Peter Baláž - Profile on Academia.edu (original) (raw)

Papers by Peter Baláž

Social Science Research Network, 2022

In recent years, mechanochemistry has experienced a massive resurgence allowing for solvent-free ... more In recent years, mechanochemistry has experienced a massive resurgence allowing for solvent-free preparation of many important materials with minimal energy requirements. This paper provides a review of the mechanochemical preparation of nanocrystalline metal halides for applications as inorganic phosphor materials. The review puts strong emphasis on our recent work on optical and X-ray storage phosphors such as the matlockite BaFCl:Sm 3? . In addition, previously unpublished results are presented including the effect on the samarium oxidation state when using ball-milling, as well as results on other rare earthdoped matlockites. We outline how mechanochemical methods can be applied to synthesise, without the need for solvents and high temperatures, a wide range of halides ranging from the most important commercial X-ray storage phosphor BaFBr:Eu 2? to lead perovskites of the formula APbX 3 with A = Cs ? , CH 3 NH 3 ? , etc., and X = F, Cl, Br, I or a mixture thereof. We also demonstrate that a wide variety of solid solutions of the general formula M 1 x M 2 1Àx FX 1 y X 2 1Ày (with M 1 and M 2 = Ba, Sr, Ca; X 1 , X 2 = Cl, Br, I) that can be suitable hosts for luminescent activator ions, can be prepared by mechanochemical methods. Importantly, for prolonged grinding times with a high-energy ball-mill, crystallites on the nanoscale can be obtained as can be confirmed by Rietveld refinements of powder XRD patterns and electron microscopy.

Acta Physica Polonica A, Oct 1, 2014

Nanosuspension based on melt-quenched arsenic sulde of nominal As55S45 composition was prepared b... more Nanosuspension based on melt-quenched arsenic sulde of nominal As55S45 composition was prepared by nanomilling and tested as potential anticancer drug. Polyvinylpyrrolidone was used as steric stabilizer and inhibitor of agglomeration. Individual nanoparticles had average size of 192 nm (determined by photon cross-correlation spectroscopy) and had several times better dissolution ability in comparison with bulk As55S45. Eect of nanomilling is shown to be associated with formation of arsenic sulde crystalline nanoparticles and free-volume entities located at the interface between nanoparticles and surrounding matrix as it follows from positron annihilation measurements. Cytotoxicity tests were performed using human melanoma cell line Bowes and conrmed high toxicity of the studied nanosuspension.

Journal of Materials Science, Mar 19, 2018

The present study demonstrates a mechanochemical ''micro-nano'' approach toward the future solar ... more The present study demonstrates a mechanochemical ''micro-nano'' approach toward the future solar cell absorber material Cu 2 ZnSnS 4 (CZTS) with upscaling potential. For this purpose, synthetic copper sulfide CuS and tin sulfide SnS nanoparticles along with microsized zinc metal and elemental sulfur as solid precursors were utilized. These precursors were milled in a planetary ball mill in an argon atmosphere for a period of 1-240 min. Moreover, we compare it to a ''micro'' approach starting from the elements and maintaining the same milling conditions. The phase composition of reaction mixtures was analyzed by X-ray diffractometry. The final products of syntheses were further analyzed by means of scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis spectroscopy. The phase purity of the prepared materials was verified by confocal Raman microscopy. In both cases, a polydisperse system of a nearly stoichiometric Cu 2 ZnSnS 4 phase was readily obtained after 60 min of milling with only traces of unreacted Cu 2-x S phases. Based on the results, we conclude there is no definite difference in reaction speed. However, the crystallite size and optical properties of the prepared CZTS samples slightly differ when various precursors are used.

Processing of natural mineral magnetite for medical applications

Abstract Magnetic nanoparticles consisting of magnetite (Fe 3 O 4 ) are promising therapeutic and... more Abstract Magnetic nanoparticles consisting of magnetite (Fe 3 O 4 ) are promising therapeutic and/or diagnostic tools in medicine. In this chapter, the ball milling processing of natural mineral magnetite for medical applications is described. The chapter is focused on the preparation of bifunctional materials where magnetic component (Fe 3 O 4 ) is combined with fluorescent (ZnS) and therapeutic (As 4 S 4 ) entities. The properties of the prepared powder materials including microstructure characterization are described in details. Subsequently, the coating with biocompatible surfactants is presented. The physico-chemical properties including stability are also demonstrated. Finally, the possibilities of up-scaling the process is described referring to the latest knowledge regarding to this issue.

Leachability of mechanochemically pretreated chalcopyrite

Transactions of The Indian Institute of Metals, 1998

Environmental Research, Mar 1, 2019

A semi-industrial approach for simultaneous treatment of eggshell and industrial polyvinyl chlori... more A semi-industrial approach for simultaneous treatment of eggshell and industrial polyvinyl chloride waste utilizing tools of ball milling is reported therein. On a hundred-gram scale, it is possible to transfer more than 55% of chlorine present in the polyvinyl chloride representing an environmental burden, into harmless soluble form. On a laboratory scale, a complete dechlorination was achieved. The ratio of eggshell-to-polyvinyl chloride plays a significant role for the effective dechlorination and the kinetics of semi-industrial process follows zero-order kinetics with the rate constant 1.23 × 10 -5 s -1 . Chlorine is mainly in the form of calcium chloride. This study is an example of efficient simultaneous valorization of two waste materials on a semi-industrial scale, as the products can be utilized again.

Scalable and environmentally friendly mechanochemical synthesis of nanocrystalline rhodostannite (Cu2FeSn3S8)

Powder Technology, Aug 1, 2021

Abstract This study demonstrates scalable mechanochemical synthesis of rhodostannite Cu2FeSn3S8 n... more Abstract This study demonstrates scalable mechanochemical synthesis of rhodostannite Cu2FeSn3S8 nanocrystals. On the contrary to the previous reports focused on the synthesis of stannite Cu2FeSnS4 reporting the rhodostannite impurity, we succeeded in preparing stannite-free product after milling. Pure elements were used for a solvent-free production in a batch of 100 g using an eccentric vibratory mill. The progress of the synthesis was monitored by X-ray diffraction and magnetometry, which both confirmed a successful reaction progress until 6 h of milling. However, further treatment (until 10 h) did not result in an improvement, as quite a high saturation magnetization (7.8 emu/g) and clearly evident diffraction at around 44° in the XRD pattern of the product due to the presence of ferromagnetic un-reacted iron with content slightly above 5% was evidenced. The product is sulfur- and tin-deficient, with crystallite size of around 12 nm. In-depth SEM/EDS analysis has shown the inhomogeneity of Fe distribution due to unfinished reaction. The bandgap of the produced material was 1.29 eV. The spark plasma sintering treatment resulted in complete consumption of non-reacted iron, but partial decomposition to stannite Cu2FeSnS4 was observed. The product is an intrinsic semiconductor with high electrical resistivity, and is therefore unsuitable for thermoelectric application. However, its thermal conductivity is low, thus it could be used as an electrically and thermally insulating material.

Leaching of chalcopyrite concentrate with ferric chloride

International Journal of Mineral Processing, Apr 1, 1995

... 43 (1995) 61-72 Leaching of chalcopyrite concentrate with ferric chloride Tom Havl'k a, ... more ... 43 (1995) 61-72 Leaching of chalcopyrite concentrate with ferric chloride Tom Havl'k a, Milan ~krobian a, Peter Bal b, Roland ... Zevgolis and Cooke (1975 ) observed a 200 to 400% difference in the electroleaching rates of five different chalcopyrite samples serving as anodes. ...

Journal of Physics and Chemistry of Solids, 2019

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Journal of Thermal Analysis and Calorimetry, Aug 14, 2018

Temperature-modulated DSC TOPEM Ò method was applied to study amorphization in directly synthesiz... more Temperature-modulated DSC TOPEM Ò method was applied to study amorphization in directly synthesized high-temperature polymorph of tetra-arsenic tetra-sulfide b-As 4 S 4 affected to high-energy mechanical milling in a dry mode with 100-600 min -1 rotational speeds. The appeared amorphous phase is shown to possess dual nature, being related to As-rich glassy-like substances with low-and high-temperature glass transition midpoints. In respect of DSC TOPEM Ò studies, the crystalline-amorphous heterogeneity of chemical environment around b-As 4 S 4 crystallites results in incongruent doublepeak melting revealed through two endothermic effects at* 305 °C and * 315 °C. Amorphous phase continuously generated under ball milling with increased rotational speed is identified as compositionally authentic to arsenic monosulfide, but different in medium-range order from stoichiometric As 2 S 3 . The overall amorphization in commercial arsenic sulfide prepared by direct synthesis from elemental constituents under high-energy ball milling occurs from two sources, these being high-to-low-T g amorphous phase transformation and direct vitrification of b-As 4 S 4 phase. These data testifies in favor of ''shell'' model treated solid-state amorphization in terms of defect generation in parent b-As 4 S 4 phase, the amorphous substance being nucleated heterogeneously from grain boundaries followed by stretching into crystalline grain interior.

Applied Nanoscience, Oct 17, 2022

Employing positron annihilation lifetime (PAL) spectroscopy, nanomilling-driven volumetric change... more Employing positron annihilation lifetime (PAL) spectroscopy, nanomilling-driven volumetric changes driven are identified in multiparticulate nanocomposites of As 4 S 4 -ZnS-Fe 3 O 4 system, considered in transitions between their respective hierarchical derivatives from triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) to biparticulate (1⋅As 4 S 4 /1⋅Fe 3 O 4 , 1⋅As 4 S 4 /4⋅ZnS) and monoparticulate (As 4 S 4 ) ones. Unconstrained three-component PAL spectra of nanocomposites are parameterized in terms of positron-Ps trapping conversion obeying x3-x2-CDA (coupling decomposition algorithm). Coexistence of nanocrystalline nc-β-As 4 S 4 and amorphous a-AsS phase is shown to be crucial feature of these nanocomposites, the latter being generated continuously due to reamorphization of initial disordered phase and/or vitrification of nc-β-As 4 S 4 phase. The inverse positron-to-Ps trapping conversion prevails in transition from biparticulate (1⋅As 4 S 4 /1⋅Fe 3 O 4 ) and monoparticulate (As 4 S 4 ) nanocomposites (both dominated by trapping in As 4 S 4 -bearing sub-system) to triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) one, disappeared positron traps being vacancy defects in a-As-S matrix, and Ps-decay sites formed instead being triple junctions between amorphized nc-β-As 4 S 4 grains. The normal Ps-to-positron-trapping conversion prevails in transition from biparticulate (1⋅As 4 S 4 /4⋅ZnS) nanocomposite dominated by positron trapping in ZnS sub-system to triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) one, disappeared Ps-decay sites being triple junctions between amorphized nc-β-As 4 S 4 grains, and positron traps formed instead being vacancy-type defects in the packing of the finest ZnS crystallites (~ 2-3 nm). * Shpotyuk Oleh

Nanoscale Research Letters, Jan 25, 2017

Microstructure hierarchical model considering the free-volume elements at the level of interactin... more Microstructure hierarchical model considering the free-volume elements at the level of interacting crystallites (nonspherical approximation) and the agglomerates of these crystallites (spherical approximation) was developed to describe free-volume evolution in mechanochemically milled As 4 S 4 /ZnS composites employing positron annihilation spectroscopy in a lifetime measuring mode. Positron lifetime spectra were reconstructed from unconstrained three-term decomposition procedure and further subjected to parameterization using x3-x2-coupling decomposition algorithm. Intrinsic inhomogeneities due to coarse-grained As 4 S 4 and fine-grained ZnS nanoparticles were adequately described in terms of substitution trapping in positron and positronium (Ps) (bound positron-electron) states due to interfacial triple junctions between contacting particles and own free-volume defects in boundary compounds. Compositionally dependent nanostructurization in As 4 S 4 /ZnS nanocomposite system was imagined as conversion from o-Ps trapping sites to positron traps. The calculated trapping parameters that were shown could be useful to characterize adequately the nanospace filling in As 4 S 4 /ZnS composites.

Materials, 2022

The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating po... more The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating positrons to probe atomic-deficient sub-nanometric imperfections in a condensed matter, are analyzed in application to glassy arsenoselenides g-As x Se 100-x (0 < x < 65), subjected to dry and wet (in 0.5% PVP water solution) nanomilling. A preliminary analysis was performed within a modified two-state simple trapping model (STM), assuming slight contributions from bound positron-electron (Ps, positronium) states. Positron trapping in g-As x Se 100-x /PVP nanocomposites was modified by an enriched population of Ps-decay sites in PVP. This was proven within a three-state STM, assuming two additive inputs in an overall trapping arising from distinct positron and Ps-related states. Formalism of x3-x2-CDA (coupling decomposition algorithm), describing the conversion of Ps-decay sites into positron traps, was applied to identify volumetric nanostructurization in wet-milled g-As-Se, with respect to dry-milled ones. Under wet nanomilling, the Ps-decay sites stabilized in inter-particle triple junctions filled with PVP replaced positron traps in dry-milled substances, the latter corresponding to multi-atomic vacancies in mostly negative environments of Se atoms. With increased Se content, these traps were agglomerated due to an abundant amount of Se-Se bonds. Three-component lifetime spectra with nanostructurally-and compositionally-tuned Ps-decay inputs and average lifetimes serve as a basis to correctly understand the specific "rainbow" effects observed in the row from pelletized PVP to wet-milled, dry-milled, and unmilled samples.

Nucleation and Atmospheric Aerosols, 2018

Atomic-deficient void structure is studied in nanocomposites prepared by mechanochemical milling ... more Atomic-deficient void structure is studied in nanocomposites prepared by mechanochemical milling of glassy g-As2Se3 in a water solution of polyvinylpyrrolidone (PVP) employing positron annihilation lifetime spectroscopy. Formalism of Ps-to-positron trapping conversion known as x3-x2-CDA (coupling decomposition algorithm) is applied to identify free-volume defects in the pelletized g-As2Se3/PVP nanocomposite in respect to dry-milled g-As2Se3 one. Under wet-milling, the inter-nanoparticle Ps-decaying sites in preferential PVP environment replace free-volume positron traps (in dry-milled g-As2Se3) with defect-specific lifetime of 0.352 ns, corresponding to di-/tri-atomic vacancies in g-As-Se.

Acta Physica Polonica A, Apr 1, 2017

High-energy milling of sulphides with a reactive metal in so-called mechanochemical reduction mod... more High-energy milling of sulphides with a reactive metal in so-called mechanochemical reduction mode can lead to products in nanorange and to composition which simplifies the following metallurgical processing. Chalcopyrite CuFeS2, a ternary semiconductor with antiferromagnetic properties represents promising candidate as an advanced material for use in inexpensive nanoelectronics (solar cells, magnetic area), as well as copper ore source in metallurgical operations. In this work, the process of mechanochemical reduction of chalcopyrite with elemental iron is studied. The composition and properties of nanopowder prepared by high-energy milling were analyzed by X-ray diffraction and magnetic measurements. Most of the reaction takes place during 30 min with chalcocite Cu2S and troilite FeS as the only reaction products. The magnetic investigations reveal significant increase of saturation magnetization as a result of milling. Unlike the conventional high-temperature reduction of chalcopyrite, the mechanochemical reduction is fast and ambient temperature and atmospheric pressure are sufficient for its propagation.

Materials, 2022

The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating po... more The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating positrons to probe atomic-deficient sub-nanometric imperfections in a condensed matter, are analyzed in application to glassy arsenoselenides g-AsxSe100−x (0 < x < 65), subjected to dry and wet (in 0.5% PVP water solution) nanomilling. A preliminary analysis was performed within a modified two-state simple trapping model (STM), assuming slight contributions from bound positron–electron (Ps, positronium) states. Positron trapping in g-AsxSe100−x/PVP nanocomposites was modified by an enriched population of Ps-decay sites in PVP. This was proven within a three-state STM, assuming two additive inputs in an overall trapping arising from distinct positron and Ps-related states. Formalism of x3-x2-CDA (coupling decomposition algorithm), describing the conversion of Ps-decay sites into positron traps, was applied to identify volumetric nanostructurization in wet-milled g-As-Se, with respect ...

Proceedings of the IV Advanced Ceramics and Applications Conference, 2017

ZnS nanoparticles were synthesized mechanochemically by high-energy milling. Samples were produce... more ZnS nanoparticles were synthesized mechanochemically by high-energy milling. Samples were produced in three different milling times. The morphology of samples has been investigated by scanning electron microscopy (SEM). X-ray diffraction (XRD) investigation of synthesized nanocrystals identified cubic structure, and crystallite size was estimated to 1.9 nm (5 min milling), 2.3 nm (10 min) and 2.4 nm (20 min). These dimensions ensure strong confinement regime. Raman spectroscopy studies (100-500 cm -1 ) have been performed. Excitation source was 514.5 nm (E L = 2.41 eV), implying that we are in off-resonance regime. Dominant spectral structures are registered in spectral region 130-180 cm -1 , around 265 cm -1 and around 345 cm -1 . First two are assigned as combination modes and mode at 345 cm -1 as confined ZnS LO type phonon. Absence of TO mode with visible excitation is consequence of poor scattering efficiency and anti-resonant behavior. We report relatively strong, compared to confined ZnS LO type phonon, Raman activities of combination modes away from the resonance in the strong confinement regime in ZnS quantum dots (QD). We find that off-resonance Raman spectroscopy can be used for quick estimation of the dimension of produced ZnS QDs. Sum of second-order Raman active modes centered at 265 cm -1 dominates over LO-like mode at 345 cm -1 in strong confinement regime.

In the presented work, possibilities of intensification of copper leaching from chalcopyrite CuFe... more In the presented work, possibilities of intensification of copper leaching from chalcopyrite CuFeS2 induced by mechanical activation was studied. In this article, the influence of mechanical activation time on copper leaching efficiency is compared. This study also shows how mechanical activation time influences selectivity of copper and iron leaching. For mechanical activation, planetary mill Fritsch Pulverisette 6 at 400 rpm and room temperature was used. Grinding chamber (250 cm3 in volume) and 50 balls (10 mm in diameter) made of tungsten carbide were used. Specifically, the effect of mechanical activation time (4, 20, 30 minutes), the effect of temperature (40, 60, 80°C) on the copper recovery by leaching and the effect of the leaching atmosphere (air, argon) were examined. The results showed that the highest possible recovery of copper from chalcopyrite was obtained after 20 minutes of milling and leached in hydrochloric acid at 80°C, with air atmosphere without any oxidizing ...

Physicochemical Problems of Mineral Processing, 1991

In this study, α-and β-phase As4S4 nanoparticles were prepared by wet nanomilling using sodium do... more In this study, α-and β-phase As4S4 nanoparticles were prepared by wet nanomilling using sodium dodecyl sulfate as a surfactant. The properties of the nanoparticles were characterized by particle size distribution and Raman scattering. A monomodal distribution, in the 150 -200 nm range characterized the particle size of both phases after milling. Raman scattering revealed a common pattern for all studied particles. The existence of pararealgar was documented by Raman spectroscopy. The anticancer effects, of the milled species were confirmed for two multiple myeloma cell lines (RPMI-LR5 and OPM1) invitro.

Social Science Research Network, 2022

In recent years, mechanochemistry has experienced a massive resurgence allowing for solvent-free ... more In recent years, mechanochemistry has experienced a massive resurgence allowing for solvent-free preparation of many important materials with minimal energy requirements. This paper provides a review of the mechanochemical preparation of nanocrystalline metal halides for applications as inorganic phosphor materials. The review puts strong emphasis on our recent work on optical and X-ray storage phosphors such as the matlockite BaFCl:Sm 3? . In addition, previously unpublished results are presented including the effect on the samarium oxidation state when using ball-milling, as well as results on other rare earthdoped matlockites. We outline how mechanochemical methods can be applied to synthesise, without the need for solvents and high temperatures, a wide range of halides ranging from the most important commercial X-ray storage phosphor BaFBr:Eu 2? to lead perovskites of the formula APbX 3 with A = Cs ? , CH 3 NH 3 ? , etc., and X = F, Cl, Br, I or a mixture thereof. We also demonstrate that a wide variety of solid solutions of the general formula M 1 x M 2 1Àx FX 1 y X 2 1Ày (with M 1 and M 2 = Ba, Sr, Ca; X 1 , X 2 = Cl, Br, I) that can be suitable hosts for luminescent activator ions, can be prepared by mechanochemical methods. Importantly, for prolonged grinding times with a high-energy ball-mill, crystallites on the nanoscale can be obtained as can be confirmed by Rietveld refinements of powder XRD patterns and electron microscopy.

Acta Physica Polonica A, Oct 1, 2014

Nanosuspension based on melt-quenched arsenic sulde of nominal As55S45 composition was prepared b... more Nanosuspension based on melt-quenched arsenic sulde of nominal As55S45 composition was prepared by nanomilling and tested as potential anticancer drug. Polyvinylpyrrolidone was used as steric stabilizer and inhibitor of agglomeration. Individual nanoparticles had average size of 192 nm (determined by photon cross-correlation spectroscopy) and had several times better dissolution ability in comparison with bulk As55S45. Eect of nanomilling is shown to be associated with formation of arsenic sulde crystalline nanoparticles and free-volume entities located at the interface between nanoparticles and surrounding matrix as it follows from positron annihilation measurements. Cytotoxicity tests were performed using human melanoma cell line Bowes and conrmed high toxicity of the studied nanosuspension.

Journal of Materials Science, Mar 19, 2018

The present study demonstrates a mechanochemical ''micro-nano'' approach toward the future solar ... more The present study demonstrates a mechanochemical ''micro-nano'' approach toward the future solar cell absorber material Cu 2 ZnSnS 4 (CZTS) with upscaling potential. For this purpose, synthetic copper sulfide CuS and tin sulfide SnS nanoparticles along with microsized zinc metal and elemental sulfur as solid precursors were utilized. These precursors were milled in a planetary ball mill in an argon atmosphere for a period of 1-240 min. Moreover, we compare it to a ''micro'' approach starting from the elements and maintaining the same milling conditions. The phase composition of reaction mixtures was analyzed by X-ray diffractometry. The final products of syntheses were further analyzed by means of scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis spectroscopy. The phase purity of the prepared materials was verified by confocal Raman microscopy. In both cases, a polydisperse system of a nearly stoichiometric Cu 2 ZnSnS 4 phase was readily obtained after 60 min of milling with only traces of unreacted Cu 2-x S phases. Based on the results, we conclude there is no definite difference in reaction speed. However, the crystallite size and optical properties of the prepared CZTS samples slightly differ when various precursors are used.

Processing of natural mineral magnetite for medical applications

Abstract Magnetic nanoparticles consisting of magnetite (Fe 3 O 4 ) are promising therapeutic and... more Abstract Magnetic nanoparticles consisting of magnetite (Fe 3 O 4 ) are promising therapeutic and/or diagnostic tools in medicine. In this chapter, the ball milling processing of natural mineral magnetite for medical applications is described. The chapter is focused on the preparation of bifunctional materials where magnetic component (Fe 3 O 4 ) is combined with fluorescent (ZnS) and therapeutic (As 4 S 4 ) entities. The properties of the prepared powder materials including microstructure characterization are described in details. Subsequently, the coating with biocompatible surfactants is presented. The physico-chemical properties including stability are also demonstrated. Finally, the possibilities of up-scaling the process is described referring to the latest knowledge regarding to this issue.

Leachability of mechanochemically pretreated chalcopyrite

Transactions of The Indian Institute of Metals, 1998

Environmental Research, Mar 1, 2019

A semi-industrial approach for simultaneous treatment of eggshell and industrial polyvinyl chlori... more A semi-industrial approach for simultaneous treatment of eggshell and industrial polyvinyl chloride waste utilizing tools of ball milling is reported therein. On a hundred-gram scale, it is possible to transfer more than 55% of chlorine present in the polyvinyl chloride representing an environmental burden, into harmless soluble form. On a laboratory scale, a complete dechlorination was achieved. The ratio of eggshell-to-polyvinyl chloride plays a significant role for the effective dechlorination and the kinetics of semi-industrial process follows zero-order kinetics with the rate constant 1.23 × 10 -5 s -1 . Chlorine is mainly in the form of calcium chloride. This study is an example of efficient simultaneous valorization of two waste materials on a semi-industrial scale, as the products can be utilized again.

Scalable and environmentally friendly mechanochemical synthesis of nanocrystalline rhodostannite (Cu2FeSn3S8)

Powder Technology, Aug 1, 2021

Abstract This study demonstrates scalable mechanochemical synthesis of rhodostannite Cu2FeSn3S8 n... more Abstract This study demonstrates scalable mechanochemical synthesis of rhodostannite Cu2FeSn3S8 nanocrystals. On the contrary to the previous reports focused on the synthesis of stannite Cu2FeSnS4 reporting the rhodostannite impurity, we succeeded in preparing stannite-free product after milling. Pure elements were used for a solvent-free production in a batch of 100 g using an eccentric vibratory mill. The progress of the synthesis was monitored by X-ray diffraction and magnetometry, which both confirmed a successful reaction progress until 6 h of milling. However, further treatment (until 10 h) did not result in an improvement, as quite a high saturation magnetization (7.8 emu/g) and clearly evident diffraction at around 44° in the XRD pattern of the product due to the presence of ferromagnetic un-reacted iron with content slightly above 5% was evidenced. The product is sulfur- and tin-deficient, with crystallite size of around 12 nm. In-depth SEM/EDS analysis has shown the inhomogeneity of Fe distribution due to unfinished reaction. The bandgap of the produced material was 1.29 eV. The spark plasma sintering treatment resulted in complete consumption of non-reacted iron, but partial decomposition to stannite Cu2FeSnS4 was observed. The product is an intrinsic semiconductor with high electrical resistivity, and is therefore unsuitable for thermoelectric application. However, its thermal conductivity is low, thus it could be used as an electrically and thermally insulating material.

Leaching of chalcopyrite concentrate with ferric chloride

International Journal of Mineral Processing, Apr 1, 1995

... 43 (1995) 61-72 Leaching of chalcopyrite concentrate with ferric chloride Tom Havl'k a, ... more ... 43 (1995) 61-72 Leaching of chalcopyrite concentrate with ferric chloride Tom Havl'k a, Milan ~krobian a, Peter Bal b, Roland ... Zevgolis and Cooke (1975 ) observed a 200 to 400% difference in the electroleaching rates of five different chalcopyrite samples serving as anodes. ...

Journal of Physics and Chemistry of Solids, 2019

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Journal of Thermal Analysis and Calorimetry, Aug 14, 2018

Temperature-modulated DSC TOPEM Ò method was applied to study amorphization in directly synthesiz... more Temperature-modulated DSC TOPEM Ò method was applied to study amorphization in directly synthesized high-temperature polymorph of tetra-arsenic tetra-sulfide b-As 4 S 4 affected to high-energy mechanical milling in a dry mode with 100-600 min -1 rotational speeds. The appeared amorphous phase is shown to possess dual nature, being related to As-rich glassy-like substances with low-and high-temperature glass transition midpoints. In respect of DSC TOPEM Ò studies, the crystalline-amorphous heterogeneity of chemical environment around b-As 4 S 4 crystallites results in incongruent doublepeak melting revealed through two endothermic effects at* 305 °C and * 315 °C. Amorphous phase continuously generated under ball milling with increased rotational speed is identified as compositionally authentic to arsenic monosulfide, but different in medium-range order from stoichiometric As 2 S 3 . The overall amorphization in commercial arsenic sulfide prepared by direct synthesis from elemental constituents under high-energy ball milling occurs from two sources, these being high-to-low-T g amorphous phase transformation and direct vitrification of b-As 4 S 4 phase. These data testifies in favor of ''shell'' model treated solid-state amorphization in terms of defect generation in parent b-As 4 S 4 phase, the amorphous substance being nucleated heterogeneously from grain boundaries followed by stretching into crystalline grain interior.

Applied Nanoscience, Oct 17, 2022

Employing positron annihilation lifetime (PAL) spectroscopy, nanomilling-driven volumetric change... more Employing positron annihilation lifetime (PAL) spectroscopy, nanomilling-driven volumetric changes driven are identified in multiparticulate nanocomposites of As 4 S 4 -ZnS-Fe 3 O 4 system, considered in transitions between their respective hierarchical derivatives from triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) to biparticulate (1⋅As 4 S 4 /1⋅Fe 3 O 4 , 1⋅As 4 S 4 /4⋅ZnS) and monoparticulate (As 4 S 4 ) ones. Unconstrained three-component PAL spectra of nanocomposites are parameterized in terms of positron-Ps trapping conversion obeying x3-x2-CDA (coupling decomposition algorithm). Coexistence of nanocrystalline nc-β-As 4 S 4 and amorphous a-AsS phase is shown to be crucial feature of these nanocomposites, the latter being generated continuously due to reamorphization of initial disordered phase and/or vitrification of nc-β-As 4 S 4 phase. The inverse positron-to-Ps trapping conversion prevails in transition from biparticulate (1⋅As 4 S 4 /1⋅Fe 3 O 4 ) and monoparticulate (As 4 S 4 ) nanocomposites (both dominated by trapping in As 4 S 4 -bearing sub-system) to triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) one, disappeared positron traps being vacancy defects in a-As-S matrix, and Ps-decay sites formed instead being triple junctions between amorphized nc-β-As 4 S 4 grains. The normal Ps-to-positron-trapping conversion prevails in transition from biparticulate (1⋅As 4 S 4 /4⋅ZnS) nanocomposite dominated by positron trapping in ZnS sub-system to triparticulate (1⋅As 4 S 4 /4⋅ZnS/1⋅Fe 3 O 4 ) one, disappeared Ps-decay sites being triple junctions between amorphized nc-β-As 4 S 4 grains, and positron traps formed instead being vacancy-type defects in the packing of the finest ZnS crystallites (~ 2-3 nm). * Shpotyuk Oleh

Nanoscale Research Letters, Jan 25, 2017

Microstructure hierarchical model considering the free-volume elements at the level of interactin... more Microstructure hierarchical model considering the free-volume elements at the level of interacting crystallites (nonspherical approximation) and the agglomerates of these crystallites (spherical approximation) was developed to describe free-volume evolution in mechanochemically milled As 4 S 4 /ZnS composites employing positron annihilation spectroscopy in a lifetime measuring mode. Positron lifetime spectra were reconstructed from unconstrained three-term decomposition procedure and further subjected to parameterization using x3-x2-coupling decomposition algorithm. Intrinsic inhomogeneities due to coarse-grained As 4 S 4 and fine-grained ZnS nanoparticles were adequately described in terms of substitution trapping in positron and positronium (Ps) (bound positron-electron) states due to interfacial triple junctions between contacting particles and own free-volume defects in boundary compounds. Compositionally dependent nanostructurization in As 4 S 4 /ZnS nanocomposite system was imagined as conversion from o-Ps trapping sites to positron traps. The calculated trapping parameters that were shown could be useful to characterize adequately the nanospace filling in As 4 S 4 /ZnS composites.

Materials, 2022

The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating po... more The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating positrons to probe atomic-deficient sub-nanometric imperfections in a condensed matter, are analyzed in application to glassy arsenoselenides g-As x Se 100-x (0 < x < 65), subjected to dry and wet (in 0.5% PVP water solution) nanomilling. A preliminary analysis was performed within a modified two-state simple trapping model (STM), assuming slight contributions from bound positron-electron (Ps, positronium) states. Positron trapping in g-As x Se 100-x /PVP nanocomposites was modified by an enriched population of Ps-decay sites in PVP. This was proven within a three-state STM, assuming two additive inputs in an overall trapping arising from distinct positron and Ps-related states. Formalism of x3-x2-CDA (coupling decomposition algorithm), describing the conversion of Ps-decay sites into positron traps, was applied to identify volumetric nanostructurization in wet-milled g-As-Se, with respect to dry-milled ones. Under wet nanomilling, the Ps-decay sites stabilized in inter-particle triple junctions filled with PVP replaced positron traps in dry-milled substances, the latter corresponding to multi-atomic vacancies in mostly negative environments of Se atoms. With increased Se content, these traps were agglomerated due to an abundant amount of Se-Se bonds. Three-component lifetime spectra with nanostructurally-and compositionally-tuned Ps-decay inputs and average lifetimes serve as a basis to correctly understand the specific "rainbow" effects observed in the row from pelletized PVP to wet-milled, dry-milled, and unmilled samples.

Nucleation and Atmospheric Aerosols, 2018

Atomic-deficient void structure is studied in nanocomposites prepared by mechanochemical milling ... more Atomic-deficient void structure is studied in nanocomposites prepared by mechanochemical milling of glassy g-As2Se3 in a water solution of polyvinylpyrrolidone (PVP) employing positron annihilation lifetime spectroscopy. Formalism of Ps-to-positron trapping conversion known as x3-x2-CDA (coupling decomposition algorithm) is applied to identify free-volume defects in the pelletized g-As2Se3/PVP nanocomposite in respect to dry-milled g-As2Se3 one. Under wet-milling, the inter-nanoparticle Ps-decaying sites in preferential PVP environment replace free-volume positron traps (in dry-milled g-As2Se3) with defect-specific lifetime of 0.352 ns, corresponding to di-/tri-atomic vacancies in g-As-Se.

Acta Physica Polonica A, Apr 1, 2017

High-energy milling of sulphides with a reactive metal in so-called mechanochemical reduction mod... more High-energy milling of sulphides with a reactive metal in so-called mechanochemical reduction mode can lead to products in nanorange and to composition which simplifies the following metallurgical processing. Chalcopyrite CuFeS2, a ternary semiconductor with antiferromagnetic properties represents promising candidate as an advanced material for use in inexpensive nanoelectronics (solar cells, magnetic area), as well as copper ore source in metallurgical operations. In this work, the process of mechanochemical reduction of chalcopyrite with elemental iron is studied. The composition and properties of nanopowder prepared by high-energy milling were analyzed by X-ray diffraction and magnetic measurements. Most of the reaction takes place during 30 min with chalcocite Cu2S and troilite FeS as the only reaction products. The magnetic investigations reveal significant increase of saturation magnetization as a result of milling. Unlike the conventional high-temperature reduction of chalcopyrite, the mechanochemical reduction is fast and ambient temperature and atmospheric pressure are sufficient for its propagation.

Materials, 2022

The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating po... more The possibilities surrounding positronics, a versatile noninvasive tool employing annihilating positrons to probe atomic-deficient sub-nanometric imperfections in a condensed matter, are analyzed in application to glassy arsenoselenides g-AsxSe100−x (0 < x < 65), subjected to dry and wet (in 0.5% PVP water solution) nanomilling. A preliminary analysis was performed within a modified two-state simple trapping model (STM), assuming slight contributions from bound positron–electron (Ps, positronium) states. Positron trapping in g-AsxSe100−x/PVP nanocomposites was modified by an enriched population of Ps-decay sites in PVP. This was proven within a three-state STM, assuming two additive inputs in an overall trapping arising from distinct positron and Ps-related states. Formalism of x3-x2-CDA (coupling decomposition algorithm), describing the conversion of Ps-decay sites into positron traps, was applied to identify volumetric nanostructurization in wet-milled g-As-Se, with respect ...

Proceedings of the IV Advanced Ceramics and Applications Conference, 2017

ZnS nanoparticles were synthesized mechanochemically by high-energy milling. Samples were produce... more ZnS nanoparticles were synthesized mechanochemically by high-energy milling. Samples were produced in three different milling times. The morphology of samples has been investigated by scanning electron microscopy (SEM). X-ray diffraction (XRD) investigation of synthesized nanocrystals identified cubic structure, and crystallite size was estimated to 1.9 nm (5 min milling), 2.3 nm (10 min) and 2.4 nm (20 min). These dimensions ensure strong confinement regime. Raman spectroscopy studies (100-500 cm -1 ) have been performed. Excitation source was 514.5 nm (E L = 2.41 eV), implying that we are in off-resonance regime. Dominant spectral structures are registered in spectral region 130-180 cm -1 , around 265 cm -1 and around 345 cm -1 . First two are assigned as combination modes and mode at 345 cm -1 as confined ZnS LO type phonon. Absence of TO mode with visible excitation is consequence of poor scattering efficiency and anti-resonant behavior. We report relatively strong, compared to confined ZnS LO type phonon, Raman activities of combination modes away from the resonance in the strong confinement regime in ZnS quantum dots (QD). We find that off-resonance Raman spectroscopy can be used for quick estimation of the dimension of produced ZnS QDs. Sum of second-order Raman active modes centered at 265 cm -1 dominates over LO-like mode at 345 cm -1 in strong confinement regime.

In the presented work, possibilities of intensification of copper leaching from chalcopyrite CuFe... more In the presented work, possibilities of intensification of copper leaching from chalcopyrite CuFeS2 induced by mechanical activation was studied. In this article, the influence of mechanical activation time on copper leaching efficiency is compared. This study also shows how mechanical activation time influences selectivity of copper and iron leaching. For mechanical activation, planetary mill Fritsch Pulverisette 6 at 400 rpm and room temperature was used. Grinding chamber (250 cm3 in volume) and 50 balls (10 mm in diameter) made of tungsten carbide were used. Specifically, the effect of mechanical activation time (4, 20, 30 minutes), the effect of temperature (40, 60, 80°C) on the copper recovery by leaching and the effect of the leaching atmosphere (air, argon) were examined. The results showed that the highest possible recovery of copper from chalcopyrite was obtained after 20 minutes of milling and leached in hydrochloric acid at 80°C, with air atmosphere without any oxidizing ...

Physicochemical Problems of Mineral Processing, 1991

In this study, α-and β-phase As4S4 nanoparticles were prepared by wet nanomilling using sodium do... more In this study, α-and β-phase As4S4 nanoparticles were prepared by wet nanomilling using sodium dodecyl sulfate as a surfactant. The properties of the nanoparticles were characterized by particle size distribution and Raman scattering. A monomodal distribution, in the 150 -200 nm range characterized the particle size of both phases after milling. Raman scattering revealed a common pattern for all studied particles. The existence of pararealgar was documented by Raman spectroscopy. The anticancer effects, of the milled species were confirmed for two multiple myeloma cell lines (RPMI-LR5 and OPM1) invitro.