One-component Solutions Research Articles

Arsenate and cadmium ions removal from multicomponent solutions of ionic polymers using mesoporous activated biocarbons

Activated biocarbons (AC) obtained in the process of simultaneous pyrolysis and activation of lemon balm (LB) and mint (MT) herbs with H3PO4 were used to purify aqueous solutions of cadmium, arsenate, polyethylenimine (PEI) and poly(acrylic acid) (PAA). The metals show high toxicity in the whole range of their concentrations, whereas the polymers are cytotoxic at high concentrations.The efficiency of As(V) removal from an aqueous solution depends on the pH value, while the Cd(II) adsorption on the activated biocarbons surface is independent on this parameter. The maximum adsorbed amounts are 135.8 mg/g for Cd(II) and 109.6 mg/g for As(V), respectively. The removal of metals ions and polymers from binary systems is lower in comparison to the one-component solutions. This is a consequence of the formation of polymer-metal complexes, that tend to remain in the solution. Additionally, the surface charge density, zeta potential, the size of activated biocarbons aggregates in the aqueous suspensions and the influence of toxic metal ions on the determination of the concentration of polymers in water samples was investigated. The obtained results proved that the PEI concentration can be effectively determined in the presence of metal ions, whereas the procedure of PAA determination requires additional validation.

Investigation of Ionic Polymers' Stabilizing and Flocculating Properties in Dispersed Activated Carbons Systems.

Activated carbons obtained via the thermochemical treatment of lemon balm and mint herbs were applied for ionic polymers adsorption, which directly affects the stability of these types of aqueous suspensions. The examined carbonaceous materials were characterized by well-developed specific surface area (approximately 1000 m2/g) and mesoporous structure. The adsorbed amounts of anionic poly(acrylic acid) and cationic polyethyleneimine from one-component solutions reached significant levels, but the efficiency of adsorption of these compounds from binary solutions slightly decreased. Moreover, the ionic polymers showed stabilizing properties towards the activated carbons suspensions. For both adsorbents, the most stable suspensions were systems containing both types of polymeric macromolecules with different ionic characters. This was due to the occurrence of electrosteric and depletion stabilization mechanisms. Furthermore, the zeta potential and size of particle aggregates were also influenced by the presence of polymers in the aqueous suspensions of activated carbons.

Low cross-linked terpenes-based porous polymers with reduced content of divinylbenzene: synthesis, physicochemical properties and sorption abilities

The low cross-linked porous polymers were prepared using terpene compounds (citral, limonene and pinene) and divinylbenzene with a suspension method. The prepared materials were characterized by: ATR-FTIR, low temperature nitrogen adsorption–desorption, TGA, swelling ratio and solid phase extraction (SPE) experiments. ATR-FTIR verified the chemical structures of the polymers. All the materials had developed internal structure with SBET in the range of 45–190 m2/g and high thermal stability. Sorption properties of the terpene-based polymers were tested for phenolic compounds (phenol, 2-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol) and popular non-steroidal anti-inflammatory drugs (aspirin, paracetamol and ibuprofen) and an antibiotic (ampicillin) with a dynamic solid phase extraction (SPE) method. The recoveries of 2,4-dichlorophenol and 2,4,6-trichlorophenol remained at a level 80–100% for all new materials even for 10–13 concentration cycles. Very high recoveries (70–100%) were also obtained for ibuprofen and aspirin from the citral- and limonene-based polymers using one-component solutions. However, when using ternary component solutions, the maximum recoveries of ibuprofen reached 70%. Paracetamol recoveries did not exceed 20%, while these for ampicillin ranged from 40 to 80%. The performed studies have proven that the process is affected by both chemical nature of adsorbents and adsorbates. Especially in the case of multicomponent solutions, the acid—base balance of solutes in the solution and on the polymer—solution interface should be taken into account as an important factor determining obtained recoveries.

Pd(II) and Pt(IV) dispersive or non-dispersive extraction from model and real leach solutions with alkoxyimine-1-propylpyridinium derivatives

The studies present results of Pt(IV) and Pd(II) conventional liquid–liquid extraction and non-dispersive extraction in pseudo-emulsion hollow fiber strip dispersion (PEHFSD) with alkoxyimine-1-propylpyridinium derivatives. Liquid-liquid extraction was used to extract Pd(II) and Pt(IV) both from the model solutions (single and two-component) and from the real solutions, obtained after the leaching PGM from spent automotive catalysts with aqua regia or HCl/H2O2/H2SO4 mixture. The extraction efficiency of Pt(IV) or Pd(II) from one-component solutions with all extractants used (except 4-[1-(2-ethylhexyloxyimine)methyl]-1-propylpyridinium chloride) was high (>90%). However, phase separation took place after 24 h. Also, the coextraction of the H+ ions into the organic phases was observed. It was found that the coextraction of H+ with PGM from one- and two-component model solutions was slight and did not affect the extraction efficiency of PGM. However, for real solutions, the higher the concentration of H+ ions in the feed solution, the stronger the H+ coextraction effect was noted, and resulted in decrease in the extraction efficiency of metal ions from real leach solutions. 3-[1-(decyloxyimine)ethane]-1-propyl-pyridinium chloride (D3EI-PrCl) was found to be asuitable Pd(II) carrier for the liquid membrane technique PEHFSD for the removal of Pd(II) from the Pd(II)/Pt(IV) mixture. The kinetics of the Pd(II) removal depended on the composition of the feed solution; in the presence of Pt(IV), Pd(II) extraction took 2 h, while almost 100% Pd(II) was removed from one-component model solution in 1 h.

Исследование экологических и агрохимических показателей осадков сточных вод методом фитотестирования

Purpose: to assess environmental and agrochemical indicators of sewage sludge from municipal wastewater treatment plants through phytotesting. Materials and methods. Sewage sludge from municipal wastewater treatment plants with a three-year stay on the sludge map was studied. The examined sludge contains a high amount of sulfate ions (0.720 g/100 g) with a content of calcium ions of 0.350 g/100 g. The remaining salt ions and heavy metals are in small quantities. Phytotesting was carried out by studying the phytoresponse of the test plants seeds in contact with an aqueous extract and directly with precipitation. In the first variant, solutions of various concentrations were prepared: an aqueous extract of sediments, its two-fold dilution and four-and eight-fold dilution. To control the indicators, the distilled water and one-component model solutions of sodium sulfate with concentrations identical to the tested solutions were used. Testing was carried out on the seeds of oats and vetch. In the second variant, under laboratory conditions, seeds of oats, vetch, white mustard, radish and watercress were sown in vegetation vessels with sewage sludge. Results and discussion. Phytotesting allowed revealing the complex effect of precipitation due to their composition. In the variant of undiluted aqueous extract from sewage sludge, the inhibitory effect of sulfates on seed germination and biomass growth is revealed. In the variant with two-fold dilution, the stimulating effect of precipitation components on seed germination and biomass growth was noted. To clarify the effect of the stimulating effect of sewage sludge, an experiment on sowing test plants directly into the sludge was carried out. The best indicators were noted in the variants with oats sowing. Conclusions. The inhibitory effect of sewage sludge from municipal wastewater treatment plants in Novocherkassk is due to the content of sulfates in them. The best comparability of indicators in both variants was noted for oat seeds.

Evaluation of the various reagents sorption activity with respect to rare earth elements

Pilot experiments to remove lanthanum and cerium ions from model one-component solutions using reagents: opoka, brucite, amorphous silica, thermovermiculite (500 °С, 2 hours), sawdust, thermally activated brucite (600 °С, 2 hours), activated carbon, zeolite, were carried out. Promising sorbents of rare-earth elements of the light group have been identified, which can be used to purify water with a high content of the elements under consideration or in combined sorption technologies for restoring disturbed lands in the areas of extraction and enrichment of rare metal ores.

One-component and two-component Peregrine bump and integrated breather solutions for a partially nonlocal nonlinearity with a parabolic potential

Objective:We establish a projecting transformation from nonautonomous equation into autonomous one, and seek out explicit one-component and two-component solutions of a (2+1)-dimensional coupled nonautonomous nonlinear Schrödinger model for a partially nonlocal nonlinearity with a parabolic potential. Methods:We combine these solutions of autonomous one into the projecting transformation and use the Darboux method to find solutions. Result:We take into account a (2+1)-dimensional coupled nonautonomous nonlinear Schrödinger model for a partially nonlocal nonlinearity with a parabolic potential, and establish a projecting transformation from nonautonomous equation into autonomous one. Moreover, we seek out explicit one-component and two-component solutions, e.g. explicit Peregrine bump solution and explicit integrated breather solutions.

MATHEMATICAL MODEL OF TWO-CHAMBER ELECTROLYSER DYNAMICS FOR STUDYING PROPERTIES OF ION EXCHANGE MEMBRANES BASED ON PROTON IONIC LIQUIDS

A mathematical model of mass transfer processes in the electrolysis of one-component solutions of 1,1 symmetric strong electrolytes NaOH and NaCl in a two-chamber electrochemical reactor with mesh electrodes based on platinum titanium is formulated. Experimental modeling of processes is performed was carried out under conditions of continuous precise monitoring of the system (NaOH concentration and volume of solution in the chambers).The electrolysis system was designed to balance the flow of components through the membrane to study its properties and to determine five unknown parameters of mathematical modeling of the process. The mathematical model is a system of equations, which includes the unknown transfer numbers of counterions through the membrane, the electrolyte diffusion coefficient, the electroosmotic flux constant, and the empirical parameters of the approximating expressions.

Synergistic Effect of Binary Surfactant Mixtures in Two-Phase and Three-Phase Systems.

Cationic alkyltrimethylammonium bromides (CnTAB, with n = 8, 12, 16, 18) and their mixtures with n-octanol as a nonionic surfactant were chosen as a model system to study the synergistic effect on foamability (two-phase system) and floatability (three-phase system) of quartz in the presence of binary mixtures of ionic/nonionic surfactants. The foam height of one-component solutions and binary mixtures and floatability of quartz particles were characterized as a function of the surfactant concentration and the number of carbons (n) in the alkyl chain of CnTAB. The experimental results of foamability and floatability measurements in one-component and mixed solutions revealed the synergistic effect, causing a significant enhancement in the foam height and recovery of quartz. In the presence of n-octanol, the height of foam increased remarkably for all CnTAB solutions studied, and this effect, whose magnitude depended on the CnTAB hydrophobic tail length, could not be justified by a simple increase in total surfactant concentration. A similar picture was obtained in the case of flotation response. The mechanism of synergistic effect observed in mixed CnTAB/n-octanol solutions was proposed. The discussion was supported by molecular dynamics simulations, and the probable mechanism responsible for synergism was discussed. In addition, an analysis allowing accurate determination of the concentration regimes, where the synergistic effect can be expected, was given. It was shown that for the two-phase system, the n-octanol molecule preadsorption at the liquid/gas interface causes an increase in CnTAB adsorption coverage over the level expected from its equilibrium value in the one-component solution. In the case of the three-phase system, the synergistic effect was related to the ionic surfactants serving as an anchor layer for n-octanol, which, in water/n-octanol solution (one-component system), do not adsorb on the surface of quartz.

Recovery of Palladium(II) and Platinum(IV) in Novel Extraction Systems.

Recovery of platinum group metals (PGM) from complex aqueous solutions generated as a result of leaching of various spent materials (e.g., spent automotive converters) is a vital issue in the context of the circular economy. In this study pyridinium derivatives containing an imidoamide or imine moiety (i.e., 3-[1-(2-ethylhexyloxyimine)methane]-1-propylpyridinium chloride, 3-[1-(decyloxyimine)methane]-1-propylpyridinium chloride, 3-[1-(decyloxyimine)ethane]-1-propylpyridinium chloride and 4-[1-amine(2-ethylhexyloxyimine)]-1-propylpyridinium chloride) are proposed as novel extractants for recovery of palladium(II) and platinum(IV) from model chloride aqueous solutions. The results of liquid-liquid extraction from one-component solutions of palladium(II) or platinum(IV) showed that quaternary pyridinium salts can be used as effective extractants for platinum metal ions. Moreover, PGM extraction from a two-component mixture proved no evident selectivity in the transfer of one of the metal ions to the organic phase. As the best extractant among the investigated ones, D3EI-PrCl (with straight alkyl chain at substituent) can be pointed out, however, problems with effective stripping or phase disengagement after stripping should be indicated as a drawback of the organic phases used. Further investigation should focus on the improvement of the organic phase properties (e.g., increase in hydrophobicity of the extractants and addition of an organic phase modifier) towards stripping efficiency.

The Peculiarities of Singlet Electronic Excitation Energy Transfer Processes in Alq3 Films

The absorption and luminescence of new boron-containing dyes in two-component films of Alq3 (matrix)-dye(impurity) (obtained by the method of thermal vacuum deposition) are studied. The comparison of the spectra of absorption, fluorescence, and fluorescence excitation of a dyes in one-component solutions and double-component films shows the existence of the effective electronic excitation energy transfer (EEET) from the matrix to dye molecules. Time-resolved spectra of two-component films also manifest strong EEET in these systems. For the estimation of the average exciton spreading length in Alq3 films, the diffusion model of the motion of singlet excitons is used. The diffusion coefficient is evaluated using time-resolved spectroscopy. The optimum concentrations of dyes in a light-emitting layer of OLED are evaluated based on experimental data and the used model of EEET.

Critical Synergistic Concentration of Binary Surfactant Mixtures

This paper presents a simple method for determination of synergism in binary surfactant mixtures. A homologous series of cationic alkyltrimethylammonium bromides (CnTAB, with n = 8, 12, 16, 18) mixed with three non-ionic surfactants (n-octanol, methyl isobutyl carbinol, tri(propylene glycol) butyl ether) was chosen as a model system. In addition to the cationic-non-ionic system, the mixture of anionic-non-ionic surfactants (sodium dodecyl sulphate and tri(propylene glycol) butyl ether) was investigated. The foam behavior of one-component solutions and binary mixtures was characterized as a function of surfactant concentration, number of carbons (n) in alkyl chain of CnTAB as well as type of surfactant. It was shown that synergism in foamability could be produced by the ionic-non-ionic systems, and the concentration below the synergism occurs, called the critical synergistic concentration (CSC), that can be easily predicted based on the surface tension data on individual components.

Determination of the total phenol antioxidants content in the model mixtures using the Folin-Ciocalteu assay and the FRAP assay

The total content of phenolic antioxidants ( PhA ) in tea, wine and other foodstuffs is usually determined without their separation. Active oxidizing agents, mainly Folin-Ciocalteu reagent ( FC ), are used as group reagents. The results obtained with the FC assay and later recalculated to the standard substance vary significantly from the results obtained with the other spectrophotometric assays such as the FRAP assay. In order to elucidate the real reason of the above-mentioned discrepancies, the authors have analyzed the water solutions with the known PhA total content (10 -5 –10 -4 mol/dm 3 ). The correct results were obtained only for one-component solutions. For the model mixtures containing 2 or 3 components, the results of c Σ measurement with the standard FC procedure were distorted with significant systematic errors. When the universally used standard (gallic acid) has been applied, the error values (δ с ) were positive to the point of 50 % rel.; for the other standards the corresponding errors were much greater (by modulo). The main source of systematic errors during the PhA total content estimation was an intragroup selectivity of the signals. This effect could be related to the reaction stoichiometry features when FC reacts with the individual polyphenols. The subsidiary source of the systematic errors was the non-additivity of the light absorbance by the reaction products (reduced forms of the FC-reagent). For some mixtures, the deviations from the additivity were near 20% rel., this effect was detected for the first time. The substitution of the FC reagent with a less active oxidizing agent (FRAP reagent: Fe 3+ + 2,2'-dipyridil) during c Σ determination depressed the intragroup selectivity of the signals and totally prevented the non-additivity of the light absorbance. These effects assured more correct estimates of the total PhA content (δ с < 25 %). In addition, the FPAP assay was more sensitive and more specific method to determine the total polyphenols than the widely used FC assay. Therefore, authors recommend replacing the FC assay with the FRAP assay in the food industry to improve the quality control performance of tea, wines and other foodstuffs. Keywords: phenolic antioxidants, total content of polyphenols, spectrophotometry, model mixtures, Folin-Ciocalteu assay, FRAP assay, systematic errors DOI: http://dx.doi.org/10.15826/analitika.2019.23.3.008 (Russian) V.I. Vershinin, E.V. Belova Dostoevsky Omsk State University, Mira str., 55a, Omsk, 644077, Russian Federation

Ozone Solubility in Aqueous Solutions of Perchlorates and Other Electrolytes: Correction of the Weisenberger-Schumpe Model Parameters for the ClO4− and O3

ABSTRACTThe solubility of ozone in the aqueous solutions of acids, HClO4 and H2SO4, and salts, LiClO4, NaClO4, KClO4, Mg(ClO4)2, Ca(ClO4)2, NaCl, KCl, Na2SO4, K2SO4, and NaNO3, is studied. On the basis of experimental results and published data, the values of the Weisenberger-Schumpe model parameters for the perchlorate ion and ozone are proposed to be = 0.0391 M−1 and hG,0 = −0.0152 M−1 (t = 25°C), respectively. The values of the similar parameters for the van Krevelen-Hoftijzer model are found to be = 0.336 M−1 and xG = −0.215 M−1, respectively. The discrepancies between the values of Sechenov constants calculated using the van Krevelen-Hoftijzer model for the one-component salty solutions, are somewhat smaller than between those determined using the Weisenberger-Schumpe model. The Sechenov constants are satisfactorily predicted (to a ~ 20% accuracy) by the Weisenberger-Schumpe model with the new and hG,0 values.

Absorption of foliar applied micronutrients by apple leaves

Foliar fertilization is used to correct nutritional deficiencies in plants. Nutrient concentration and combinations of elements are important for the use and efficiency of fertilizers. The aim of the experiment was to investigate how nutrients, in the form of one-component solutions, are absorbed by leaves and how the combination of multiple elements in the solution affect nutrient uptake. The experiment was carried out on the 20-year-old apple tree 'Selena', in the beginning of August 2016, in the experimental orchard of Crop Research Institute in Prague - Ruzyně. Defined solutions of micronutrients (Fe, Zn, Mn, B) and their mixture were applied in spots (5 μL by micropipette) on marked leaves of apple trees in the orchard. Leaves (4 repetitions, 12 leaves in each variant) were harvested, washed and analyzed five days after application. The increase of studied nutrients concentration in a leaf depended on the concentration of the applied solution. An observed higher content of the nutrients in leaf petioles indicates transport of applied nutrients (including slowly - moving Mn and Fe) from leaves to another place of consumption. Zinc showed the best absorption among the observed elements. Nutrient combination (application of all tested nutrients in one solution) positively influenced the iron intake. Foliar application of investigated elements increased their concentration in leaves from low to optimum levels.

Magnesium ferrite nanoparticles as a magnetic sorbent for the removal of Mn2+, Co2+, Ni2+ and Cu2+ from aqueous solution

The aim of this research was to prepare magnesium ferrite (MgFe2O4) magnetic nanoparticles and to investigate their sorption characteristics towards Mn2+, Co2+, Ni2+, Cu2+ ions in aqueous solution. MgFe2O4 was synthesized by glycine-nitrate combustion method and was characterized by low crystallinity with crystallite size of 8.2 nm, particle aggregates of 13–25 nm, BET surface area of 14 m2/g and pore size of 8.0 nm. Sorption properties of MgFe2O4 towards Mn2+, Co2+, Ni2+, Cu2+ ions were studied using one-component model solutions and found to be dependent on metal ions concentration, contact time, pH and conditions of regeneration experiment. The highest sorption capacity of MgFe2O4 was detected towards Co2+ (2.30 mmol g1) and Mn2+ (1.56 mmol g−1) and the lowest towards Ni2+ (0.89 mmol g−1) and Cu2+ (0.46 mmol g−1). It was observed that sorption equilibrium occurs very quickly within 20–60 min. The pHzpc of sorbent was calculated to be 6.58. At studied pH interval (3.0–7.0) the sorption capacity of MgFe2O4 was not significantly affected. Regeneration study showed that the metal loaded sorbent could be regenerated by aqueous solution of 10−3 M MgCl2 at pH 6.0 within 120 min of contact time. Regeneration test suggested that MgFe2O4 magnetic sorbent can be efficiently used at least for four adsorption-desorption cycles. The high sorption properties and kinetics of toxic metal ion sorption indicates good prospects of developed sorbent in practice for wastewater treatment.

Mutual action of copper (II) and a nonionic surfactant (oxyethylated alcohols) on their simultaneous removal by a neutral hyper-cross-linked polystyrene adsorbent

The mutual action of Cu(II) and nonionic surfactant Lutensol AO-10 on their sorption onto neutral hyper-cross-linked polystyrene Macronet MN-200 from mixtures has been investigated by the analysis of sorption equilibrium and kinetic data. The experimental equilibrium data were analyzed using the Langmuir and Freundlich models. The sorption mechanism of Cu(II) from one-component solutions or Cu(II) and AO-10 from their mixture corresponded to the Langmuir model rather than to the Freundlich one, whereas the sorption mechanism of AO-10 from one-component solutions proceeded according to the Freundlich rather than to the Langmuir model. The pseudo-second-order-reaction and intraparticle diffusion models (Weber–Morris plot) were used to describe the sorption kinetics, and to determine the sorption rate (k 2), intraparticle (k i) and external diffusion (k s) constants. The k 2 values obtained for Cu(II) sorption from solutions free from AO-10 was higher than those obtained for sorption from solutions free from...

The influence of selected parameters on the photocatalytic degradation of azo-dyes in the presence of TiO2 aqueous suspension

The aim of this study was to determine the influence of various parameters such as the initial concentration of dye and catalyst, the volume of irradiated solution and its absorbance on the kinetics of photocatalytic degradation of azo-dyes. The studies were carried out in aqueous solutions containing the individual azo-dyes (Acid Black 1, Acid Orange 7, Basic Orange 66) and in their mixtures, in the presence of two types of TiO2 as photocatalyst and under UV light irradiation. It was found that under given experimental conditions, the photocatalytic degradation of investigated dyes exhibited pseudo first-order kinetics according to the Langmuir-Hinshelwood's heterogeneous catalysis model but only in the limited range of initial dyes concentrations. Moreover, the optimum TiO2 concentration, the pH value of zero charge point, the adsorption efficiency of dyes on catalysts and the optimum volume of irradiated solution were found. It was stated that in mixtures, dyes underwent photodegradation slower than in the one-component solutions. This phenomenon has been connected with the absorbance of irradiated solutions.

Formation of viologen radical cation condensed phase through two-dimensional molecular organization process on an HOPG electrode surface in binary viologen solutions

Viologens possessing long alkyl chains are condensed to monolayers of their radical cations upon one-electron reduction on a basal plane of a highly oriented pyrolytic graphite (HOPG) electrode in contact with not only one-component viologen aqueous solutions but also binary mixtures. For three types of binary mixtures of viologen including ten different combinations, the condensed phase formation processes were described using the results of voltammetric measurements. First, in the case of the binary mixture of symmetric di-alkyl viologens ( dA) with different chain lengths, two-dimensional (2D) phase separation into two domains took place in the course of cathodic potential scan in a certain range of the solution molar fraction when the chain length difference is two methylene units or more. Second, in the case of the mixture of a dA and its both-end carboxylated derivative (bis-carboxylated viologen: bC), either pure bC condensed phase or dA + bC well-mixed phase covered the entire surface area. Third, in the case of the mixture of dA and bC with far different chain lengths, the molar fraction dependent condensation processes took place while bC always dominates the phase formation behavior. The implications of these results were discussed as typical 2D molecular nano-organization processes in the terms of homo- and hetero-intermolecular interactions on the HOPG surface.

Sorption of phenol by modified schungites

The sorption properties of schungite and its aminated form for phenol extracted from its one-component solutions and solutions in the presence of organic admixtures were examined depending on the carbon content of schungite samples and the phenol concentration in solution. It was shown that the modification of the schungite surface by the introduction of amino groups results in the formation of new sorption sites and porosity, thus enhancing the removal of phenol from its solutions.