Myroslav Sprynskyy

The separation of uranium ions by natural and modified diatomite from aqueous solution

In this work the natural and the surfactant modified diatomite has been tested for ability to remove uranium ions from aqueous solutions. Such controlling factors of the adsorption process as initial uranium concentration, pH, contact time and ionic strength have been investigated. Effect of ionic strength of solution has been examined using the solutions of NaCl, Na(2)CO(3) and K(2)SO(4). The pseudo-first order and the pseudo-second order models have been used to analyze the adsorption kinetic results, whereas the Langmuir and the Freundlich isotherms have been used to the equilibrium adsorption data. The effects of the adsorbent modification as well as uranium adsorption on the diatomite surface have been studied using X-ray powder diffraction, scanning electron microscopy and FTIR spectroscopy. The maximum adsorption capacities of the natural and the modified diatomite towards uranium were 25.63 micromol/g and 667.40 micromol/g, respectively. The desorptive solutions of HCl, NaOH, Na(2)CO(3), K(2)SO(4), CaCO(3), humic acid, cool and hot water have been tested to recover uranium from the adsorbent. The highest values of uranium desorption (86%) have been reached using 0.1M HCl.

Kinetic and equilibrium studies of phenol adsorption by natural and modified forms of the clinoptilolite

The contribution presents results of investigation of phenol adsorption by the raw, HDTMA- and NaOH-modified clinoptilolite. The experimental data on the sorption kinetic process are modelled using the particle and the film diffusion models with calculation of a rate constant of intraparticle mass transfer. Two main stages may be divided in the kinetic sorption process: (1) initial rapid sorption (amount of phenol sorbed 85-90%) extending over the first 60 min and (2) stage of slow approach to equilibrium covering about 8h. Equilibrium isotherms for phenol adsorption are modelled using the Langmuir, Freundlich and Dubinin-Radushkevich equations. The Freundlich isotherm describes in a greater degree phenol sorption from aqueous solutions of low phenol concentrations, while the Langmuir isotherm fits better to sorption at high initial concentrations.

Adsorption of Ammonium Ions onto a Natural Zeolite: Transcarpathian Clinoptilolite

A study was carried out of ammonium ion sorption from synthetic aqueous solutions by Transcarpathian clinoptilolite, a natural zeolite, under static conditions. The main physical properties of the clinoptilolite and the basic parameters of its porous structure were determined. Values of the specific surface area and of the pore volume occupied by sorbed substances were calculated using the relative moisture content established and the maximum sorption capacity exhibited towards ammonium ions as well as a nitrogen adsorption/desorption method. Ammonium ion sorption by the zeolite appeared to be complete within 24 h for all fraction sizes, initial NH4+ ion concentration and adsorbate volumes. The amounts of NH4+ ions sorbed increased with increasing initial NH4+ concentration and decreasing adsorbate volumes, with the maximum sorption capacity exhibited by the clinoptilolite being 0.64 mequiv/g. The sorption effectiveness decreased somewhat with increasing fraction size. The Langmuir and Freundlich models were applied to the data obtained from the batch studies with the first model exhibiting the more satisfactory correlation coefficient value (0.996 and 0.959, respectively).

Study of sorption kinetics of some ionic liquids on different soil types

In the present contribution sorption kinetics experiments under static conditions were utilized in three selected ionic liquids cations (1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium chlorides) study with five type of soil, differing in total organic carbon (TOC) content. The experimental results indicate the sorption capacity growth with increase in TOC content and hydrophobicity of ionic liquid cation. The obtained kinetic sorption parameters as well as distribution coefficients (K(d)) were used to estimate the sorption properties of the soil types towards the ionic liquids in question. The Gibbs free energy values indicate that ionic liquid cations sorption on soils could be generally considered as a physical adsorption with exothermic effect. But the values of -dG for studied cations sorption on soil with very high of TOC content in soil (45%) may testify to nature of chemical adsorption. Sorption of the analyzed compounds occurs probably by means of hydrogen bonds, electrostatic and pi three dots pi interaction with the organic matter and the clay minerals of the soils.

Removal of zearalenone toxin from synthetics gastric and body fluids using talc and diatomite: a batch kinetic study.

Adsorption kinetics of zearalenone (ZEA) toxin from synthetic gastric fluid (SGF) and synthetic body fluid (SBF) by talc and diatomite was studied in the batch experiments. Chemical composition, morphology and structure of the used adsorbents were examined by scanning electron microscopy, FTIR spectroscopy and low-temperature nitrogen adsorption/desorption method. High performance liquid chromatography (HPLC) method was used for ZEA determining. The study results showed that ZEA is more effectively adsorbed on the talc (73% and 54% from SGF and SBF respectively). The efficiency on the diatomite was lower (53% and 42% from SGF and SBF respectively). The first order kinetics model was applied to describe the adsorption process. Rate of the ZEA adsorption from SGF is very rapid initially with about 95% of amount of the toxin adsorbed during first 5 min, while ZEA is adsorbed from SBF in two steps. The values of determined Gibbs free energy of adsorption (from -13 to -17 kJ/mol) indicated that adsorption of ZEA toxin by the both adsorbents are spontaneous and exothermic.

The study of zinc ions binding to casein

The presented research was focused on physicochemical study of casein properties and the kinetics of zinc ions binding to the protein. Moreover, a fast and simple method of casein extraction from cows milk has been proposed. Casein isoforms, zeta potential (ζ) and particle size of the separated caseins were characterized with the use of capillary electrophoresis, zeta potential analysis and field flow fractionation (FFF) technique, respectively. The kinetics of the metal-binding process was investigated in batch adsorption experiments. Intraparticle diffusion model, first-order and zero-order kinetic models were applied to test the kinetic experimental data. Analysis of changes in infrared bands registered for casein before and after zinc binding was also performed. The obtained results showed that the kinetic process of zinc binding to casein is not homogeneous but is expressed with an initial rapid stage with about 70% of zinc ions immobilized by casein and with a much slower second step. Maximum amount of bound zinc in the experimental conditions was 30.04mgZn/g casein.

Silver-Lactoferrin Nanocomplexes as a Potent Antimicrobial Agent

The process of silver immobilization onto and/or into bovine lactoferrin (LTF), the physicochemical properties of bovine lactoferrin and obtained silver-lactoferrin complexes, as well as antibacterial activity of silver-lactoferrin complexes were investigated in this work. Kinetic study of the silver immobilization into lactoferrin was carried out using batch sorption techniques. Spectrometric (MALDI-TOF/TOF-MS, ICP-MS), spectroscopic (FTIR, SERS), electron microscopic (TEM) and electrophoretic (I-DE) techniques, as well as zeta potential measurements, were applied for characterization of LTF and binding nature of silver in Ag-LTF complexes. On the basis of the results of the kinetics study, it was established that the silver binding to LTF is a heterogeneous process involving two main stages: (i) internal diffusion and sorption onto external surface of lactoferrin globules; and (ii) internal diffusion and binding into lactoferrin globule structure. Spectroscopic techniques combined with TEM analysis confirmed the binding process. Molecular dynamics (MD) analysis was carried out in order to simulate the mechanism of the binding process, and locate potential binding sites, as well as complement the experimental findings. Quantum mechanics (QM) simulations were performed utilizing density functional theory (DFT) in order to support the reduction mechanism of silver ions to elemental silver. Antimicrobial activity of synthesized lactoferrin complexes against selected clinical bacteria was confirmed using flow cytometry and antibiograms.

The Adsorption Properties of Agricultural and Forest Soils Towards Heavy Metal Ions (Ni, Cu, Zn, and Cd)

Adsorption of Cu, Cd, Ni, and Zn in single and multi-metal solutions by agricultural and forest soils was investigated in batch sorption experiments. The results showed significant differences in sorption capacities of the studied soils. The selectivity order was as follows: agricultural soil≫ top forest soil > bottom forest soil. The adsorption sequence Cu > Zn > Ni > Cd was established for the agricultural and bottom forest soil, while the order for the top forest soil was Cu > Ni > Zn > Cd. The experimental isotherms for the metal sorption were described satisfactorily by the Freundlich and Langmuir models. The competitive adsorption experiment indicated a reduction in the amount of metals adsorbed by the soils from the multi-metal solution compared to the single metal solution. Properties of the soils, such as pH, content of clay and organic matter, exchangeable bases and hydrolytic acidity, showed a significant influence on adsorption capacities of the studied soils.

State of environment in the Dniester river basin (West Ukraine).

This contribution presents the results of the hydroand lithochemical investigations on the Dniester river basin (Ukraine) performed during the period of 1995-2001. The main goal of this study was the estimation of the current state of surface and subsurface water quality in the Dniester valley as well as the definition of the intensity, the localisation and the distribution scale of the anthropogenic influences.

Application of novel hierarchical niobium-containing zeolites for synthesis of alkyl lactate and lactic acid

Novel hierarchical niobium-containing zeolites were synthesized for the first time and applied for isomerization of dihydroxyactetone to alkyl lactate and lactic acid (95-97% yield). These materials possess secondary mesoporosity, thus facilitating access to active sites of the material by larger reagent molecules, preserving acidity and crystallinity of the zeolites.