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ABSTRACT The influence of non-ionic alkylamide and alkylamine tensides on the weathering of films made from both additive-free and stabilized low density polyethylene (LDPE) has been studied. The results of our previous studies carried... more
ABSTRACT The influence of non-ionic alkylamide and alkylamine tensides on the weathering of films made from both additive-free and stabilized low density polyethylene (LDPE) has been studied. The results of our previous studies carried out in the liquid phase apply also to the solid polymer. Alkylamide tenside accelerates PE degradation whereas alkylamine tenside shows a favourable effect.
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ABSTRACT The influence of non-ionic alkylamide and alkylamine tensides on the weathering of films made from both additive-free and stabilized low density polyethylene (LDPE) has been studied. The results of our previous studies carried... more
ABSTRACT The influence of non-ionic alkylamide and alkylamine tensides on the weathering of films made from both additive-free and stabilized low density polyethylene (LDPE) has been studied. The results of our previous studies carried out in the liquid phase apply also to the solid polymer. Alkylamide tenside accelerates PE degradation whereas alkylamine tenside shows a favourable effect.
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ABSTRACT The influence of non-ionic alkylamide and alkylamine tensides on the weathering of films made from both additive-free and stabilized low density polyethylene (LDPE) has been studied. The results of our previous studies carried... more
ABSTRACT The influence of non-ionic alkylamide and alkylamine tensides on the weathering of films made from both additive-free and stabilized low density polyethylene (LDPE) has been studied. The results of our previous studies carried out in the liquid phase apply also to the solid polymer. Alkylamide tenside accelerates PE degradation whereas alkylamine tenside shows a favourable effect.
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ABSTRACT The influence of non-ionic alkylamide and alkylamine tensides on the weathering of films made from both additive-free and stabilized low density polyethylene (LDPE) has been studied. The results of our previous studies carried... more
ABSTRACT The influence of non-ionic alkylamide and alkylamine tensides on the weathering of films made from both additive-free and stabilized low density polyethylene (LDPE) has been studied. The results of our previous studies carried out in the liquid phase apply also to the solid polymer. Alkylamide tenside accelerates PE degradation whereas alkylamine tenside shows a favourable effect.
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In this work, the effect of prewetting native and electron beam-modified wool on the resulting sorption of Cu(II) from wool solutions was studied. The following conditions and combinations were applied: 6 mM and 50 mM solutions,... more
In this work, the effect of prewetting native and electron beam-modified wool on the resulting sorption of Cu(II) from wool solutions was studied. The following conditions and combinations were applied: 6 mM and 50 mM solutions, prewetting time 0–24 h, contact time 1–24 h. The sorption results showed that wetting the wool before sorption from the low concentrated solution can fundamentally improve the efficiency of the separation process. The opposite result was achieved when applying a more concentrated solution; that is, prewetting slightly reduced the sorptivity. The reasons for such results are discussed. The application of these findings can be used to optimize the separation process in technological practice, however, will require solute specification.
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This work analyses 10 adsorption isotherm models applied to adsorption of Cr(III) and Cu(II) from binary solutions on electron-irradiated sheep wool (0-24-100) kGy. The results are compared with fitting the same adsorbates from... more
This work analyses 10 adsorption isotherm models applied to adsorption of Cr(III) and Cu(II) from binary solutions on electron-irradiated sheep wool (0-24-100) kGy. The results are compared with fitting the same adsorbates from corresponding single solutions. The competing cation significantly changes the fitting of the selected isotherms to the extent that even simultaneous fitting of the same cation in the single and binary solution is rare. In the case of Cr(III), 4 favourable matches were found out of 30 compared cases, while in the case of Cu(II), only 2 conformities were found. Having the Cr(III) coordination number exclusively of 6, but Cu(II) up to 4, 5, 6, the last coordinates more easily with the ligands provided by keratin, resulting in preferential chemisorption. If there is still a lack of cysteic acid in the wool to interact with Cr(III) also, this is adsorbed on the wool physically, too. The amount of cysteic acid increasing in the wool with the absorbed dose of energ...
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Acid modification of sheep wool changed the surface charge from a negative to a positive one as demonstrated by means of zero-charge point determination. The positive surface facilitated the adsorption of nitrate (NO3 −) anions. The... more
Acid modification of sheep wool changed the surface charge from a negative to a positive one as demonstrated by means of zero-charge point determination. The positive surface facilitated the adsorption of nitrate (NO3 −) anions. The amount of nitrates in solution within 20–100 mg/dm3 was determined applying a home-developed ultraviolet spectrometry method. A little more effective modifier was 0.01 M hydrochloric acid (HCl) than the 0.1 M one. In the case of citric acid concentration, the effect was opposite. Wool modified with hydrochloric acid showed higher nitrate adsorption (up to 5 mg/g) compared with the sample modified with citric acid, (up to 1.7 mg/g of nitrate and 3, respectively). Testing eight adsorption isotherm models indicated inhomogeneity of the adsorbed layer from chemical as well as physical aspects. The Freundlich, Temkin and Halsey models fitted best. The study demonstrated that biopolymer modified using a suitable acid has the potential to remove nitrates from a...
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Chlorophylls and carotenoids are abundant pigments in plants, algae and cyanobacteria. In this study we verified the applicability of two previously developed UV-vis spectrophotometric methods for simultaneous quantitative determination... more
Chlorophylls and carotenoids are abundant pigments in plants, algae and cyanobacteria. In this study we verified the applicability of two previously developed UV-vis spectrophotometric methods for simultaneous quantitative determination of chlorophylls (a, b) and carotenoids (lycopene, β-carotene or total carotenoids). The pigments were extracted from the strawberries, apricots and raspberries in both the acetone-water and acetone-hexane mixtures. Based on the statistical evaluation of the results the combination of mechanical disruption and sonication of fruit samples seems to be a suitable way to improve the pigment extraction efficiency from fruits in both types of solvents. In the case of apricot and raspberry fruit extracts the amount of chlorophylls and carotenoids calculated from the proposed equations was comparable to those published by other authors. However, the spectrophotometric determination of β-carotene content in strawberry acetone-hexane extract appeared to be prob...
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In this work, wool samples a) degreased and stored in desiccator (WD), b) degreased and stored freely (WF), c) cleaned in water and stored freely (WW) were irradiated by accelerated electron beam with doses within the range (0-400) kGy in... more
In this work, wool samples a) degreased and stored in desiccator (WD), b) degreased and stored freely (WF), c) cleaned in water and stored freely (WW) were irradiated by accelerated electron beam with doses within the range (0-400) kGy in air. Content of S-sulphonate as primary oxidation product was determined in WD using FTIR spectra inverted in the second-order derivative spectra. The uptake of humidity by all the samples at room temperature and 97% relative humidity was examined gravimetrically. As expected, the highest humidity uptake was observed for WD and the smallest one for WW. Development of the humidity uptake showed some fluctuation for all samples and, for WD the fluctuation corresponded with generated S-sulphonate, presumably due to formation of numerous H-bonds. The increasing uptake of humidity for WD and WW was observed up to 40 kGy dose while for WF, the uptake decreased below the initial level already from 16 kGy. Surface tension was measured using sink-float meth...
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Polyamides (PAs) are largely used either as engineering materials in virgin form or as composites and a component of polymer blends. Various processes have been used to modify some properties of polymers to improve their utility. For this... more
Polyamides (PAs) are largely used either as engineering materials in virgin form or as composites and a component of polymer blends. Various processes have been used to modify some properties of polymers to improve their utility. For this purpose, radiation technologies present clear, one-step procedures and offer improvement to the performance of PA materials. Irradiation by accelerated electron beams, γ-rays, and accelerated protons is applied on PAs, particularly PA-6, as well as PA composites. Variations of important characteristics, such as chemical structure, supermolecular structure, mechanical properties, thermal resistance, water absorption, and other parameters, are analyzed involving results obtained by other authors. The application of irradiation on incompatible polymer blends involving PA is presented as well. The selection of radiation treatment of PAs has to be considered to obtain optimal results.
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Electron beam irradiated sheep wool with absorbed radiation doses ranging from 0 to 165 kGy showed good adsorption properties toward copper cations. The Cu(ii) being Lewis acid generated several types of complex salts based on... more
Electron beam irradiated sheep wool with absorbed radiation doses ranging from 0 to 165 kGy showed good adsorption properties toward copper cations. The Cu(ii) being Lewis acid generated several types of complex salts based on carboxylates or cysteinates with ligands available in keratin. Under these conditions, cross-links were formed between the keratin chains. Experimental data obtained from Cu(ii) adsorption using the concentration of 800–5,000 mg/L were tested for fitting to 10 isotherm models. Various compositions and architectures of the Cu(ii)-complexes were specified to be responsible for different isotherm model fittings. The copper cation showed adherence to Langmuir, Flory–Huggins, and partially Redlich–Peterson models. The latter clearly distinguished the native wool from the modified ones. Another aim is to investigate the conditions for the adsorption of anti-microbial nanoparticles in addition to the redox-active metals on radiation-modified wool taking into account ...
The effect of humidity on sheep wool during irradiation by an accelerated electron beam was examined. Each of the samples with 10%, 53%, and 97% relative humidity (RH) absorbed a dose of 0, 109, and 257 kGy, respectively. After being... more
The effect of humidity on sheep wool during irradiation by an accelerated electron beam was examined. Each of the samples with 10%, 53%, and 97% relative humidity (RH) absorbed a dose of 0, 109, and 257 kGy, respectively. After being freely kept in common laboratory conditions, the samples were subjected to batch Co(II) sorption experiments monitored with VIS spectrometry for different lapses from electron beam exposure. Along with the sorption, FTIR spectral analysis of the wool samples was conducted for cysteic acid and cystine monoxide, and later, the examination was completed, with pH measuring 0.05 molar KCl extract from the wool samples. Besides a relationship to the absorbed dose and lapse, the sorptivity results showed considerable dependence on wool humidity under exposure. When humidity was deficient (10% RH), the sorptivity was lower due to limited transformation of cystine monoxide to cysteic acid. The wool pre-conditioned at 53% RH, which is the humidity close to common...
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We examined the characteristics of an electron beam irradiated wool with an absorbed dose of (21–410) kGy in comparison with natural wool with respect to the determination of the isoelectric point (IEP), zero charge point (ZCP), mechanism... more
We examined the characteristics of an electron beam irradiated wool with an absorbed dose of (21–410) kGy in comparison with natural wool with respect to the determination of the isoelectric point (IEP), zero charge point (ZCP), mechanism of Cr(III) sorption from higher concentrated solutions, and the modelling of the wool-Cr(III) interaction. The data of ZPC and IEP differed between natural and irradiated samples. Increasing the dose shifted the pH of ZPC from 6.85 for natural wool to 6.20 for the highest dosed wool, while the natural wool IEP moved very little, from pH = 3.35 to 3.40 for all of the irradiated samples. The sorption experiments were performed in a pH bath set at 3.40, and the determination of the residual Cr(III) in the bath was performed by VIS spectrometry under optimized conditions. The resulting sorptivity showed a monotonically rising trend with increasing Cr(III) concentration in the bath. Lower doses, unlike higher doses, showed better sorptivity than the natural wool. FTIR data indicated the formation of complex chromite salts of carboxylates and cysteinates. Crosslinks via ligands coming from different keratin chains were predicted, preferably on the surface of the fibers, but to a degree that did not yet inhibit the diffusion of Cr(III)-cations into the fiber volume. We also present a concept of a complex octahedral structure.
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Sorption of Co(II) was investigated on natural as well as accelerated electron beam modified sheep wool involving low and high concentrations up to 200 mmol·dm−3. The sorption experiments confirmed the dependence of the sorption capacity... more
Sorption of Co(II) was investigated on natural as well as accelerated electron beam modified sheep wool involving low and high concentrations up to 200 mmol·dm−3. The sorption experiments confirmed the dependence of the sorption capacity not only on sorbate concentration and absorbed dose of energy, but also on post-exposure time. Post-exposure heating to accelerate transformation of the wool structure was of no effect on the sorption comparing with a simple storage for a period of 100 days. Under all tested conditions, the sorption maximum was measured for Co(II) concentration of 125 mmol·dm−3 and that was assigned to form a Co(II) complex with keratin. This assumption was tested on visible spectra of mixed solutions of Arginine and Co(II) to be a simplified model of Co(II) interaction with keratin. The sorption decrease is associated with generation of cross links between macro-chains through ligands of the Co-complex. The nodal points are a hindrance to diffusion of next ions int...
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Sorption of higher concentrations of Cu(II) solution onto natural sheep wool or wool irradiated by an electron beam was studied. Sorption isotherms were of unexpected character, showing extremes. The samples with lower absorbed doses... more
Sorption of higher concentrations of Cu(II) solution onto natural sheep wool or wool irradiated by an electron beam was studied. Sorption isotherms were of unexpected character, showing extremes. The samples with lower absorbed doses adsorbed less than non-irradiated wool, while higher doses led to increased sorption varying with both concentration and dose. FTIR spectra taken from the fibre surface and bulk were different. It was concluded that there was formation of Cu(II)-complexes of carboxylic and cysteic acids with ligands coming from various keratin macromolecules. Clusters of chains crosslinked through the ligands on the surface limit diffusion of Cu(II) into the bulk of fibre, thus decreasing the sorption. After exhausting the available ligands on the surface the remaining Cu(II) cations diffuse into the keratin bulk. Here, depending on accessibility of suitable ligands, Cu(II) creates simple or complex salts giving rise to the sorption extremes. Suggestion of a mechanism f...
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Abstract Sheep wool water-washed in ultrasonic bath and slightly pre-dried was irradiated by accelerated electron beam applying dose of (0–350) kGy. The samples underwent sorption examination with Cr(III), Cd(II) and Pb(II). Sorption of... more
Abstract Sheep wool water-washed in ultrasonic bath and slightly pre-dried was irradiated by accelerated electron beam applying dose of (0–350) kGy. The samples underwent sorption examination with Cr(III), Cd(II) and Pb(II). Sorption of Cr(III) by the irradiated wool investigated at unified concentration of 24 mmol dm −3 for each absorbed dose showed intensive increase of Cr(III) sorption up to 3.13 × against the non-irradiated sample. It is concluded that some residual humidity in irradiated wool, being a rich oxygen source, enhances sorption due to faster cysteic acid formation. Sorption experiments with Cr(III), Cd(II) and Pb(II) ions of lower concentration up to 1.4 mmol dm −3 individually indicated equal sorption as for non-irradiated wool up to 0.4 mmol dm −3 . Beyond this concentration the sorption for the non-irradiated wool was lower compared with irradiated wool for any dose. The sorption increase depending on dose was different for particular doses. The order of the sorption in mg ion/1 g wool is in conformity with published data and correlates with size of the ionic radii (Pb(II) > Cd(II) > Cr(III)).
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Wool scoured in tap water with no special degreasing and containing a balanced humidity responding to usual laboratory conditions was irradiated by accelerated electron beam in the range of 0–350 kGy dose. Time variations of the wool... more
Wool scoured in tap water with no special degreasing and containing a balanced humidity responding to usual laboratory conditions was irradiated by accelerated electron beam in the range of 0–350 kGy dose. Time variations of the wool structure were measured using FTIR, Raman, and EPR spectroscopy. The aim was to determine whether preexposure treatment of the wool, as well as postexposure time, affects the properties of the irradiated wool. Reactive products such as S-sulfonate, cystine monoxide, cystine dioxide, cysteic acid, disulphides, and carboxylates displayed a considerable fluctuation in quantity depending on both the absorbed dose and time. Mutual transformations of S-oxidized products into cysteic acid appeared to be faster than those in dry and degreased wool assuming that the present humidity inside the fibres is decisive as an oxygen source. EPR results indicated a longer lifetime for free radicals induced by lower doses compared with the radicals generated by higher one...
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Electron beam (EB) irradiated wool was examined for sorption of chromic ions. Sorption increased with the adsorbed dose non-monotonously, which is a result of the generation of S-oxidized groups, secondary structure variation, and the... more
Electron beam (EB) irradiated wool was examined for sorption of chromic ions. Sorption increased with the adsorbed dose non-monotonously, which is a result of the generation of S-oxidized groups, secondary structure variation, and the breaking of the keratin backbone. For a dose of 400 kGy, an increase by 120 % was observed at the cystine dioxide and cysteine acid amounts. Examining sorption of unexposed wool and that irradiated with doses of 25 kGy and 40 kGy for basic, methylene blue (MB), or acidic, pyrogallol red (PR) dyes revealed that such low doses have no effect on the carboxylic or amino groups of keratin. Sorption of MB is independent of the EB treatment and is identical for both samples due to the interaction of MB amino groups with the carboxylic groups of wool; however, the sorption capacity for PR is a function of the EB treatment. The sample irradiated with the dose of 25 kGy showed higher PR sorption than that with the EB dose of 40 kGy, which was equal to that of un...
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Crosslinking of polyamide 6 (PA) and filled one with glass fibres (PA/GF) was initiated via macroradical formation by gamma irradiation either in air or in inert argon atmosphere. The crosslinked portion was found to start at absorbed... more
Crosslinking of polyamide 6 (PA) and filled one with glass fibres (PA/GF) was initiated via macroradical formation by gamma irradiation either in air or in inert argon atmosphere. The crosslinked portion was found to start at absorbed dose around 300 kGy and achieved about 60 and 40 wt% for PA and PA/GF, respectively, if irradiation proceeded in inert, while in air molecular weight increase was only observed without crosslinked gel formation. DSC indicated that irradiation leads to a decrease in crystallinity as well as lamellae thickness. Besides crosslinking, scission of polymer chains also occurs. Modest increase of impact strength was found for PA while small decrease for PA/GF was observed. The dependence of Young’s modulus values on the irradiation dose indicates a minimum around gel point being more pronounced for PA compared to the composite. Irradiation resulted in minor changes in tensile strength and elongation at break while a substantial increase in the elongation at yield was found for PA if irradiated in inert atmosphere. Generally, the application of an optimal dose of gamma irradiation in air results in an increase of toughness of PA without changing other mechanical properties.
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The title compounds, bis(μ-3,5-dichloro-2-oxidobenzoato)-κ3O1,O2:O2;κ3O2:O1,O2-bis[(3,5-dichloro-2-hydroxybenzoic acid-κO1)(1,10-phenanthroline-κ2N,N′)copper(II)], [Cu2(C7H2Cl2O3)2(C7H4Cl2O3)2(C12H8N2)2], (I), and... more
The title compounds, bis(μ-3,5-dichloro-2-oxidobenzoato)-κ3O1,O2:O2;κ3O2:O1,O2-bis[(3,5-dichloro-2-hydroxybenzoic acid-κO1)(1,10-phenanthroline-κ2N,N′)copper(II)], [Cu2(C7H2Cl2O3)2(C7H4Cl2O3)2(C12H8N2)2], (I), and bis(μ-5-chloro-2-oxidobenzoato)-κ3O1,O2:O1;κ3O1:O1,O2-bis[(5-chloro-2-hydroxybenzoic acid-κO1)(1,10-phenanthroline-κ2N,N′)copper(II)] ethanol monosolvate, [Cu2(C7H3ClO3)2(C7H5ClO3)2(C12H8N2)2]·C2H6O, (II), contain centrosymmetric dinuclear complex molecules in which Cu2+cations are surrounded by a chelating 1,10-phenanthroline ligand, a chelating 3,5-dichloro-2-oxidobenzoate or 5-chloro-2-oxidobenzoate anionic ligand and a monodentate 3,5-dichloro-2-hydroxybenzoic acid or 5-chloro-2-hydroxybenzoic acid ligand. The chelating benzoate ligand also bridges to the other Cu2+ion in the molecule, but the O atom involved in the bridge is different in the two complexes, being the phenolate O atom in (I) and a carboxylate O atom in (II). The bridge completes a 4+1+1 axially elongate...
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Abstract Initiation of crosslinking of polyamide-6 (PA6) by proton beam irradiation was investigated for a virgin material as well as for PA6 containing up to 5 wt% of triallyl cyanurate (TAC) as a crosslinking coagent. The gel point was... more
Abstract Initiation of crosslinking of polyamide-6 (PA6) by proton beam irradiation was investigated for a virgin material as well as for PA6 containing up to 5 wt% of triallyl cyanurate (TAC) as a crosslinking coagent. The gel point was found to be 144 and 40 kGy for virgin PA6 and for PA6 with 1 wt% of TAC, while for higher TAC content gel content was determined to be around zero absorbed dose. The ratio between crosslinking and scission of macroradicals formed by irradiation was found to be around 0.65 regardless on presence or absence of TAC and its concentration. The more detailed discussion on chemical processes as well as on final structure formation after irradiation is based on data from differential scanning calorimetry, detecting a decrease of both lamellar thickness and crystalline portion, but an increase of glass transition temperature.