode. ► Electrochemiluminescence (ECL) of the modified electrode was studied. ► The ECL intensity is higher than that of Ru(bpy)32+ modified

  9. Quince seed mucilage magnetic nanocomposites as novel bioadsorbents for efficient removal of cationic dyes from aqueous solutions.

    Hosseinzadeh, Hossein; Mohammadi, Sina


    This study investigated the potential use of quince seed mucilage (QSM) as alternative bioadsorbents for methylene blue (MB) dye from aqueous solutions. This novel magnetic nanocomposite adsorbent (MNCA) based on QSM was synthesized by in situ formation of magnetic iron oxide nanoparticles into QSM solution. The MNCAs were characterized using FTIR, SEM, TEM, XRD, and VSM. Removal of MB was investigated by batch adsorption technique. The thermodynamic parameters suggest that the dye adsorption process is spontaneous and exothermic in nature. Moreover, the adsorbents showed high selectivity for the adsorption of cationic dyes with regenerated properties. The pseudo-second-order kinetics and Langmuir adsorption isotherm models also provide the best correlation of the experimental data for MB adsorption. The results indicate that the MNCAs can be employed as efficient low cost adsorbents with excellent dye adsorption performance in wastewater treatment process. PMID:26428118

  10. Interaction of a biosurfactant, Surfactin with a cationic Gemini surfactant in aqueous solution.

    Jin, Lei; Garamus, Vasil M; Liu, Fang; Xiao, Jingwen; Eckerlebe, Helmut; Willumeit-Römer, Regine; Mu, Bozhong; Zou, Aihua


    The interaction between biosurfactant Surfactin and cationic Gemini surfactant ethanediyl-1,3-bis(dodecyldimethylammonium bromide) (abbreviated as 12-3-12) was investigated using turbidity, surface tension, dynamic light scattering (DLS) and small angle neutron scattering (SANS). Analysis of critical micelle concentration (CMC) values in Surfactin/12-3-12 mixture indicates that there is synergism in formation of mixed Surfactin/12-3-12 micelles. Although Surfactin and 12-3-12 are oppositely charged in phosphate buffer solution (PBS, pH7.4), there are no precipitates observed at the concentrations below the CMC of Surfactin/12-3-12 system. However, at the concentration above CMC value, the Surfactin/12-3-12 mixture is severely turbid with high 12-3-12 content. DLS and SANS measurements follow the size and shape changes of mixed Surfactin/12-3-12 aggregates from small spherical micelles via elongated aggregates to large bulk complexes with increasing fraction of Gemini surfactant. PMID:27475707

  11. Shape and size of simple cations in aqueous solutions: A theoretical reexamination of the hydrated ion via computer simulations

    Martínez, José M.; Pappalardo, Rafael R.; Marcos, Enrique Sánchez


    The simplest representation of monoatomic cations in aqueous solutions by means of a sphere with a radius chosen on the basis of a well-defined property (that of the bare ion or its hydrate) is reexamined considering classical molecular dynamics simulations. Two charged sphere-water interaction potentials were employed to mimic the bare and hydrated cation in a sample of 512 water molecules. Short-range interactions of trivalent cations were described by Lennard-Jones potentials which were fitted from ab initio calculations. Five statistically independent runs of 150 ps for each of the trivalent spheres in water were carried out in the microcanonical ensemble. A comparison of structural and dynamical properties of these simple ion models in solution with those of a system containing the Cr3+ hydrate ([Cr(H2O)6]3+) is made to get insight into the size and shape definition of simple ions in water, especially those that are highly charged. Advantages and shortcomings of using simple spherical approaches are discussed on the basis of reference calculations performed with a more rigorous hydrated ion model [J. Phys. Chem. B 102, 3272 (1998)]. The importance of nonspherical shape for the hydrate of highly charged ions is stressed and it is paradoxically shown that when spherical shape is retained, the big sphere representing the hydrate leads to results of ionic solution worse than those obtained with the small sphere. A low-cost method to generate hydrated ion-water interaction potentials taking into account the shape of the ionic aggregate is proposed.

  12. The role of multivalent metal cations and organic complexing agents in bitumen-mineral interactions in aqueous solutions

    Gan, Weibing

    A systematic investigation was carried out to study the interactions between bitumen (or hexadecane) and minerals (quartz, kaolinite and illite) in aqueous solutions containing multivalent metal cations Ca2+, Mg2+ and Fe2+/Fe3+, in the absence and presence of organic complexing agents (oxalic acid, EDTA and citric acid). A range of experimental techniques, including coagulation measurement, visualization of bitumen-mineral attachment, metal ion adsorption measurement, zeta potential measurement, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopic analyses, were employed in the investigation. Free energy changes of adsorption of metal cations on the minerals and bitumen were evaluated using the James & Healy thermodynamic model. Total interaction energies between the minerals and bitumen were calculated using classical DLVO theory. It was observed that while the tested minerals showed varying degrees of mutual-coagulation with bitumen (or hexadecane), the presence of the multivalent metal cations could prominently increase the mutual coagulation. It was also found that such enhancement of the mutual coagulation was only significant when the metal cations formed first-order hydroxyl complexes (such as CaOH +, MgOH+, etc.) or metal hydroxides (such as Fe(OH) 3, Mg(OH)2, etc.). Therefore, the increase of the bitumen-mineral mutual coagulation by the metal cations was strongly pH dependent. Organic complexing agents (oxalic acid, citric acid and EDTA) used in this study, citric acid in particular, significantly reduced or virtually eliminated the mutual coagulation between bitumen (or hexadecane) and minerals caused by metal cations Ca2+, Mg2+, Fe 2+ and Fe3+. Due to its ability to substantially lower the mutual coagulation between bitumen and mineral particles, citric acid was found the most effective in improving bitumen-mineral liberation in solutions containing the multivalent metal cations at pH 8--10. In small scale flotation experiments

  13. Selective adsorption of cationic dyes from aqueous solution by polyoxometalate-based metal-organic framework composite

    Liu, Xiaoxia; Gong, Wenpeng; Luo, Jing; Zou, Chentao; Yang, Yun; Yang, Shuijin


    A novel environmental friendly adsorbent H6P2W18O62/MOF-5 was synthesized by a simple one-step reaction under solvothermal conditions and characterized by XRD, FTIR, thermogravimetric analyses (TGA) and N2 adsorption-desorption isotherms. The removal rate of H6P2W18O62/MOF-5 was quite greater (85%) than that of MOF-5 (almost zero), showing that the adsorption performance of porous MOF-5 can be improved through the modification of H6P2W18O62. Further study revealed that H6P2W18O62/MOF-5 exhibited a fast adsorption rate and selective adsorption ability towards the cationic dyes in aqueous solution. The removal rate was up to 97% for cationic dyes methylene blue (MB) and 68% for rhodamine B(Rhb) within 10 min. However, anionicdye methyl orange(MO) can only reach to 10%. The influences including initial concentration, contact time, initial solution pH and temperature of MB adsorption onto H6P2W18O62/MOF-5 were investigated in detail. The kinetic study indicated that the adsorption of MB onto H6P2W18O62/MOF-5 followed the pseudo second-order model well. The isotherm obtained from experimental data fitted the Langmuir model, yielding maximum adsorption capacity of 51.81 mg/g. The thermodynamic parameters analysis illustrated that the MB adsorption onto H6P2W18O62 immobilized MOF-5 was spontaneous and endothermic process. Besides, these results implied that designing a novel material polyoxometalate-based metal-organic frameworks is great potential for removing cationic organic pollutants and even extended to improve other specific application.

  14. Evaluation of ethylenediamine-modified nanofibrillated cellulose/chitosan composites on adsorption of cationic and anionic dyes from aqueous solution.

    Liu, Kai; Chen, Lihui; Huang, Liulian; Lai, Yaoneng


    A multi-functional adsorbent was prepared by modifying nanofibrillated cellulose/chitosan composites with ethylenediamine (E-NFC/CS). The E-NFC/CS was characterized by FTIR and used for adsorption of cationic dye methylene blue (MB) and anionic dye new coccine (NC) from aqueous solution. The FTIR results showed that the E-NFC/CS contained more amino groups than the NFC/CS due to the modification for the NFC/CS with ethylenediamine. The results indicated that the maximum adsorption capacities occurred at pH 4.0 for MB and pH 2.0 for NC, respectively. The adsorption equilibrium time for MB and NC was 30 and 50min, respectively. In addition, the regenerated E-NFC/CS exhibited excellent adsorption performance for NC. It can keep almost 98% of the adsorption capacity after reused three times. Therefore, the E-NFC/CS can be potentially used as an effective adsorbent of cationic and anionic dyes in industrial effluents. PMID:27474662

  15. Effect of Magnesium Cation on the Interfacial Properties of Aqueous Salt Solutions

    Callahan, K. M.; Casillas-Ituarte, N. N.; Xu, M.; Roeselová, Martina; Allen, H. C.; Tobias, D. J.


    Roč. 114, č. 32 (2010), s. 8359-8368. ISSN 1089-5639 R&D Projects: GA MŠk LC512; GA MŠk ME09064; GA MŠk 1P05ME798 Grant ostatní: NSF(US) CHE-0749807 Institutional research plan: CEZ:AV0Z40550506 Keywords : magnesium cation * chloride ion * interface * molecular dynamics * sum frequency Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.732, year: 2010

  16. Photoinitiated Polymerization of Cationic Acrylamide in Aqueous Solution: Synthesis, Characterization, and Sludge Dewatering Performance

    Huaili Zheng


    Full Text Available A copolymer of acrylamide (AM with acryloyloxyethyl trimethyl ammonium chloride (DAC as the cationic monomer was synthesized under the irradiation of high-pressure mercury lamp with 2,2-azobis(2-amidinopropane dihydrochloride (V-50 as the photoinitiator. The compositions of the photoinduced copolymer were characterized by Fourier transform infrared spectra (FTIR, ultraviolet spectra (UV, and scanning electron microscope (SEM. The effects of 6 important factors, that is, photo-initiators concentration, monomers concentration, CO(NH22 (urea concentrations, pH value, mass ratio of AM to DAC, and irradiation time on the molecular weight and dissolving time, were investigated. The optimal reaction conditions were that the photo-initiators concentration was 0.3%, monomers concentration was 30 wt.%, irradiation time was 60 min, urea concentration was 0.4%, pH value was 5.0, and mass ratio of AM to DAC was 6 : 4. Its flocculation properties were evaluated with activated sludge using jar test. The zeta potential of supernatant at different cationic monomer contents was simultaneously measured. The results demonstrated the superiority of the copolymer over the commercial polyacrylamide as a flocculant.

  17. Enhanced aqueous solubility of polycyclic aromatic hydrocarbons by green diester-linked cationic gemini surfactants and their binary solutions

    Panda, Manorama; Fatma, Nazish; Kabir-ud-Din


    Three homologues of a novel biodegradable diester-linked cationic gemini surfactant series, CmH2m+1 (CH3)2N+(CH2COOCH2)2N+(CH3)2CmH2m+1.2Cl- (m-E2-m; m = 12, 14, 16), were used for investigation of the solubilization of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, anthracene and pyrene in single as well as binary surfactant solutions. Physicochemical parameters of the pure/mixed systems were derived by conductivity and surface tension measurements. Dissolution capacity of the equimolar binary surfactant solutions towards the PAHs was studied from the molar solubilization ratio (MSR), micelle-water partition coefficient (Km) and free energy of solubilization (ΔGs0) of the solubilizates. Influence of hydrophobic chain length of the dimeric surfactants on solubilization was characterized. Aqueous solubility of the PAHs was enhanced linearly with concentration of the surfactant in all the pure and mixed gemini-gemini surfactant systems.

  18. Removal of cationic surfactant (CTAB from aqueous solution on to activated carbon obtained from corncob.

    S. M. Yakout


    Full Text Available Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before water is released to the environment or delivered for public use. Using powdered activated carbon (PAC as adsorbent may be an effective technique to remove surfactants. In this study, the removal of surfactants by PAC was investigated and the influencesof the operating parameters on the effectiveness on adsorption rate were studied. Cationic surfactant, Cetyl trimethyl ammonium bromide (CTAB was selected for the experiments. A series of batch experiments were performed to determine the sorption isotherms of surfactants to PAC. The results showed that carbon structure affect mainly on the surfactant adsorption. Surfactant equilibrium data fitted very well to the binary langmuir model. The pseudo first-,second- order and intraparticle diffusion kinetic models were applied. Both, the external mass transfer and intraparticle diffusion mechanisms involve in CTAB sorption.

  19. Chromium(VI) adsorption from aqueous solution onto Moroccan Al-pillared and cationic surfactant stevensite.

    Benhammou, Abdelaziz; Yaacoubi, Abdelrani; Nibou, Lahbib; Tanouti, Boumediane


    Batch adsorption of the chromium(VI) onto Moroccan stevensite pillared by Keggin aluminium hydroxypolycation (Al-stevensite) and cationic surfactant cetyltrimethylammoniumbromide (CTA-stevensite) was investigated. The results showed that the CTA-stevensite has a higher affinity than that of Al-stevensite for chromium(VI) adsorption. The adsorption capacities for natural stevensite, Al-stevensite and CTA-stevensite calculated according to the Dubinin-Kaganer-Radushkevich isotherm (DKR) are 13.7, 75.4 and 195.6mmolkg(-1), respectively. The study of the pH effect showed that the optimal range corresponding to the Cr(VI) maximum adsorption on Al-stevensite is pH 3.5-6 and that on CTA-stevensite is pH 2-6. The adsorption rates evaluated according to the pseudo-second-order model are 7.2, 207.2 and 178.5mmolkg(-1)min(-1) for the natural stevensite, Al-stevensite and CTA-stevensite, respectively. The low values of the adsorption energy calculated by (DKR) suggest that anion exchange is the main mechanism that governs the chromate adsorption. PMID:16876943

  20. Temperature-Induced Aggregate Transitions in Mixtures of Cationic Ammonium Gemini Surfactant with Anionic Glutamic Acid Surfactant in Aqueous Solution.

    Ji, Xiuling; Tian, Maozhang; Wang, Yilin


    The aggregation behaviors of the mixtures of cationic gemini surfactant 1,4-bis(dodecyl-N,N-dimethylammonium bromide)-2,3-butanediol (C12C4(OH)2C12Br2) and anionic amino acid surfactant N-dodecanoylglutamic acid (C12Glu) in aqueous solution of pH = 10.0 have been studied. The mixture forms spherical micelles, vesicles, and wormlike micelles at 25 °C by changing mixing ratios and/or total surfactant concentration. Then these aggregates undergo a series of transitions upon increasing the temperature. Smaller spherical micelles transfer into larger vesicles, vesicles transfer into solid spherical aggregates and then into larger irregular aggregates, and entangled wormlike micelles transfer into branched wormlike micelles. Moreover, the larger irregular aggregates and branched micelles finally lead to precipitation and clouding phenomenon, respectively. All these transitions are thermally reversible, and the transition temperatures can be tuned by varying the mixing ratios and/or total concentration. These temperature-dependent aggregate transitions can be elucidated on the basis of the temperature-induced variations in the dehydration, electrostatic interaction, and hydrogen bonds of the headgroup area and in the hydrophobic interaction between the hydrocarbon chains. The results suggest that the surfactants carrying multiple binding sites will greatly improve the regulation ability and temperature sensitivity. PMID:26750978

  1. Effect of potassium monopersulfate (oxone) and operating parameters on sonochemical degradation of cationic dye in an aqueous solution.

    Soumia, Fassi; Petrier, Christian


    In this study, removal of Cresol Red (CR), a cationic triphenylmethane dye, by 300kHz ultrasound was investigated. The effect of additive such as potassium monopersulfate (oxone) was studied. Additionally, sonolytic degradation of CR was investigated at varying power and initial pH. RC can be readily eliminated by the ultrasound process. The obtained results showed that. Sonochemical degradation of CR was strongly affected by ultrasonic power and pH. The degradation rate of the dye increased substantially with increasing ultrasonic power in the range of 20-80W. This improvement could be explained by the increase in the number of active cavitation bubbles. The significant degradation was achieved in acidic conditions (pH=2) where the color removal was 99% higher than those observed in higher pH aqueous solutions. The ultrasonic degradation of dye was enhanced by potassium monopersulfate (oxone) addition. It was found that the degradation of the dye was accelerated with increased concentrations of oxone for a reaction time of 75min. PMID:27150780

  2. Reactions of aliphatic free radicals with copper cations in aqueous solutions

    Helium-saturated solutions containing copper sulphate and an aliphatic alcohol (methanol, ethanol or propan-2-ol) were pulse irradiated. The kinetics of the reactions thus initiated were followed by the spectrophotometric and conductometric techniques. The results indicate that all three radicals, CR1R2OH, react with Cu2+sub(aq) to yield Cu+sub(aq) + CR1R2O+H3O+. CH2OH radicals react with Cu+sub(aq) according to Cu+sub(aq) + CH2OH yields reversibly Cusup(II) -CH2OH+, K approximately 5 x 103 dm3 mol-1. (Note: In writing Cusup(II) - R+ or Cusup(III) - R2+ the accepted nomenclature is followed for organometallic compounds. This notation does not imply that the nature of the chemical bond is ionic. Furthermore, the results indicate that the Cu - C bond has at least partially a covalent nature.) The corresponding equilibrium constants for Cusup(II) - CH(CH3)OH+ and Cusup(II) - C(CH3)2OH+ are too low to be measured and the corresponding intermediates are not observed. Cu+sub(aq) reacts with the β radicals, CH2CH2OH and CH2CH(CH3)OH, according to Cu+sub(aq) + CH2CR1R2OH → Cusup(II) - CH2CR1R2OH+. The latter intermediates decompose via acid catalysed reactions to yield Cu2+sub(aq) + H2C = CR1R2 + H2O. (author)

  3. Effects of cationic ammonium gemini surfactant on micellization of PEO-PPO-PEO triblock copolymers in aqueous solution.

    Wang, Ruijuan; Tang, Yongqiang; Wang, Yilin


    Effects of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) on the micellization of two triblock copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), F127 (EO97PO69EO97) and P123 (EO20PO70EO20), have been studied in aqueous solution by differential scanning calorimetry (DSC), dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and NMR techniques. Compared with traditional single-chain ionic surfactants, 12-6-12 has a stronger ability of lowering the CMT of the copolymers, which should be attributed to the stronger aggregation ability and lower critical micelle concentration of 12-6-12. The critical micelle temperature (CMT) of the two copolymers decreases as the 12-6-12 concentration increases and the ability of 12-6-12 in lowering the CMT of F127 is slightly stronger than that of P123. Moreover, a combination of ITC and DLS has shown that 12-6-12 binds to the copolymers at the temperatures from 16 to 40 °C. At the temperatures below the CMT of the copolymers, 12-6-12 micelles bind on single copolymer chains and induce the copolymers to initiate aggregation at very low 12-6-12 concentration. At the temperatures above the CMT of the copolymers, the interaction of 12-6-12 with both monomeric and micellar copolymers leads to the formation of the mixed copolymer/12-6-12 micelles, then the mixed micelles break into smaller mixed micelles, and finally free 12-6-12 micelles form with the increase of the 12-6-12 concentration. PMID:24528103

  4. Formation of OH radicals from radical cations of some substituted benzenes in aqueous solutions at 800 C and at room temperature: effect of oxygen

    The reactions of a number of simple substituted-benzene radical cations with water at 800 C and at room temperature have been investigated. The radical cations were produced by thermal decomposition of Na2S2O8. The authors searched for the formation of OH radicals, which they identified by their reaction with nitrobenzene to give nitrophenols. The thermal decomposition of peroxydisulfate in deoxygenated, nitrobenzene-saturated aqueous solutions of chlorobenzene, bromobenzene, and tert-butylbenzene gave o- and p-nitrophenols, whereas fluorobenzene, iodobenzene, phenol, and chlorophenols gave no nitrophenols. With nitrobenzene alone, no nitrophenols were obtained. The structural requirements for the reaction of aromatic radical cations with water to produce OH radicals are discussed. In the presence of oxygen, the yield of chlorophenols and bromophenols increased dramatically, producing mainly the para isomer, but in the bromobenzene case also significant amounts of m-bromophenol. The mechanism of this oxidation is discussed. 3 tables

  5. Introduction of a cation in aqueous solution by electrolytic dissolution of metal. Applications to the decontamination of radioactive effluents

    This research thesis aims at comparing results obtained in chemical decontamination of radioactive effluents with a metallic cation introduced by metal electro-dissolution or by dose addition. After an overview of methods used for the purification of radioactive effluents and a more precise presentation of chemical co-precipitation, the author reports preliminary tests of the application of chemical co-precipitation to the decontamination of radioactive effluents, reports the analysis of iron, zinc and copper behaviour in aqueous environment by means of thermodynamic diagrams and current-voltage curves. He reports the design and use of two electro-dissolution sets, and the application of copper electrolytic dissolution to the elimination of ruthenium in radioactive effluents. He finally addresses the purification treatment of effluents of nuclear reactors

  6. Tautomeric equilibrium of creatinine and creatininium cation in aqueous solutions explored by Raman spectroscopy and density functional theory calculations

    Gao, Jiao [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Hu, Yongjun, E-mail: [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Li, Shaoxin, E-mail: [School of Information Engineering, Guangdong Medical College, Dongguan 523808 (China); Zhang, Yanjiao [School of Basic Medicine, Guangdong Medical College, Dongguan 523808 (China); Chen, Xue [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China)


    Highlights: Black-Right-Pointing-Pointer The tautomeric equlibrium and behavior of creatinine in aqueous solutions have been firstly studied by means of Raman spectroscopy and theoretical calculations (DFT). Black-Right-Pointing-Pointer As 7 water molecules are gradually aggregated around the creatinine, theoretical results show an excellent accordance with the experimental spectrum. Black-Right-Pointing-Pointer Analysis of molecular electrostatic potential (MEP) for creatinine (two tautomers and one protonated form) could explain why typical experimental Raman spectra with different pH values have obvious discrepancies at the electrical level. -- Abstract: The Raman spectral studies of creatinine with pH dependence were performed to explore the effects of pH values on the Raman spectroscopy of creatinine. Firstly, we calculated vibrational spectra by DFT to derive the equilibrium geometries and protonated form of creatinine. Comparing simulated and observed Raman spectra of creatinine in aqueous solution at pH 2, it is found the theoretical predicted spectra agree well with those of the experiment while seven water molecules are aggregated around the creatinine. Additionally, the tautomeric equilibrium of creatinine in aqueous solutions was studied and two tautomers are found to coexist by comparing its experimental and calculated Raman spectra. A water dimer being used to solvate creatinine would make the thermodynamic energy favor convert from the imino tautomer to the amino tautomer. Besides, the molecular electrostatic potential (MEP) analysis of the creatinine further confirms their discrepancies of typical experimental Raman spectra at different pH values.

  7. Study of lanthanide tri-cations in aqueous solution by molecular dynamic; Etude des trications lanthanide en solution aqueuse par dynamique moleculaire

    Duvail, M


    This is essentially a lanthanide tri-cation hydration study by means of classical molecular dynamics (CLMD) simulations using explicit polarization. Explicit polarization is calculated with a Car-Parrinello type of dynamics on induced dipoles, which decreases the CPU time as compared to the self-consistent resolution. Several pair interaction potentials are parametrized from ab initio calculations (MP2) and tested for the La{sup 3+}-OH{sub 2} interaction. The best results are obtained with an exponential-6 Buckingham potential. Next, the La{sup 3+}-OH{sub 2} interaction potential parameters are extrapolated to the other Ln{sup 3+}-OH{sub 2} interactions, only by using the ionic radii. The CLMD results reproduce the reliable experimental data (EXAFS distances), and the sigmoidal variation of the coordination number (with S shape), from 9 for La{sup 3+} to 8 for Lu{sup 3+}. This variation is explained by the linear variation of DrG0 (9,298) vs. atomic number. Insights are also given on the Co{sup 2+} hydration, CPMD simulations, reconstruction of EXAFS signal from MD simulations, and OH{sup -} complexation of La{sup 3+} in aqueous solution. (author)

  8. Removal of some cationic dyes from aqueous solutions using magnetic-modified multi-walled carbon nanotubes

    Highlights: ► MMMWCNTs effectively removes color from dye-containing wastewater. ► MMMWCNTs has high adsorption capacity and fast adsorption rate. ► MMMWCNTs showed high efficiency. ► The modified nanoparticles are highly monodisperse and magnetically separable. - Abstract: An adsorbent, magnetic-modified multi-walled carbon nanotubes, was used for removal of cationic dyes crystal violet (CV), thionine (Th), janus green B (JG), and methylene blue (MB) from water samples. Prepared nanoparticles were characterized by SEM, TEM, BET and XRD measurements. The prepared magnetic adsorbent can be well dispersed in the water and easily separated magnetically from the medium after loaded with adsorbate. The influences of parameters including initial pH, dosage of adsorbent and contact time have been investigated in order to find the optimum adsorption conditions. The optimum pH for removing of all the investigated cationic dyes from water solutions was found to be 7.0. The experimental data were analyzed by the Langmuir adsorption model. The maximum predicted adsorption capacities for CV, JG, Th and MB dyes were obtained as 227.7, 250.0, 36.4 and 48.1 mg g−1, respectively. Desorption process of the adsorbed cationic dyes was also investigated using acetonitrile as the solvent. It was notable that both the adsorption and desorption of dyes were quite fast probably due to the absence of internal diffusion resistance.

  9. Specific Na+ and K+ Cation Effects on the Interfacial Water Molecules at the Air/Aqueous Salt Solution Interfaces Probed with Non-resonant Second Harmonic Generation (SHG)

    Bian, Hong-tao; Guo, Yuan; Wang, Hong-fei


    Here we report the polarization dependent non-resonant second harmonic generation (SHG) measurement of the interfacial water molecules at the aqueous solution of the following salts: NaF, NaCl, NaBr, KF, KCl, and KBr. Through quantitative polarization analysis of the SHG data,the orientational parameter D value and the relative surface density of the interfacial water molecules at these aqueous solution surfaces were determined. From these results we found that addition of each of the six salts caused increase of the thickness of the interfacial water layer at the surfaces to a certain extent. Noticeably, both the cations and the anions contributed to the changes, and the abilities to increase the thickness of the interfacial water layer were in the following order: KBr > NaBr > KCl > NaCl ~ NaF > KF. Since these changes can not be factorized into individual anion and cation contributions, there are possible ion pairing or association effects, especially for the NaF case. We also found that the orientational ...

  10. Stability and instability of the isoelectronic UO22+ and PaO2+ actinyl oxo-cations in aqueous solution from density functional theory based molecular dynamics

    In this work, Pa(V) mono-cations have been studied in liquid water by means of density functional theory (DFT) based molecular dynamic simulations (CPMD) and compared with their U(VI) isoelectronic counterparts to understand the peculiar chemical behavior of Pa(V) in aqueous solution. Four different Pa(V) monocationic isomers appear to be stable in liquid water from our simulations: [PaO2(H2O)5]+(aq), [Pa(OH)4(H2O)2]+(aq), [PaO(OH)2(H2O)4]+(aq), and [Pa(OH)4(H2O)3]+(aq). On the other hand, in the case of U(VI) only the uranyl, [UO2(H2O)5]2+(aq), is stable. The other species containing hydroxyl groups replacing one or two oxo bonds are readily converted to uranyl. The Pa-OH bond is stable, while it is suddenly broken in U-OH. This makes possible the formation of a broad variety of Pa(V) species in water and participates to its unique chemical behavior in aqueous solution. Further, the two actinyl oxo-cations in water are different in the ability of the oxygen atoms to form stable and extended H-bond networks for Pa(V) contrary to U(VI). In particular, prot-actinyl is found to have between 2 and 3 hydrogen bonds per oxygen atom while uranyl has between zero and one. (authors)

  11. The assessment of removing strontium and cesium cations from aqueous solutions based on the combined methods of ionic liquid extraction and electrodeposition

    Chen, Po-Yu [Faculty of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung City 807, Taiwan (China)]. E-mail:


    The extraction of Sr{sup 2+} and Cs{sup +} from aqueous solutions by using the ionophores dicyclohexano-18-crown-6 (DCH18C6) and calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6), respectively, was demonstrated in the hydrophobic, room-temperature ionic liquid (RTIL), tri-1-butylmethylammonium bis((trifluoromethyl)sulfonyl)imide (Bu{sub 3}MeN-TFSI). The water contents of several hydrophobic ionic liquids and the absorption/desorption reversibility of oxygen and moisture in the Bu{sub 3}MeN-TFSI ionic liquid were determined by electrochemical techniques. The relationship between the distribution coefficient, D{sub M}, and the concentration ratios of C{sub ionophore,IL}/C{sub metal{sub ion,aq}} were investigated. The values of D {sub M} increase with increasing the concentration ratios and they are also influenced with the counter ions of Sr{sup 2+} and Cs{sup +} in the aqueous solutions. In the previous study, it was demonstrated that the Sr{sup 2+} and Cs{sup +} cations in the Bu{sub 3}MeN-TFSI ionic liquid could be coordinated by DCH18C6 and BOBCalixC6, respectively, and formed the DCH18C6.Sr{sup 2+} and BOBCalixC6.2Cs{sup +} ions, which would be cathodically reduced to Sr- and Cs-amalgam at a mercury film electrode (MFE). In this study, the probability was evaluated if the Sr{sup 2+} and Cs{sup +} cations extracted from the aqueous solutions can be really reduced to respective amalgam.

  12. Modeling the competition between solid solution formation and cation exchange on the retardation of aqueous radium in an idealized bentonite column

    Clays and clay rocks are considered viable geotechnical barriers in radioactive waste disposal. One reason for this is the propensity for cation exchange reactions in clay minerals to retard the migration of radionuclides. Although another retardation mechanism, namely the incorporation of radionuclides into sulfate or carbonate solid solutions, has been known for a long time, only recently has it been examined systematically. In this work, we investigate the competitive effect of both mechanisms on the transport of radium (Ra) in the near-field of a low- and intermediate level nuclear waste repository. In our idealized geochemical model, numerical simulations show that barium (Ba) and strontium (Sr) needed for Ra sulfate solid solutions also partition to the cation exchange sites of montmorillonite (Mont), which is the major mineral constituent of bentonite that is used for tunnel backfill. At high Mont content, most Ra tends to attach to Mont, while incorporation of Ra in sulfate solid solutions is more important at low Monte content. To explore the effect of the Mont content on the transport of radium, a multi-component reactive transport model was developed and implemented in the scientific software OpenGeoSys-GEM. It was found that a decrease of fixation capacity due to low Mont content is compensated by the formation of solid solutions and that the migration distance of aqueous Ra is similar at different Mont/water ratios. (author)

  13. Effect of the cation model on the equilibrium structure of poly-L-glutamate in aqueous sodium chloride solution

    Marchand, Gabriel; Soetens, Jean-Christophe; Jacquemin, Denis; Bopp, Philippe A.


    We demonstrate that different sets of Lennard-Jones parameters proposed for the Na+ ion, in conjunction with the empirical combining rules routinely used in simulation packages, can lead to essentially different equilibrium structures for a deprotonated poly-L-glutamic acid molecule (poly-L-glutamate) dissolved in a 0.3M aqueous NaCl solution. It is, however, difficult to discriminate a priori between these model potentials; when investigating the structure of the Na+-solvation shell in bulk NaCl solution, all parameter sets lead to radial distribution functions and solvation numbers in broad agreement with the available experimental data. We do not find any such dependency of the equilibrium structure on the parameters associated with the Cl- ion. This work does not aim at recommending a particular set of parameters for any particular purpose. Instead, it stresses the model dependence of simulation results for complex systems such as biomolecules in solution and thus the difficulties if simulations are to be used for unbiased predictions, or to discriminate between contradictory experiments. However, this opens the possibility of validating a model specifically in view of analyzing experimental data believed to be reliable.

  14. Modification of an Iranian clinoptilolite nano-particles by hexadecyltrimethyl ammonium cationic surfactant and dithizone for removal of Pb(II) from aqueous solution.

    Anari-Anaraki, Mostafa; Nezamzadeh-Ejhieh, Alireza


    Natural clinoptilolite tuff was mechanically converted to micro (MCP) and nano (NCP) particles. The MCP and NCP powders were respectively modified with hexadecyltrimethyl ammonium bromide (HDTMA) and dithizone (DTZ). The raw and modified samples were characterized by X-ray diffraction (XRD), Fourier transformation infra red (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) and thermogravimetry (TG) and used for the removal of Pb(II) from aqueous solution. The results confirm that both ion exchange and complexation processes are responsible for removal of Pb(II) cations in the modified samples, while Pb(II) cations were only removed via an ion exchange process by the raw clinoptilolite. In this sorbent, the anionic removal property of surfactant modified zeolites (SMZs) changed to cationic removal property by an additional modification step. The best removal efficiency was observed by NCP-HDTMA-DTZ at the following experimental conditions: C(Pb(II)): 800 mg L(-1), HDTMA dosage: 0.2 mol L(-1), DTZ dosage: 5 mmol L(-1), contact time of DTZ with NCP-HDTMA: 1800 min and contact time of the sorbent with Pb(II): 360 min. The NCP-HDTMA-DTZ sorbent showed good efficiency for the removal of lead in the presence of different multivalent cations. Adsorption isotherms of Pb(II) ions obey the Langmuir equation that indicate the monolayer sorption of Pb(II). The adsorption kinetics based on the pseudo-second-order rate equation indicates that the rate limiting step involving a chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneous process. PMID:25460715

  15. The study of furfural removal from aqueous solutions using activated carbon and bentonite modified with cetyltrimethylammonium bromide (CTAB, a cationic surfactant

    M Leili


    Full Text Available Background and Objectives: Furfural is one of the toxic chemical compounds used in many industries such as petrochemical, food, paper products, pharmaceutical, etc., due to having some characteristics. Therefore, furfural could be found at different concentrations in the effluent from these industries and can enter the environment. Hence, the aim of this study was the assessment the efficiency of a low cost bentonite modified with cationic surfactant in the removal of furfural from aqueous solution. Material and Methods: In this experimental study, bentonite was purchased from one of the Mines of Zanjan Province, Iran and then the efficiency of bentonite modified with the cationic surfactant CTAB (CTAB-Bent was assessed in the adsorption of furfural from aqueous solution. Activated carbon (AC was also purchased as commercial grade. Results: Under optimum conditions, the removal efficiency of AC and CTAB-Bent was about 52 and 66%, respectively. For both adsorbents used in this study, the increase of contact time and sorbent dosage resulted in increasing the removal efficiency, but the removal efficiency was decreased with the increase of furfural initial concentrations. Regarding pH, the removal efficiency was the highest in relative acidic and neutral environment, (60 and 69% for AC and CTAB-Bent respectively. The kinetics studies revealed that the highest correlation coefficients were obtained for the pseudo-second order rate kinetic model. Adsorption data from both adsorbents was also fitted with Langmuir isotherm.   Conclusion: It was found that modified bentonite with CTAB as a natural adsorbent could have better efficiencies compared with activated carbon in the furfural removal, although more contact times is needed.


    Zaira Zaman Chowdhury,


    Full Text Available The feasibility of granular activated carbon (GAC derived from Mangostene (Mangostana garcinia fruit shell to remove lead, Pb2+ cations was investigated in batch and fixed bed sorption systems. Batch experiments were carried out to study equilibrium isotherms, kinetics, and thermodynamics by using an initial lead (Pb2+ ions concentration of 50 to 100 mg/L at pH 5.5. Equilibrium data were fitted using Langmuir, Freundlich, and Temkin linear equation models at temperatures 30°C, 50°C, and 70°C. Langmuir maximum monolayer sorption capacity was 25.00 mg/g at 30°C. The experimental data were best represented by pseudo-second-order and Elovich models. The sorption process was found to be feasible, endothermic, and spontaneous. In column experiments, the effects of initial cation concentration (50 mg/L, 70 mg/L, and 100 mg/L, bed height (4.5 cm and 3 cm, and flow rate (1 mL/min and 3 mL/min on the breakthrough characteristics were evaluated. Breakthrough curves were further analyzed by using Thomas and Yoon Nelson models to study column dynamics. The column was regenerated and reused consecutively for four cycles. The result demonstrated that the prepared activated carbon was suitable for removal of Pb2+ from synthetic aqueous solution using batch, as well as fixed bed sorption systems.

  17. Alkaline earth cation extraction from acid solution

    Dietz, Mark; Horwitz, E. Philip


    An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

  18. Novel tannin-based adsorbent in removing cationic dye (Methylene Blue) from aqueous solution. Kinetics and equilibrium studies.

    Sánchez-Martín, J; González-Velasco, M; Beltrán-Heredia, J; Gragera-Carvajal, J; Salguero-Fernández, J


    Natural tannin-based adsorbent has been prepared on the basis of the gelification of Quebracho bark extract. The resulting product, Quebracho Tannin Gel (QTG) was tested as cationic dye adsorbent with Methylene Blue (MB). Kinetics of adsorption process were studied out and a period of 15 days was determined for reaching equilibrium. The influences of pH and temperature were evaluated. As pH or temperature raise q capacity of QTG increases. Theoretical modelization of dye-QTG adsorption was carried out by multiparametric adjustment according to Langmuir's hypothesis. Values of the k(l1), k(l2) and activation energies were calculated. PMID:19782466

  19. Removal of Copper-phthalocyanine from Aqueous Solution by Cationically Templated MCM-41 and MCM-48 Nanoporous Adsorbents

    ANBIA Mansoor; MOHAMMADI Kaveh


    The effect of cationic template on the adsorption of copper-phthalocyanine-3,4',4",4'"-tetrasulfonic acid tetra-sodium salt [Cu(tsPc)-4·4Na+] in MCM-41 and MCM-48 mesoporous materials was investigated,using cetyl-trimethylammonium bromide(CTAB)as the cationic template and tetraethyl-orthosilicate as the silica source for synthesis of mesoporous materials.The properties of synthesized samples were characterized with XRD-Iow angle and scanning electron microscopy.The as-synthesized mesoporous samples were used for the separation of Cu(tsPc)tion speed,contact time,composition of adsorbents(presence or absence of surfactants)and initial analyte concen-trations.Adsorption uptakes were rapid on the adsorbents reaching equilibrium in 1/5 h for MCM-48 and 2 h for MCM-41.The materials showed excellent adsorption capacity toward copper-phthalocyanine anion(300.5 mg/g of Cu(tsPc)-4 for as-MCM48 and 285.5 mg/g for as-MCM-41).The materials without surfactant did not show signifi-cant affinity for analyte.Dominant sorption mechanisms were interactions including electrostatic,hydrophobicity,hydrogen bonding and π-π interactions.

  20. Equilibrium, kinetics and thermodynamics studies of chitosan-based solid phase nanoparticles as sorbent for lead (II) cations from aqueous solution

    Shaker, Medhat A., E-mail: [Current address: Chemistry Department, Faculty of Science, University of Jeddah, Jeddah (Saudi Arabia); Permanent address: Chemistry Department, Faculty of Science, Damanhour University, Damanhour (Egypt)


    Ternary nanoparticles of chitosan, non-viable biomass (Pseudomonas sp.) and gelatin, CPG were synthesized by chemical crosslinking method and applied as a novel and cost-effective solid phase to adsorb Pb(II) cations from aqueous solution. Characterization of the fabricated CPG nanoparticles and their complexation behavior were extensively interrogated by dynamic light scattering (DLS), FTIR, TGA, XRD and SEM techniques. The extent of adsorption was found to be a function of medium pH, contact time, initial Pb(II) concentration and temperature. The Langmuir, Freundlich, Dubinin–Radushkevich and Redlich–Peterson models were used to illustrate the isotherms of the adsorption system. The adsorption of Pb(II) cations onto CPG best-fits the Langmuir isotherm model which predicts two stoichiometric temperature-independent adsorption sites, A and B with variable capacities, 35.4 and 91.1 mg g{sup −1}, respectively and removal capacity above 90%. Thermodynamic studies revealed that the adsorption process was physical, spontaneous, and endothermic. The adsorption rate is influenced by temperature and the adsorption kinetic is well confirmed with pseudo-second-order equation compared with three other investigated kinetic models. Present study indicated potential applications of CPG nanoparticles as excellent natural and promising solid phase for Pb(II) extraction in wastewater treatment. - Graphical abstract: Display Omitted - Highlights: • Kinetics and thermodynamics of Pb{sup 2+} biosorption onto CPG nanoparticles are studied. • Adsorption kinetic data are best modeled using second-order rate equations. • The Pb{sup 2}adsorption onto CPG was physical diffusion controlled reaction. • The experimental equilibrium results well fit the Langmuir model. • The thermodynamics show endothermic, favorable and spontaneous adsorption processes.

  1. Equilibrium, kinetics and thermodynamics studies of chitosan-based solid phase nanoparticles as sorbent for lead (II) cations from aqueous solution

    Ternary nanoparticles of chitosan, non-viable biomass (Pseudomonas sp.) and gelatin, CPG were synthesized by chemical crosslinking method and applied as a novel and cost-effective solid phase to adsorb Pb(II) cations from aqueous solution. Characterization of the fabricated CPG nanoparticles and their complexation behavior were extensively interrogated by dynamic light scattering (DLS), FTIR, TGA, XRD and SEM techniques. The extent of adsorption was found to be a function of medium pH, contact time, initial Pb(II) concentration and temperature. The Langmuir, Freundlich, Dubinin–Radushkevich and Redlich–Peterson models were used to illustrate the isotherms of the adsorption system. The adsorption of Pb(II) cations onto CPG best-fits the Langmuir isotherm model which predicts two stoichiometric temperature-independent adsorption sites, A and B with variable capacities, 35.4 and 91.1 mg g−1, respectively and removal capacity above 90%. Thermodynamic studies revealed that the adsorption process was physical, spontaneous, and endothermic. The adsorption rate is influenced by temperature and the adsorption kinetic is well confirmed with pseudo-second-order equation compared with three other investigated kinetic models. Present study indicated potential applications of CPG nanoparticles as excellent natural and promising solid phase for Pb(II) extraction in wastewater treatment. - Graphical abstract: Display Omitted - Highlights: • Kinetics and thermodynamics of Pb2+ biosorption onto CPG nanoparticles are studied. • Adsorption kinetic data are best modeled using second-order rate equations. • The Pb2adsorption onto CPG was physical diffusion controlled reaction. • The experimental equilibrium results well fit the Langmuir model. • The thermodynamics show endothermic, favorable and spontaneous adsorption processes

  2. Functionalization of magnetic chitosan with graphene oxide for removal of cationic and anionic dyes from aqueous solution.

    Gul, Kashif; Sohni, Saima; Waqar, Muttaqia; Ahmad, Faiza; Norulaini, N A Nik; A K, Mohd Omar


    In the present study, we decorated chitosan (©) with Fe3O4 nanoparticles followed by cross-linking with GO to prepare Fe3O4 supported chitosan-graphene oxide composite (Fe3O4©-GO). Different properties of synthesized material were investigated by SEM, XRD, FTIR, TGA and EDX. Batch adsorption experiments were performed to remove toxic cationic and anionic dyes from industrial wastewater. To maximize removal efficiency of composite material, effect of pH (4-12), time (0-80min), Fe3O4©-GO dosage (2-10mg), initial dye concentration (2-30μgmL̄ (1)) and temperature (303, 313, and 323K) were studied. The uptake of dyes presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model. To understand the interaction of dye with adsorbent, Langmuir and Freundlich isotherm were applied. Thermodynamic studies were conducted to calculate the changes in free energy (ΔG(0)), enthalpy (ΔH(0)) and entropy (ΔS(0)). In view of practical application, the influence of ionic strength, recycling as well as investigations based on percent recoveries from spiked real water samples were also taken into account. PMID:27516300

  3. Aqueous polyethylene oxide solutions

    A number of aspects concerning the reorientation of polymer, water and ion hydration complexes have been studied in aqueous solution of polyethylene oxide (PEO). The polymer dynamics are investigated by 1H-PEO and 13C-PEO nuclear relaxation experiments. 162 refs.; 30 figs.; 19 tabs

  4. Specific Na+ and K+ Cation Effects on the Interfacial Water Molecules at the Air/Aqueous Salt Solution Interfaces Probed with Non-resonant Second Harmonic Generation (SHG)

    Bian, Hong-tao; Feng, Ran-Ran; Guo, Yuan; Wang, Hong-fei


    Here we report the polarization dependent non-resonant second harmonic generation (SHG) measurement of the interfacial water molecules at the aqueous solution of the following salts: NaF, NaCl, NaBr, KF, KCl, and KBr. Through quantitative polarization analysis of the SHG data,the orientational parameter D value and the relative surface density of the interfacial water molecules at these aqueous solution surfaces were determined. From these results we found that addition of each of the six sal...

  5. Preparation of cationic polyacrylamide by aqueous two-phase polymerization


    Full Text Available Cationic polyacrylamide (CPAM was synthesized by aqueous two-phase polymerization technique using acrylamide (AM and dimethylaminoethyl methacrylate methyl chloride (DMC as raw materials, aqueous polyethylene glycol 20000 (PEG 20000 solution as dispersant, 2,2′-azobis(2-amidinopropane dihydrochloride (V-50 as initiator and poly(dimethylaminoethyl methacrylate methyl chloride (PDMC as stabilizer. The polymer was characterized by infrared (IR spectroscopy, 1H-NMR spectrum and transmission electron microscopy (TEM. The copolymer composition was analyzed. The effect of monomers concentration, PEG 20000 concentration and stabilizer concentration on copolymer were investigated, respectively. The optimum reaction conditions for obtaining a stable CPAM aqueous two-phase system were monomers concentration 8~15%, PEG 20000 concentration 15~25%, and PDMC concentration 0.5~1.5%. Finally, the formation process of copolymer particles was investigated by optical microscope.

  6. Bespoke cationic nano-objects via RAFT aqueous dispersion polymerisation

    Williams, M.; Penfold, NJW; Lovett, JR; Warren, NJ; Douglas, CWI; Doroshenko, N; Verstraete, P; Smets, J; Armes, SP


    A range of cationic diblock copolymer nanoparticles are synthesised via polymerisation-induced self-assembly (PISA) using a RAFT aqueous dispersion polymerisation formulation. The cationic character of these nanoparticles can be systematically varied by utilising a binary mixture of two macro-CTAs, namely non-ionic poly(glycerol monomethacrylate) (PGMA) and cationic poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride (PQDMA), with poly(2-hydroxypropyl methacrylate) (PHPMA) being selected...

  7. Disposal of heavy metal cations in aqueous media by adsorption on coal to Ghazni

    О.М. Заславський


    Full Text Available  Adsorption of Pb and Cu cations and their mixture on the surface of modified and non-modified anti-gas coal trough different time intervals have been studied. The maximum adsorption capacity of coal relative to each cations have been determined. Absence  of concurrence between cations of Pb and Cu during adsorption from mixture is explained by difference of  types of their interaction with coal surface. The high effectiveness and perspectivities of application of anti-gas coal for neutralization of heavy metal cations in aqueous solution was shown.

  8. Application of longan shell as non-conventional low-cost adsorbent for the removal of cationic dye from aqueous solution

    Wang, Ya; Zhu, Lin; Jiang, Haitao; Hu, Fang; Shen, Xiangqian


    With simple physical treatment, adsorption potential of longan shell for the methylene blue (MB) from aqueous solution was studied as a low-cost material under the conditions of adsorbent dosage (1-6 g/L), initial solution pH (2-12), contact time (5-180 min), temperature (293, 313, 313 K) and initial dye concentration (100-500 mg/L). The SEM images and FTIR spectra of longan shell before and after dye adsorption were analyzed to understand the adsorption process of MB onto longan shell. The kinetic data and the equilibrium data were simulated by different kinetic and isotherm models, respectively. The results showed that the adsorption process was well described by the pseudo-second-order kinetic model, and the experimental equilibrium data were better fit to Langmuir equation than Freundlich equation with the maximum adsorption capacity of 141.04 mg/g. In addition, main activation parameters (Ea, ΔH#, ΔS# and ΔG#) and thermodynamic parameters (ΔG°, ΔH° and ΔS°) of the absorption process were also determined.

  9. Mercury(II) removal from aqueous solutions and wastewaters using a novel cation exchanger derived from coconut coir pith and its recovery

    A new adsorbent (PGCP-COOH) having carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto coconut coir pith, CP (a coir industry-based lignocellulosic residue), using potassium peroxydisulphate as an initiator and in the presence of N,N'-methylenebisacrylamide as a cross-linking agent. The adsorbent was characterized with the help of infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and potentiometric titrations. The ability of PGCP-COOH to remove Hg(II) from aqueous solutions was assessed using batch adsorption technique under kinetic and equilibrium conditions. Adsorbent exhibits very high adsorption potential for Hg(II) and more than 99.0% removal was achieved in the pH range 5.5-8.0. Adsorption process was found to follow first-order-reversible kinetics. An increase of ionic strength of the medium caused a decrease in metal removal, indicating the occurrence of outer-sphere surface complex mechanism. The equilibrium data were fitted well by the Freundlich isotherm model (R2 = 0.99; χ2 1.81). The removal efficiency was tested using chlor-alkali industry wastewater. Adsorption isotherm experiments were also conducted for comparison using a commercial carboxylate-functionalized ion exchanger, Ceralite IRC-50. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <9.0%

  10. Method of precipitating uranium from an aqueous solution and/or sediment

    Tokunaga, Tetsu K; Kim, Yongman; Wan, Jiamin


    A method for precipitating uranium from an aqueous solution and/or sediment comprising uranium and/or vanadium is presented. The method includes precipitating uranium as a uranyl vanadate through mixing an aqueous solution and/or sediment comprising uranium and/or vanadium and a solution comprising a monovalent or divalent cation to form the corresponding cation uranyl vanadate precipitate. The method also provides a pathway for extraction of uranium and vanadium from an aqueous solution and/or sediment.

  11. Spectroscopic studies of solutes in aqueous solution.

    Chai, Bing-hua; Zheng, Jian-ming; Zhao, Qing; Pollack, Gerald H


    Absorption and fluorescence characteristics of aqueous solutions of salts, sugars, and amino acids were studied using UV-vis spectroscopy and spectrofluorometry. Motivation stemmed from unanticipated absorption spectral and fluorescence features of the "exclusion zone" seen adjacent to various hydrophilic surfaces. Those features implied a structure distinct from that of bulk water (Adv. Colloid Interface Sci. 2006, 127, 19). Absorption peaks at approximately 270 nm similar to those observed in the exclusion zone were seen in solutions of the following substances: salts, Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose. To determine the fate of the absorbed energy, we studied the fluorescence properties of these solutions. The salts showed fluorescence emission around 480-490 nm under different excitation wavelengths. The fluorescence intensity of LiCl was higher than NaCl, which was in turn higher than KCl-the same ordering as the absorption intensities. Fluorescence of Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose were observed as well, with multiple excitation wavelengths. Hence, at least some of the absorbed energy is released as fluorescence. The results show features closely similar to those observed in the exclusion zone, implying that the aqueous region around the solutes resembles the aqueous zone adjacent to hydrophilic surfaces. Both may be more extensively ordered than previously thought. PMID:18298105

  12. 2010 Water & Aqueous Solutions

    Dor Ben-Amotz


    Water covers more than two thirds of the surface of the Earth and about the same fraction of water forms the total mass of a human body. Since the early days of our civilization water has also been in the focus of technological developments, starting from converting it to wine to more modern achievements. The meeting will focus on recent advances in experimental, theoretical, and computational understanding of the behavior of the most important and fascinating liquid in a variety of situations and applications. The emphasis will be less on water properties per se than on water as a medium in which fundamental dynamic and reactive processes take place. In the following sessions, speakers will discuss the latest breakthroughs in unraveling these processes at the molecular level: Water in Solutions; Water in Motion I and II; Water in Biology I and II; Water in the Environment I and II; Water in Confined Geometries and Water in Discussion (keynote lecture and poster winners presentations).

  13. The Optimization of Aniline Adsorption from Aqueous Solutions by Raw Bentonite and Bentonite Modified with Cationic Surfactants Using the Taguchi Model

    F. Taherkhani


    Full Text Available Introduction & Objectives: Aniline is an organic compound widely used in various industries. The release of this compound has had various environmental impacts. Thus, the assessment of efficient and practical methods for the removal of aniline from wastewater of these industries is remarkable. Taguchi model is a model for the analysis of experiments, that predicts both the effects of each factors and the optimum level of them using a certain number of experiment. The purpose of this study was the optimization of aniline adsorption on the raw and modified bentonite with a cationic surfactant using Taguchi model. Materials & Methods: In this experimental study, the raw bentonite and modified bentonite was prepared in a few steps. Then, 4 main factors (i.e. pollutant concentration, contact time, pH, and adsorbent dosage on 4 levels were selected by Matrix L16 trials and the experiments were conducted in this matrix. The factors were also ranked based on the R-value. Then , the data were analyzed with Minitab 17 software. Finally, the adsorption of aniline on raw and modified bentonite was determined in optimal conditions. Results: The optimization of adsorption process using Taguchi model showed that the factors of importance for optimizing respectively were: contact time of 360 minutes, pH =10 pH, ani-line initial concentration of 300 mg/L and adsorbent dosages of 40 g/L. The maximum ad-sorption of aniline onto raw bentonite and modified bentonite with cationic surfactant in op-timal conditions were determined 81.86 and 8.75, respectively. The results revealed that Freundlich isotherm and pseudo-second-order kinetic model provided a better ?t to the ex-perimental data. Conclusion: The results showed that the bentonite modified with cationic surfactant is efficient in the removal of aniline. At the same time, since bentonite is cheap and easily accessible ,it is considered a desirable adsorbant. (Sci J Hamadan Univ Med Sci 2015; 22 (1:55-64

  14. Thermodynamic and Spectroscopic Investigation of Interactions between Reactive Red 223 and Reactive Orange 122 Anionic Dyes and Cetyltrimethyl Ammonium Bromide (CTAB Cationic Surfactant in Aqueous Solution

    Muhammad Irfan


    Full Text Available The present study describes the conductometric and spectroscopic study of the interaction of reactive anionic dyes, namely, reactive red 223 and reactive orange 122 with the cationic surfactant cetyltrimethyl ammonium bromide (CTAB. In a systematic investigation, the electrical conductivity data was used to calculate various thermodynamic parameters such as free energy (ΔG, enthalpy (ΔH, and the entropy (ΔS of solubilization. The trend of change in these thermodynamic quantities indicates toward the entropy driven solubilization process. Moreover, the results from spectroscopic data reveal high degree of solubilization, with strong interactions observed in the cases of both dyes and the CTAB. The spontaneous nature of solubilization and binding was evident from the observed negative values of free energies (ΔGp and ΔGb.

  15. Flotation separation of hafnium(IV) from aqueous solutions

    A simple, rapid method for the separation of hafnium from aqueous solutions was investigated using sup(175+181)Hf tracer. Cationic hafnium complex ions were floated from dilute acid solutions with sodium lauryl sulfate (SLS) and anionic hafnium complexes were floated from basic and oxalic acid solutions with hexadecyltrimethyl ammonium bromide (HTMAB). The conditions necessary for quantitative recovery of the metal and mechanisms of flotation are described. (author)

  16. Chemical studies on polyaniline titanotungstate as a new composite cation exchanger and its analytical applications for removal of cesium from aqueous solutions

    Polyaniline titanotungstate has been synthesized by incorporation of organic polymer polyaniline into the inorganic precipitate of titanotungstate. This material was characterized using IR, X-Ray, SEM and DTA-TGA analysis. The influences of initial concentration of metal ions, particle size and temperature have been reported. The material stability was investigated in water, acids, alkaline solutions, and at high temperature up to 850 degree C. Ion-exchange capacity and distribution coefficients (Kd) for ten metal ions have been determined. It was found that the polyaniline titanotungstate has high affinity and high selectivity for Cs+. The material has high separation for Cs+ ion from other metal ions. The comparison of composite (PATiW) and inorganic material (TiW) was studied and indicated that the composite material is better than the inorganic one in selectivity of Cs+. Thermodynamic parameter of Cs+ exchange process, such as changes in Gibbs free energy (δGo), enthalpy (δHo), and entropy (δSo) have been calculated. It was found that numerical value of δG decrease with an increase in temperature,indicating that the sorption reaction of adsorbent was spontaneous and more favorable at higher temperature. The positive value of δHo corresponds to the endothermic nature of sorption processes and suggested that chemisorptions were the predominant mechanism. A comparison of kinetic models applied to the sorption rate data of Cs+ was evaluated for the pseudo first-order, pseudo second-order, homogeneous particle diffusion, shell model and intraparticle diffusion models. The results showed that Cs+ is sorption onto PATiW and TiW with particle diffusion mechanism. Self diffusion coefficient (Di), Activation energy (Ea) and entropy (δS*) of activation were also computed from thelinearized form of Arrhenius equation. Column studies in acid and alkaline solutions were studied. A kinetic study for removal cesium from milk was investigated.

  17. Organic non-aqueous cation-based redox flow batteries

    Jansen, Andrew N.; Vaughey, John T.; Chen, Zonghai; Zhang, Lu; Brushett, Fikile R.


    The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte is selected to have a higher redox potential than the redox reactant of the negative electrolyte.

  18. Radiolysis of Aqueous Toluene Solutions

    Aqueous toluene solutions have been irradiated with Co γ-rays. In unbuffered solutions the various cresol isomers are formed in a total yield of 0.45, 0.87 and 0.94 molecules/100 eV absorbed energy in argon-, N2O- and air - saturated solutions, respectively. The yields are reduced in acid (pH 3) solutions (G 0.14, 0.14 and 0.52, respectively) but the reduction is compensated by the formation of 1,2-di-phenylethane in yields of 0.49 and 1.60 in argon- and N2O-saturated solutions, respectively. Benzyl radicals are formed through an acid catalysed water elimination reaction from the initially formed hydroxymethylcyclohexadienyl radical. Phenyltolylmethanes, dimethylbiphenyls and partly reduced dimers are also formed during the radiolysis. Hydrogen is formed in the same yield as the molecular yield, g(H2). Xylene isomers and benzene are formed in trace quantities. The most remarkable effects of the addition of Fe(III) ions to deaerated acid toluene solutions are the formation of benzyl alcohol and benzaldehyde and an increase in the yield of 1,2-diphenylethane


    Steinman, Gary; Kenyon, Dean H.; Calvin, Melvin


    EARLIER investigations have demonstrated that di-cyandiamide (DCDA), the dimer of cyanamide, can successfully promote the dehydration condensation of: (1) glucose and orthophosphate to give glucose-6-phosphate; (2) adenosine and orthophosphate to give adenosine-5'-monophosphate; (3) orthophosphate to give pyrophosphate; (4) alanine to give alanylalanine and alanylalanylalanine. These reactions were carried out in dilute aqueous solutions in the dark. (It was also demonstrated that the combination of ultra-violet light and dicyandiamide could promote the synthesis of dipeptides. This observation has since been confirmed by other investigators.) These experiments were designed to demonstrate one possible means by which such compounds could have been formed on the prebiotic Earth, thus providing materials needed for the origin of living systems. Dicyandiamide itself could have been, present on the primitive Earth as was demonstrated with the ultra-violet irradiation of cyanide solution.

  20. Radiolysis of Aqueous Benzene Solutions

    Aerated and deaerated aqueous solutions of benzene have been irradiated with 60Co γ-rays. The products of radiolysis in deaerated, unbuffered or acid, solutions were phenol, biphenyl, hydrogen and in acid solutions also hydrogen peroxide with the following yields: G(phenol) = 0. 37 (0. 37), G(biphenyl) = 1.3 (1.7), G(H2) = 0.44 (0. 43) and G(H2O2) = 0 (0.60), the figures in brackets giving the results for acid solutions. The results are shown to agree with the conclusion that k(e-aq + H2O2) >> k(H + H2O2). Furthermore, the results indicate that a competition takes place between the reactions: 2 C6H6OH · -> dimer -> biphenyl. C6H7 · + C6H6OH · -> dimer -> biphenyl. The yields in aerated, unbuffered or acid, solutions were: G(phenol) = 2.1 (2.3), G(biphenyl) = 0 (0), and G(H2O2) = 2.2 (3.1), the figures in brackets being valid for acid solutions. The ratio k(H + C6H6)/k(H + O2) was 1.4x10-2. The results indicate that peroxides, or more probably hydroperoxides, take part in the reactions. After the addition of Fe2+ or Fe3+ to aerated acid solutions G(phenol) was increased to 6.6 and 3.4 respectively. Oxygen was consumed more rapidly in the presence of Fe. Reaction mechanisms are discussed

  1. Molecular simulation study on Hofmeister cations and the aqueous solubility of benzene.

    Ganguly, Pritam; Hajari, Timir; van der Vegt, Nico F A


    We study the ion-specific salting-out process of benzene in aqueous alkali chloride solutions using Kirkwood-Buff (KB) theory of solutions and molecular dynamics simulations with different empirical force field models for the ions and benzene. Despite inaccuracies in the force fields, the simulations indicate that the decrease of the Setchenow salting-out coefficient for the series NaCl > KCl > RbCl > CsCl is determined by direct benzene-cation correlations, with the larger cations showing weak interactions with benzene. Although ion-specific aqueous solubilities of benzene may be affected by indirect ion-ion, ion-water, and water-water correlations, too, these correlations are found to be unimportant, with little to no effect on the Setchenow salting-out coefficients of the various salts. We further considered LiCl, which is experimentally known to be a weaker salting-out agent than NaCl and KCl and, therefore, ranks at an unusual position within the Hofmeister cation series. The simulations indicate that hydrated Li(+) ions can take part of the benzene hydration shell while the other cations are repelled by it. This causes weaker Li(+) exclusion around the solute and a resulting, weaker salting-out propensity of LiCl compared to that of the other salts. Removing benzene-water and benzene-salt electrostatic interactions in the simulations does not affect this mechanism, which may therefore also explain the smaller effect of LiCl, as compared to that of NaCl or KCl, on aqueous solvation and hydrophobic interaction of nonpolar molecules. PMID:24792435

  2. Study of free acidity determinations in aqueous solution

    The object of this work is the study of the principal methods which can be applied to the measurement of 'free' acidity. In the first part, we define the various types of acidity which can exist in aqueous solution; then, after having studied some hydrolysis reactions, we compare the value of the neutralisation pH of the hydrated cation and that of the precipitation of the hydroxide. In the second part we have started to study the determination of the acidity of an aqueous solution. After having rapidly considered the 'total' acidity determination, we deal with the problem of the 'free' acidity titration. We have considered in particular certain methods: extrapolation of the equivalent point, colorimetric titrations with or without a complexing agent, and finally the use of ion-exchange resins with mixed aqueous and solvent solutions. (author)

  3. Pulse Radiolysis of Methyl Viologen in Aqueous Solutions

    Solar, S.; Solar, W.; Getoff, N.; Holcman, Jerzy; Sehested, Knud

    Pulse radiolysis of air-free aqueous methyl viologen (MV2+) solutions was carried out at various pH. The attack of e–aq on MV2+, with k(e–aq+ MV2+)= 7.5 × 1010 dm3 mol–1 s–1, leads to the formation of the long-lived radical cation (MV˙+), which possesses two absorption maxima at 392.5 nm (ε392...

  4. Transient formation of the oxo-iron(IV) porphyrin radical cation during the reaction of iron(III) tetrakis-5,10,15,20-(N-methyl-4-pyridyl)porphyrin with hydrogen peroxide in aqueous solution.

    Saha, Tapan Kumar; Karmaker, Subarna; Tamagake, Keietsu


    The reaction of iron(III) tetrakis-5,10,15,20-(N-methyl-4-pyridyl)porphyrin (Fe(III)TMPyP) with hydrogen peroxide (H(2)O(2)) and the catalytic activity of the reaction intermediates on the luminescent peroxidation of luminol in aqueous solution were studied by using a double-mixing stopped-flow system. The observed luminescence intensities showed biphasic decay depending on the conditions. The initial flashlight decayed within flashlight appeared during the formation of the oxo-iron(IV) porphyrin, TMPyPFe(IV) = O, which is responsible for the sustained emission. The absorption spectra 0.0-0.5 s did not reproduce well by a simple combination of the two spectra of Fe(III)TMPyP and TMPyPFe(IV) = O, indicating that transient species was formed at the initial stage. Addition of uric acid (UA) caused a significant delay in the initiation of the luminol emission as well as in the formation of the TMPyPFe(IV) = O. Both of them were completely diminished in the presence of UA equimolar with H(2)O(2), while mannitol had no effect at all. The delay of the light emission as well as the appearance of TMPyPFe(IV) = O was directly proportional to the [UA](0) but other kinetic profiles were not changed significantly. Based on these observations and the kinetic analysis, we confirmed the involvement of the oxo-iron(IV) porphyrin radical cation, (TMPyP)(.+)Fe(IV) = O, as an obligatory intermediate in the rate-determining step of the overall reaction, Fe(III)TMPyP + H(2)O(2) --> TMPyPFe(IV) = O, with a rate constant of k = 4.3 x 10(4)/mol/L/s. The rate constants for the reaction between the (TMPyP)(.+)Fe(IV) = O and luminol, and between the TMPyPFe(IV) = O and luminol were estimated to be 3.6 x 10(6)/mol/L/s and 1.31 x 10(4)/mol/L/s, respectively. PMID:12701092

  5. Mercury removal from aqueous and organo-aqueous solutions by natural Mexican erionite

    The sorption of Hg(II) from aqueous and organo aqueous solutions was investigated by Mexican natural erionite. The mercury chemical species (anionic, cationic or neutral) were determined by high voltage electrophoresis, and the mercury chemical species present in the aqueous media were simulated by a program MEDUSA. The mercury sorption process was monitored during 48 hours. The mercury content was determined by neutron activation analysis. Mixtures of benzene/water[Hg(II)], toluene/water[Hg(II)] and ethanol/water[Hg(II)] were chosen as organo-aqueous media. It was found that both the mercury chemical species and the dielectric constant of solvents play an important role in the mercury sorption by erionite. (author)

  6. Dual fluorescence of naphthylamines in alkaline aqueous solution

    Ma, Li-Hua; Wen, Zhen-Chang; Lin, Li-Rong; Jiang, Yun-Bao


    Dual fluorescence was observed with N-(1-naphthyl)aminoacetate (1-NAA) in aqueous solution of pH 13.0 in the presence of cationic surfactants, cetyltrimethylammonium bromide (CTAB) and chloride (CTAC), below and after the critical micelle concentration (CMC). Similar dual fluorescence was also found with 1- and 2-naphthylamine (1-NA, 2-NA), N-(2-naphthyl)aminoacetate (2-NAA) and (1-naphthyl)ethylenediamine (1-NEDA), in the presence and absence of the cationic surfactants, but not with N, N-disubstituted 1- and 2-NAs. We concluded that the dual fluorescence was due to the excited-state deprotonation of the amino group in these NAs. The p Ka*s of the dual fluorescent NAs were estimated to be around 14 from the dual fluorescence pH titrations. No clear correlation was found for p Ka* with the amino substitution and the presence of cationic micelle.

  7. Interfacial Thermodynamics of Coexisting Aqueous Polymer Solutions

    Vis, M.


    Phase separation is commonly observed when two different polymers are present in aqueous solution, forming aqueous two-phase systems which typically consist for 90% of water. It is demonstrated that the presence of charge on one of the polymers results in an electric potential difference between the

  8. Tannin (Polyphenol) Stability in Aqueous Solutions

    Understanding the chemical stability of tannins (polyphenolics) in soils is critical to understanding their biological activities and fate. We examined the stability of chemically defined tannins in aqueous solutions under conditions simulating natural and laboratory conditions. We evaluated tanni...

  9. Modeling reactive geochemical transport of concentrated aqueous solutions

    Zhang, Guoxiang; Zheng, Zuoping; Wan, Jiamin


    Aqueous solutions with ionic strength larger than 1 M are usually considered concentrated aqueous solutions. These solutions can be found in some natural systems and are also industrially produced and released into accessible natural environments, and as such, they pose a big environmental problem. Concentrated aqueous solutions have unique thermodynamic and physical properties. They are usually strongly acidic or strongly alkaline, with the ionic strength possibly reaching 30 M or higher. Chemical components in such solutions are incompletely dissociated. The thermodynamic activities of both ionic and molecular species in these solutions are determined by the ionic interactions. In geological media the problem is further complicated by the interactions between the solutions and sediments and rocks. The chemical composition of concentrated aqueous solutions when migrating through the geological media may be drastically altered by these strong fluid-rock interactions. To effectively model reactive transport of concentrated aqueous solutions, we must take into account the ionic interactions. For this purpose we substantially extended an existing reactive transport code, BIO-CORE2D©, by incorporating a Pitzer ion interaction model to calculate the ionic activity. In the present paper, the model and two test cases of the model are briefly introduced. We also simulate a laboratory column experiment in which the leakage of highly alkaline waste fluid stored at Hanford (a U.S. Department of Energy site, located in Washington State) was studied. Our simulation captures the measured pH evolution and indicates that all the reactions controlling the pH evolution, including cation exchanges and mineral dissolution/precipitation, are coupled.

  10. Interfacial Thermodynamics of Coexisting Aqueous Polymer Solutions

    Vis, M


    Phase separation is commonly observed when two different polymers are present in aqueous solution, forming aqueous two-phase systems which typically consist for 90% of water. It is demonstrated that the presence of charge on one of the polymers results in an electric potential difference between the two phases. Upon phase separation, the polyelectrolyte is confined in majority to one of the phases. Although small ions can equilibrate freely between the phases, the restriction of macroscopic c...

  11. Pulse Radiolysis of Aqueous Solutions of Aniline and Substituted Anilines

    The primary reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals with aniline and the aniline cation in aqueous solutions have been studied by the technique of pulse radiolysis and by determination of end products after y-radiolysis. Hydrogen atoms and hydrated electrons react with aniline under formation of the cyclohexadienyl type radical with absorption maximum at 355 nm and an extinction coefficient of 4100/M/cm. A similar radical formed by reaction of hydrogen atoms with the aniline cation has its absorption maximum at 31 0 nm and an extinction coefficient of 3200/M/cm. Hydrogen atoms react with the acid and neutral forms of aniline with rate constants of (1.3 ± 0.2 ) x 109/M/s and (2.9 ± 0.7) x 109/M/s, respectively. OH radicals react with aniline with a rate constant of (1.4 ± 0.3) x 1010/M/s under formation of the cyclohexadienyl radical with absorption maximum at 355 nm and the anilino radical with absorption maxima at 300 and 400 nm. The cyclohexadienyl radical decayed in a first order process with a rate constant of 1.4 x 105/s by elimination of NH3, whereas the anilino radical disappeared in a second order reaction under formation of hydrazobenzene. O- radicals react with aniline at pH 13.3 with a rate constant of (3.1 ± 0.6) x 109 under formation of anilino radicals. The reaction of OH radicals with the aniline cation produced the anilino radical cation with a rate constant of (4.8 ± 0.8) x 109 . The absorption maximum was placed at 415 nm, The cyclohexadienyl type radical with absorption maximum at 350 nm was also found in aqueous solutions of 2-amino-1,3-dimethylbenzene but was not formed in solutions of N,N' -dimethylaniline

  12. Precipitation of neptunium dioxide from aqueous solution

    Roberts, K E


    Tens of thousands of metric tons of highly radioactive, nuclear waste have been generated in the US. Currently, there is no treatment or disposal facility for these wastes. Of the radioactive elements in high-level nuclear waste, neptunium (Np) is of particular concern because it has a long half-life and may potentially be very mobile in groundwaters associated with a proposed underground disposal site at Yucca Mountain, Nevada. Aqueous Np concentrations observed in previous, short-term solubility experiments led to calculated potential doses exceeding proposed long-term regulatory limits. However, thermodynamic data for Np at 25 C showed that these observed aqueous Np concentrations were supersaturated with respect to crystalline NpO{sub 2}. It was hypothesized that NpO{sub 2} is the thermodynamically stable solid phase in aqueous solution, but it is slow to form in an aqueous solution of NpO{sub 2}{sup +} on the time scale of previous experiments. The precipitation of NpO{sub 2} would provide significantly lower aqueous Np concentrations leading to calculated doses below proposed regulatory limits. To test this hypothesis, solubility experiments were performed at elevated temperature to accelerate any slow precipitation kinetics. Ionic NpO{sub 2}{sup +} (aq) was introduced into very dilute aqueous solutions of NaCl with initial pH values ranging from 6 to 10. The reaction vessels were placed in an oven and allowed to react at 200 C until steady-state aqueous Np concentrations were observed. In all cases, aqueous Np concentrations decreased significantly from the initial value of 10{sup {minus}4} M. The solids that formed were analyzed by x-ray powder diffraction, x-ray absorption spectroscopy, and scanning electron microscopy. The solids were determined to be high-purity crystals of NpO{sub 2}. This is the first time that crystalline NpO{sub 2} has been observed to precipitate from NpO{sub 2}{sup +}(aq) in near-neutral aqueous solutions. The results obtained

  13. Organo/Zn-Al LDH Nanocomposites for Cationic Dye Removal from Aqueous Media.

    Starukh, G; Rozovik, O; Oranska, O


    Cationic dye sorption by Zn-Al-layered double hydroxides (LDHs) modified with anionic surfactants was examined using methylene blue (MB) dye as a compound model in aqueous solutions. The modification of Zn-Al LDHs was performed by reconstruction method using dodecyl sulfate anion (DS) solutions. DS contained Zn-Al LDHs were characterized by XRD, FTIR, thermogravimetric, and SEM analysis. The reconstructed organo/Zn-Al LDHs comprise the crystalline phases (DS-intercalated LDHs, hydrotalcite), and the amorphous phase. The intercalation of DS ions into the interlayer galleries and DS adsorption on the surface of the LDHs occurred causing the MB adsorption on the external and its sorption in the internal surfaces of modified LDHs. The presence of DS greatly increased the affinity of organo/Zn-Al LDHs for MB due to hydrophobic interactions between the surfactants and the dye molecules. The optical properties of sorbed MB were studied. PMID:27119156

  14. Organo/Zn-Al LDH Nanocomposites for Cationic Dye Removal from Aqueous Media

    Starukh, G.; Rozovik, O.; Oranska, O.


    Cationic dye sorption by Zn-Al-layered double hydroxides (LDHs) modified with anionic surfactants was examined using methylene blue (MB) dye as a compound model in aqueous solutions. The modification of Zn-Al LDHs was performed by reconstruction method using dodecyl sulfate anion (DS) solutions. DS contained Zn-Al LDHs were characterized by XRD, FTIR, thermogravimetric, and SEM analysis. The reconstructed organo/Zn-Al LDHs comprise the crystalline phases (DS-intercalated LDHs, hydrotalcite), and the amorphous phase. The intercalation of DS ions into the interlayer galleries and DS adsorption on the surface of the LDHs occurred causing the MB adsorption on the external and its sorption in the internal surfaces of modified LDHs. The presence of DS greatly increased the affinity of organo/Zn-Al LDHs for MB due to hydrophobic interactions between the surfactants and the dye molecules. The optical properties of sorbed MB were studied.

  15. Recovery of niobium anions from aqueous solutions by ion flotation

    In principle the feasibility of recovering niobates (K2NbOF5 and K2NbF7) from aqueous media by ion flotation was established. When using quaternary ammonium bases or amines as the collectors, the optimal conditions lie in the interval pH = 5.0-9.0. The interaction of niobates with cationic surfactants may proceed through an anion-exchange mechanism. The presence of acid in the solution suppresses this interaction, owing to the competition from the anions that are present and owing to binding of the surface-active collectors into a complex. 3 figures

  16. Diffusion coefficients of paracetamol in aqueous solutions

    Highlights: ► Mutual diffusion coefficients of paracetamol in aqueous dilute solutions. ► Influence of the thermodynamic factors on the variation of their mutual diffusion coefficients. ► Estimation of the mutual limiting diffusion coefficients of the molecular, Dm0, and ionized forms, D±0, of this drug. - Abstract: Binary mutual diffusion coefficients measured by the Taylor dispersion method, for aqueous solutions of paracetamol (PA) at concentrations from (0.001 to 0.050) mol·dm−3 at T = 298.15 K, are reported. From the Nernst–Hartley equation and our experimental results, the limiting diffusion coefficient of this drug and its thermodynamic factors are estimated, thereby contributing in this way to a better understanding of the structure of such systems and of their thermodynamic behaviour in aqueous solution at different concentrations.

  17. Hydrophobic Solvation: Aqueous Methane Solutions

    Konrod, Oliver; Lankau, Timm


    A basic introduction to concept of a solvation shell around an apolar solute as well as its detection is presented. The hydrophobic solvation of toluene is found to be a good teaching example which connects macroscopic, phenomenological thermodynamic results with an atomistic point of view.

  18. Issues in Freeze Drying of Aqueous Solutions

    王维; 陈墨; 陈国华


    Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry. The in-creased importance Of the process is gaining a worldwide interest of research. A growing body of literature has demonstrated that the scientific approach can result in improved product quality with minimum trial and error em-piricism. Formulation and process development need a systematical understanding of the physical chemistry of freezing and freeze drying, material science and mechanisms of heat and mass transfer. This paper presents an overview on freeze ding of aqueous solutions based on publications in the past few decades. The important issuesof the process are analyzed.

  19. Thermo-responsive properties driven by hydrogen bonding in aqueous cationic gemini surfactant systems.

    Wei, Xi-Lian; Han, Chuan-Hong; Geng, Pei-Pei; Chen, Xiao-Xiao; Guo, Yan; Liu, Jie; Sun, De-Zhi; Zhang, Jun-Hong; Yu, Meng-Jiao


    A series of unexpected thermo-responsive phenomena were discovered in an aqueous solution of the cationic gemini surfactant, 2-hydroxypropyl-1,3-bis(alkyldimethylammonium chloride) (n-3(OH)-n(2Cl), n = 14, 16), in the presence of an inorganic salt. The viscosity change trend for the 14-3(OH)-14(2Cl) system was investigated in the 20-40 °C temperature range. As the temperature increased, the viscosity of the solution first decreased to a minimum point corresponding to 27 °C, and then increased until a maximum was reached, after which the viscosity decreased again. In the 16-3(OH)-16(2Cl) system, the gelling temperature (T(gel)) and viscosity changes upon heating were similar to those in the 14-3(OH)-14(2Cl) system above 27 °C. The reversible conversion of elastic hydrogel to wormlike micelles in the aqueous solution of the 16-3(OH)-16(2Cl) system in the presence of an inorganic salt was observed at relatively low temperatures. Various techniques were used to study and verify the phase-transition processes in these systems, including rheological measurements, cryogenic transmission electron microscopy (cryo-TEM), electric conductivity, and differential scanning calorimetry. The abovementioned phenomena were explained by the formation and destruction of intermolecular hydrogen bonds, and the transition mechanisms of the aggregates were analyzed accordingly. PMID:26659081

  20. Quasi-Immiscible Spreading of Aqueous Surfactant Solutions on Entangled Aqueous Polymer Solution Subphases

    Sharma, Ramankur; Corcoran, Timothy E.; Garoff, Stephen; Przybycien, Todd M.; Swanson, Ellen R.; Tilton, Robert D.


    Motivated by the possibility of enhancing aerosol drug delivery to mucus-obstructed lungs, the spreading of a drop of aqueous surfactant solution on a physically entangled aqueous poly(acrylamide) solution subphase that mimics lung airway surface liquid was investigated. Sodium dodecyl sulfate was used as the surfactant. To visualize spreading of the drop and mimic the inclusion of a drug substance, fluorescein, a hydrophilic and non-surface active dye, was added to the surfactant solution. T...

  1. Physical chemistry of the interface between oxide and aqueous solution

    The behavior and properties of small oxide particles in aqueous suspension are dominated by the physico-chemistry of their surface. It is electrostatically charged and strongly solvated. The origin of the surface charge is discussed through the MUSIC model [Hiemstra 1996], allowing to estimate the acid-base behavior of surface oxygen atoms. The stability of aqueous dispersions of particles is analysed following the DLVO model, with a special attention on the hydration layers allowing the peptization of flocs. Different adsorption mechanisms of metal cations are presented in terms of coordination chemistry (outer- and inner-sphere complexes) emphasizing the coordinating ability of the surface towards metal complexes in solution. The anion adsorption is also studied in relation with some interesting consequences on spinel iron oxide nano-particles. (author)

  2. Radium removal from aqueous sulphate solutions

    A process for removing radium from an aqueous sulphate solution also containing magnesium is claimed. The pH of the solution is less than 10. A soluble barium salt is added to the solution to precipitate radium as barium radium sulphate. The pH of the solution is then raised to at least 11 to precipitate an insoluble magnesium compound which collects the barium radium sulphate precipitate. The precipitates are separated from the solution. If the sulphate solution contains dissolved magnesium and other impurities at a pH not greater than 7, then the first step in the process involves raising the pH of the solution to a value not greater than 10 to precipitate some of the magnesium and a substantial proportion of the other impurities and separating the precipitate from the solution. The radium removal is a step in the treatment of liquids resulting from the sulphuric acid leaching of uranium ores

  3. Aqueous solutions of ionic liquids: microscopic assembly

    J.M. Vicent-Luna; D. Dubbeldam; P. Gómez-Álvarez; S. Calero


    Aqueous solutions of ionic liquids are of special interest, due to the distinctive properties of ionic liquids, in particular, their amphiphilic character. A better understanding of the structure-property relationships of such systems is hence desirable. One of the crucial molecular-level interactio


    Peppard, D.F.; Nachtman, E.S.


    This patent relates to a process for the separation of scandium from yttrium, thorium, and trivalent rare earths and with their separation from each other. It has been found that scandium and yttrium can be separated from trivalent rare earths in acidic solution, for example, a solution 6 M in HCl, by contacting with tributyl phosphate, whereupon the scandum is preferentially extracted into the organic phase, leaving the yttrium and trivalent rare earths in the aqueous phase.

  5. Study of aqueous solutions of sodium linoleate

    Van der Linde, G.J. (Phosphate Development Corporation, Phalaborwa); Van Berge, P.C. (Rand Afrikaans Univ., Johannesburg (South Africa))


    During the development of a technique for measuring fatty acid absorption on finely divided minerals using a radiochemical method, absorption isotherms were obtained which displayed maxima. It was found that these results were due to the presence of stable micelles in the solutions. This has been established by measuring the surface tension, surface film pressure, and specific conductance of dilute aqueous solutions of sodium linoleate.

  6. Adsorption of Organic Dyes from Aqueous Solution by Surfactant Modified Corn Straw

    C. Umpuch; B. Jutarat


    The modification of adsorbent with a cationic surfactant is an effective and inexpensive method to enhance sorption capability of adsorbent. In this study, raw corn straw, modified with a cationic surfactant, tetradecyltrimethyl ammonium bromide was used as adsorbent for dye removal from aqueous solution. The modification caused surface properties of the adsorbent altered from hydrophilic to hydrophobic. To comprehend the modification, the physical property of adsorbents was characterized by ...

  7. Adsorption of and acidic dye from aqueous solution by surfactant modified bentonite

    The aim of this paper is to study the adsorption of an acidic dye S. Y. 4 GL (i.e: Supranol yellow 4GL) from aqueous solution on inorgano-organo clay. Bentonite is a kind of natural clay with good exchanging ability. By exchanging its inter lamellar cations with Cetyltrimethylammonium bromide (CTAB) and hydroxy aluminic or chromium poly cations, the properties of natural bentonite can be greatly improved. (Author)

  8. Thermodynamics of dilute aqueous solutions of imidazolium based ionic liquids

    Research highlights: → The thermodynamic behaviour of aqueous imidazolium ILs has been investigated. → Volumetric and ultrasonic results indicated the hydrophobic hydration of ILs. → Viscometric studies revealed studied ionic liquids as water-structure makers. → Hydration number increased with increase in alkyl chain length of the cation. - Abstract: Experimental measurements of density ρ, speed of sound u, and viscosity η of aqueous solutions of various 1-alkyl-3-methylimidazolium based ionic liquid (IL) solutions have been performed in dilute concentration regime at 298.15 K to get insight into hydration behaviour of ILs. The investigated ILs are based on 1-alkyl-3-methylimidazolium cation, [Cnmim] having [BF4]-, [Cl]-, [C1OSO3]-, and [C8OSO3]- as anions where n = 4 or 8. Several thermodynamic parameters like apparent molar volume φV, isentropic compressibility βs, and viscosity B-coefficients have been derived from experimental data. Limiting value of apparent molar volume has been discussed in terms of intrinsic molar volume (Vint) molar electrostriction volume (Velec), molar disordered (Vdis), and cage volume (Vcage). Viscosity B-coefficients have been used to quantify the kosmotropic or chaotropic nature of ILs. Hydration number of ILs obtained using elctrostriction volume, isentropic compressibility, viscosity, and differential scanning calorimetry have been found to be comparative within the experimental error. The hydrophobic hydration has found to play an important role in hydration of ILs as compared to hydration due to hydrogen bonding and electrostriction. Limiting molar properties, hydration numbers, and B-coefficients have been discussed in terms of alkyl chain length of cation or nature of anion.

  9. Influence of coal properties on mercury uptake from aqueous solution

    Lakatos, J.; Brown, S.D.; Snape, C.E. [Miskolc University, Miskolc-Egyetemvaros (Hungary). Research Inst. of Applied Chemistry


    The uptake of mercury (II) from aqueous solution by a range of coals has been studied and the results have been compared to those for a number of other sorbents, including commercial active carbons and cation-exchange resins. At pH 5 in a buffer medium, the capacities for mercury removal of the low-rank coals and the oxidized bituminous coals investigated are comparable to those of the other sorbents tested. For the lignites investigated, a high content of organic sulfur does not markedly affect the capacity for mercury uptake in relatively neutral and low chloride media, owing to redox reactions being the most likely mechanism involved. However, in highly acidic solutions, the capacities for mercury uptake are considerably greater for the high-sulfur coals investigated than for their low-sulfur counterparts due to chelation being the major sorption process involved. 36 refs., 4 figs., 7 tabs.

  10. An electrochemical treatment for aqueous radioactive solutions using pottery

    A bench scale electrolytic cell made from plexiglas was used for electrochemical separation of 137Cs and 60Co from simullated aqueous radioactive solutions. In this cell, a stainless steel plate represented the anode. The electrochemical treatment technique used depends on forcing the radioactive cations of the solution (137Cs+ and 60Co++) towards the opposite electrode under the influence of applied electric current, where they highly sorbed in the pottery body. The highest removal for137Cs+ and 60Co was in the alkalina medium, especially at pH>9. The investigated factors affected the electrochemicla processes are, applied voltage, treatment duration, hydrogen ion concentration of the radioactive solution, and the consumed electrical energy . It was found that at pH 11, applied voltage 30V and current 100 mA, the highest removal of 137Cs is 99.8% after 2.5 hours, and 99.3% and 99.3% for 60Co after 1.25 hour.The total consumed energy for 137Cs and 60Co were 33.75 and 16.88, respectively. Comparing with other treatment methods, the electrochemical method revealed three advantages: shorter treatment time, low-cost materials, and low consumed energy. The results obtained showed that the dual application of electric current and sorption on the surface of pottery are feasible for the treatment of aqueous radioactive solutions

  11. Removal of radium from aqueous sulphate solutions

    Radium is often present in ores and an aqueous solution associated with the ore may consequently contain dissolved radium. It is frequently necessary to remove radium from such solutions to reduce the total radium content to a prescribed low level before the solution can be returned to the environment. The present invention is based on the discovery that the total radium content can be reduced to a satisfactory level within a reasonable time by adding a soluble barium salt to a radium-containing sulphate solution which also contains dissolved magnesium at a pH not greater than about 0 to precipitate radium as barium radium sulphate, raising the pH to at least 11 to precipitate an insoluble magnesium compound which collects the barium radium sulphate precipitate, and separating substantially all of the precipitates from the solution

  12. Uranyl fluoride luminescence in acidic aqueous solutions

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO2F2. Studies on the effect of added LiNO3 or Na2WO4·2H2O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF6 content of WF6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF6

  13. Zeolites as alcohol adsorbents from aqueous solutions

    Cekova Blagica


    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  14. Does Dimeric Melittin Occur in Aqueous Solutions?

    Schubert, D; Pappert, G.; Boss, K.


    Melittin, a peptide from bee venom, is known to undergo a monomer / tetramer conversion in aqueous solutions. We have studied the possible participation of dimers in the association equilibrium of melittin by sedimentation equilibrium experiments in the analytical ultracentrifuge and subsequent mathematical analysis of the concentration distributions obtained. It was found that the dimeric state is not significantly populated, the contribution of dimer to the total peptide weight probably bei...

  15. Aqueous solution dispersement of carbon nanotubes

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)


    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  16. Photolysis of imidacloprid in aqueous solution

    The photolysis of the insecticide imidacloprid in aqueous solution has been examined. Irradiation at 290 nm resulted in 90 % substrate transformation in 4 h. The degradation approximately followed first order kinetics; the rate constant is 1.6 × 10−4s−1 and half-life 1.2 h. 6-Chloronicotinaldehyde, N-methylnicotinacidamide, 1-(6-chloronicotinyl)imidazolidone and 6-chloro-3-pyridyl-methylethylendiamine were the main photoproducts identified by CG-MS analysis. (author)

  17. Simple Molecular Models of Aqueous Solutions

    Jirsák, Jan; Škvor, J.; Nezbeda, Ivo

    - : -, 2013. ISBN N. [EMLG - JMLG Annual Meeting 2013 Global Perspectives in the Structure and Dynamics in Liquids and Mixtures: Experiment and Simulation. Lille (FR), 09.09.2013-13.09.2013] Grant ostatní: GA ČR(CZ) GPP208/12/P710 Institutional support: RVO:67985858 Keywords : aqueous solutions * thermodynamic modeling * simulation data Subject RIV: CF - Physical ; Theoretical Chemistry

  18. Autoxidation of tryptophan in aqueous solutions



    Autoxidation of tryptophan was investigated in aqueous solutions by the gamma radiolytic technique. The oxygen uptake and formation of peroxide materials was followed as a function of pH, dose rate and concentration of tryptophan. The results obtained indicate that TrpH(OH)OO. radicals react with tryptophan by adduct formation thus propagating autoxidation. The chain propagation length (CPL) for a 2·102 mol dm3 tryptophan solution at pH 9.5 and a dose rate 0.01 Gy s1 was estimated to be ~ 5.8...

  19. Equilibrium Studies of Some Metal Ions onto Modified Orange Mesocarp Extract in Aqueous Solution

    Ibezim-Ezeani, Millicent U.; Okoye, Francis A.; Akaranta, Onyewuchi


    This paper examines the equilibrium removal of Zinc, Copper, Nickel and Cobalt ions from aqueous solutions by cation exchange resins synthesized using orange mesocarp extract. The percentage metal ion exchange of Carboxylated-Toluene Di-isocyanate Orange Mesocarp Extract Resin (CTOR) increased with increase in pH of the solution phase, while that of Sulphonated-Toluene Di-isocyanate Orange Mesocarp Extract Resin (STOR) was relatively uniform with increase in solution pH. The results also show...


    E. V. Avramenko


    Full Text Available Subject of Research. The paper presents the results of measurements of refractometric properties (refractive index n, its temperature factor dn/dt and the ultraviolet spectral absorption in carbonic acid diamide aqueous solutions (carbamide depending on solid residue mass fraction md = 0-50 % and on temperaturet = 10-70 °C.Method of Research. Laboratory methods ofliquid-phase medium refractometry and ultraviolet spectrophotometry were applied for the research. We carried out computational modeling of electronic states spectrum for the carbonic acid diamide molecule and theoretical calculation of the fundamental electronic absorption of the molecule in the ultraviolet wavelenght region.Main Results. We have established that the solution concentration md has a nonlinear character and may be represented by the quadratic polynomial with the error Δn= ± 0,0005. We have shown the refractive indexdependence on temperature n(t changes in linear fashion att = 10-70 °C.At that, the inclination of lines n(t increases at the increase of md; so, the temperature factor dn/dt may be approximated by the quadratic polynomial. Transmission spectra of solutions in the spectral region λ= 225-760 nm have no special features except for the sharp edge in the short-wavelength region; the fundamental electronic absorptionis responsible for it. We have established that dispersion dependences of the refraction index n(λ;md in aqueous solutions of carbamide at λ= 360-760 nm and at md = 0-50 % may be calculated with the satisfactory error without additional adjustable parameters from the ultraviolet absorption data in terms of the one-dimentional oscillator Lorentz model.PracticalRelevance. Representedmeasurements of carbonic acid diamide aqueous solutions optical properties may be applied for the adjustment and calibration of commercial refractometers at processing lines of the AdBlue reagent manufacture for the selective catalytic reduction (SCR of motor transport

  1. Influence of thermal treatment on bentonite used as adsorbent for Cd, Pb, Zn retention from mono-solute and poly-solute aqueous solutions

    Susana Yamila Martinez Stagnaro


    Full Text Available The retentions of Zn, Cd and Pb cations by one treated bentonite up to 750 °C were analyzed. The retentions were evaluated by using mono-and poly-solute aqueous solutions of such cations. The adsorptions were carried out in batch system at room temperature. The solid/liquid ratio was 2% wt.v-1. The solids were characterized by X-ray diffraction, thermal and chemical analyses. The Zn cation from mono- or polysolute-solutions was retained in higher amount than Cd and Pb cations in similar solution types by bentonite. The retentions were effective up to 450 °C calcined bentonite, after that, the retention capacity decreased in concordance with dehydroxylation of the structure of clay minerals.

  2. Preparation of fluorescent polyaniline nanoparticles in aqueous solutions

    Alves, Kleber G. B. [Universidade Federal de Pernambuco, Departamento de Engenharia Mecanica (Brazil); Melo, Etelino F. de [Universidade Federal de Pernambuco, Departamento de Quimica Fundamental (Brazil); Andrade, Cesar A. S. [Universidade Federal de Pernambuco, Departamento de Bioquimica (Brazil); Melo, Celso P. de, E-mail: [Universidade Federal de Pernambuco, Departamento de Fisica (Brazil)


    We report the synthesis of stable polyaniline nanoparticles (PANI{sub N}Ps) based on the chemical oxidative polymerization of aniline in aqueous solutions of surfactants. Surfactants of three different types-cationic (dodecyltrimethylammonium bromide-DTAB), anionic (sodium dodecyl sulfate-SDS), and non-ionic (Triton X-405-TX-405)-were used. The resulting PANI{sub N}Ps{sub s}urfactant samples were characterized through UV-Vis, fluorescence and Fourier transform infrared spectroscopies, and scanning electronic microscopy (SEM). We have verified that the color of the PANI{sub N}Ps{sub s}urfactant dispersions is affected by a change in the pH of the solution. The PANI-NPs{sub s}urfactant colloidal suspensions in aqueous solution present a surprising high fluorescence quantum yield value (ranging from 1.9 Multiplication-Sign 10{sup -3} to 6.9 Multiplication-Sign 10{sup -3}) that can be controlled as a function of the pH, a fact that we associate to the corresponding protonation degree of the PANI polymeric chains. We suggest that these fluorescent nanocomposites can find important technological applications in different areas such as organic light emitting devices, biosensors, and pigments for coatings.

  3. Density of aqueous solutions of CO2

    Garcia, Julio E.


    In this report, we present a numerical representation for the partial molar volume of CO2 in water and the calculation of the corresponding aqueous solution density. The motivation behind this work is related to the importance of having accurate representations for aqueous phase properties in the numerical simulation of carbon dioxide disposal into aquifers as well as in geothermal applications. According to reported experimental data the density of aqueous solutions of CO2 can be as much as 2-3% higher than pure water density. This density variation might produce an influence on the groundwater flow regime. For instance, in geologic sequestration of CO2, convective transport mixing might occur when, several years after injection of carbon dioxide has stopped, the CO2-rich gas phase is concentrated at the top of the formation, just below an overlaying caprock. In this particular case the heavier CO2 saturated water will flow downward and will be replaced by water with a lesser CO2 content.

  4. Optical manipulation of proteins in aqueous solution

    Optical trapping of lysozyme, cytochrome c, or myoglobin based on photon pressure generated by focusing 1064 nm laser beam in an aqueous solution was explored. For all the proteins, microparticle formation was observed at the focal point under an optical microscope. Furthermore, the microparticles were identified to the molecular assemblies of the corresponding protein by means of confocal Raman microspectroscopy. For lysozyme, molecular clusters in solution were optically trapped to form the microparticle and it took more than 1 h to produce the microparticle. By contrast, molecular assembling proceeded within 1 min for cytochrome c and myoglobin. Since heme in cytochrome c or myoglobin would have a high polarizability, that would contribute to rapid assembling of the protein. Thus we demonstrated that a focused laser beam was a powerful tool to manipulate protein molecules in solution.

  5. NIR Spectroscopic Properties of Aqueous Acids Solutions

    Mohd Zubir MatJafri


    Full Text Available Acid content is one of the important quality attributes in determining the maturity index of agricultural product, particularly fruits. Despite the fact that much research on the measurement of acidity in fruits through non-destructive spectroscopy analysis at NIR wavelengths between 700 to 1,000 nm has been conducted, the same response towards individual acids is not well known. This paper presents NIR spectroscopy analysis on aqueous citric, tartaric, malic and oxalic solutions through quantitative analysis by selecting a set of wavelengths that can best be used to measure the pH of the solutions. The aquaphotomics study of the acid solutions has generated R2 above 0.9 for the measurement of all acids. The most important wavelengths for pH are located at 918–925 nm and 990–996 nm, while at 975 nm for water.

  6. Thermodynamics of micellization of alkylimidazolium surfactants in aqueous solution

    Alkylimidazolium salts are a very important class of compounds. So far, calorimetry has hardly been used to characterize their solution behaviour. The enthalpies obtained from indirect methods have an intrinsic large uncertainty, and nowadays it is clear that calorimetry is the most sensitive technique for directly measuring the thermodynamic properties of aggregation. In this work, isothermal titration calorimetry (ITC) was used along with conductivity to determine the thermodynamics of aggregation of 1-alkyl-3-methylimidazolium chlorides ([Cnmim]Cl, n = 8, 10, 12, and 14) in aqueous solution. The critical micelle concentrations, cmc, were obtained from conductivity and calorimetry, and the enthalpies of micelle formation, ΔHmic, were derived from the calorimetric titrations. From conductivity, we could also derive the values for the degree of ionisation of the micelles (α), the molar conductivity (ΛM) of the [Cnmim]Cl micellar species and the molar conductivity at infinite dilution (Λ∞) for the [Cnmim]+ cations. Values are therefore reported for the enthalpy (ΔHmic), the Gibbs free energy (ΔGmic) and entropy (ΔSmic) changes for micelle formation. Further, the aggregate sizes and aggregation numbers were obtained by light scattering (LS) measurements. The observed variation of the thermodynamic properties with the alkyl chain length is discussed in detail and compared with the traditional cationic surfactants 1-alkyl-trimethylammonium chlorides, [CnTA]Cl. The difference in the values of the thermodynamic parameters for both types of surfactants is here related to the structure of their head groups

  7. Aqueous Solution Vessel Thermal Model Development II

    Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    The work presented in this report is a continuation of the work described in the May 2015 report, “Aqueous Solution Vessel Thermal Model Development”. This computational fluid dynamics (CFD) model aims to predict the temperature and bubble volume fraction in an aqueous solution of uranium. These values affect the reactivity of the fissile solution, so it is important to be able to calculate them and determine their effects on the reaction. Part A of this report describes some of the parameter comparisons performed on the CFD model using Fluent. Part B describes the coupling of the Fluent model with a Monte-Carlo N-Particle (MCNP) neutron transport model. The fuel tank geometry is the same as it was in the May 2015 report, annular with a thickness-to-height ratio of 0.16. An accelerator-driven neutron source provides the excitation for the reaction, and internal and external water cooling channels remove the heat. The model used in this work incorporates the Eulerian multiphase model with lift, wall lubrication, turbulent dispersion and turbulence interaction. The buoyancy-driven flow is modeled using the Boussinesq approximation, and the flow turbulence is determined using the k-ω Shear-Stress-Transport (SST) model. The dispersed turbulence multiphase model is employed to capture the multiphase turbulence effects.

  8. Stopped-Flow Spectrophotometric Study of the Kinetics and Mechanism of CO2 Uptake by cis-[Cr(C2O4(BaraNH2(OH22]+ Cation and the Acid-Catalyzed Decomposition of cis-[Cr(C2O4(BaraNH2OCO2]− Anion in Aqueous Solution

    Lech Chmurzyński


    Full Text Available The kinetics of CO2 uptake by the cis-[Cr(C2O4(BaraNH2(OH22]+ complex cation and the acid hydrolysis of the cis-[Cr(C2O4(BaraNH2OCO2]− complex anion (where BaraNH2 denotes methyl 3-amino-2,3-dideoxy-b-D-arabino-hexopyranoside were studied using the stopped-flow technique. The reactions under study were investigated in aqueous solution in the 288–308 K temperature range. In the case of the reaction between CO2 and cis-[Cr(C2O4(BaraNH2(OH22]+ cation variable pH values (6.82–8.91 and the constant ionic strength of solution (H+, Na+, ClO4− = 1.0 were used. Carbon dioxide was generated by the reaction between sodium pyruvate and hydrogen peroxide. The acid hydrolysis of cis-[Cr(C2O4(BaraNH2OCO2]− was investigated for varying concentrations of H+ ions (0.01–2.7 M. The obtained results enabled the determination of the number of steps of the studied reactions. Based on the kinetic equations, rate constants were determined for each step. Finally, mechanisms for both reactions were proposed and discussed. Based on the obtained results it was concluded that the carboxylation (CO2 uptake reactions of cis-[Cr(C2O4(BaraNH2(OH22]+ and the decarboxylation (acid hydrolysis of the cis-[Cr(C2O4(BaraNH2OCO2]− are the opposite of each other.

  9. Enhanced separation of Compound Xueshuantong capsule using functionalized carbon nanotubes with cationic surfactant solutions in MEEKC.

    Cao, Jun; Li, Ping; Chen, Jue; Tan, Ting; Dai, Han-Bin


    A novel additive of multi-walled carbon nanotubes (MWNTs) dispersed with cationic surfactants or mixed cationic/anionic surfactants was used for MEEKC separation of eight phenolic compounds, four glycosides, and one phenanthraquinone. In this context, several parameters affecting MEEKC separation were studied, including the dispersion agents of MWNTs, MWNTs content, oil type, SDS concentration, and the type and concentration of cosurfactant. Compared with conventional MEEKC, the addition of all types of MWNTs dispersions using single or mixed cationic surfactant solutions in running buffers was especially useful for improving the separation of solutes tested, as they influenced the partitioning between the oil droplets and aqueous phase due to the exceptional electrical properties and large surface areas of MWNTs. Use of cationic surfactant-coated MWNTs (6.4 μg/mL) as the additive in a microemulsion buffer (0.5% octanol, 2.8% SDS, 5.8% isopropanol, and 5 mM borate buffer) yielded complete resolution of 13 analytes. The proposed method has been successfully applied for the detection and quantification of the studied compounds in a complex matrix sample (Compound Xueshuantong capsule). PMID:23161282

  10. Pulse Radiolysis of Aqueous Thiocyanate Solution

    The pulse radiolysis of N2O saturated aqueous solutions of KSCN was studied under neutral pH conditions. The observed optical absorption spectrum of the SCN#lgbullet# radical in solution is more complex than previously reported, but it is in good agreement with that measured in the gas phase. Kinetic traces at 330 nm and 472 nm corresponding to SCN#lgbullet# and (SCN)2#lgbullet#-, respectively, were fit using a Monte Carlo simulation kinetic model. The rate coefficient for the oxidation of SCN- ions by OH radicals, an important reaction used in competition kinetics measurements, was found to be 1.4 ± 0.1 x 1010 M-1 s-1, about 30% higher than the normally accepted value. A detailed discussion of the reaction mechanism is presented

  11. Stability of selenourea in aqueous solutions

    Mel' chekova, Z.E.


    Studies of the synthesis of metal selenides from aqueous solutions are being conducted within the framework of investigations on the creation of new semiconductor materials. Selenourea in solution is a complex multicomponent system. The products of hydrolytic decomposition are H/sub 2/CN/sub 2/, Se/sup 2 -/, and HSe/sup -/. As a result of the oxidation of selenium-containing decomposition products by atmospheric oxygen, elementary selenium is formed. The decomposition of selenourea in alkaline sulfite solutions is accompanied by the dissolution of Se/sup 2 -/ and HSe/sup 0/ ions (Se/sup 0/), with the formation of selenosulfate. A study of the kinetics of decomposition was conducted under the conditions of formation of metal selenides, which do not exclude the oxidation process. The end product of the decomposition of selenourea in alkaline sulfite solutions is selenosulfate. The formation of selenosulfate was demonstrated by the isolation of elementary selenium under the action of formaldehyde. The rate constants of the decomposition of selenourea were calculated by the method of changes in concentration, slope of the straight lines, and a logarithmic method. The use of methods of monitoring of selenourea and its decomposition products permitted a theoretical substantiation of the selection of the optimum conditions of formation of metal selenides.

  12. Catalyzed reduction of nitrate in aqueous solutions

    Sodium nitrate and other nitrate salts in wastes is a major source of difficulty for permanent disposal. Reduction of nitrate using aluminum metal has been demonstrated, but NH3, hydrazine, or organic compounds containing oxygen would be advantageous for reduction of nitrate in sodium nitrate solutions. Objective of this seed money study was to determine minimum conditions for reduction. Proposed procedure was batchwise heating of aqueous solutions in closed vessels with monitoring of temperatures and pressures. A simple, convenient apparatus and procedure were demonstrated for observing formation of gaseous products and collecting samples for analyses. The test conditions were 250 degree C and 1000 psi max. Any useful reduction of sodium nitrate to sodium hydroxide as the primary product was not found. The nitrate present at pHs 3 or NH4NO3 is easily decomposed, and the effect of nitromethane at these low pHs was confirmed. When acetic acid or formic acid was added, 21 to 56% of the nitrate in sodium nitrate solutions was reduced by methanol or formaldehyde. With hydrazine and acetic acid, 73 % of the nitrate was decomposed to convert NaNO3 to sodium acetate. With hydrazine and formic acid, 36% of the nitrate was decomposed. If these products are more acceptable for final disposal than sodium nitrate, the reagents are cheap and the conversion conditions would be practical for easy use. Ammonium acetate or formate salts did not significantly reduce nitrate in sodium nitrate solutions

  13. Heterogeneous nucleation of aspartame from aqueous solutions

    Kubota, Noriaki; Kinno, Hiroaki; Shimizu, Kenji


    Waiting times, the time from the instant of quenching needed for a first nucleus to appear, were measured at constant supercoolings for primary nucleation of aspartame (α-L-aspartyl-L-phenylalanine methylester) from aqueous solutions, which were sealed into glass ampoules (solution volume = 3.16 cm 3). Since the waiting time became shorter by filtering the solution prior to quenching, the nucleation was concluded to be heterogeneously induced. The measured waiting time consisted of two parts: time needed for the nucleus to grow to a detactable size (growth time) and stochastic time needed for nucleation (true waiting time). The distribution of the true waiting time, is well explained by a stochastic model, in which nucleation is regarded to occur heterogeneously and in a stochastic manner by two kinds of active sites. The active sites are estimated to be located on foreign particles in which such elements as Si, Al and Mg were contained. The amount of each element is very small in the order of magnitude of ppb (mass basis) of the whole solution. The growth time was correlated with the degree of supercooling.

  14. Lifetimes of -halo and -azidobenzyl carbocations in aqueous solution

    R Sanjeev; V Jagannadham


    The title cations were produced in aqueous solution by chemical initiation (solvolysis) of benzyl-gem-dihalides and benzyl-gem-diazides. The solvolysis reactions of benzyl-gem-dihalides and benzyl-gem-diazides in water proceed by a stepwise mechanism through -halobenzyl carbocation and -azidobenzyl carbocation intermediates, which are captured by water to give the corresponding carbonyl compounds as the sole detectable products. Rate constant ratio / (M-1) for partitioning of the carbocation between reaction with halide/azide ion and reaction with water is determined by analysis of halide/azide common ion inhibition of the solvolysis reaction. The rate constants (s-1) for the reaction of the cation with solvent water were determined from the experimental values of / and solv, for the solvolysis of the benzyl-gem-dihalides and benzyl-gem-diazides respectively, using = 5 × 109 M-1 s-1 for diffusion-limited reaction of halide/azide ion with -substituted benzyl carbocations. The values of 1/ are thus the lifetimes of the -halobenzyl carbocations and -azidobenzyl carbocations respectively.

  15. Interactions between calcium phosphate and heavy metal ions in aqueous solution

    Fernane F.; Boudia S.; Saouli H.


    Synthetic and natural calcium phosphates were tested for removal metallic pollution in aqueous solution. Calcium phosphates with Ca/P ratio between 1,33 and 1,67 are fluently called apatite. They have a strong capacity to immobilize metallic ions when they are brought into contact with aqueous solutions. Ca2+ ions can substituted completely or partly by cations such as metallic ions (Ni2+; Cu2+; Co2+ and Cd2+). PO43− ions can be replaced by anions such as AsO43−, CO32−, … etc. Sorption of Cu2...

  16. Solution Versus Gas-Phase Modification of Peptide Cations with NHS-Ester Reagents

    Mentinova, Marija; Barefoot, Nathan Z.; McLuckey, Scott A.


    A comparison between solution and gas phase modification of primary amine sites in model peptide cations with N-hydroxysuccinimide (NHS) ester reagents is presented. In all peptides, the site of modification in solution was directed to the N-terminus by conducting reactions at pH = 5, whereas for the same peptides, a lysine residue was preferentially modified in the gas phase. The difference in pKa values of the N-terminus and ɛ-amino group of the lysine allows for a degree of control over sites of protonation of the peptides in aqueous solution. With removal of the dielectric and multiple charging of the peptide ions in the gas phase, the accommodation of excess charge can affect the preferred sites of reaction. Interaction of the lone pair of the primary nitrogen with a proton reduces its nucleophilicity and, as a result, its reactivity towards NHS-esters. While no evidence for reaction of the N-terminus with sulfo-NHS-acetate was noted in the model peptide cations, a charge inversion experiment using bis[sulfosuccinimidyl] suberate, a cross-linking reagent with two sulfo-NHS-ester functionalities, showed modification of the N-terminus. Hence, an unprotonated N-terminus can serve as a nucleophile to displace NHS, which suggests that its lack of reactivity with the peptide cations is likely due to the participation of the N-terminus in solvating excess charge.

  17. Functionalized polymers for binding to solutes in aqueous solutions

    Smith, Barbara F.; Robison, Thomas W.


    A functionalized polymer for binding a dissolved molecule in an aqueous solution is presented. The polymer has a backbone polymer to which one or more functional groups are covalently linked. The backbone polymer can be such polymers as polyethylenimine, polyvinylamine, polyallylamine, and polypropylamine. These polymers are generally water-soluble, but can be insoluble when cross-linked. The functional group can be for example diol derivatives, polyol derivatives, thiol and dithiol derivatives, guest-host groups, affinity groups, beta-diphosphonic acids, and beta-diamides

  18. Photodegradation of Lincomycin in Aqueous Solution


    Full Text Available Aqueous solutions of lincomycin were irradiated with UV light in homogeneous and heterogeneous systems. Lincomycin disappeared in both systems but the presence of TiO 2 noticeably accelerated the degradation of the antibiotic in comparison with direct photolysis. The rate of decomposition was dependent on the concentration of lincomycin and followed a pseudo-first-order kinetics. Photolysis involved only the oxidation of lincomycin without mineralization. Differently, the treatment with TiO 2 and UV light resulted in a complete mineralization of the antibiotic. The degradation pathways involved S- and N-demethylation and propyldealkylation. The mineralization of the molecule led to the formation of sulfate, ammonium, and nitrate ions.

  19. Radiolysis of paracetamol in dilute aqueous solution

    Using radiolytic experiments hydroxyl radical (main reactant in advanced oxidation processes) was shown to effectively destroy paracetamol molecules. The basic reaction is attachment to the ring. The hydroxy-cyclohexadienyl radical produced in the further reactions may transform to hydroxylated paracetamol derivatives or to quinone type molecules and acetamide. The initial efficiency of aromatic ring destruction in the absence of dissolved O2 is c.a. 10%. The efficiency is 2–3 times higher in the presence of O2 due to its reaction with intermediate hydroxy-cyclohexadienyl radical and the subsequent ring destruction reactions through peroxi radical. Upon irradiation the toxicity of solutions at low doses increases with the dose and then at higher doses it decreases. This is due to formation of compounds with higher toxicity than paracetamol (e.g. acetamide, hidroquinone). These products, however, are highly sensitive to irradiation and degrade easily. - Highlights: ► Paracetamol is easily degraded in aqueous solution by low dose irradiation. ► Main degradation products are hydroxylated molecules, acetamide and hydroquinone. ► Toxicity of solutions goes through a maximum as a function of dose.

  20. Simultaneous micro-electromembrane extractions of anions and cations using multiple free liquid membranes and acceptor solutions.

    Kubáň, Pavel; Boček, Petr


    Micro-electromembrane extractions (μ-EMEs) across free liquid membranes (FLMs) were applied to simultaneous extractions of anions and cations. A transparent narrow-bore polymeric tubing was filled with adjacent plugs of μL volumes of aqueous and organic solutions, which formed a stable five-phase μ-EME system. For the simultaneous μ-EMEs of anions and cations, aqueous donor solution was the central phase, which was sandwiched between two organic FLMs and two aqueous acceptor solutions. On application of electric potential, anions and cations in the donor solution migrated across the two FLMs and into the two peripheral acceptor solutions in the direction of anode and cathode, respectively. Visual monitoring of anionic (tartrazine) and cationic (phenosafranine) dye confirmed their simultaneous μ-EMEs and their rapid (in less than 5 min) transfers into anolyte and catholyte, respectively. The concept of simultaneous μ-EMEs was further examined with selected model analytes; KClO4 was used for μ-EMEs of inorganic anions and cations and ibuprofen and procaine for μ-EMEs of acidic and basic drugs. Quantitative analyses of the resulting acceptor solutions were carried out by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D). Good extraction recoveries (91-94%) and repeatability of peak areas (≤6.3%) were achieved for 5 min μ-EMEs of K(+) and ClO4(-). Extraction recoveries and repeatability of peak areas for 5 min μ-EMEs of ibuprofen and procaine were also satisfactory and ranged from 35 to 63% and 7.6 to 11.3%, respectively. Suitability of the presented micro-extraction procedure was further demonstrated on simultaneous μ-EMEs with subsequent CE-C(4)D of ibuprofen and procaine from undiluted human urine samples. PMID:26826693

  1. Process for separating cesium ions from aqueous solutions

    A precipitation agent is added to the aqueous solution and the resulting precipitate containing Cs+ ions is separated from the solution. By this process, caesium is to be separated selectively compared with other alkaline metal ions with great efficiency from aqueous solutions, particularly aqueous MAW (medium activity waste). This is achieved by using a sodium tetraphenyl borate attracting electrons to the phenyl rings and having substitutes. (orig./PW)

  2. Extraction of certain radionuclides from aqueous schungite solutions

    The sorption of 90Sr, 106Ru, 137Cs, and 238Pu from aqueous solutions over a wide pH range was studied. Swelled schungite chips (Nigozero, Kondopozhsk region) (1) and schungite (Onezhsk lake) (2) were tested as sorbents. The minerals were used both untreated and after oxidation (HNO3, 1:1, contact time 1 day). The oxidation, judging from the literature, facilitates the formation of carboxylic and phenolic functional groups on the surface of the carbon-containing sorbents. The presence of such groups is responsible for the high selectivity of the sorbents for multicharged cations. Futhermore, the hydrophobicity of the schungites enormously decreases after the oxidation. The studied sorbents had an average particle size of 0.08-0.1 mm. The schungite was contacted with the solution under static conditions with periodic stirring in order to establish equilibrium. The concentration of the radionuclides was 2-4 MBq/liter. The solution volumes were 10 ml. The sorbent content was 0.01 g. The required pH was set by adding HCl or NaOH

  3. The radiation chemistry of aqueous dihydropyrimidine solutions

    The radiation chemistry of N2O-saturated aqueous solutions of dihydropyrimidines in the presence pf various oxidants has been studied. From dihydrouracil (DHU) solutions in the presence of Fe(CN)63- the major products are uracil and 5-hydro-6-hydroxyuracil which have been isolated by chromatographic techniques using DHU-14C. From 6-methyldihydrouracil (6-MeDHU), under similar conditions, the parent pyrimidine and the 6-hydroxy compound are also formed. The pH-dependence of the yields of these products in the above DHU and 6-MeDHU systems have been determined and the results interpreted in terms of an electron transfer reaction from the organic radicals to the oxidant. Pulse radiolysis has shown that the isomerisation of the isopyrimidine is base catalysed. The influence of the oxidants IO4-, S2O82-, H2O2 and p-nitroacetophenone has been investigated using various dihydropyrimidines. Specific effects have been noted, particularly a chain reaction in the case of IO4- and S2O82-, and also the formation of barbituric acid derivatives in addition to pyrimidines and the 6-hydroxy compounds, more particularly in the case of IO4- and H2O2. The pH-dependencies of the yields have been studied and possible specific mechanisms discussed. These particular studies are of interest with regard to radiation sensitisation in vivo. (author)

  4. Uptake of Hg2+ from aqueous solutions by microporous titano- and zircono-silicates

    Cláudia B. Lopes


    Full Text Available Being mercury one of the most toxic heavy metals present in the environment, it is of major concern to develop cleanup technologies to remove it from wastewater and recover mercury polluted ecosystems. In this context, we study the potential of some microporous titanosilicates and zirconosilicates for taking up Hg2+ from aqueous solutions. These materials have unique chemical and physical properties, and here we are able to confirm that they readily remove Hg2+ from aqueous solutions. Moreover, the presence of the competitive Mg2+ and Na+, which are some of the dominant cations in natural waters, does not reduce the uptake capacity of some of these materials. Thus, several inorganic materials reported here may have important environmental applications, efficiently removing Hg2+ from aqueous solutions.

  5. Kinetics of pramlintide degradation in aqueous solution as a function of temperature and pH

    Kenley, Richard A.; Tracht, Scott; Stepanenko, Anna; Townsend, Michael; L'Italien, James


    The stability of the 37-amino acid peptide pramlintide, in aqueous solution, was studied as a function of pH and temperature. Samples of pramlintide formulated as a parenteral product were exposed to elevated temperatures and to realistic storage conditions for as long as 30 months. Pramlintide degradation was monitored by three high-performance liquid chromatography (HPLC) methods: a reversedphase (RP-HPLC) and a strong-cation exchange (SCX-HPLC) method for percentage purity determination by...

  6. Acetic acid extraction from aqueous solutions using fatty acids

    IJmker, H.M.; Gramblicka, M.; Kersten, S.R.A.; Ham, van der A.G.J.; Schuur, B.


    A major challenge for production of acetic acid via bio-based routes is cost-effective concentration and purification of the acetic acid from the aqueous solutions, for which liquid–liquid extraction is a possible method. A main challenge in extraction of acetic acid from dilute aqueous solutions is

  7. ESR study on carboxymethyl chitosan radicals in an aqueous solution

    Saiki, Seiichi, E-mail: saiki.seiichi@jaea.go.j [Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Muroya, Yusa; Kudo, Hisaaki [Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Katsumura, Yosuke [Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1195 (Japan)


    Carboxymethyl chitosan (CMCTS) at a highly concentrated aqueous solution forms hydrogel by ionizing irradiation. To study on radiation-induced reaction mechanism of CMCTS in an aqueous solution, CMCTS radicals formed by reactions with OH radical were observed by ESR method. As a result of ESR spectral analysis, CMCTS radicals were identified as radicals on carboxymethyl groups.

  8. Raman spectroscopy application to analyses of components in aqueous solutions

    Li, Gang; Zhang, Guoping


    The characterization of species in aqueous solutions has presented a challenge to analytical and physical chemist, because the JR absorption of the aqueous solvent is so intense that it becomes difficult to observe the solute in the water by JR absorption. In contrast, Raman spectrum of the solute is unaffected by the water, so the weak scattering of water makes the technique well suited to aqueous samples, and the Raman spectrum exhibits well-defined bands corresponding to fundamental modes of vibration. In addition, Raman spectroscopy has some inherent advantages in aqueous solution analysis, because the spectral features of signals from different species are much more distinct, and it provides characteristic signatures for samples, such as blood, protein and cholesterol. All the advantages make Raman spectroscopy be a potential alternative for the study of aqueous solutions. Now, Raman spectroscopy has been applied to studying samples in aqueous solutions, blood serum, intracellular protein levels. Now, industrial wasted water contains many organic contaminants, and it is necessary to determine and monitor these contaminants. The paper first introduces Raman spectroscopy, and then describes its applications to determining the components in aqueous solutions, analyzes and assignes the Raman spectra of o-dichlorobenzene, o-xylene, m-xyiene and p-xylene in detail. The experimental results demonstrate that Raman spectroscopy is a particularly powerful technique for aqueous solutions analyses.

  9. Peptide-lanthanide cation equilibria in aqueous phase. I. Bound shifts for L-carnosine-praseodymium complexes

    Mossoyan, J.; Asso, M.; Benlian, D.

    L-Carnosine complexes of Pr 3+ were characterized in aqueous solution by 1H NMR and potentiometric titration. A rigorous treatment of chemical shifts and pH variation data with lanthanide concentration is presented. Two different forms of the peptide ligand, forming simultaneously two complexes, were taken into account. At low pH values the cation is only coordinated at the carboxylate site of the ligand in a weak complex ( β2 = 6) whereas in neutral solution a stronger complex ( β1 = 37) is present as a consequence of the deprotonation of the imidazole ring. The computation of induced bound shifts † 2 and Δ1 for resonating nuclei of the peptide in both forms yields consistent figures. These provide the experimental basis for a conformational model which is usually not obtainable for labile complexes with low stability constants.

  10. Reactions of alkoxy radicals in aqueous solutions

    The kinetic and mechanistic properties of alkoxy radicals in organic solvents are briefly reviewed. Owing to the scarcity of such data in aqueous solutions and since reactions at the membrane/water interface may be also biologically important, we have studied the reactivity of these radicals in water and the results of our investigations are reported. Alkoxy radicals were generated by photolytic or radiolytic cleavage of peroxide precursors (tert-butyl hydroperoxide and di-tert-butyl peroxide as well as hydroperoxides of polyunsaturated fatty acids). A quantitative correlation between the structure of various substances, in particular, phenolic antioxidants, and their activity in inhibiting the alkoxy radical-induced bleaching of the water-soluble carotenoid crocin will be discussed. Rate constants for intermolecular reactions of t-BuO. radicals were determined by pulse radiolysis. The diffusion-controlled reaction with the catechol antioxidant nordihydroguaiaretic acid demonstrates an effective competition with the very rapid intra molecular β-fragmentation in water. The results aupport the view that a considerable amount of alkoxy radicals interact with substrates before they can rearrange intramolecularly

  11. Reactions of alkoxy radicals in aqueous solutions

    Bors, W.; Tait, D.; Michel, C.; Saran, M.; Erben-Russ, M. (Gesellschaft fuer Strahlen- und Umweltforschung m.b.H. Muenchen, Neuherberg (Germany, F.R.). Abt. fuer Strahlenbiologie)


    The kinetic and mechanistic properties of alkoxy radicals in organic solvents are briefly reviewed. Owing to the scarcity of such data in aqueous solutions and since reactions at the membrane/water interface may be also biologically important, we have studied the reactivity of these radicals in water and the results of our investigations are reported. Alkoxy radicals were generated by photolytic or radiolytic cleavage of peroxide precursors (tert-butyl hydroperoxide and di-tert-butyl peroxide as well as hydroperoxides of polyunsaturated fatty acids). A quantitative correlation between the structure of various substances, in particular, phenolic antioxidants, and their activity in inhibiting the alkoxy radical-induced bleaching of the water-soluble carotenoid crocin will be discussed. Rate constants for intermolecular reactions of t-BuO. radicals were determined by pulse radiolysis. The diffusion-controlled reaction with the catechol antioxidant nordihydroguaiaretic acid demonstrates an effective competition with the very rapid intra molecular ..beta..-fragmentation in water. The results aupport the view that a considerable amount of alkoxy radicals interact with substrates before they can rearrange intramolecularly.

  12. Removal of radium from aqueous solutions

    Adsorption of radium from aqueous solution with montmorillonite clay was investigated. Adsorption isotherm data of the radium and montmorillonite clay system were developed and fitted to both the Langmuir and Freundlich isotherm equations. The Langmuir isotherm equation was determined to be q = 6.700 C/1 + 8.447 x 10-5C and the Freundlich isotherm equation is q = 45.431 C/sup 1/1.401/. A rotary precoat filtration technique was used for dewatering the slurries of the montmorillonite clay and diatomaceous earth mixture. The rate of filtration was found to be a function of the weight percent of the clay, applied vacuum, drum speed and precoat thickness. The functional relationship is of the form Q = (0.682 + 0.035 X1 - 0.014 X2 + 0.140 X3 + 0.007 X1X2)/1 + (3.744 - 0.767 X3 + 0.079 X1X2)C125. 15 figures, 11 tables

  13. Ionic liquids based aqueous biphasic systems: Effect of the alkyl chains in the cation versus in the anion

    Highlights: • Alkyl-3-methylimidazolium alkylsulfonate ILs for implemention of aqueous biphasic systems. • Study of the effect of alkyl chain length and position on ILs hydrophobicity. • Evaluation of ILs extractive power on L-tryptophan aqueous solutions. • The alkyl chain in the anion contributes more to the hydrophobicity of the IL. • Less hydrophobic ILs have the better extraction coefficients for L-tryptophan. -- Abstract: The use of alkyl-3-methylimidazolium alkylsulfonate ionic liquids for implementing aqueous biphasic systems is studied in this work for the first time. The ability of high charge density inorganic salts, such as K3PO4, to promote phase segregation in aqueous solutions containing the ionic liquids 1,3-dimethylimidazolium methylsulfonate ([C1mim][C1SO3]), 1-ethyl-3-methylimidazolium hexylsulfonate ([C2mim][C6SO3]), 1-ethyl-3-methylimidazolium butylsulfonate ([C2mim][C4SO3]), 1-butyl-3-methylimidazolium methylsulfonate ([C4mim][C1SO3]), 1-butyl-3-methylimidazolium ethylsulfonate ([C4mim][C2SO3]), 1-pentyl-3-methylimidazolium methylsulfonate ([C5mim][C1SO3]), 1-hexyl-3-methylimidazolium methylsulfonate ([C6mim][C1SO3]) and 1-hexyl-3-methylimidazolium ethylsulfonate ([C6mim][C2SO3]) was experimentally determined at 298.15 K and atmospheric pressure. In general, the hydrophobicity of the ionic liquids studied is affected by the increase of the alkyl chain length. However, the position of the alkyl chain, whether in the cation or in the anion affects in a different way the lipophilic effect of the ionic liquid. Two ionic liquids with the same number of carbon atoms, the one with a longer chain in the anion is the more hydrophobic. Furthermore, four ionic liquids were chosen to extract the aminoacid L-tryptophan from aqueous solutions. The chain lengths of the anion or cation were fixed and the partition coefficients compared. The extractions, carried out at 298.15 K, showed the good extractive power of these ionic liquids and also that

  14. Revised Ionic Radii of Lanthanoid(III) Ions in Aqueous Solution

    A new set of ionic radii in aqueous solution has been derived for lanthanoid(III) cations starting from a very accurate experimental determination of the ion water distances obtained from extended X-ray absorption fine structure (EXAFS) data. At variance with previous results, a very regular. trend has been obtained, as expected for this series of elements. A general procedure to compute ionic radii in solution by combining the EXAFS technique and molecular dynamics (MD) structural data has been developed. This method can be applied to other ions allowing one to determine ionic radii in solution with an accuracy comparable to that of the Shannon crystal ionic radii. (authors)

  15. The effects of mono- and divalent metal cations on the solution structure of caffeine and theophylline

    Nafisi, Shohreh; Monajemi, Majid; Ebrahimi, Saeedeh


    The interactions of caffeine and theophylline with potassium +, cobalt 2+ and nickel 2+ ions were studied in aqueous solution at physiological pH with constant ligand concentration and various metal ion contents. Fourier Transform infrared spectroscopy and absorption spectra were used to determine the cation binding mode and association constants. Spectroscopic results showed direct and indirect cation interactions for Co 2+, Ni 2+ and K + through O6 and N9 atoms (caffeine) and O6, N9 and N7 atoms (theophylline). The overall binding constants were, K(Co-caffeine)=6.92×10 4 M -1, K(Ni-caffeine)=2.22×10 4 M -1, K(K-caffeine)=5.08×10 3 M -1, K(Co-theophylline)=5.06×10 4 M -1, K(Ni-theophylline)=4.84×10 4 M -1 and K(K-theophylline)=2.13×10 3 M -1. The association constants showed weaker interaction for monovalent cation than divalent metal ions.

  16. Ozone photolysis of paracetamol in aqueous solution.

    Neamţu, Mariana; Bobu, Maria; Kettrup, Antonius; Siminiceanu, Ilie


    The degradation of a paracetamol (N-acetil-para-aminofenol) aqueous solution (C (0) P = 5 mmol L(-1)) is studied in a bench-scale setup by means of simple ozonation (O3) and ozonation catalyzed with UV light (O3/UV) in order to quantify the influence of UV light on the degradation process. The results have shown that under the adopted experimental conditions (25°C, applied ozone dose = 9.8 mg L(-1) and gas flow rate of 20 L h(-1)) both oxidative systems are capable of removing the substrate with mineralization degrees up to 51% for ozonation and 53% for O3/UV. HPICE chromatography allowed the detection of nitrate ions and maleic and oxalic acids as ultimate carboxylic acids. The experimental data have been interpreted through 5 indicators: the conversion of paracetamol (XP ), the conversion degree of TOC (XTOC ), the apparent rate constant (kap ), the Hatta number (Ha) and the enhancement factor (E). The main advantage of photo-ozonation compared to simple ozonation was a more advanced conversion (79% vs. 92% after 90 min). The paracetamol decay follows a pseudo-first-order reaction with a superior rate constant (higher by 54%) for the UV catalyzed system in comparison with direct ozonation. Mineralization is slightly accelerated (+4%) in the O3/UV system, due to the additional production of hydroxyl radicals induced by the UV light and a higher Hatta number (+24%). Nevertheless, the process was still in the slow reaction kinetic regime (Ha < 0.3), and the enhancement factor was not significantly increased. The results are useful for the design and scale-up of the gas-liquid processes. PMID:23647117

  17. Removal of low levels of uranium from aqueous solutions by coprecipitation and ion exchange (Preprint no. SST-02)

    Coprecipitation of uranium(VI) from aqueous solutions with ferric hydroxide has been evaluated as a means of removing uranium from aqueous effluents. Experiments with different amounts of uranium and added carbonate showed that it was possible to remove better than 95% of uranium in a single precipitation at low concentrations of uranium. Sorption on weak acid cation exchange resin has also been studied and can be used if the uranium is to be recovered. (author)

  18. Thermophysical Properties of Aqueous Solutions Used as Secondary Working Fluids

    Melinder, Åke


    Secondary working fluids (secondary refrigerants, heat transfer fluids, antifreezes, brines) have long been used in various indirect re-frigeration and heat pump systems. Aqueous solutions (water solu-tions) have long been used as single phase (liquid only) secondary working fluids for cooling in supermarkets, ice rinks, heat recovery systems, heat pumps and other applications. However, aqueous solutions are increasingly used also for freezers in supermarkets and other applications in low tem...

  19. Removal of uranyl ions from aqueous solutions using barium titanate

    Remediation of water sources contaminated with radioactive waste products is a major environmental issue that demands new and more efficient technologies. For this purpose, we report a highly efficient ion-exchange material for the removal of radioactive nuclides from aqueous solutions. The kinetic characteristics of adsorption of uranyl ions on the surface of barium titanate were investigated using a spectrophotometric method under a wide range of conditions. By controlling the pH it was possible to exert fine control over the speciation of uranium, and by optimizing the temperature and grain size of the exchanger, almost total removal was achieved in a matter of just hours. The highest efficiency (>90 % removal) was realized at high temperature (80 deg C). Moreover, the effect of competitive ion adsorption from a range of different cations and anions was quantified. Adsorption was found to follow first-order kinetics and both Freundlich and Langmuir isotherms could be applied to this system. The results of a mathematical treatment of the kinetic data combined with the observation that adsorption was independent of stirring speed and dependent on the ion-exchanger grain size, indicate that the dominant mechanism influencing adsorption is particle spreading. The adsorption behavior was not influenced by exposure to high-intensity gamma radiation, indicating potential for use of this ion-exchanger in systems containing radioactive material. These results will be of use in the development of uranium extraction systems for contaminated water sources. (author)

  20. Growth kinetics of sulfur nanoparticles in aqueous surfactant solutions.

    Chaudhuri, Rajib Ghosh; Paria, Santanu


    Sulfur is an important element has many practical applications when present as nanoparticles. Despite the practicable applications, limited studies are available in the literature related to synthesis of sulfur nanoparticles. Growth kinetics of colloidal sulfur particles synthesized from aqueous solutions using different surfactants have been studied here. The effects of different parameters such as reactant concentration, temperature, sonication, types of acids, types of surfactants, and even surfactant concentration are studied on the growth kinetics. Since the reaction rate is fast, particle growth depends on the parameters which affect diffusion of sulfur molecules. There is a linear relationship found among the reactant concentration and the particle coarsening rate constant. The growth kinetics was studied in the presence of different surfactants such as nonionic (poly(oxyethylene) p-tert-octylphenyl ether, TX-100), anionic (sodium dodecylbenzene sulfonate, SDBS), cationic (cetyltrimethyammonium bromide, CTAB) and results show the coarsening constant changes according to the following order: water>TX-100>SDBS>CTAB. The particle growth rate also depends on the surfactant concentration, coarsening rate constant decreases with the increase in surfactant concentration and become constant close to the critical micellar concentration (CMC). The coarsening rate constant also highly depends on the types of acid used as catalyst. PMID:21147482

  1. Cationic ruthenium-nitrosyl complexes in radioactive waste solutions

    By means of counterpressure column electrophoresis using Lichroprep Si 60 as carrier medium it has been possible for the first time to preparatively isolate and thus analyse all cationic ruthenium-nitrosylnitrato complexes. The composition of the various complexes is determined from the ion charge revealed by the migration path during the electrophoresis, and from the content of Ru, NO and NO3-. The denitration of simulated high-activity and medium-activity waste solution with formaldehyde or formic acid results in the formation of formiato complexes, the composition of which can be determined by a new method corresponding to the one used for nitrato complexes. The extraction of ruthenium with TBP Dodecan will predominantly yield neutral complexes, but a reduction in temperature and a high amount of impurity electrolytes will favour the extraction of all complexes. (orig./RB)

  2. A New Efficient Analytical Method for Picolinate Ion Measurements in Complex Aqueous Solutions

    Parazols, M.; Dodi, A. [CEA Cadarache, Lab Anal Radiochim and Chim, DEN, F-13108 St Paul Les Durance (France)


    This study focuses on the development of a new simple but sensitive, fast and quantitative liquid chromatography method for picolinate ion measurement in high ionic strength aqueous solutions. It involves cation separation over a chromatographic CS16 column using methane sulfonic acid as a mobile phase and detection by UV absorbance (254 nm). The CS16 column is a high-capacity stationary phase exhibiting both cation exchange and RP properties. It allows interaction with picolinate ions which are in their zwitterionic form at the pH of the mobile phase (1.3-1.7). Analysis is performed in 30 min with a detection limit of about 0.05 {mu}M and a quantification limit of about 0.15 {mu}M. Moreover, this analytical technique has been tested efficiently on complex aqueous samples from an effluent treatment facility. (authors)

  3. Radiolysis of aqueous-ethanolic solution of tryptophan

    The effect of ethanol on radiation stability of tryptophan during γ-irradiation of its aqueous solutions was investigated. In comparison with radiation losses of tryptophan irradiated in pure water, the losses in aqueous-ethanolic solutions are considerably higher and they increase with increasing ethanol concentration. Basic radiation products of tryptophan formed on irradiation of its aqueous-ethanolic solutions in consequence of the reaction of tryptophan with acetaldehyde as the main product of radiolysis of ethanol were followed by paper electrophoresis. (author)

  4. Resonant X-ray scattering studies of concentrated aqueous solutions

    The microscopic structure of concentrated aqueous electrolyte solutions has been studied by resonant X-ray diffraction (RXD). This technique provides a method for the measurement of the structure around a specific atom or ion in solution. In that sense, RXD is the X-ray equivalent of neutron diffraction with isotopic substitution (NDIS). The use of RXD as an alternative to NDIS has been considered of interest for some time; it is potentially one of the best methods for overcoming the most important limitation of the neutron diffraction technique, i.e. the lack of suitable isotopes for every atomic species. Third generation synchrotron sources offer an unprecedented opportunity for the further development of RXD to study the microscopic structure of liquids and amorphous materials. One of the main aims of this thesis was to check whether it could be possible to obtain results of comparable accuracy to those of NDIS. In this work, the hydration structures of Br-, Rb+, Sr2+ and Y3+ in concentrated aqueous solutions have been studied by RXD. A detailed account of how the experiments were carried out and the data analysis procedure is given. The results are compared with those obtained for the same ion by other techniques and to those obtained for similar systems by NDIS. The reliability of these results and the observed trends in the measured structure when compared to other ions in the same series are discussed. A comparative study of the structure of the three cations is also presented in this thesis. This work illustrates one of the main advantages of RXD: the possibility of carrying out systematic structural studies on all elements with atomic number greater than 28 (Ni). Finally, a critical discussion on the actual stage of development of RXD is presented. The results shown offer evidence of the future prospects of the technique and justify further efforts to develop it to the level of reliability and ease of use that NDIS has reached after more than three decades

  5. Sorption characteristics of technetium on crosslinked chitosan from aqueous solutions

    of 99Tc from reprocessing facilities have received attention in recent year, prediction of Tc behavior in various environments is desirable. The behavior of Tc depends on its chemical form. In aerobic aqueous solution, Tc is present in the heptavalent form as pertechnetate [TcO4- : Tc (VII)], which is both highly soluble and mobile in the environment. This chemical form is readily available to plants and acts as a sulfate analog. As contrasted with Tc (VII), Tc (IV) is insoluble and immobile due to strong sorption of this species by solid materials. This work was aimed to study influence of contact time, effect of pH and foreign anions and cations on sorption of pertechnetate anions on glutaraldehyde crosslinked chitosan. (authors)

  6. Unique role of ionic liquid [bmin][BF 4] during curcumin-surfactant association and micellization of cationic, anionic and non-ionic surfactant solutions

    Patra, Digambara; Barakat, Christelle


    Hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroburate, modified the properties of aqueous surfactant solutions associated with curcumin. Because of potential pharmaceutical applications as an antioxidant, anti-inflammatory and anti-carcinogenic agent, curcumin has received ample attention as potential drug. The interaction of curcumin with various charged aqueous surfactant solutions showed it exists in deprotonated enol form in surfactant solutions. The nitro and hydroxyl groups of o-nitrophenol interact with the carbonyl and hydroxyl groups of the enol form of curcumin by forming ground state complex through hydrogen bonds and offered interesting information about the nature of the interactions between the aqueous surfactant solutions and curcumin depending on charge of head group of the surfactant. IL[bmin][BF 4] encouraged early formation of micelle in case of cationic and anionic aqueous surfactant solutions, but slightly prolonged micelle formation in the case of neutral aqueous surfactant solution. However, for curcumin IL [bmin][BF 4] favored strong association (7-fold increase) with neutral surfactant solution, marginally supported association with anionic surfactant solution and discouraged (˜2-fold decrease) association with cationic surfactant solution.

  7. Removal of aluminum from aqueous solution by organic materials of agricultural use

    With the objective of identify characteristics of organic materials of common use in agriculture, related to the aluminum removal from aqueous systems, a chemical characterization of six organic materials was carried out. Their capacity to remove aluminum was evaluated in the laboratory by correlating the observed Al-removal with their characteristics. 6 materials were used as follows: rice straw, chicken manure, cowpea, compost, earth warm compost and leonardite oxidable organic C, total N, P, Ca, Mg, Na, K and Al, pH, carbonates, CEC, exchangeable cations, hydrosoluble n and p, fulvic and humic acids, together with their totals acidity and functional groups (carboxylic and phenolic) were evaluated. To estimate the al-removal capacity by the organic materials in aqueous systems, seven aqueous solutions with different Al concentrations (from o to 900 mmol/L) were prepared at an initial pH value of 4.2 and a relation of organic material: aqueous of 180 mg: 200 ml. after shaking and filtration, the pH values and al concentration (by atomic absorption) were determined in the equilibrium solution. The adsorbed Al by the organic materials was calculated by the difference between the initial al concentrations and the amount found in the equilibrium solution. The al removal using all the organic materials was also measured from an aqueous solution, which contained 900 mmol/L of Al in a pH value range between 2.4 and 4.2. The most effective organic material to remove al was the chicken manure, this material removed up to the 80% of Al, leaving in the aqueous solutions concentrations up to 50 mmol/L. the effectiveness of the rest organic materials was as follows: compost, earth warm compost, cowpea, rice straw and leonardite. Positive and significative correlations were obtained between the Al-retention and the following variables: pH values of organic materials, pH values of the equilibrium solution, CaCO3 content, total and hydrosoluble P, total sum and exchangeable sum

  8. Advanced material and approach for metal ions removal from aqueous solutions

    Turhanen, Petri A; Vepsäläinen, Jouko J; Peräniemi, Sirpa


    A Novel approach to remove metals from aqueous solutions has been developed. The method is based on a resin free, solid, non-toxic, microcrystalline bisphosphonate material, which has very low solubility in water (59 mg/l to ion free Milli-Q water and 13 mg/l to 3.5% NaCl solution). The material has been produced almost quantitatively on a 1 kg scale (it has been prepared also on a pilot scale, ca. 7 kg) and tested successfully for its ability to collect metal cations from different sources, ...

  9. Nanoscale lubricating film formation by linear polymer in aqueous solution

    Liu, Shuhai; Guo, Dan; Xie, Guoxin


    Film-forming properties of polymer in aqueous solution flowing through a nanogap have been investigated by using a thin film interferometry. The film properties of linear polymer in aqueous solution flowing through a confined nanogap depend on the ratio of water film thickness to averaged radius of polymer chains H0/RPolymer. It was found that the lubrication film thickness of linear polymer in aqueous solution decreases as the polymer molecular weight increasing when H0/RPolymer < 2 ˜ 3. A new lubrication map was proposed, which includes the lubrication regime of weak confinement influence, the lubrication regime of strong confinement influence (LRSCI), and the transition regime of confinement influence. It is very difficult to increase the lubrication film thickness using the higher molecule weight in the LRSCI regime. The lubrication mechanism inferred from our experimental results may help to better understand the dynamic film properties of linear polymer in aqueous solution flowing through a nanogap.

  10. Desalination of aqueous solutions by LTA and MFI zeolite membranes using pervaporation method

    A. Malekpour


    Full Text Available LTA and MFI zeolite membranes were hydrothermally grown on the surface of an α-alumina porous support. The synthesized membranes were used for removal of cationic and anionic species from aqueous solutions by the pervaporation method. The perfection of the membranes was improved by employing the multi-stage synthesis method. The membranes were characterized by XRD, SEM and IR methods. The membranes were initially evaluated by the pervaporation separation of water from aqueous 2-propanol mixtures. The separation factors obtained were 7081 and 105 for NaA and ZSM-5 membranes, respectively. The ability of membranes for desalination of some aqueous solutions containing I-, Cs+ and Sr2+ ions was examined in various conditions. These ionic species were chosen because of their importance in the nuclear sciences. Both membranes effectively removed (more than 99 wt% I-, Cs+ and Sr2+ from their singlesalt solutions (0.001mol dm-3 over a temperature range of 298-338 K. The effects of parameters such as time and temperature on the separation factors and fluxes were investigated. This work shows that, due to their excellent chemical, thermal and mechanical stability, the zeolitic membranes are useful for desalination of aqueous solutions and treating saline wastewaters by pervaporation. Therefore, this method has the ability to desalinate harsh environment solutions involving strong solvent and radioactive components.

  11. Surface tension and related thermodynamic quantities of aqueous electrolyte solutions

    Matubayasi, Norihiro


    Surface tension provides a thermodynamic avenue for analyzing systems in equilibrium and formulating phenomenological explanations for the behavior of constituent molecules in the surface region. While there are extensive experimental observations and established ideas regarding desorption of ions from the surfaces of aqueous salt solutions, a more successful discussion of the theory has recently emerged, which allows the quantitative calculation of the distribution of ions in the surface region. Surface Tension and Related Thermodynamic Quantities of Aqueous Electrolyte Solutions provides a d

  12. γ-Irradiation-induced radiolysis of inulin in aqueous solutions

    Radiochemical transformations of inulin in aqueous solutions, in air, in the presence of inert gases, helium, nitrogen and in nitrous oxide exposed to various doses of 60Co γ-irradiation were investigated. It was shown that interactions in inulin with OH radicals are principally responsible for radiolytic decomposition of inulin. The data on radiolysis of more simple model systems were used to make available decomposition spectra of γ-irradiated aerated aqueous solution of inulin. 9 refs., 6 figs

  13. Structure of hydrated complexes formed by metal ions of groups I-III of the Periodic table in aqueous electrolyte solutions under ambient conditions

    Published and authors' experimental data on the structure of aqueous electrolyte solutions under standard conditions were generalized to ascertain the dependences of the solution structural parameters on chemical nature of dissolved compounds of alkali, alkaline-earth metals, cadmium, scandium, yttrium, lanthanum and indium. Hydrate complexes of metal ions formed in aqueous solutions were systematized, depending on cation size, charge and structure of their external electronic shell

  14. Fabrication of cationic cellulosic nanofibrils through aqueous quaternization pretreatment and their use in colloid aggregation.

    Liimatainen, Henrikki; Suopajärvi, Terhi; Sirviö, Juho; Hormi, Osmo; Niinimäki, Jouko


    The aqueous pre-treatment of cellulose with periodate and Girard' reagent T was employed as a novel and promising method to promote nanofibrillation of wood pulp and to obtain cellulosic nanofibrils with cationic functionality (CNFC). To demonstrate the feasibility of CNFCs in particle aggregation, a kaolin clay model suspension was aggregated by the CNFCs. Direct high-pressure homogenization of cationized cellulose resulted in nanofibrils exhibiting typical widths of 10-50 nm and cationic charge densities ranging from 1.10 to 2.13 mequiv.g(-1). The nanofibril suspensions existed in the form of highly transparent gels and possessed cellulose I crystalline structures. All of the CNFCs promoted strong aggregation of kaolin and produced voluminous kaolin-CNFC aggregates with lateral dimensions of several millimeters. Moreover, the CNFCs maintained good aggregation performance through wide pH (3-9) and temperature (25-60 °C) ranges. Thus, CNFCs were shown to be highly potential candidates for replacement of present synthetic soluble flocculation and coagulation aids. PMID:24528718

  15. Cation-inverting-injection: a novel method for synthesis of aqueous ZnSe quantum dots with bright excitionic emission and suppressed trap emission

    In the conventional synthesis of aqueous ZnSe quantum dots (QDs), highly reactive Se monomers are rapidly injected into a Zn-thiol complexes solution at room temperature, resulting in a poor excitionic luminescence and a serious trap emission of as-prepared ZnSe QDs. In this paper, we develop a novel cation-inverting-injection method to prepare aqueous ZnSe QDs with a bright excitionic luminescence. In this method, highly reactive Se monomers are first diluted in the reaction solution, followed by low-reaction Zn-thiol complexes slowly dropped at a high reaction temperature (90 °C). The inverting monomer injection order, the suppressed monomer reactivity and the high nucleation temperature in the cation-inverting-injection method can contribute to low-concentration but high-quality ZnSe nuclei, thereby promoting the formation of ZnSe QDs with large-sized particles, a high excitionic emission and a weak trap emission. As-prepared ZnSe QDs exhibit an intense deep-blue excitionic emission, which is the first reported case of a visible excitionic emission instead of a trap emission resulting from ZnSe QDs that are directly synthesized in an aqueous media. Using three types of dyes, via two measuring methods, the accurate photoluminescence quantum yield of the as-prepared ZnSe QDs is measured as 15%, which is a new record for mercaptocarboxylic acid stabilized ZnSe QDs synthesized in an aqueous media. (paper)

  16. Aminoguanidinium closo-borates and their reactions with copper(2) salts in aqueous solutions

    Amino guanidine hexa-, deca- and dodecaborates of the (AguH)2BnHn · xH2O, where Agu - (CN4H6); n = 6, 10, 12; x = 1, 2, composition were synthesized and defined by means of element, magnetic susceptibility and IR spectroscopy analyses. Their reaction with the copper(2) salts in aqueous solutions was studied. It was shown that cation-anion interaction, which was enhanced in the B12 10 6 row, were the case in the amino guanidine closo-borates. The reaction of the amino guanidine closo-borates with the copper(2) salts in aqueous solutions leads to formation either complexes (n = 10, 12) or elemental copper (in the case of B6H62- anion) depending on closo-borate anion BnHn2-

  17. Study on specific enthalpy of ice including solute in aqueous solution

    Kumano, Hiroyuki; Hirata, Tetsuo; Izumi, Yasuyuki [Department of Mechanical Systems Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan)


    Effects of solute included in a sample on the specific enthalpy of ice are investigated experimentally. In the experiments, ice including the solute was made from an aqueous solution, and the specific enthalpy was measured by melting the ice in the aqueous solution. Moreover, a physical model of the ice including the solute is proposed. As a result, when the concentration of the aqueous solution is set at a value equivalent to the concentration of the sample, the specific enthalpy of the sample increases with the concentration of the sample. The measurement results and the calculated values agree well, and it was found that the method for calculating the specific enthalpy of the sample is valid. Moreover, when the concentration of the aqueous solution is higher than that of the ice including the solute, it was found the calculation method for the specific enthalpy of the sample is appropriate. (author)

  18. Acidities of Water and Methanol in Aqueous Solution and DMSO

    Gao, Daqing


    The relative acidities of water and methanol have been a nagging issue. In gas phase, methanol is more acidic than water by 36.0 kJ/mol; however, in aqueous solution, the acidities of methanol and water are almost identical. The acidity of an acid in solution is determined by both the intrinsic gas-phase ionization Gibbs energy and the solvent…


    Rimshaw, S.J.


    A method of separating technetium in the 4+ oxidation state from an aqueous basic solution containing products of uranium fission is described. The method consists of contacting the solution with finely divided magnetite and recovering a technetium-bearing precipitate. (AEC)

  20. Radiolysis of aqueous solutions of sodium sulfides. Chapter 8

    To study the radiolysis of the aqueous solutions of sodium sulphide, use was made of infrared spectroscopy, mass-spectrometry and iodometric titration. During the γ-irradiation of the aqueous solutions of sodium sulphide one can observe the appearance of various stable sulphur-containing products. Data are discussed on the radiolysis in a nitrous environment, on oxygen bubbling, at varying radiation doses, pH and temperature values. Consideration is also given to the low-temperature radiolysis of the aqueous solutions of sodium sulphide by the EPR method. In the radiolysis of both crystalline and glassy solutions of Na2S there appear an ion-radical S- and a radical SO2-

  1. Antiscalant properties of Spergularia rubra and Parietaria officinalis aqueous solutions

    Cheap-Charpentier, Hélène; Gelus, Dominique; Pécoul, Nathalie; Perrot, Hubert; Lédion, Jean; Horner, Olivier; Sadoun, Jonathan; Cachet, Xavier; Litaudon, Marc; Roussi, Fanny


    The formation of calcium carbonate in water has important implications in industry. Chemical antiscalant is usually used to control scale depositions. Plant extracts have been recently used as new green antiscalant agents, as they can be easily prepared and are environmentally friendly. In this study, stock aqueous solutions of Spergularia rubra and Parietaria officinalis, two plants used in traditional medicine to treat or prevent urolithiasis, were obtained by infusion. The antiscaling properties of these extracts towards CaCO3 formation were tested by using chronoamperometry and Fast Controlled Precipitation methods. The aqueous solution of S. rubra was further fractionated to isolate compounds of lower polarity. Their efficiency towards CaCO3 precipitation was characterized by Fast Controlled Precipitation method. The inhibiting efficiency of this fractionated solution was greater than that of the stock aqueous solution.

  2. Tritium exchange reactions in imidazole in aqueous and organic solutions

    Tritium exchange reactions were studied in aqueous and organic solutions of imidazole and methylimidazole. For the exchange in an aqueous solution the mechanism through ylide intermediate formation postulated by VAUGHAN et al. was modified in this study. The rate constant obtained by MASLOVA et al. was found to be too small compared to ours. For the exchange reaction of methylimidazole in an aqueous solution the rate decreased due to the effect of a methyl group attached to the aromatic ring. The C-2 tritiation of imidazole was studied in chloroform, acetone and dioxane for the first time. It was dependent on polymer properties. An intramolecular exchange mechanism was applicable to the trimer while an intermolecular exchange mechanism was applicable to the dimer. The rate constants of the exchange reactions in organic solutions were obtained for both mechanisms. (orig.)

  3. Synthesis and Aqueous Solution Viscosity of Hydrophobically Modified Xanthan Gum

    QIAN Xiao-lin; WU Wen-hui; YU Pei-zhi; WANG Jian-quan


    Two xanthan gum derivatives hydrophobically modified by 4 or 8 tetradecyl chains per 100 xanthan gum structure units were synthesized. The derivatives were studied by scanning electron microscope and pyrene fluorescence spectrometry. And the aqueous solution apparent viscosity of the derivatives was investigated. The results indicate that the network of the derivatives with more hydrophobic groups is closer and tighter. With increasing of alkyl chain substitution degree, the hydrophobically associating interactions enhance in aqueous solution. Aqueous solution apparent viscosity of the derivatives increases with increasing of polymer concentration and alkyl substitution degree, and decreases with the increase of temperature. In the brine solution, the strong viscosity enhancement phenomenon appears. The interaction between the derivatives and surfactant sodium dodecylbenzene sulfonate is strong.

  4. [Photochemical degradation of chlorothalonil in aqueous solution].

    Li, Xuede; Hua, Rimao; Yue, Yongde; Li, Ying; Tang, Feng; Tang, Jun


    The study on the effects of light source, solution pH and temperature, and surfactant on the photochemical degradation of chlorothalonil showed that the half-life of chlorothalonil photodegradation under high pressure mercury lamp (HPML), UV lamp and sunlight was 22.4, 82.5 and 123.8 min, respectively. Under HPML and sunlight, chlorothalonil had a higher photolysis rate in alkaline solution than in neutral and acid solution. The photolysis rate increased with increasing solution temperature in the range of 10 degrees C - 40 degrees C, which was doubled when the temperature increased every 10 degrees C. Sodium laurylsulfonate (SDS), sodium dodecylbenzene sulfonate (SDBS), Tween 60 and Span 20 showed significant photosensitizing effects, while cetyltrimethylammonium bromide (CTAB) had significant photoquench effect on the photolysis of chlorothalonil. PMID:16964947

  5. Strontium separation with ultrafiltration membranes from dilute aqueous solutions

    The separation of Sr2+ from dilute and trace solutions of low activity by means of hollow fiber Amicon ultrafiltration membranes is studied. The cation is absorbed on colloidal particles of titanium oxide formed directly in solution, and the coloidal dispersion is filtrated. The method has been studied under several different operative conditions (pH, Ti/Sr ratio, the presence of interfering ions, colloid formation time) with the aim of determining the optimum conditions to develop a separation process

  6. Extraction of niobium anions from aqueous solutions by ionic flotation method

    A conceptual possibility of niobate (K2NbOF5 and K2NbF7) extraction from aqueous media using the ion flotation method is established. The optimum conditions, when using quaternary ammonium bases and amines as collectors, lie in the pH range 5.0-9.0. The interaction of niobates with cation-active surfactants can follow the ion-exchange mechanism. The presence of acid in a solution suppresses the interaction due to competitive effect of anions present and due to complexing of surfactant collectors

  7. The foam separation of thorium(IV) from dilute aqueous solutions

    The foam separation of thorium(IV) from the dilute aqueous solutions was investigated at pH values ranging from 1.2 to 12 using the cationic surfactant cetyl trimethyl ammonium bromide and the anionic collector sodium lauryl sulphate. Cetyl trimethyl ammonium bromide could not remove soluble thorium but partially floated the hydrous oxide. The percentage removal was found to depend on the pH. With sodium lauryl sulphate, removals approaching 100% could be achieved at all the pH values tested. The various factors that can affect the separation process investigated and the results are discussed in terms of the hydrolysis of thorium. (orig.)

  8. Extraction of uranyl nitrate from aqueous nitrate solutions by open cell polyurethane foam sponge (OCPUFS)

    The extraction of uranyl nitrate into open cell polyurethane foam sponge (OCPUFS) from aqueous solution, in the presence of salting agents, was examined. The extraction efficiency was observed to depend on the concentration of uranyl and nitrate ions. The charge of the cation was also found to influence the distribution ratio. The effect of the change in temperature and pH was also studied. The results are interpreted in terms of OCPUFS acting as a viscous organic ether of moderate dielectric constant. (author) 14 refs.; 6 figs

  9. Kinetics and Adsorption Isotherms Studies of Acridine Orange Dye from Aqueous Solution by Activated Charcoal

    2N. Qamar; R. Azmat; Naz, R.; Malik, B.


    The goal of this research is to evaluate the efficiency of charcoal as low coast and effective adsorbent for acridine orange (a cationic dye) from aqueous solution at room temperature. Effect of initial pH (2-8), shaking time (5min. - 1hour), adsorbent dose (0.1gm- 0.9gm) and dye concentration (37mg/30ml-185mg/30ml) were investigated. Results demonstrated that charcoal act as good adsorbent for the removal AO where 99.15% of the dye was adsorbed within 30 minutes. For the maximum dye removal ...

  10. Hydration properties and ionic radii of actinide(III) ions in aqueous solution

    Ionic radii of actinide(III) cations (from U(III) to Cf(III)) in aqueous solution have been derived for the first time starting from accurate experimental determination of the ion-water distances obtained by combining extended X-ray absorption fine structure (EXAFS) results and molecular dynamics (MD) structural data. A strong analogy has been found between the lanthanide and actinide series concerning hydration properties. The existence of a contraction of the An-O distance along the series has been highlighted, while no decrease of the hydration number is evident up to Cf(III). (authors)

  11. Method and device for removing ruthenium in aqueous solution

    Highly soluble and reactive high order ruthenium oxides assumed to be ruthenium tetraoxide, it they are not reduced on a cathode immediately, would evaporate as they are or react with nitrogen oxides formed by oxidation-decomposition of nitrosyl complex to return again to their nitrosyl complex. Accordingly, it is necessary for the aqueous solution to brought into contact with the anode and the cathode repeatedly. The present invention complies with the demand, in which one or plural pairs of plate-like electrodes are stacked as layers and an aqueous solution incorporating ruthenium is passed between the layers so that it is brought into contact with the anode and the cathode repeatedly to repeat oxidations and reductions. In view of the above, since the water soluble high order ruthenium oxides generated on the anode in the aqueous solution are immediately brought into contact with the cathode and reduced into insoluble lower order oxides, ruthenium can be removed. (T.M.)

  12. Molecular Weight and Aggregation of Erwinia Gum in Aqueous Solutions


    Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weight-average molecular weights Mw, number-average molecular weights Mn and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.

  13. Self-aggregation of liquids from biomass in aqueous solution

    Highlights: • Aggregation behaviour of liquids from biomass in aqueous solution has been studied. • Standard Gibbs free energies of aggregation have been calculated. • Solubility in water of these compounds has been determined. • Critical aggregation concentration decreases as the solubility in water does. -- Abstract: Aggregation of several chemicals from biomass: furfural derived compounds (furfural, 5-methylfurfural, furfuryl alcohol and tetrahydrofurfuryl alcohol), lactate derived compounds (methyl lactate, ethyl lactate and butyl lactate), acrylate derived compound (methyl acrylate) and levulinate compounds (methyl levulinate, ethyl levulinate and butyl levulinate) in aqueous solution has been characterised at T = 298.15 K through density, ρ, speed of sound, u, and isentropic compressibilities, κS, measurements. In addition the standard Gibbs free energies of aggregation have been also calculated. Furthermore, in order to deepen insight the behaviour of these chemicals in aqueous solution, the solubility of these compounds has been measured at T = 298.15 K

  14. Mutual diffusion coefficients of L-lysine in aqueous solutions

    Highlights: • Mutual diffusion coefficients of L-lysine in aqueous solutions. • Influence of the thermodynamic factors on the variation of their mutual diffusion coefficients. • Estimation of the hydrodynamic radius of L-lysine. - Abstract: Mutual diffusion coefficients, D, were determined for aqueous solutions of L-lysine at T = 298.15 K at concentrations from (0.001 to 0.100) mol · dm−3. From these experimental results, the hydrodynamic radius Rh, diffusion coefficients at infinite dilution D0, the thermodynamic factors and activity coefficients γ, by using the Hartley equation, have been estimated, permitting us to have a better understanding of the thermodynamic of these systems of L-lysine in aqueous solutions

  15. Removal of Phosphate from Aqueous Solution with Modified Bentonite

    唐艳葵; 童张法; 魏光涛; 李仲民; 梁达文


    Bentonite combined with sawdust and other metallic compounds was used to remove phosphate from aqueous solutions in this study. The adsorption characteristics of phosphate on the modified bentonite were investigated, including the effects of temperature, adsorbent dosage, initial concentration of phosphate and pH on removal of phosphate by conducting a series of batch adsorption experiments. The results showed that 98% of phosphate removal rate was obtained since sawdust and bentonite used in this investigation were abundantly and locally available. It is concluded that modified bentonite is a relatively efficient, low cost and easily available adsorbent for the removal of phosphate from aqueous solutions.

  16. Degradation kinetics of benzyl nicotinate in aqueous solution

    Mbah C


    Full Text Available The degradation of benzyl nicotinate in aqueous solution over a pH range of 2.0-10.0 at 50±0.2 o was studied. The degradation was determined by high performance liquid chromatography. The degradation was observed to follow apparent first-order rate kinetics and the rate constant for the decomposition at 25 o was estimated by extrapolation. The reaction was shown to be hydroxide ion catalyzed and the Arrhenius plots showed the temperature dependence of benzyl nicotinate degradation. A significant increase in the stability of benzyl nicotinate was observed when glycerol or polyethylene glycol 400 was incorporated into the aqueous solution.

  17. Ionisation constants of inorganic acids and bases in aqueous solution

    Perrin, D D


    Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution, Second Edition provides a compilation of tables that summarize relevant data recorded in the literature up to the end of 1980 for the ionization constants of inorganic acids and bases in aqueous solution. This book includes references to acidity functions for strong acids and bases, as well as details about the formation of polynuclear species. This text then explains the details of each column of the tables, wherein column 1 gives the name of the substance and the negative logarithm of the ionization constant and column 2

  18. Single and Tertiary System Dye Removal from Aqueous Solution Using Bottom Ash: Kinetic and Isotherm Studies

    R. Gandhimathi


    Full Text Available This paper investigates the ability of Bottom ash to adsorb three cationic dyes from aqueous solution in single and tertiary systems. Crystal Violet (CV, Methylene Blue (MB and Malachite Green (MG were used as cationic dye models. The surface characteristics of Bottom ash were investigated using Fourier Transform Infrared (FTIR. Pseudo second order model was fitted better than Pseudo First order model for all system of MG, MB and CV. From the isotherm study, the adsorption capacity increased in the order of MB< MG

  19. Hydrogen-atom attack on methyl viologen in aqueous solution studied by pulse radiolysis

    Using hydrogen at high pressures of up to 150 bar as an OH scavenger in aqueous MV2+ solutions (pH 1) it is possible to differentiate between two kinds of transient formed simultaneously by H-atom attack on methyl viologen. One of them is assigned to an H adduct on the N atom, MV+H+, with absorption bands identical to those of the radical cation, MV+. The MV+H+ species deprotonates forming the long-lived radical cation, MV+. The second type of transient produced is attributed to an H-adduct on the ring carbon, MV2+H, decaying by second-order kinetics. The formation of MV+ by electron transfer from the propan-2-ol radical has been reinvestigated (pH 0 to 7); its absorption spectrum does not change in this pH range. Rate constants and molar extinction coefficients are presented. (U.K.)

  20. Synthesis and characterization of quaternized bacterial cellulose prepared in homogeneous aqueous solution.

    Zhang, Hairong; Guo, Haijun; Wang, Bo; Shi, Silan; Xiong, Lian; Chen, Xinde


    In this work, bacterial cellulose (BC) was activated by ethylenediamine (EDA) and then dissolved in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) aqueous solutions. The resulting transparent solution was cast on a glass plate to prepare regenerated BC. Then cationic BC was prepared homogeneously by the reaction between regenerated BC and 3-chloro-2-hydroxypropyl-trimethyl ammonium chloride (CHPTAC) in a NaOH/urea aqueous solution. Structure and properties of the BC and its products were characterized by different techniques such as X-ray diffraction (XRD), Fourier transform spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The results showed that there was no significant difference between the structures of BC, activated BC and regenerated BC. The effects of different temperature and molar ratio of CHPTAC to anhydroglucose unit (AGU) on the degree of substitution (DS) value were examined. The DS values of cationic BC ranged between 0.21 and 0.51. PMID:26572343

  1. Valence Electronic Structure of Aqueous Solutions: Insights from Photoelectron Spectroscopy

    Seidel, Robert; Winter, Bernd; Bradforth, Stephen E.


    The valence orbital electron binding energies of water and of embedded solutes are crucial quantities for understanding chemical reactions taking place in aqueous solution, including oxidation/reduction, transition-metal coordination, and radiation chemistry. Their experimental determination based on liquid-photoelectron spectroscopy using soft X-rays is described, and we provide an overview of valence photoelectron spectroscopy studies reported to date. We discuss principal experimental aspects and several theoretical approaches to compute the measured binding energies of the least tightly bound molecular orbitals. Solutes studied are presented chronologically, from simple electrolytes, via transition-metal ion solutions and several organic and inorganic molecules, to biologically relevant molecules, including aqueous nucleotides and their components. In addition to the lowest vertical ionization energies, the measured valence photoelectron spectra also provide information on adiabatic ionization energies and reorganization energies for the oxidation (ionization) half-reaction. For solutes with low solubility, resonantly enhanced ionization provides a promising alternative pathway.

  2. Contact nuclei formation in aqueous dextrose solutions

    Cerreta, Michael K.; Berglund, Kris A.


    A laser Raman microprobe was used in situ to observe the growth of alpha dextrose monohydrate on alpha anhydrous dextrose crystals. The Raman spectra indicate growth of the monohydrate below 28.1°C, but the presence of only the anhydrous form above 40.5°C. Contact nucleation experiments with parent anhydrous crystals yielded only monohydrate nuclei below 28.1°C, while contacts in solutions between 34.5 and 41.0°C produced both crystalline forms, and contacts in solutions above 43.5°C produced only anhydrous nuclei. The inability of the monohydrate to grow on anhydrous crystals in the same solution that forms the two crystalline phases with a single contact precludes a simple attrition mechanism of nuclei formation. For the same reason, the hypothetical mechanism involving parent crystal stabilization of pre-crystalline clusters, allowing the clusters to grow into nuclei, is also contradicted. A third, mechanism, which may be a combination of the two, is believed to apply.

  3. Preliminary study on lithium-salt aqueous solution blanket

    Aqueous solution blanket using lithium salts such as LiNO3 and LiOH have been studied in the US-TIBER program and ITER conceptual design activity. In the JAERI/LANL collaboration program for the joint operation of TSTA (Tritium Systems Test Assembly), preliminary design work of blanket tritium system for lithium ceramic blanket, aqueous solution blanket and liquid metal blanket, have been performed to investigate technical feasibility of tritium demonstration tests using the TSTA. Detail study of the aqueous solution blanket concept have not been performed in the Japanese fusion program, so that this study was carried out to investigate features of its concept and to evaluated its technical problems. The following are the major items studied in the present work: (i) Neutronics of tritium breeding ratio and shielding performance Lithium concentration, Li-60 enrichment, beryllium or lead, composition of structural material/beryllium/solution, heavy water, different lithium-salts (ii) Physicochemical properties of salts Solubility, corrosion characteristics and compatibility with structural materials, radiolysis (iii) Estimation of radiolysis in ITER aqueous solution blanket. (author)

  4. Phytoremediation of Heavy Metals in Aqueous Solutions

    Felix Aibuedefe AISIEN; Oluwole FALEYE; Eki Tina AISIEN


    One of the major environmental problems is the pollution of water and soil by toxic heavy metals. This study investigated the phytoremediation potential of water hyacinth, for the removal of cadmium (Cd), lead (Pb) and zinc (Zn). Water hyacinths were cultured in bore-hole water, supplemented with 5mg/l of Zn and Pb and 1mg/l of Cd at pH 4.5, 6.8 and 8.5. The plants were separately harvested each week for six weeks. The results showed that removal of these metals from solution was fast especia...

  5. Chemical denitration of aqueous nitrate solutions

    The Plant for Active Waste Liquids (PAWL) at CRNL will immobilize in glass the fission products in waste from Mo-99 production. The nitrate ions in the waste can be destroyed by heating, but also by chemical reaction with formic acid (HCOOH). Since chemical denitration has several advantages over thermal denitration it was studied in the course of vitrification process development. Two free radical mechanisms are examined here to explain kinetic data on chemical denitration of nitric acid solutions with formic acid. One mechanism is applicable at > 1 mol/L HNO3 and involves the formate radical (HCOO.). The second mechanism holds at 3 and involves the hyponitrous radical (HNO.). Mass balances for various species were written based on the law of mass action applied to the equations describing the reaction mechanism. Analytical and numerical solutions were obtained and compared. Literature data on batch denitration were used to determine some of the rate constants while others were set arbitrarily. Observed stoichiometry and trends in reactant concentrations are predicted accurately for batch data. There are no literature data to compare with the prediction of negligible induction time

  6. Photocatalytic degradation of molinate in aqueous solutions.

    Bizani, E; Lambropoulou, D; Fytianos, K; Poulios, I


    In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H2O2 and K2S2O8) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron's and electron scavenger's concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri. The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes. PMID:24928378


    Olga Lobacheva


    Full Text Available Yttrium (III and ytterbium (III cations ion flotation from diluted aqueous solutions in the presence of chloride ions using sodium dodecyl sulfate as collector agent were studied. Y (III and Yb (III distribution and recovery coefficients as a function of aqueous phase рН value at different sodium chloride concentrations were received. Yttrium (III and ytterbium (III chloro and hydroxo complexes instability constants were calculated. The calculation of separation coefficient at рН specified values depending on chloride ion concentration was conducted. Maximum separation coefficient was observed when chloride concentration of 0.01 M is 50 at рН 7.8. Ksep is minimal in nitrate medium ans is 3 at рН 7.0. At sodium chloride concentration of 0.05 М Ksep is 9 at рН 7.8.

  8. Drag enhancement of aqueous electrolyte solutions in turbulent pipe flow.

    Doherty, Andrew P; Spedding, Peter L; Chen, John J J


    Detailed experimental results are presented for both laminar and turbulent flow of aqueous solutions in pipes of different diameters. Nonelectrolytes, such as sugar solutions followed the normal Moody pressure loss curves. Drag enhancement was demonstrated for turbulent flow of aqueous electrolyte solutions but not for laminar flow. The increased pressure drop for turbulent electrolyte flow was attributed to an electroviscous effect and a theory was developed to explain the drag enhancement. The increased pressure drop for the turbulent region of flow was shown to depend on the Debye length in the laminar sublayer on the pipe wall. Reasonable predictions of the increasing drag were obtained for both 1:1 and 2:1 electrolyte solutions. PMID:20337452

  9. γ-radiation induced tetracycline removal in an aqueous solution

    Degradation effect of tetracycline (TC) by γ-radiation was investigated in an aqueous solution. The effects of initial concentrations of TC, pH values, combining with H2O2 or CH3OH on degradation of TC were studied. Results showed that TC can be effectively degradated by γ-irradiation in an aqueous solution. Degradation of TC could be remarkably improved both in acid solution and alkaline solution, especially when pH value was 9.0. In addition, H2O2 could gently promote degradation of TC induced by γ-radiation. While, CH3OH markedly restrained degradation of TC induced by γ-radiation. The degradation mechanism of TC was supposed by results of quantum chemical calculations and LC-MS. Results proved that degradation of TC induced by γ-radiation was mainly ascribed to · OH oxidation. (authors)

  10. Dissociation of methane hydrate in aqueous NaCl solutions.

    Yagasaki, Takuma; Matsumoto, Masakazu; Andoh, Yoshimichi; Okazaki, Susumu; Tanaka, Hideki


    Molecular dynamics simulations of the dissociation of methane hydrate in aqueous NaCl solutions are performed. It is shown that the dissociation of the hydrate is accelerated by the formation of methane bubbles both in NaCl solutions and in pure water. We find two significant effects on the kinetics of the hydrate dissociation by NaCl. One is slowing down in an early stage before bubble formation, and another is swift bubble formation that enhances the dissociation. These effects arise from the low solubility of methane in NaCl solution, which gives rise to a nonuniform spatial distribution of solvated methane in the aqueous phase. We also demonstrate that bubbles form near the hydrate interface in dense NaCl solutions and that the hydrate dissociation proceeds inhomogeneously due to the bubbles. PMID:25237735

  11. Radiolysis of paracetamol in dilute aqueous solution

    Szabó, László; Tóth, Tünde; Homlok, Renáta; Takács, Erzsébet; Wojnárovits, László


    Using radiolytic experiments hydroxyl radical (main reactant in advanced oxidation processes) was shown to effectively destroy paracetamol molecules. The basic reaction is attachment to the ring. The hydroxy-cyclohexadienyl radical produced in the further reactions may transform to hydroxylated paracetamol derivatives or to quinone type molecules and acetamide. The initial efficiency of aromatic ring destruction in the absence of dissolved O2 is c.a. 10%. The efficiency is 2-3 times higher in the presence of O2 due to its reaction with intermediate hydroxy-cyclohexadienyl radical and the subsequent ring destruction reactions through peroxi radical. Upon irradiation the toxicity of solutions at low doses increases with the dose and then at higher doses it decreases. This is due to formation of compounds with higher toxicity than paracetamol (e.g. acetamide, hidroquinone). These products, however, are highly sensitive to irradiation and degrade easily.

  12. Highly-acidic aqueous solution as a medium for radiation chemical studies: redox chemistry of phenol

    Although the aqueous medium is a common choice for radiation induced generation of a variety of transients (radicals), typically a non-aqueous solvent (or even a frozen matrix) is employed to study a transient with a labile H+ (TrH.+), mainly to maintain low propensity of its deprotonation reaction TrH.+→Tr. + H+, that otherwise occur promptly in an aqueous type medium. However, in addition to the relative difficulty encountered in routine handling of such specific non-aqueous reaction media, low transient yield (GTrH.+) therein also restrict their use. Furthermore, any comparative study of the two species TrH.+ and Tr. remains unattainable. In this context we have probed the highly acidic aqueous solution as an alternative medium for radiation induced generation and subsequent chemical studies of acidic radical cation, TrH.+ vis-a-vis the de-protonated radical Tr.. This presentation highlights these results in three parts deals with (a) measurement of oxidizing and reducing radical yields for reactions in H2SO4 and HClO4 solutions, with highest acidity maintained at ∼14 M or Hammett acidity constant H0 - 7 in case of former and ∼10 M or H0 -5.2 in case of the latter; (b) measurement of the H-atom (the sole reducing radical) scavenging efficiency of dissolved O2 in such solution for maintaining exclusive oxidizing condition; and (c) employing these results, oxidation of phenol (C6H5OH) in such medium was probed and the reactions of its radical cation C6H5OH.+ against the phenoxyl radical C6H5O. were compared. Consequently, these studies also revealed an error in the previous measurement of the C6H5OH.+ pKa value (-2.0) which was corrected to -2.75. Details of these studies will be presented to show the efficacy of highly-acidic aqueous solutions as a regular medium for radiation chemical studies. (authors)

  13. Photocatalytical oxidation of de-icing agents in aqueous solutions and aqueous extract of jet fuel.

    Krichevskaya, M; Malygina, T; Preis, S; Kallas, J


    Improper handling of jet fuel at abandoned military bases has resulted in heavy pollution of the soil and groundwater. Experimental research of photocatalytical oxidation (PCO) of jet fuel aqueous extract and aqueous solutions of de-icing agents was undertaken. The influence of different parameters - pH, concentration of substances to be oxidised, presence of inorganic admixtures, effect of OH. radical generators--on the PCO of solutions of de-icing agents and jet fuel aqueous extract was determined. The role of OH. radicals was found to be less important in determining the PCO rate. The PCO of organic pollutants was also investigated using a catalyst immobilised onto the surface of buoyant hollow glass microspheres. Attached titanium dioxide (TiO2) showed lower photocatalytical activity than when suspended in slurry, although it allows waters to be treated in simple shallow ponds without intensive stirring. The biodegradability of aqueous solutions of de-icing agents and jet fuel aqueous extract increased as PCO proceeded. PMID:11695445

  14. The coacervation of aqueous solutions of tetraalkylammonium halides

    The coacervation of aqueous solutions of tatraalkylammonium halides in the presence of not of inorganic halides and acids has been studied, considering thermodynamic and spectroscopic aspects. The importance of dispersion forces as well as forces resulting from hydrophobic hydration has been assessed. The analogy between these systems and anionic ion exchange resins has been shown especially for Uranium VI extraction

  15. Ion equilibrium in aqueous solutions of pectin materials

    By means of electro conductivity method the comparative study of ion equilibrium of pectin materials of apple, orange and sunflower in aqueous solution at various ph was conducted. According to experimental data on specific conductivity the value of equivalent conductivity, level, functions and dissociation constant were evaluated. (author)

  16. Why Urea Eliminates Ammonia Rather Than Hydrolyzes in Aqueous Solution

    Alexandrova, Anastassia N.; Jorgensen, William L.


    A joint QM/MM and ab initio study on the decomposition of urea in the gas phase and in aqueous solution is reported. Numerous possible mechanisms of intramolecular decomposition and hydrolysis have been explored; intramolecular NH3-elimination assisted by a water molecule is found to have the lowest activation energy. The solvent effects were elucidated using the TIP4P explicit w...

  17. Reactive Extraction of Alcohols from Apolar Hydrocarbons with Aqueous Solutions


    The aqueous solutions are evaluated as sustainable reactive extraction solvents for the recovery of monohydroxyl alcohols (benzyl alcohol, 1-hexanol, cyclohexanol) present in few-percent concentrations in apolar hydrocarbons (toluene, n-hexane, and cyclohexane) by considering two approaches. An aqueous solution containing a reactive extractant, like borate salts, borate complexes, a monosalt of dicarboxylic acid,hydroxypropyl-cyclodextrins, and silver nitrate, shows limited potential to be used. Another approach, in which the alcohol is chemically modified prior to the extraction into an easy-extractable form, in this case a monoesterlcarboxylic acid, shows much more potential. An environmentally benign aqueous solution of sodium hydrogen carbonate can provide a distribution ratio of benzyl alcohol up to 200, leaving the solubility of the organic solvent in the aqueous solution unchanged relative to pure water and therefore increasing the selectivity with two orders of magnitude. The modification of aromatic, cyclo-aliphatic, and linear aliphatic alcohols can be performed efficiently in the apolar organic solvent without need for a catalyst. The recovery of the modified alcohol can be performed by back-extraction in combination with a spontaneous hydrolysis.

  18. Photolysis of Periodate and Periodic Acid in Aqueous Solution

    Sehested, Knud; Kläning, U. K.


    The photochemistry of periodate and periodic acid in aqueous solution was studied (i) by quantum yield measurements at low light intensity (ii) by flash photolysis, and (iii) by photolysis of glassy samples at 77 K. The photochemical studies were supplemented with pulse radiolysis studies of...

  19. NMR study of thermosensitive homopolymers and copolymers in aqueous solutions

    Spěváček, Jiří; Šťastná, J.; Starovoytova, Larisa; Hanyková, L.

    Ireland : University College Dublin, 2012. s. 198. [EUROMAR 2012. Magnetic Resonance Conference. 01.07.2012-05.07.2012, Dublin] R&D Projects: GA ČR GA202/09/1281 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : thermosensitive polymer * aqueous solution * phase transition Subject RIV: CD - Macromolecular Chemistry

  20. Accurate Description of Calcium Solvation in Concentrated Aqueous Solutions

    Kohagen, Miriam; Mason, Philip E.; Jungwirth, Pavel


    Roč. 118, č. 28 (2014), s. 7902-7909. ISSN 1520-6106 R&D Projects: GA ČR GBP208/12/G016; GA MŠk LH12001 Institutional support: RVO:61388963 Keywords : calcium chloride * aqueous solution * molecular dynamics * neutron scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.302, year: 2014

  1. Neodymium(3) complexing with bischloromethylphosphinic acid in aqueous solution

    High resolution spectrography is used to study Nd3+ complexing with (ClCH2)2POOH(HL) in aqueous solution. NdL2+ complex (lg Kstab = 0.44±0.04) with the corresponding absorption band with a maximum at λ=4283 A is formed in a system

  2. Densities concentrations of aqueous of uranyl nitrate solutions

    The ratio density-concentration of aqueous uranyl nitrate solutions expressed as U3O8 grams/liter, U grams/liter and hexahydrate uranyl nitrate weight percent at different temperatures, are established. Experimental values are graphically correlated and compared whit some published data. (Author) 2 refs

  3. [Pulsed radiolysis of aqueous solutions of serum albumin containing naphthoquinones].

    Pribush, A G; Savich, A V


    As was shown by the pulse radiolysis method the simultaneous presence of naphthoquinone and human serum albumin molecules in an aqueous solution leads to the adsorption of the former on the surface of the latter. It is suggested that in these conditions the protein tertiary structure changes. New conformation reduces the reactivity of albumin toward the hydrated electron. PMID:3628723

  4. Gamma radiolysis of aqueous solutions of glycerin α-monochlorohydrin

    Data on γ-radiolysis of 0.1 mol/l aqueous solutions of glycerin α-monochlorohydrin (GMC) are presented. The radiolysis mechanism is considered. The rate constant of GMC reaction with esub(aq) k=(6.8+-0.8)x108 l/molxs is determined on the basis of experimental data

  5. Solubility of carbon dioxide in aqueous piperazine solutions

    Derks, P. W. J.; Dijkstra, H. B. S.; Hogendoorn, J. A.; Versteeg, G. F.


    In the present work, new experimental data are presented on the solubility of carbon dioxide in aqueous piperazine solutions, for concentrations of 0.2 and 0.6 molar piperazine and temperatures of 25, 40, and 70°C respectively. The present data, and other data available in the literature, were corr

  6. Demonstration of reverse symmetry waveguide sensing in aqueous solutions

    Horvath, R.; Pedersen, H.C.; Larsen, N.B.


    A reverse symmetry waveguide is presented for evanescent wave sensing in aqueous solutions. The waveguide consists of a thin polystyrene film, supported by a thicker substrate layer of nanoporous silica on glass. The nanoporous substrate layer has a refractive index of n(S)=1.193, hence, with an ...

  7. EXAFS studies of actinide ions in aqueous solution

    The applicability of the EXAFS technique in the study of actinide systems is discussed. Uranium L/sub III/-edge spectra obtained on an in-lab rotating anode EXAFS facility are presented and analyzed for crystalline UO2F2 and aqueous solutions containing hexavalent uranium ions. Methods for the extension of the technique to more dilute systems are discussed

  8. Adsorption of lead ions from aqueous solutions using clinoptilolite

    Golomeova, Mirjana; Zendelska, Afrodita; Krstev, Boris; Golomeov, Blagoj; Blažev, Krsto; Krstev, Aleksandar


    The adsorption of lead ions from synthetic aqueous solutions was performed by using natural zeolite (clinoptilolite). In order to determine the effectivity of clinoptilolite a series of experiments were performed under batch conditions from single ion solutions. Experiments were carried out at different initial concentration of lead ions, different initial pH values and different adsorbent mass. The adsorption kinetics is reasonably fast. It means that in the first 20 min approximately 90...

  9. Adsorption of copper ions from aqueous solutions on natural zeolite

    Zendelska, Afrodita; Golomeova, Mirjana; Blažev, Krsto; Krstev, Boris; Golomeov, Blagoj; Krstev, Aleksandar


    The adsorption of copper ions from synthetic aqueous solutions on natural zeolite (clinoptilolite) was examined. In order to determine the rate of adsorption and the copper uptake at equilibrium, a series of experiments were performed under batch conditions from single ion solutions. Equilibrium data were evaluated based on adsorption (Langmuir and Freundlich) isotherms. The adsorption kinetics is reasonably fast. In the first 20 min of the experiment, approximately 80% of Cu2+ io...

  10. A study of aqueous solutions of sodium linoleate

    During the development of a technique for measuring fatty acid absorption on finely divided minerals using a radiochemical method, absorption isotherms were obtained which displayed maxima. It was found that these results were due to the presence of stable micelles in the solutions. This has been established by measuring the surface tension, surface film pressure, and specific conductance of dilute aqueous solutions of sodium linoleate

  11. Removal of azo dye from aqueous solutions using chitosan

    Zuhair Jabbar; G. Hadi Ferdoos Sami; A , Angham


    Adsorption of Congo Red (CR) from aqueous solution onto chitosan was investigated in a batch system. The effects of solution pH, initial dye concentration, and temperature were studied. Results indicated that chitosan could be used as a biosorbent to remove the azo dyes from contaminated water. Synthesize of chitosan involved three main stages as preconditioning, demineralization, deproteinization and deacetylation. Chitosan was characterized using Fourier Transform Infrared Spectroscopy (FTI...

  12. Interaction of molybdophosphates with palladium(II) salts in aqueous solutions

    The methods of electron and 31P NMR spectroscopies were used to study the interaction of H3PMo12O40 with H2PdCl4 or PdSO4 in aqueous solution at pH 3.0-4.5 and the ratio [Pd(II)]:[H3PMo12O40]=1:1. Palladium(II) remains in solution in the form of intensely colored hydroxo species and does not change the structure of the newly formed unsaturated heteropolymolybdates PMo11O397- and PMo9O349- as shown by NMR data. Heteropoly compounds precipitated from tetrabutylammonium or cesium salts were characterized using IR spectroscopy, differential dissolution and elemental analysis. It was found that the composition of a compound was affected by not only formation conditions in the solution but also the precipitant cation

  13. Block copolymer membranes for aqueous solution applications

    Nunes, Suzana Pereira


    Block copolymers are known for their intricate morphology. We review the state of the art of block copolymer membranes and discuss perspectives in this field. The main focus is on pore morphology tuning with a short introduction on non-porous membranes. The two main strategies for pore formation in block copolymer membranes are (i) film casting and selective block sacrifice and (ii) self-assembly and non-solvent induced phase separation (SNIPS). Different fundamental aspects involved in the manufacture of block copolymer membranes are considered, including factors affecting the equilibrium morphology in solid films, self-assembly of copolymer in solutions and macrophase separation by solvent-non-solvent exchange. Different mechanisms are proposed for different depths of the SNIPS membrane. Block copolymer membranes can be prepared with much narrower pore size distribution than homopolymer membranes. Open questions and indications of what we consider the next development steps are finally discussed. They include the synthesis and application of new copolymers and specific functionalization, adding characteristics to respond to stimuli and chemical environment, polymerization-induced phase separation, and the manufacture of organic-inorganic hybrids.

  14. Phytoremediation of Heavy Metals in Aqueous Solutions

    Felix Aibuedefe AISIEN


    Full Text Available One of the major environmental problems is the pollution of water and soil by toxic heavy metals. This study investigated the phytoremediation potential of water hyacinth, for the removal of cadmium (Cd, lead (Pb and zinc (Zn. Water hyacinths were cultured in bore-hole water, supplemented with 5mg/l of Zn and Pb and 1mg/l of Cd at pH 4.5, 6.8 and 8.5. The plants were separately harvested each week for six weeks. The results showed that removal of these metals from solution was fast especially in the first two weeks, after which it became gradual till saturation point was reached. The accumulation of Cd and Zn in leaves and roots increased with increase in pH. The highest accumulation was in the roots with metal concentration of 4870mg/kg, 4150mg/kg and 710mg/kg for Zn, Pb and Cd respectively at pH 8.5. The maximum values of bioconcentration factor (BCF for Zn, Pb and Cd were 1674, 1531 and 1479 respectively, suggesting that water hyacinth was good accumulator of Zn, Pb and Cd, and could be used to treat industrial wastewater contaminated with heavy metals such as Zn, Pb and Cd.

  15. Assembly of DNA Architectures in a Non-Aqueous Solution

    Thomas J. Proctor


    Full Text Available In the present work, the procedures for the creation of self-assembled DNA nanostructures in aqueous and non-aqueous media are described. DNA-Surfactant complex formation renders the DNA soluble in organic solvents offering an exciting way to bridge the transition of DNA origami materials electronics applications. The DNA retains its structural features, and these unique geometries provide an interesting candidate for future electronics and nanofabrication applications with potential for new properties. The DNA architectures were first assembled under aqueous conditions, and then characterized in solution (using circular dichroism (CD spectroscopy and on the surface (using atomic force microscopy (AFM. Following aqueous assembly, the DNA nanostructures were transitioned to a non-aqueous environment, where butanol was chosen for optical compatibility and thermal properties. The retention of DNA hierarchical structure and thermal stability in non-aqueous conditions were confirmed via CD spectroscopy. The formation and characterization of these higher order DNA-surfactant complexes is described in this paper.

  16. Mechanisms of strand breaks in DNA induced by OH radicals in aqueous solution

    The gamma irradiation of N2O-saturated aqueous solutions of DNA in the absence of O2 leads to the formation of three detached altered sugars. It is predominantly OH radical which leads to the permanent and biological significant damage of DNA, and it is especially the OH radical which produces chain breaks. The OH radicals in aqueous solutions react with DNA predominantly (about 80%) by addition to the C=C bonds of the bases, and about 20% abstracts H atoms from sugar moiety. All three isolated sugars show new C=O bonds only at the position C-4. Chain-breaking reaction is identified as the heterolytic splitting of the sugar phosphoric acid ester bond, producing a cation radical of the sugar moiety and an anion of the DNA phosphoric acid ester (SN1 reaction). The formation of the observed detached and attached altered sugars as end products is explained by the reaction of the cation radical with water in which branching in the reaction occurs, and by the subsequent reaction of the radicals formed. Two important features of the Scheme I mechanism are, first, the much faster bond breaking at the position 3' as compared with that at the position 5', and secondly, the formation of not only detached altered sugars but also altered sugar end groups. Quantitative results show that a large fraction of DNA chain breaks induced by OH radicals can be accounted for by the Scheme I. (Yamashita, S.)

  17. Effect of Counterion and Configurational Entropy on the Surface Tension of Aqueous Solutions of Ionic Surfactant and Electrolyte Mixtures

    Youichi Takata; Hiroaki Tagashira; Atsushi Hyono; Hiroyuki Ohshima


    In order to clarify the adsorption behavior of cationic surfactants on the air/aqueous electrolyte solution surface, we derived the theoretical equation for the surface tension. The equation includes the electrical work required for charging the air/water surface and the work attributable to the configurational entropy in the adsorbed film. By fitting the equation to the experimental data, we determined the binding constant between adsorbed surfactant ion and counterion, and found that the br...

  18. Electrodeposition of metals from non-aqueous solutions

    Electrodeposition of metals from non-aqueous solutions is reviewed. Attention is paid mainly to surface morphology of deposits and their adhesion. The major reasons for carrying out electrodeposition in non-aqueous electrolytes (such as conventional organic solvents, ionic liquids and molten salts) are the water and air stability and the wide electrochemical window of these media. The following metals have been electrodeposited and investigated for the last 15 years: aluminum, zinc, silver, palladium, tantalum, zirconium, gadolinium, plutonium, nickel, cobalt, and other alloys.

  19. Adsorption of EDTA on activated carbon from aqueous solutions

    In this study, the adsorption of EDTA on activated carbon from aqueous solutions has been investigated in a batch stirred cell. Experiments have been carried out to investigate the effects of temperature, EDTA concentration, pH, activated carbon mass and particle size on EDTA adsorption. The experimental results manifest that the EDTA adsorption rate increases with its concentration in the aqueous solutions. EDTA adsorption also increases with temperature. The EDTA removal from the solution increases as activated carbon mass increases. The Langmuir and Freundlich equilibrium isotherm models are found to provide a good fitting of the adsorption data, with R2 = 0.9920 and 0.9982, respectively. The kinetic study shows that EDTA adsorption on the activated carbon is in good compliance with the pseudo-second-order kinetic model. The thermodynamic parameters (Ea, ΔG0, ΔH0, ΔS0) obtained indicate the endothermic nature of EDTA adsorption on activated carbon.

  20. Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives - their stability, complexation ability in solution or when deposited on solid anionic surface.

    Popr, Martin; Filippov, Sergey K; Matushkin, Nikolai; Dian, Juraj; Jindřich, Jindřich


    The thermal stability of the monosubstituted cationic cyclodextrin (CD) derivatives PEMEDA-β-CD and PEMPDA-β-CD, which differ in their substituent linker length (ethylene and propylene, respectively), was studied via (1)H NMR experiments. PEMPDA-β-CD exhibited higher resistance towards the Hofmann degradation and was chosen as a more suitable host molecule for further studies. Inclusion properties of PEMPDA-β-CD in solution with a series of simple aromatic guests (salicylic acid, p-methoxyphenol and p-nitroaniline) were determined by isothermal titration calorimetry (ITC) and compared to the native β-CD. Permanently charged cationic CD derivatives were successfully deposited on the anionic solid surface of polymeric Nafion(®) 117 membrane via electrostatic interactions. Deposition kinetics and coverage of the surface were determined by ELSD. Finally, the ability of the CD derivatives bound to the solid surface to encapsulate aromatic compounds from aqueous solution was measured by UV-vis spectroscopy. The obtained results are promising for future industrial applications of the monosubstituted β-CD derivatives, because the preparation of cationic CD derivatives is applicable in large scale, without the need of chromatographic purification. Their ionic deposition on a solid surface is simple, yet robust and a straightforward process as well. PMID:25815069

  1. Speciation of native cations and added radionuclides in raw bovine milk. I. membraneless dialysis in aqueous biphasic systems

    Partition of native sodium, potassium, magnesium, calcium and radioisotopes of cesium, strontium and europium was investigated in the aqueous liquid-liquid systems formed after agitation of fresh pasteurized skim bovine milk with 4% w/w water solution of pectin of various degree of esterification (60-93%). The partition of the ions in the 'membraneless dialysis' was described by Donnan equilibria and ion-exchange in the macro-and microheterogenous systems and, within uncertainty of results, does not depend on the degree of esterification. Strong negative non-ideality of Sr and Eu in milk phase is attributed to binding with proteins, casein particles in particular, and complexation with low molecular ligands. Separation factor α = D(Sr)/D(Ca) is 0.70 ±0.06, in favor of strontium concentration in pectin phase. While>96% of cesium is diffusible to pectin phase, only 43-56% (depending on physico-chemical model of dialysis) of strontium behaves in that way, and in original milk phase the percent of strontium cationic from may be as low as 13%. (author). 24 refs., 8 figs., 4 tabs

  2. Nanoporous activated carbon cloth for capacitive deionization of aqueous solution

    Oh, Han-Jun [Department of Materials Science, Hanseo University, Seosan, 352-820 (Korea, Republic of); Lee, Jong-Ho [Department of Chemistry, Hanseo University, Seosan, 352-820 (Korea, Republic of); Ahn, Hong-Joo [Korea Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Jeong, Yongsoo [Korea Institute of Machinery and Materials, Changwon, 641-010 (Korea, Republic of); Kim, Young-Jig [Department of Metallurgical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Chi, Choong-Soo [School of Advanced Materials Engineering, Kookmin University, Seoul, 136-702 (Korea, Republic of)]. E-mail:


    Activated nanostructured-carbon cloths with a high ratio of surface area to volume are used as electrode for capacitive deionization. The electrochemical properties on capacitive deionization for NaCl solution have been investigated to improve efficiency of capacitive deionization properties from aqueous solution, employing chemical surface-modification by etching in alkaline and acidic solution. The removal efficiency of inorganic salts of activated carbon cloths by chemical modification significantly increased. Specially the carbon cloth surface modified in HNO{sub 3} showed an effect of improvement in the CDI efficiency due to not only ion adsorption by an electric double layer, but also electron transfer by Faradaic reaction.

  3. ESR spectra of VOBr2 in alcohols and aqueous solutions

    ESR spectra of VOBr2 solutions in absolutized alcohols ROH (R - Me, Et, i-Pr) and aqueous solutions in the presence of LiBr and HBr are investigated and parameters of spin-hamiltonian of vanadium oxocomplexes are determined. Stabilization of [VOBr(ROH)4]+ complex, in which bromide-ion occupies position in xy plane, is detected. Isotropic additional HFS from 79,81Br atoms at the temperature close to the solution boiling point is found, and at 77 K -anisotropic additional HFS in the range of transitions corresponding to perpendicular orientation of particles as to magnetic field

  4. Synergistic extraction of transition metal cations from aqueous media by two separated organic phases

    We have therefore initiated novel approaches to the study of the mechanism of the synergistic extraction of metal ions by means of two separated organic phases, which are brought in contact with the same aqueous phase. The present work is concerned with the extraction of transition metals and actinides ions from nitric acid by chelating agents e.g., HTTA thenoyltrifluoroacetone in a diluent - the first organic phase, and by natural donor, e.g., TBP, tri-butyl phosphate in a diluent the second organic phase. The adduct formation was studied by means of spectrochemical and radiochemical methods. In the first approach the aqueous phase was attacked with both organic phases simultanously (the static or parallel extraction). In this method organic phase are separated one from the other. It was shown that even in the absence of mixing, synergism is observed under this experimental conditions. The results indicate, that adduct formation occurs in both organic phases. Nevertheless the enhanchment of extraction in the TBP phase is by far greater than that in the HTTA containing phase. This approach has one disadvatage, viz., the experiments are very time consuming, a typical experiment requiring over 10 days. In order to overcome this difficulty, the following experiments were carried out: the aqueous phase were first shaken with diluent containing an anionic ligand and the phases were allowed to separate. Then the aqueous solution were shaken with diluent containing a netural donor and the phase again were allowed to separate. The concentration of the metal ions in all the phases were determined. The experiments were repeated with an other diluent replacing the first diluent in one or both organic phases. In this way eight sequences of experiments were carried out for each concentration set chosen. The results thus point out that this experimental approach open new possibilities to investigate the mechanism and the kinetics of synergistic extraction processes. (author) the

  5. Dephosphorization of Steelmaking Slag by Leaching with Acidic Aqueous Solution

    Qiao, Yong; Diao, Jiang; Liu, Xuan; Li, Xiaosa; Zhang, Tao; Xie, Bing


    In the present paper, dephosphorization of steelmaking slag by leaching with acidic aqueous solution composed of citric acid, sodium hydroxide, hydrochloric acid and ion-exchanged water was investigated. The buffer solution of C6H8O7-NaOH-HCl system prevented changes in the pH values. Kinetic parameters including leaching temperature, slag particle size and pH values of the solution were optimized. The results showed that temperature has no obvious effect on the dissolution ratio of phosphorus. However, it has a significant effect on the dissolution ratio of iron. The dephosphorization rate increases with the decrease of slag particle size and the pH value of the solution. Over 90% of the phosphorus can be dissolved in the solution while the corresponding leaching ratio of iron was only 30% below the optimal condition. Leaching kinetics of dephosphorization follow the unreacted shrinking core model with a rate controlled step by the solid diffusion layer, the corresponding apparent activation energy being 1.233 kJ mol-1. A semiempirical kinetic equation was established. After leaching, most of the nC2S-C3P solid solution in the steelmaking slag was selectively dissolved in the aqueous solution and the iron content in the solid residue was correspondingly enriched.

  6. Effect of 60Co gamma-ray irradiation on dilute aqueous solutions of surfactants

    Present work deals with the effects of gamma irradiation from 60Co γ-ray source upon aqueous solutions of three kinds of surfactants. When dilute aqueous solutions of sodium dodecyl sulfate (SDS, anionic), cethyl trimethyl ammonium chloride (CTAC, cationic), and polyoxyethylene lauryl ether (POE, non-ionic) were irradiated with γ-rays at a room temperature, the residual concentration, products, surface tension, and forming power were examined by colorimetric method, IR spectrophotometric method, gaschromatography, Ross-Miles method, and Traube's stalagmometer etc. These surfactants were decomposed by the irradiation and thus the surface tension increased and the forming power, on the contrary, decreased with dose. Radiation chemical yields (G-value) of the degradation were about 1 for the solutions of SDS and CTAC, and about 0.3 for the POE solution. From the experimental results, it was found that following chemical reactions seem to occur followed by the radiolysis of water: a) bond cleavage of ester for SDS, of CN for CTAC, and of oxyethylene for POE, b) hydrogen abstraction from the surfactants, c) production of CO bond in the presence of dissolved oxygen. (auth.)

  7. Purification and concentration of DNA from aqueous solutions.

    Moore, David; Dowhan, Dennis


    This unit presents basic procedures for manipulating solutions of single- or double-stranded DNA through purification and concentration steps. These techniques are useful when proteins or solute molecules need to be removed from aqueous solutions, or when DNA solutions need to be concentrated. The Basic Protocol, using phenol extraction and ethanol (or isopropanol) precipitation, is appropriate for purification of DNA from small volumes (DNA using butanol, and extract residual organic solvents with ether, respectively. An alternative to these methods is nucleic acid purification using glass beads, and this technique is also presented. These protocols may also be used for purifying RNA. The final two alternate protocols are used for concentrating RNA and extracting and precipitating DNA from larger volumes and from dilute solutions, and for removing low-molecular-weight oligonucleotides and triphosphates. PMID:21948158

  8. Radiation induced intra-track reactions in aqueous solutions

    Radiation chemistry of aqueous solutions is inevitably important not only in physics and chemistry but also in biology and medicine. More than five decades much effort has been paid to clarify the elementary processes induced by irradiation. Then, pulse radiolysis study in the time scale of picosecond is now available. In addition, radiation chemistry studies with high LET radiation have been actively investigated. Furthermore, radiolysis study of aqueous solution at high temperatures and even in supercritical water is under progress. In the present lecture, experimental results on the radiolysis of water in ps time scale and LET effect obtained at Nuclear Engineering Research Laboratory (NERL), the University of Tokyo, will be presented relevant to the theoretical calculation. (author)

  9. Vapor Pressure of Aqueous Solutions of Ethylene Glycol

    Fujita, Toshihiko; Kikuchi, Sakae

    Vapor pressures of aqueous solutions of ethylene glycol are measured in the range of temperature from -10 to 60°C and concentration from 20 to 50wt%. In a low concentration range, the measured values of vapor pressure decrease according to the Raoult's law independent of temperature, while in a high concentration range, they show a trend to decrease towards the estimated values of freezing point with decreasing temperature. The following correlation equation is obtained for practical calculations on heating towers and the like. log(p/P0) = 5.351 - 6.4×10-4y + (1817 + 0.008y(y + 10))/(t + 240) where p, vapor perssure of aqueous solutions of ethylene glycol [kPa] ; P0, atmospheric pressure [=101.325kPa] ; y, concentration [wt%] ; t, temperature [°C].

  10. A lithium ion battery using an aqueous electrolyte solution

    Chang, Zheng; Li, Chunyang; Wang, Yanfang; Chen, Bingwei; Fu, Lijun; Zhu, Yusong; Zhang, Lixin; Wu, Yuping; Huang, Wei


    Energy and environmental pollution have become the two major problems in today’s society. The development of green energy storage devices with good safety, high reliability, high energy density and low cost are urgently demanded. Here we report on a lithium ion battery using an aqueous electrolyte solution. It is built up by using graphite coated with gel polymer membrane and LISICON as the negative electrode, and LiFePO4 in aqueous solution as the positive electrode. Its average discharge voltage is up to 3.1 V and energy density based on the two electrode materials is 258 Wh kg−1. It will be a promising energy storage system with good safety and efficient cooling effects. PMID:27328707