High Sorption and Selective Extraction of Actinides from Aqueous Solutions

The selective elimination of long-lived radioactive actinides from complicated solutions is crucial for pollution management of the environment. Knowledge about the species, structures and interaction mechanism of actinides at solid–water interfaces is helpful to understand and to evaluate physicochemical behavior in the natural environment. In this review, we summarize recent works about the sorption and interaction mechanism of actinides (using U, Np, Pu, Cm and Am as representative actinides) on natural clay minerals and man-made nanomaterials. The species and microstructures of actinides on solid particles were investigated by advanced spectroscopy techniques and computational theoretical calculations. The reduction and solidification of actinides on solid particles is the most effective way to immobilize actinides in the natural environment. The contents of this review may be helpful in evaluating the migration of actinides in near-field nuclear waste repositories and the mobilization properties of radionuclides in the environment.     

Sorption of Hydrophobic Organic Compounds by Aqueous Latexes

Summary: Optical absorption measurements are used for the first time to investigate the uptake of pure organic solvents or solutions by latex particles. Sorption into glassy polymer particles is a two‐stage process with distinctly different characteristic times, which reflects that an initial softening of the outer particle layer facilitates further uptake. The sorption of solutions containing highly water‐insoluble compounds allows the preparation of composite nanoparticles, which are hardly accessible by other routes.

Photograph of the neat 100 nm latex (right) particles and the particles after dying by sorption with the hydrophobic pigment Sudan IV (left).     

Investigations of the Properties of l-Histidine in Aqueous NaCl Solutions at Different Temperatures

Density and viscosity experimental data for l-histidine in NaCl aqueous solutions were obtained at different salt and different amino acid concentrations in the range of temperatures between 293.15 and 323.15 K. The results have been correlated and analyzed in order to evaluate the influence of electrolyte concentration and temperature on the volumetric and viscometric properties of the solutions. The apparent molar volumes and the transfer volumes of l-histidine in aqueous NaCl solutions at different salt and amino acid molalities over entire temperature range were calculated from experimental density data. The viscosity experimental data have been analyzed with Jones–Dole equation and the Falkenhagen (A) and the Jones–Dole coefficient (B) have been calculated in order to evaluate the interactions occurring in the systems. The B viscosity coefficients were found to be positive for all conditions, showing a kosmotropic effect of solutes, indicating an alignment of zwitterions with ions/water dipoles. A comparison of standard partial molar volumes for some amino acids in water and NaCl aqueous solutions shows that they increase with molecular mass and complexity of the lateral side chain of the amino acid.     

Sorption of Nickel Ions from Aqueous Solutions by Ion Exchangers

Sorption of Ni²⁺ions from aqueous solutions by ion exchangers differed in their chemical nature and structure was studied. Based on the endothermic curves of ice melting obtained by a differential scanning calorimetry, the amounts of freezing and non-freezing water present in free volumes (pores) of the studied ion exchangers were calculated. Comparison of results obtained from the kinetic curves of nickel ion sorption with data on differential scanning calorimetry indicates a role of structural factor in the sorption of nickel ions. It was found that, depending on the total amount of freezing and non-freezing water, the KU-2-8 sulfonated cationite is the most preferable ion exchanger for the sorption of nickel ions from aqueous solutions. Therefore, sorbent efficiency in this case is determined by its structure rather than by chemical nature.     

Density and Sound Velocity Studies of Aqueous Solutions of Tetradecyltrimethylammonium Nitrate at Different Temperatures

The density and ultrasound velocity of aqueous solutions of tetradecyltrimethylammonium nitrate were measured in the temperature range of 15 to 35°C in 5°C intervals. The concentration range covered the premicellar and micellar regimes. By assuming a pseudophase separation model for the micellar system, we applied the densitometric data to estimate the apparent molar volumes and the apparent thermal expansibility coefficients of the surfactant in monomeric and micellar forms. Ultrasound velocity and density data enabled us to estimate the isentropic compressibility of the surfactant in both forms. The results are compared with relevant literature data for alkyltrimethylammonium bromides.     

Interactions of Phenylalanine,Tyrosine and Histidine in Aqueous Caffeine Solutions at Different Temperatures

Densities, ρ, viscosities, η, and refractive indices, n_D of aqueous caffeine (0.5 M) and of solutions of amino acids, l‐phenylalanine (Phe), l‐tyrosine (Tyr) and l‐histidine (His), (0.01–0.05 M) in aqueous‐caffeine have been measured at 298.15, 303.15, 308.15 and 313.15 K. From these experimental data, apparent molar volume, ?_v, limiting partial molar volume, ?^º_ν and the slope, S_v, transfer volume, ?^º_ν,tr, Falkenhagen coefficient, A, Jones‐Dole coefficients, B, free energies of activation per mole of solvent, Δμ^o#₁ and per mole of solute, Δμ^o#₂, enthalpy, ΔH^* and entropy, ΔS^* of activation of viscous flow, and molar refraction, R_m were calculated. The results are interpreted from the point of view of solute‐solvent and solute‐solute interactions in these systems. It has been observed that there exist strong solute‐solvent and weak solute‐solute interactions in these systems. Further, the solute‐solvent interactions decrease, whereas solute‐solute interactions increase with rise in temperature. It is observed that these amino acids act as structure‐makers in aqueous‐caffeine solvent. The thermodynamics of viscous flow have also been discussed.     

Chromatomembrane Headspace Analysis of Aqueous Solutions at Elevated Temperatures

Both theoretically and experimentally, the effect of temperature has been studied and assessed on analytical characteristics of continuous chromatomembrane gas extraction of volatile organic compounds from aqueous solutions with the aim of their subsequent gas chromatographic determination. It has been found that a rise of temperature up to 80 °C enables reduction of the detection limits of alcohols, ketones, and esters by a factor of 10 to 20. If a water vapor condenser is used in the extractant gas line, then the repeatability of results does not depend on temperature. The conditions have been optimized for the continuous headspace chromatomembrane analysis in combination with gas adsorption (purge and trap) concentration of analytes.

     

Efficient Adsorption of Chromium Ions from Aqueous Solutions by Plant-Derived Silica

Nowadays, there is great interest in the use of plant waste to obtain materials for environmental protection. In this study, silica powders were prepared with a simple and low-cost procedure from biomass materials such as horsetail and common reed, as well as wheat and rye straws. The starting biomass materials were leached in a boiling HCl solution. After washing and drying, the samples were incinerated at 700 °C for 1 h in air. The organic components of the samples were burned leaving final white powders. These powders were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), and low-temperature nitrogen sorption. The amorphous powders (biosilica) contained mainly SiO₂, as indicated by FTIR analysis. Horsetail-derived silica was chosen for testing the removal of dichromate ions from water solutions. This biosilica had a good ability to adsorb Cr(VI) ions, which increased after modification of the powder with the dodecylamine surfactant. It can be concluded that the applied procedure allowed obtaining high purity biosilica from plant waste with good efficiency. The produced biosilica was helpful in removing chromium ions and showed low cytotoxicity to human endothelial cells, suggesting that it can be safely used in environmental remediation.     

Volumetric and Viscometric Analyses for l-Glutamic Acid in NaCl Aqueous Solutions at Different Temperatures

The physico-chemical property data for l-glutamic acid in aqueous NaCl solutions were obtained at 0, 0.5, 1.0 and 2.0 mol·kg^?1 NaCl and amino acid molalities from 0 to 0.0669 mol·kg^?1 between 293.15 and 323.15 K. The influence of NaCl addition on the volumetric and viscometric properties of the amino acid has been studied. From the experimental densities, the apparent molar volumes and transfer volumes of l-glutamic acid in aqueous electrolyte solutions have been calculated. The viscosity data in the studied domain of amino acid molalities have led to the evaluation of the Falkenhagen and Jones–Dole viscosity coefficients of l-glutamic acid in NaCl aqueous solutions. The results have been discussed in terms of interactions occurring in the systems.     

Sorption Mechanism of Cadmium from Aqueous Solution on Iron Sulphide

The characterization and adsorption studies of Cd²⁺ on FeS were performed. Adsorption of Cd²⁺ from aqueous solutions on synthetic iron sulphide (FeS) was investigated as a function of pH (5–7) and temperature (303–323 K). It was found that the iron sulphide (FeS) had adsorptive properties comparable with those of other adsorbents reported in the literature. The sorption of Cd²⁺ was observed to increase with the increase in pH but not strongly sensitive to temperature. The adsorption data fitted both the Kurbatov and Langmuir adsorption models. In addition, ΔG^? values were calculated from the values of the binding constant, which showed that the cadmium adsorption process was spontaneous in nature.     

Sorption of Lead(II) from Aqueous Solutions by Synthetic Zeolites

A comparative study of the sorption of lead(II) from dilute aqueous solutions by synthetic faujasites, chabazites, mordenites, erionites, phillipsites, and type A zeolites was performed. The most promising sorbents are low-silica chabazites and potassium erionites with relatively high SiO₂/Al₂O₃ ratio.     

Sorption of Amino Acids from Aqueous Solutions by a Polarized Carbon Adsorbent

The adsorption and electrosorption of tyrosine, tryptophan, and phenylalanine on an A-4 model carbon adsorbent from 0.1 N K₂SO₄solutions were investigated at various acidity values of the medium. It was found that the sorption of tyrosine and tryptophan is significantly affected by both the polarization potential of the adsorbent and pH of the solution. For phenylalanine, electrosorption dependences were not measured because of its electrochemical instability under experimental conditions. The electrosorption effect was demonstrated for the low-molecular-weight protein, pepsin.     

水中痕量镉的准液膜富集

准液膜法是在液膜法基础上提出的新分离方法，它保持了液膜法分离富集的高效能，但省去了液膜法的制乳与破乳过程，使操作更为简便易行。本文用此法富集了水及废水中痕量镉，富集倍数可达２３０倍，镉的回收率在９７％以上。     

Competitive Sorption of Copper and Nickel Ions from Aqueous Solution Using Peat

Bicomponent aqueous solutions of copper and nickel ions have been used to investigate the sorption of metal ions onto peat. Peat, a low cost sorbent, has shown a high capacity for the sorption of single component metal ions attributed to extensive carboxylic acids within its structure. Copper and nickel ions were selected as typical metals in the effluents of electroplating industries. The effects of competitive sorption in batch systems were studied at various metal ion concentrations. In this study the Butler and Ockrent model was modified using a coefficient, . Two models were developed based on the interaction coefficient . The first model incorporates a constant fixed factor for each metal ion into the Butler-Ockrent equation. The second model incorporates a variable factor into the Butler-Ockrent equation; this interaction factor varies as a function of sorbent surface coverage. Predicted equilibrium data are found to be in excellent agreement with experimental values using both modified models for various mole ratios of copper and nickel ions in competitive sorption.     

4A沸石从水溶液中吸附氯化十四烷基吡啶

4A沸石可部分或全部代替三聚磷酸钠,以减少合成洗涤剂对水质富营养化的影响,在硬水中使用也不致降低洗涤效力.本文研究了4A沸石在不同pH水溶液中和无机盐存在下对氯化十四烷基吡啶(TPC)的吸附作用,初步探讨了吸附机制.     

Behavior of Antibacterial Ofloxacin; Hydronation Constants and Solubility in Aqueous Solutions of Sodium Chloride at Different Temperatures

Journal of Solution Chemistry - The solubility and acid–base properties of the antibacterial Ofloxacin were studied in aqueous solutions of sodium chloride at a single ionic strength value...     

Cadmium Preconcentration from Aqueous Environmental Samples Using Microcrystalline Phenolphthalein Modified by Crystal Violet

Abstract

The present work describes a novel method for cadmium preconcentration and separation with microcrystalline phenolphthalein. Phenolphthalein as an extractant modified by crystal violet was originally applied to cadmium extraction from aqueous solution. Cadmium(II) as CdI₃ ^? and CdI₄ ^2? can associate with the cationic crystal violet (CV⁺) forming water‐insoluble ion‐association complexes (CdI₃ ^?) · (CV⁺) and (CdI₄ ^2?) · (CV⁺)₂, which are quantitatively adsorbed on microcrystalline phenolphthalein over the pH range from 1.0 to 6.0. All experimental parameters necessary for successful preconcentration and separation have been investigated and optimized. The study shows that common metal ions, such as Zn(II), Fe(II), Co(II), Ni(II), Mn(II), Cr(III) and Al(III), cannot interfere with cadmium extraction in this microcrystalline system by controlling acidity. The extraction can be accomplished in 15 min. The interaction between CdI₃ ^?and CdI₄ ^2? and CV⁺ plays an important role in the extraction process. The reported method was successfully applied to the preconcentration and separation of cadmium in synthetic samples and real samples with satisfactory results. The results proved that it is an efficient and attractive technique for cadmium preconcentration and separation at trace level.