Simple Inorganic Ions Research Articles

Study on electrical double layer nanostructure on zeolitic materials’ surface in the presence of impurities of different nature

The aim of the research was to compare the adsorption mechanisms of heavy metal ions (Pb(II) and Zn(II)), as well as organic substances [diclofenac molecules and pol(acrylic acid) macromolecules on the surfaces of Na-X and Na-P1 synthetic zeolites as well their Na-X© and Na-P1© carbon composites]. The single and mixed adsorbate systems were considered. The more probable structures of the formed adsorption layers were proposed based on the results of the solid surface charge density and zeta potential experiments. The great applicability of the analysis of the parameters characterizing the electrical double layer in determination of the binding mechanism of simple inorganic ions and more complex organic molecules on the surface of the examined solids from the one- and two-component solutions was proved. Moreover, the changes of the surface and electrokinetic factors after the addition of the organic molecules enable specification of drug molecule orientation as well as the polymeric chain conformation at the solid/liquid interface.

Albumin-Hyaluronan Interactions: Influence of Ionic Composition Probed by Molecular Dynamics.

The lubrication mechanism in synovial fluid and joints is not yet fully understood. Nevertheless, intermolecular interactions between various neutral and ionic species including large macromolecular systems and simple inorganic ions are the key to understanding the excellent lubrication performance. An important tool for characterizing the intermolecular forces and their structural consequences is molecular dynamics. Albumin is one of the major components in synovial fluid. Its electrostatic properties, including the ability to form molecular complexes, are closely related to pH, solvation, and the presence of ions. In the context of synovial fluid, it is relevant to describe the possible interactions between albumin and hyaluronate, taking into account solution composition effects. In this study, the influence of Na+, Mg2+, and Ca2+ ions on human serum albumin–hyaluronan interactions were examined using molecular dynamics tools. It was established that the presence of divalent cations, and especially Ca2+, contributes mostly to the increase of the affinity between hyaluronan and albumin, which is associated with charge compensation in negatively charged hyaluronan and albumin. Furthermore, the most probable binding sites were structurally and energetically characterized. The indicated moieties exhibit a locally positive charge which enables hyaluronate binding (direct and water mediated).

VOLTAMMETRIC INVESTIGATION OF THE DISTRIBUTION OF HYDROXO-, CHLORO-, EDTA AND CARBOHYDRATE COMPLEXES OF LEAD, CHROMIUM, ZINC, CADMIUM AND COPPER: POTENTIAL APPLICATION TO METAL SPECIATION STUDIES IN BREWERY WASTEWATER

This paper reports results on complex formation reactions between OH - , Cl - , EDTA and carbohydrate ligands with Pb 2+ ions at various [LT]:[MT] ratios and at different pH values (1.5-13.0). Differential pulse anodic stripping voltammetry (DPASV) employing an ex situ plated thin mercury film electrode (TMFE) was used to measure the shifts in peak potentials. Formation of simple, polyligand as well as mixed ligand complexes are reported. The reactions between the Pb(II) and the carbohydrate ligands showed pronounced pH dependency on metal forms compared to reactions with simple inorganic ions such as chloride. Modeling of the experimental data obtained with the DPASV method was done using computer software (3D-VISE). The calculated complex formation curves (CCFC) based on mass balance equations were fitted to the experimental complex formation curves (ECFC) and the goodness of the fit evaluated (RSD KEY WORDS : Metal speciation, Carbohydrates, Brewery wastewater, Differential pulse voltammetry Bull. Chem. Soc. Ethiop. 2005, 19(1), 125-138

Redox Species of Redox Flow Batteries: A Review.

Due to the capricious nature of renewable energy resources, such as wind and solar, large-scale energy storage devices are increasingly required to make the best use of the renewable power. The redox flow battery is considered suitable for large-scale applications due to its modular design, good scalability and flexible operation. The biggest challenge of the redox flow battery is the low energy density. The redox active species is the most important component in redox flow batteries, and the redox potential and solubility of redox species dictate the system energy density. This review is focused on the recent development of redox species. Different categories of redox species, including simple inorganic ions, metal complexes, metal-free organic compounds, polysulfide/sulfur and lithium storage active materials, are reviewed. The future development of redox species towards higher energy density is also suggested.

Co-ion fluxes of simple inorganic ions in electrodialysis metathesis and conventional electrodialysis

The main functionality of ion-exchange membranes is to selectively permeate either cations or anions. However, co-ions may permeate as well to some extent through these membranes. For the production of chemicals with electrodialysis metathesis and conventional electrodialysis, these co-ion fluxes are a major source of impurities in the produced chemicals. The present paper studies the co-ion fluxes and the influence of operating parameters. The results clearly indicate that co-ion fluxes are predominately determined by the difference in ion concentration across the membrane. A more than linear increase in co-ion flux with respect to the ion concentration was observed. The current density has no significant influence on the co-ion fluxes. Therefore, a high current density leads to a smaller transport number of co-ions and improves the product purity in electrodialysis metathesis. Moreover, the co-ion flux can be decreased by the use of bulky counter-ions. In a conventional electrodialysis configuration, cation impurities are mainly caused by a diffusional flux. This flux is approximately three times larger than the co-ion flux. In contrast, the anion impurities are predominantly initiated by a co-ion flux and in magnitude smaller than the cation impurities.

Dimerization of cobalt-substituted Keggin phosphotungstate, [PW11O39Co(X)]5−, in nonpolar solvents

The tetraheptylammonium (THA) salt of cobalt-substituted polyoxotungstate with Keggin-like structure, (THA)5[PW11O39CoII(X)], was investigated by 31P NMR and UV/VIS spectroscopies in toluene. A solution obtained after transferring PW11Co from aqueous solution into toluene, using THABr as a transfer agent, and rigorous drying, gives multiple peaks in the 31P NMR spectrum. The spectrum in dry toluene significantly simplifies, after extracting a hexane solution several times with water, which removes simple inorganic ions. However, even the dry toluene solution after purification has 31P NMR and UV/VIS spectra which cannot be explained using the known equilibrium between (THA)5[PW11O39Co(H2O)] and (THA)5[PW11O39Co(__)]. Both 31P NMR and UV/VIS spectroscopies indicate the existence of dimers in dry toluene solutions, (THA)10[(PW11O39Co)2]. Pure (THA)5[PW11O39Co(_)] with five-coordinate cobalt can, however, be obtained in dry toluene in the presence of excess inert salt (high ionic strength conditions). Quantum mechanical/molecular mechanical calculations also support dimer formation in toluene.

Surface-Transfer Mass Spectrometry Imaging on a Monoisotopic Silver Nanoparticle Enhanced Target

A new method for both high-resolution laser desorption/ionization mass spectrometry and mass spectrometry imaging is described. The method could be considered as matrix-less because no additional matrix is needed for MS measurements and also because of surface-assisted laser desorption/ionization due to the nanoparticle-rich surface. The standard matrix-assisted laser desorption/ionization target containing unique monoisotopic cationic (109)Ag nanoparticles ((109)AgNPs) was used for high-resolution mass spectrometry imaging of fingermarks and also plant flower and plant stem cross sections with high mass accuracy. The methodology presented in this work allowed visualization of two drugs--anti-inflammatory ibuprofen and anticancer 5-fluorouracil--along with many other compounds found on the finger. Moreover, visualization of herbicide localization inside of the plant stem is also shown. The simple inorganic ions ionized by silver nanoparticles were also found and may be used for their localization in biological material. In addition, the methodology presented here does not require freezing of species or slice-making equipment.

Molecular “Pincer” from a Diimidazolium Salt: A Study of Binding Ability

The anion recognition ability of the dicationic imidazolium salt 3,3'-di-n-octyl-1,1'-(1,3-phenylenedimethylene)diimidazolium 1,5-naphthalenedisulfonate ([m-Xyl-(oim)2][1,5-NDS]) was investigated in acetonitrile solution by means of proton NMR titrations. A wide range of anions, comprising simple inorganic ions, halides, and mono- and dicarboxylates was taken into account. The study showed that this receptor binds carboxylate anions more strongly than halides. Moreover [m-Xyl-(oim)2][1,5-NDS] displays selectivity for di- over monocarboxylate anions. The complex stability was mainly affected by the anion basicity in the presence of monocarboxylates, whereas the flexibility of the alkyl chain linking the two carboxylate moieties appeared to play a major role in the presence of dicarboxylate anions.

Photocatalytic efficiency of nanocrystalline zeolite TS-1 for the degradation of methyl orange

The photocatalytic properties of nanocrystalline TS-1 were confirmed via the degradation of an aqueous solution of the model compound methyl orange (MO). The light intensity and quantum yield were measured by ferrioxalate actinometry and the values are 1.7 × 10−5 einstein l−1 s−1 and 0.71, respectively. The experimental parameters such as catalyst loading, pH and initial concentration of MO were optimized at 1.5 g/L, 10 and 300 μM, in order. The results showed that the dye molecules are completely degraded to CO2, H2O and simple inorganic ions.

Treatment of nano-sized rutile TiO2 powder in hydrogen peroxide under microwave irradiation and investigation on its sonocatalytic activity

In this work, a novel nano-sized mixed-crystal TiO2 catalyst was obtained under microwave irradiation in hydrogen peroxide solution and its sonocatalytic activity was also investigated through degradation of congo red dye. It was found that the sonocatalytic degradation effect of congo red using nano-sized mixed-crystal TiO2 powder was much higher than that using pure nano-sized rutile phase TiO2 powder. At last, the congo red dyes in aqueous solution were degraded completely and became some simple inorganic ions such as NO 3 − , SO 4 2− and so on. The experiments indicated that the degradation method using such treated nano-sized rutile TiO2 powder as sonocatalyst could be used to treat those non- or low-transparent wastewaters effectively.

100 000-Fold Concentration of Anions in Capillary Zone Electrophoresis Using Electroosmotic Flow Controlled Counterflow Isotachophoretic Stacking under Field Amplified Conditions

An electroosmotic flow (EOF) controlled counterflow isotachophoretic stacking boundary (cf-ITPSB) system under field amplified conditions has been examined as a way to improve the sensitivity of anions separated by capillary zone electrophoresis. The system comprised a high concentration of a high-mobility leading ion (100 mM chloride) and a low concentration of low-mobility terminating ion (1-3 mM MES or CHES) added to the sample in an unmodified fused-silica capillary at pH 8.05, buffered with Tris. Computer simulation studies using the software GENTRANS showed an increase in sensitivity of at least 10-fold over the previous cf-ITPSB system for simple inorganic ions, nitrite and nitrate. The simulations also suggested that the cf-ITPSB became stationary within the capillary and that its stationary position was not adversely affected by the concentration of MES. This was in contrast to experimental results that showed a slow and continual movement of the cf-ITPSB. This was more pronounced at lower concentrations of terminator (i.e., <3 mM) and resulted in a loss of resolution due to the cf-ITPSB being closer to the detector upon separation. This discrepancy was attributed to the change in pH across the capillary due to electrolysis and low buffering capacity in the sample, a phenomenon that cannot be simulated by the GENTRANS software. Replacement of MES with CHES as a lower mobility ion with increased buffer capacity failed to reduce the movement of the cf-ITPSB but did provide a further 3-fold improvement in sensitivity. The potential of this approach for sensitivity enhancement was demonstrated for the co-EOF separation of a mixture of six inorganic and small organic ions, with detection limits at the single-figure nanogram per liter level. These detection limits are 100,000 times better than can be achieved by normal hydrodynamic injection (ions prepared in water) and 250 times better than has been achieved by other online preconcentration approaches. The application of the EOF-controlled cf-ITPSB with counter-EOF separation of two pharmaceutical pollutants, naproxen and diflunisal, was also demonstrated with an improvement in sensitivity of 1000 giving detection limits of 350 ng/L in sewage treatment wastewater without any offline pretreatment.

Application of CE in hydrodynamically closed systems for analysis of bioactive compounds in food

CE is a family of electrokinetic separation techniques that separate compounds based upon differences in electrophoretic mobilities, phase partitioning, pI, molecular size, or a combination of one or several of these properties. CE has been used in several modes to analyze and characterize a wide variety of analytes from simple inorganic ions, small organic molecules, peptides, proteins, nucleic acids to virus, microbes and particles. Food consists of a complex mixture of a variety of components, many of which are biologically active. Components classified as "nutrients" are essential for growth, maintenance, and repair of the body. Other food constituents, typically occurring in small quantities, are classified as "biologically active substances" and they have beneficial or harmful effects on human health. There are two types of biologically active substances in food - naturally occurring and food additives. The bioactive compounds of food that will be mentioned in this review are inorganic and organic acids, amino acids, vitamins, phenolic compounds, biogenic amines, antinutrients, toxins, etc. This review is focused on the application of CE with hydrodynamically closed system (suppression of EOF) for the analysis of the above-mentioned compounds. CE can be an alternative method to HPLC or other methods for analysis of bioactive compounds in food. The main advantages of CE are low running cost (at least ten times than HPLC) and consideration to environment (hundreds of microliters of diluted water based electrolyte per analysis).

Investigation on the sonocatalytic degradation of congo red catalyzed by nanometer rutile TiO 2 powder and various influencing factors

Nanometer rutile (TiO 2) powder was introduced to act as the sonocatalyst during degradation of congo red that was chosen as a model compound. The ultrasound of low power was used as an irradiation source to induce nanometer rutile TiO 2 particles performing catalytic activity. It was found that the sonocatalytic degradation ratio of congo red in the presence of nanometer rutile TiO 2 particles was much better than ones with onefold ultrasonic irradiation. Although there are many factors influencing sonocatalytic degradation of congo red, the experimental results demonstrate that the optimal degradation effect of congo red can be obtained when the experimental conditions of initial congo red concentration of 10.0 mg/L, nanometer rutile TiO 2 adding amount of 1.0–1.5 g/L, ultrasonic frequency of 40 kHz, output power of 50 W, pH = 3.0–5.0 and 50°C within 180 min were adopted. At last, the congo red in aqueous solution was completely degraded and became some simple inorganic ions such as NO 3 − and SO 4 2− anions, etc. In this paper, the research on kinetics of sonocatalytic reaction has also been performed and found to follow pseudo first-order reaction. All experiments indicated that the sonocatalytic method in the presence of nanometer rutile TiO 2 powder was an advisable choice for the treatments of non- or low-transparent organic wastewaters in future.

Sonocatalytic degradation of methyl parathion in the presence of micron-sized and nano-sized rutile titanium dioxide catalysts and comparison of their sonocatalytic abilities

Micron-sized and nano-sized rutile titanium dioxide (TiO 2) powders were used as the catalysts for the sonocatalytic degradation of methyl parathion, an organophosphorus insecticide. The ultrasound of low power was used as an irradiation source to induce the catalytic activity of the rutile TiO 2 particles. It was found that the degradation of methyl parathion sonocatalytically progressed more rapidly in the presence of TiO 2 particles than only with ultrasonic irradiation in the absence of TiO 2 catalyst. Moreover, the sonocatalytic activity of the micron-sized rutile TiO 2 particles was obviously higher than that of nano-sized rutile TiO 2 particles. The influences of reaction parameters, such as the species of TiO 2 particles, methyl parathion concentration, TiO 2 amount, pH value, ultrasonic intensity, ultrasonic frequency and temperature have been investigated and the optimal conditions for eliminating methyl parathion have been established. The processes of methyl parathion degradation have been monitored by high performance liquid chromatography (HPLC), ion chromatography and UV–vis spectra. The results showed that methyl parathion in aqueous solution was completely degraded to give simple inorganic ions, such as NO 2 −, NO 3 −, PO 4 3−, SO 4 2−, etc. The kinetics of the degradation of methyl parathion followed the first-order reaction. The degradation percentage of methyl parathion surpassed 95% within 80 min in the optimal experimental conditions.

Investigation on the transition crystal of ordinary rutile TiO2 powder by microwave irradiation in hydrogen peroxide solution and its sonocatalytic activity

The transition crystal TiO2 catalyst with high sonocatalytic activity was obtained utilizing the microwave irradiation in hydrogen peroxide solution. At the same time a series of affecting factors (microwave irradiation time, heat-treated time and heat-treated temperature) to prepare the TiO2 catalyst on the sonocatalytic degradation of parathion were considered in this paper. The ultrasound of low power was used as an irradiation source to induce treated TiO2 particles to perform catalytic activity. The results show that the sonocatalytic activity of the transition crystal TiO2 powder is obviously higher than those of pure ordinary rutile and anatase TiO2 powders. At last, the parathion in aqueous solution was degraded completely and became some simple inorganic ions such as NO3-, PO43-, SO42-, etc. The degradation ratio of parathion in the presence of the transition crystal TiO2 catalyst attains nearly 80% within 60min ultrasonic irradiation, while corresponding ones are only 65.23% and 53.88%, respectively, for pure ordinary rutile and anatase TiO2 powders.

Investigation on degradation of azo fuchsine using visible light in the presence of heat-treated anatase TiO 2 powder

The phase transformation of TiO 2 powder from anatase phase to rutile phase was attempted by heat-treatment, and a new TiO 2 photocatalyst was obtained which could be excitated by visible light. The heat-treated TiO 2 powder at different transition stage was characterized by XRD, FT-IR and TEM methods. The test of photocatalytic activities of the heat-treated TiO 2 powders were carried out through the photocatalytic degradation of azo fuchsine dye in aqueous solution under the irradiation of visible light. The results indicate that the TiO 2 photocatalyst heat-treated at 400 °C within 60 min shows the highest photocatalytic activity which can effectively degrade the azo fuchsine under the irradiation of visible light. The remarkable improvement of photocatalytic activity of heat-treated TiO 2 powders at 400 °C was mainly illustrated by the special interphase formed between rutile and anatase phases which not only restrains the recombination of photogenerated electron–hole pairs, but also reduces the adsorbability of anatase TiO 2 powders at a certain extent. The degradation ratio of azo fuchsine in the presence of the heat-treated TiO 2 catalyst surpassed 84.36% at 3 h visible light irradiation, while the degradation ratios are only 44.2% and 64.84% for ordinary rutile and anatase TiO 2 catalysts, respectively, under the same experimental conditions. The total degradation process of azo fuchsine has been monitored by UV–vis spectra and ion chromatography. At last, the azo fuchsine molecules in aqueous solution are completely degraded and become some simple inorganic ions such as NO 3 − and SO 4 2−, etc. In this paper, the research on photocatalytic degradation kinetics was also performed and proved to be a first-order reaction.

Investigation on the sonocatalytic degradation of parathion in the presence of nanometer rutile titanium dioxide (TiO 2) catalyst

The nanometer rutile titanium dioxide (TiO 2) powder was adopted to act as the sonocatalyst after treatment of high-temperature activation and the ultrasound of low power was used as an irradiation source to induce heat-treated TiO 2 powder performing sonocatalytic degradation of parathion. Although there are many factors influencing sonocatalytic degradation of parathion, the experimental results demonstrate that the optimal degradation condition of parathion can be obtained when the experimental conditions such as initial concentration of 50 mg/L parathion, addition amount of 1000 mg/L nanometer rutile TiO 2, ultrasonic of 30–50 kHz frequency and 50 W output power, acidity of pH 10.0 and temperature of 20 °C are adopted. The degradation ratio of parathion surpassed 90% within 120 min ultrasonic irradiation in these optimal experiment conditions. The total degradation process of parathion has been monitored by UV–vis spectra and ion chromatography. At last, the parathions in aqueous solution are completely degraded and become some simple inorganic ions such as NO 3 −, PO 4 3−, SO 4 2−, etc. In addition, the sonocatalytic activities of reused TiO 2 catalysts were also studied and found to decline gradually along with the reused times. In this paper, the research on sonocatalytic degradation kinetics was also been performed and found to follow pseudo first-order reaction. All experiments indicated that the sonocatalytic method in the presence of nanometer rutile TiO 2 powder was an advisable choice for the treatments of non- or low-transparent organic wastewaters in future.

Molecular dynamics simulation of polymer electrolytes based on poly(ethylene oxide) and ionic liquids. I. Structural properties

Molecular dynamics (MD) simulations have been performed for prototype models of polymer electrolytes in which the salt is an ionic liquid based on 1-alkyl-3-methylimidazolium cations and the polymer is poly(ethylene oxide), PEO. The MD simulations were performed by combining the previously proposed models for pure ionic liquids and polymer electrolytes containing simple inorganic ions. A systematic investigation of ionic liquid concentration, temperature, and the 1-alkyl- chain length, [1,3-dimethylimidazolium]PF6, and [1-butyl-3-methylimidazolium]PF6, effects on resulting equilibrium structure is provided. It is shown that the ionic liquid is dispersed in the polymeric matrix, but ionic pairs remain in the polymer electrolyte. Imidazolium cations are coordinated by both the anions and the oxygen atoms of PEO chains. Probability density maps of occurrences of nearest neighbors around imidazolium cations give a detailed physical picture of the environment experienced by cations. Conformational changes on PEO chains upon addition of the ionic liquid are identified. The equilibrium structure of simulated systems is also analyzed in reciprocal space by using the static structure factor, S(k). Calculated S(k) display a low wave-vector peak, indicating that spatial correlation in an extended-range order prevail in the ionic liquid polymer electrolytes. Long-range correlations are assigned to nonuniform distribution of ionic species within the simulation box.

Dose‐ and time‐dependent effect of bioactive gel‐glass ionic‐dissolution products on human fetal osteoblast‐specific gene expression

Bioactive glasses dissolve upon immersion in culture medium, and release their constitutive ions into solution. There has been some evidence suggesting that these ionic-dissolution products influence osteoblast-specific processes. Here, the effect of 58S sol-gel-derived bioactive glass (60% SiO(2), 36% CaO, 4% P(2)O(5), in molar percentage) on primary osteoblasts derived from human fetal long bone explant cultures is investigated, and it is hypothesized that critical concentrations of sol-gel-dissolution products (consisting of a combination of simple inorganic ions) can enhance osteoblast phenotype in vitro by affecting the expression of a number of genes associated with the differentiation and extracellular matrix deposition processes. Cells were exposed to a range of 58S dosages continuously for a period of 4-14 days in monolayer cultures. Quantitative real-time RT-PCR analysis of a panel of osteoblast-specific markers showed a varied gene expression pattern in response to the material. The highest concentration of Ca and Si tested (96 and 50 ppm, respectively) promoted upregulation of gene expression for most markers (including alkaline phosphatase, osteocalcin, and osteopontin) at the latest time point, compared to non-58S-treated control, although this observation was not statistically significant. The same 58S concentration produced higher ALP activity levels and increased proliferation throughout the culture period, compared to lower dosages tested; however, the results generated were again not statistically significant. The data overall suggest that no significant effect can be ascribed to the ionic products of 58S bioactive gel-glass dissolution tested here and their ability to stimulate osteoblastic marker gene expression.

Unified Molecular Picture of the Surfaces of Aqueous Acid, Base, and Salt Solutions

The molecular structure of the interfacial regions of aqueous electrolytes is poorly understood, despite its crucial importance in many biological, technological, and atmospheric processes. A long-term controversy pertains between the standard picture of an ion-free surface layer and the strongly ion specific behavior indicating in many cases significant propensities of simple inorganic ions for the interface. Here, we present a unified and consistent view of the structure of the air/solution interface of aqueous electrolytes containing monovalent inorganic ions. Molecular dynamics calculations show that in salt solutions and bases the positively charged ions, such as alkali cations, are repelled from the interface, whereas the anions, such as halides or hydroxide, exhibit a varying surface propensity, correlated primarily with the ion polarizability and size. The behavior of acids is different due to a significant propensity of hydronium cations for the air/solution interface. Therefore, both cations and anions exhibit enhanced concentrations at the surface and, consequently, these acids (unlike bases and salts) reduce the surface tension of water. The results of the simulations are supported by surface selective nonlinear vibrational spectroscopy, which reveals among other things that the hydronium cations are present at the air/solution interface. The ion specific propensities for the air/solution interface have important implications for a whole range of heterogeneous physical and chemical processes, including atmospheric chemistry of aerosols, corrosion processes, and bubble coalescence.