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Chalcopyrite CuFeS2, a semiconductor with applications in chemical sector and energy conversion engineering, was synthetized in a planetary mill from elemental precursors. The synthesis is environmentally friendly, waste‐free and inexpensive. The synthesized nano‐powders were characterized by XRD, SEM, EDX, BET and UV/Vis techniques, tests of chemical reactivity and, namely, thermoelectric performance of sintered ceramics followed. The crystallite size of ∼13 nm and the strain of ∼17 were calculated for CuFeS2 powders milled for 60, 120, 180 and 240 min, respectively. The evolution of characteristic band gaps, Eg, and the rate constant of leaching, k, of nano‐powders are corroborated by the universal evolution of the parameter SBET/X (SBET‐specific surface area, X‐crystallinity) introduced for complex characterization of mechanochemically activated solids in various fields such as chemical engineering and/or energy conversion. The focus on non‐doped semiconducting CuFeS2 enabled to assess the role of impurities, which critically and often negatively influence the thermoelectric properties.

Copper(I) selenide-nanocrystalline semiconductor was synthesized via one-step mechanochemical synthesis after 5 min milling in a planetary ball mill. The kinetics of synthesis was followed by X-ray powder diffraction analysis and specific surface area measurements of milled 2Cu/Se mixtures. The X-ray diffraction confirmed the orthorhombic crystal structure of Cu2Se with the crystallite size ∼25 nm. The surface chemical structure was studied by X-ray photoelectron spectroscopy, whereby the binding energy of the Cu 2p and Se 3d signals corresponded to Cu+ and Se2− oxidation states. Transmission electron microscopy revealed agglomerated nanocrystals and confirmed their orthorhombic structure, as well. The optical properties were studied utilizing ultraviolet-visible spectroscopy and photoluminescence spectroscopy. The direct bandgap energy 3.7 eV indicated a blue-shift phenomenon due to the quantum size effect. This type of Cu2Se synthesis can be easily adapted to production dimensions using an industrial vibratory mill. The advantages of mechanochemical synthesis represent the potential for inexpensive, environmentally-friendly, and waste-free manufacturing of Cu2Se.

Nanostructured semiconductor, copper sulphide, CuS prepared by a mechanochemical synthesis in a large-scale operation industrial mill was modified by surfactant-assisted milling in a planetary mill...

Novel drug delivery systems containing advanced materials are currently the focus of many scientists, particularly in the field of medicine. Nowadays, these materials can play an important role when the authors talk about human health and especially the need to develop personalized treatment. In this work, multiparticulate As4S4/ZnS/Fe3O4 nanocomposite based on components possessing promising therapeutic, photoluminescent, and magnetic functionality was prepared by the milling. Subsequently, it was covered with the bio-compatible polymer Poloxamer 407 and/or folic acid for the functionalization of inorganic material. The samples were studied from the structural (X-ray powder diffraction analysis), magnetic, and optical (UV–Vis and photoluminescence spectroscopies) point of view. Particle size distribution and zeta potential measurements were performed to determine long-term stability of these nanosuspensions. Fourier transform infrared spectroscopy was used to identify bonding between organic and inorganic entities. Prominent optical fluorescence properties were found in a sample containing folic acid.

The CuInSe2/ZnS multiparticulate nanocomposites were first synthesized employing two-step mechanochemical synthesis. In the first step, tetragonal CuInSe2 crystals prepared from copper, indium and selenium precursors were co-milled with zinc acetate dihydrate and sodium sulfide nonahydrate as precursors for ZnS in different molar ratios by mechanochemical route in a planetary mill. In the second step, the prepared CuInSe2/ZnS nanocrystals were further milled in a circulation mill in sodium dodecyl sulphate (SDS) solution (0.5 wt.%) to stabilize the synthesized nanoparticles. The sodium dodecyl sulphate capped CuInSe2/ZnS 5:0-SDS nanosuspension was shown to be stable for 20 weeks, whereas the CuInSe2/ZnS 4:1-SDS one was stable for about 11 weeks. After sodium dodecyl sulphate capping, unimodal particle size distribution was obtained with particle size medians approaching, respectively, 123 nm and 188 nm for CuInSe2/ZnS 5:0-SDS and CuInSe2/ZnS 4:1-SDS nanocomposites. Successful stabilization of the prepared nanosuspensions due to sodium dodecyl sulphate covering the surface of the nanocomposite particles was confirmed by zeta potential measurements. The prepared CuInSe2/ZnS 5:0-SDS and CuInSe2/ZnS 4:1-SDS nanosuspensions possessed anti-myeloma sensitizing potential assessed by significantly reduced viability of multiple myeloma cell lines, with efficient fluorescence inside viable cells and higher cytotoxic efficacy in CuInSe2/ZnS 4:1-SDS nanosuspension.

In the present study, a quick and environmentally friendly approach has been developed for the synthesis of CuS nanocrystals of different shape with antibacterial activity. The process is completed...

Out of many functionalities of zinc oxide, its magnetic properties are only sparsely explored. Herein we report on the evolution of ferromagnetism of undoped ZnO nanoparticles, depending on the zinc source used for the synthesis. We started from mechanochemical synthesis of phase pure nanocrystalline hydrozincite, Zn5(CO3)2(OH)6 (ZnHC) by milling a mixture comprising either Zn(NO3)2·6H2O or ZnCl2, and Na2CO3 for 10 min. Zinc oxide nanoparticles with specific surface over 70 m2/g were obtained by subsequent heating of ZnHC up to 300 °C. Ferromagnetism was observed only for ZnO nanoparticles derived from Zn(NO3)2, while those from ZnCl2 were conventionally diamagnetic. X-ray photoelectron, Raman, as well as electron paramagnetic resonance spectrograms consistently showed significantly higher concentration of oxygen vacancies in the Zn(NO3)2-derived ZnO. We also referred to the difference in the charging states of oxygen vacancies by detailed observation of EPR spectra. Since the formation of ZnO from ZnHC is topotactic, the difference in the lattice imperfection was discussed in terms of the hydration energy of the coexisting NO3− or Cl− anion. The present simple mechanochemical – thermal procedure offers a facile method for obtaining well-dispersed active ZnO nanoparticles. More importantly, the new synthesis method offers possibility of controlling their magnetic properties by choosing anionic species of the starting zinc source.

A combination of solid-state mechanochemical and green approaches for the synthesis of silver nanoparticles (AgNPs) is explored in this study. Thymus serpyllum L. (SER), Sambucus nigra L. (SAM) and Thymus vulgaris L. (TYM) plants were successfully applied to reduce AgNO3 to AgNPs, as confirmed by X-ray diffraction analysis, with SER being the best reducing agent, and TYM being the worst. The experiments were performed via a one-step planetary milling process, where various AgNO3:plant mass ratios (1:1, 1:10, 1:50 and 1:100) were investigated. Atomic absorption spectrometry indicated that the stability of the mechanochemically produced AgNPs increased markedly when a sufficiently large quantity of the reducing plant was used. Furthermore, when larger quantities of plant material were employed, the crystallite size of the AgNPs decreased. TEM analysis revealed that all AgNPs produced from both AgNO3:plant ratios 1:1 and 1:10 exhibit the bimodal size distribution with the larger fraction with size in tens of nm and the smaller one below 10 nm in size. The antibacterial activity of the produced AgNPs was observed only for AgNO3:plant ratio 1:1, with the AgNPs prepared using SER showing the greatest antibacterial properties.

Copper(II) selenide, CuSe was prepared from Cu and Se powders in a stoichiometric ratio by a rapid, and convenient one-step mechanochemical synthesis, after 5 and 10 min of milling in a planetary, and an industrial vibratory, mill. The kinetics of the synthesis, and the structural, morphological, optical, and electrical properties of CuSe products prepared in the two types of mill were studied. Their crystal structure, physical properties, and morphology were characterized by X-ray diffraction, specific surface area measurements, particle size distribution, scanning, and transmission electron microscopy. The products crystallized in a hexagonal crystal structure. However, a small amount of orthorhombic phase was also identified. The scanning electron microscopy revealed that both products consist of agglomerated particles of irregular shape, forming clusters with a size ~50 mm. Transmission electron microscopy proved the nanocrystalline character of the CuSe particles. The optical properties were studied using UV&ndash, Vis and photoluminescence spectroscopy. The determined band gap energies of 1.6 and 1.8 eV for the planetary- and vibratory-milled product, respectively, were blue-shifted relative to the bulk CuSe. CuSe prepared in the vibratory mill had lower resistivity and higher conductivity, which corresponds to its larger crystallite size in comparison with CuSe prepared in the planetary mill.

In the present study, the mechanochemically prepared covellite, CuS and chalcocite, Cu2S nanocrystals are compared in detail. Concretely, the SEM, EDS, N2 adsorption, UV–Vis, PL, FTIR, ZP measurement, PCCS, XPS and DTA/TG were used. SEM, EDS and elemental mapping have shown that the agglomerates containing nanoparticles of the corresponding phases were formed as a result of milling. The nitrogen adsorption method has documented richer surface properties in the case of CuS sample. The specific surface area values were 2.7 m2 g−1 and 1.4 m2 g−1 for CuS and Cu2S, respectively. UV–Vis and PL measurements have shown that these materials might be suitable for optoelectronic applications, as the optical bandgaps were 1.92 eV and 3 eV for CuS and Cu2S, respectively. FTIR spectrum of CuS exhibited a peak at 621 cm−1, which is characteristic for this material. ZP values were more negative in the case of CuS and PCCS has confirmed the finer character of this sample (x50 values were 680 nm and 617 nm for Cu2S and CuS, respectively). XPS method documented the surface oxidation of the prepared Cu2S. The thermal stability measurement up to 550 °C has shown that Cu2S does not undergo significant changes (only 1.4% weight loss was observed), whereas CuS is losing sulfur and is transformed into digenite and chalcocite (14.3% weight loss was observed). The mechanochemically synthesized copper sulfides show high activities in photodecolorization of Methyl Orange dye under visible light irradiation, as Cu2S was able to completely decompose the dye in 150 min and CuS caused 80% decomposition after the same time of treatment.

Stannite Cu2FeSnS4 and kesterite Cu2ZnSnS4 were synthesized by an eco-friendly ball-milling method in an industrial mill. Both synthesized sulfides represent perspective materials in solar cell technology. Several characterization methods have been applied to determine the course of solid state mechanochemical reactions leading to the synthesis of potential chalcogenide solar cell absorbers. The phase and surface composition, solid state kinetics, and surface morphology of these quaternary sulfides were elucidated by the methods of X-ray diffractometry, X-ray photoelectron spectroscopy, Soxhlet analysis, and scanning electron microscopy. The application of eccentric vibration mills for these syntheses constitutes the big challenge for researchers in the field of photovoltaics in their permanent effort in scaling up new materials and processes.

Multiple myeloma (MM), a B cell malignancy characterized by clonal proliferation of plasma cells in the bone marrow, remains incurable despite the use of novel and conventional therapies. In this study, we demonstrated MM cell cytotoxicity triggered by realgar (REA; As4S4) nanoparticles (NREA) versus Arsenic trioxide (ATO) against MM cell lines and patient cells. Both NREA and ATO showed in vivo anti-MM activity, resulting in significantly decreased tumour burden. The anti-MM activity of NREA and ATO is associated with apoptosis, evidenced by DNA fragmentation, depletion of mitochondrial membrane potential, cleavage of caspases and anti-apoptotic proteins. NREA induced G2/M cell cycle arrest and modulation of cyclin B1, p53 (TP53), p21 (CDKN1A), Puma (BBC3) and Wee-1 (WEE1). Moreover, NREA induced modulation of key regulatory molecules in MM pathogenesis including JNK activation, c-Myc (MYC), BRD4, and histones. Importantly, NREA, but not ATO, significantly depleted the proportion and clonogenicity of the MM stem-like side population, even in the context of the bone marrow stromal cells. Finally, our study showed that both NREA and ATO triggered synergistic anti-MM activity when combined with lenalidomide or melphalan. Taken together, the anti-MM activity of NREA was more potent compared to ATO, providing the preclinical framework for clinical trials to improve patient outcome in MM.

In this study, CuInS2/ZnS nanocrystals were synthesized by a two-step mechanochemical synthesis for the first time. In the first step, tetragonal CuInS2 was prepared from copper, indium and sulphur precursors. The obtained CuInS2 was further co-milled with zinc acetate dihydrate and sodium sulphide nonahydrate as precursors for cubic ZnS. Structural characterization of the CuInS2/ZnS nanocrystals was performed by X-ray diffraction analysis, Raman spectroscopy and transmission electron microscopy. Specific surface area of the product (86 m2/g) was measured by low-temperature nitrogen adsorption method and zeta potential of the particles dispersed in water was calculated from measurements of their electrophoretic mobility. Optical properties of the nanocrystals were determined using photoluminescence emission spectroscopy.

In this paper, InAs/ZnS mixed nanocrystals were synthesized by dry high-energy milling approach in the first step. The obtained nanocrystals were characterized from structural point of view by X-ray diffraction analysis and Raman spectroscopy, and from the morphological point of view by scanning electron microscopy. In the next step, the nanocrystals were subjected to wet ultra-fine milling in order to obtain a nanosuspension of chitosan-coated InAs/ZnS nanocrystals with bio-imaging properties. The stability of the nanosuspension was examined by zeta potential and particle size distribution measurements. The prepared nanosuspension was stable with high values of zeta potential. Its optical properties were also studied using UV–Vis and PL spectroscopies. The determined fluorescent properties confirming the potential in bio-imaging applications were verified on cancer cell lines Caco-2, HCT116, HeLa, and MCF7.

The deficiency of primary raw materials and the difficult processing of sulphide concentrates with low gold content, as well as the long-time use of the dangerous cyanide method, instigated to the search a more effective and environmentally conscious method of acquirement this noble metal. For this reason, this work was focused on gold obtaining from a refractory sulphide complex concentrate (Pezinok, Slovakia) with the application of the non-cyanide mechanochemico-biological process. Gold in this complex concentrate occurs physically enclosed in the intercrystalline space of sulphide minerals, and is also isomorphic and fills structure defects in sulphides. The exclusion of gold from such complex mineral matrices of the concentrate can be achieved by using a mechanochemico-biological process. This innovative process makes possible obtaining of gold using an application of a thiourea solution, which is a convenient alternative opposite to the toxic cyanidation method. The utilized of the biological process with the application of algae has shown that algae with siliceous structures make it possible to obtain of gold from a complex concentrate (Pezinok, Slovakia) with dimension in the nano range. These algae are part of aquatic ecosystems and, in addition, are being food for other animals, utilizing for fuel production and, more recently, they are the important raw material for the production of hydrogen, methane and some types of biofuels. Limnetic algae (diatoms, golden algae) have unique properties, they create the largest mass of biomass of all plants on Earth and at the same time they are able to move. The mechanochemico-biological process is a method that enables to obtain gold nanoparticles 100 nm from the refractory sulphide concentrate (Pezinok, Slovakia). Mechanochemical activation of this concentrate and silica shells of the limnetic algae of tribes (Dinobryon, Surirella) in thiourea solution caused changes in physico-chemical properties of the minerals of gold as well as in the constituents of the algae minerals. These structural changes had under specific conditions a decisive influence on the exclusion of gold nanoparticles to the thiourea solution. The gold nanoparticles had subsequently fixed in the cellular matrix on mechanochemical activated algae shells. The reason for the fixation of gold nanoparticles was the action of biomolecules that algal cells during activation secreted while they defend again the chemical effect of metal ions present in the solution. Nanoparticles of gold were acquirement from the concentrate after less than two hours by described mechanochemico-biological process. In the case of mechanochemical activation of the concentrate, but without the activation of defined algae, the exclusion of gold nanoparticles was not confirmed even after a triple activation time (six hours). Owing to, the algae had to be activated to recover of gold from this sulphide concentrate. It follows, the entire mechanochemico-biological process had to be followed.

Synthesis of Co9Se8 phase from metallic cobalt and selenium powders by one-pot mechanochemical synthesis in a planetary ball mill and subsequent thermal treatment in argon atmosphere is reported. Crystal structure and morphology of the products were characterized by X-ray diffraction, specific surface area measurements, and transmission electron microscopy. Our study revealed that only mixture with excess of Co resulted in the formation of higher fraction of the Co9Se8 phase. While milling of Co and Se in 13.5:8 ratio resulted in the synthesis of nanocrystalline hexagonal CoSe (freboldite) and only around 13 wt.% of the targeted Co9Se8 phase, additional isothermal treatment at 450 °C increased yield of the Co9Se8 phase to more than 70%. Optical properties of the product with the highest Co9Se8 fraction showed broad absorption in whole UV–Vis optical region and band-gap energy of 1.93 eV, blue-shifted relative to the bulk Co9Se8. Both UV–Vis and photoluminescence spectra indicated quantum size effect of the finest nanocrystals in Co9Se8 product. The new combined approach represents a simple, fast, and easy up-scalable route for the synthesis of Co9Se8.

The ZnS nanocrystals were prepared in chitosan solution (0.1 wt.%) using a wet ultra-fine milling. The obtained suspension was stable and reached high value of zeta potential (+57 mV). The changes in FTIR spectrum confirmed the successful surface coating of ZnS nanoparticles by chitosan. The prepared ZnS nanocrystals possessed interesting optical properties verified in vitro. Four cancer cells were selected (CaCo-2, HCT116, HeLa, and MCF-7), and after their treatment with the nanosuspension, the distribution of ZnS in the cells was studied using a fluorescence microscope. The particles were clearly seen; they passed through the cell membrane and accumulated in cytosol. The biological activity of the cells was not influenced by nanoparticles, they did not cause cell death, and only the granularity of cells was increased as a consequence of cellular uptake. These results confirm the potential of ZnS nanocrystals using in bio-imaging applications.

Chalcogenide semiconductor cobalt monoselenide, CoSe, was prepared from metallic cobalt and selenium powders in stoichiometric ratio by simple and fast mechanochemical synthesis after 120 min of milling in a planetary ball mill Pulverisette 6 (Fritsch, Germany) in an argon atmosphere. Crystal structure and morphology of the product were characterized by X-ray diffraction, specific surface area measurements, and transmission electron microscopy. X-ray diffraction analysis confirmed the hexagonal crystal structure of the product-CoSe (freboldite) with the average size of the crystallites 26 nm. Transmission electron microscopy analysis has revealed that CoSe nanostructures are composed of agglomerated and randomly oriented nanoparticles. The optical properties were studied using UV–Vis and photoluminescence spectroscopy. Mechanochemically synthesized CoSe nanostructures showed higher absorption in whole UV–Vis optical region and the determined band-gap energy 1.70 eV is blue-shifted relative to the bulk CoSe. Both UV–Vis and photoluminescence spectra indicate quantum size effect of CoSe nanocrystals.

Within this study, a stable nanosuspension of silver nanoparticles (Ag NPs) was prepared using a two-step synthesis and stabilization approach. The Ag NPs were synthesized from a silver nitrate solution using the Origanum vulgare L. plant extract as the reducing agent. The formation of nanoparticles was finished upon 15 min, and subsequently, stabilization by polyvinylpyrrolidone (PVP) using wet stirred media milling was applied. UV-Vis spectra have shown a maximum at 445 nm, corresponding to the formation of spherical Ag NPs. Infrared spectroscopy was used to examine the interaction between Ag NPs and the capping agents. TEM study has shown the formation of Ag NPs with two different average sizes (38 ± 10 nm and 7 ± 3 nm) after the plant-mediated synthesis, both randomly distributed within the organic matrix. During milling in PVP, the clusters of Ag NPs were destroyed, the Ag NPs were fractionized and embedded in PVP. The nanosuspensions of PVP-capped Ag NPs were stable for more than 26 weeks, whereas for the non-stabilized nanosuspensions, only short-term stability for about 1 week was documented.

for Extractive Metallurgy, Materials Science and Medicine P. Balao*, M. Balao, M. Achimovi£ova, Z. Buj¬akova and E. Dutkova Institute of Geotechnics, Slovak Academy of Sciences, Watsonova 45, Ko2ice, Slovakia In this review paper recent advances in chalcogene mechanochemistry are described. Three selected areas are being covered, i.e. metallurgy, materials science, and medicine. In extractive metallurgy, the processing of copper arsenic mineral enargite (Cu3AsS4) with the aim of its dearseni cation and subsequent preparation of a new anticancer drug (Na3AsS4) and of copper in nanocrystalline state (≈ 20 nm) illustrate the non-traditional prospect of ore treatment. In material science, the new nanocrystalline semiconductors were synthesized mechanochemically, e.g. selenides of zinc and lead (ZnSe, PbSe) and bismuth sulphide (Bi2S3). Metal and chalcogene were applied as reaction precursors. In some cases, the amino acids (cystine, cysteine) were applied as sulphur precursor, in order to provide reactive sites on synthesized solid (PbS) for bioconjugation and to prevent agglomeration. The concept of nanomilling is described as a way to prepare e ective substances for cancer treatment in medicine. In vitro activity of realgar (As4S4) as an example is described. In all three areas the focus is aimed also on industrial applications where suitable large-scale mills are described. The described examples represent the contemporary aim of mechanochemists to prepare substances with the desired properties in a reproducible way under easyoperating, environmentally friendly and essentially waste-free conditions.

CdSe@ZnS nanocomposites have been prepared by a two-step solid state mechanochemical synthesis. CdSe prepared from Cd and Se elements in the first step was mixed with zinc acetate and sodium sulphide in the second step of milling to prepare a CdSe@ZnS nanocomposite. In the third step, the obtained nanocomposite was coated with l -cysteine to prepare a biocompatible system. The crystallite size of the new type of nanocomposite was 20–35 nm for cubic CdSe and 3–8 nm for hexagonal ZnS as calculated from XRD, TEM and SEM data. The synthesised samples show good crystallinity and have been tested for dissolution and cytotoxicity. The dissolution of cadmium from CdSe@ZnS was less than 0.05 μg mL−1, whereas a value of 0.8 μg mL−1 was measured for CdSe alone. The binding of ZnS with CdSe in the nanocomposite practically eliminated the release of cadmium into solution. As a consequence, a very low cytotoxic activity has been evidenced for CdSe@ZnS. The nanocomposites coated with l -cysteine have a great potential as fluorescent labels in biomedical engineering.

In this study we demonstrate the synthesis of quaternary semiconductor nanocrystals of stannite Cu2FeSnS4/rhodostannite Cu2FeSn3S8 (CFTS) via mechanochemical route using Cu, Fe, Sn and S elements as precursors in one-pot experiments. Methods of X-ray diffraction (XRD), nitrogen adsorption, high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were applied to characterize properties of the unique nanostructures. Mechanochemical route of synthesis induced new phenomena like explosive character of reaction, where three stages could be identified and the formation of nanostructures 5–10 nm in size. By using XPS method, Cu(I), Fe(II), Sn(IV) and S(-II) species were identified on the surface of CFTS. The value of optical band gap 1.27 eV is optimal for semiconductors applicable as absorbers in solar cells. The significant photocatalytic activity of the CFTS nanocrystals was also evidenced. The obtained results confirm the excellent properties of the quaternary semiconductor nanocrystals synthesized from earth-abundant elements., This work was supported by the Slovak Research and Development Agency APVV (project APVV-0103-14) and by the National Science Fund (Bulgaria) under the contract DNTS/Slovakia 01/2. The support of the Research excellence centre on earth sources, extraction and treatment - 2nd phase supported by the Research & Development Operational Programme funded by the ERDF No. 26220120038 is also gratefully acknowledged., Chalcogenide Quaternary Cu2FeSnS4 Nanocrystals for Solar Cells: Explosive Character of Mechanochemical Synthesis and Environmental Challenge

The wet mechanochemical procedure for the capping of the CdS and CdS/ZnS quantum dot nanocrystals is reported. l-cysteine and polyvinylpyrrolidone (PVP) were used as capping agents. When using l-cysteine, the dissolution of cadmium(II) was almost none for CdS/ZnS nanocrystals. Moreover, prepared CdS- and CdS/ZnS-cysteine nanosuspensions exhibited unimodal particle size distributions with very good stability, which was further supported by the zeta potential measurements. The Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy showed the successful embedment of cysteine into the structure of the nanocrystals. Additionally, the optical properties were examined, and the results showed that the cysteine nanosuspension has promising fluorescence properties. On the other hand, PVP was not determined to be a very suitable capping agent for the present system. In this case, the release of cadmium(II) was higher in comparison to the l-cysteine capped samples. The nanosuspensions were successfully used for in vitro studies on selected cancer cell lines. Using fluorescence microscopy, it was evidenced that the nanocrystals enter the cell and that they can serve as imaging agents in biomedical applications.

CdSe@ZnS nanocrystals have been prepared by a two-step solid state mechanochemical synthesis. CdSe prepared from elements in the first step is mixed with ZnS synthesized from zinc acetate and sodium sulfide in the second step. The crystallite size of the new type CdSe@ZnS nanocrystals determined by X-ray diffraction Rietveld refined method was 35 nm and 10 nm for CdSe and ZnS, respectively. Energy dispersive/transmission electron microscopy/energy dispersive spectroscopy methods show good crystallinity of the nanoparticles and scanning electron microscopy elemental mapping illustrate consistent distribution of Cd, Se, Zn and S elements in the bulk of samples. UV-VIS spectra show an onset at 320 nm with calculated bandgap 3.85 eV. This absorption arises from the vibration modes of Zn-S bonds. The nanocrystals show the blue shift from the bandgap of bulk ZnS (3.66 eV). The synthesized CdSe@ZnS nanocrystals have been tested for dissolution, cytotoxicity and L-cysteine conjugation. The dissolution of Cd was less than 0.05 μg mL -1 (in comparison with 0.8 μg mL -1 which was evidenced for CdSe alone). The very low cytotoxic activity for selected cancer cell lines has been evidenced. CdSe@ZnS nanocrystals coated with L-cysteine are water-soluble and have a great potential in biomedical engineering as fluorescent labels.

The mechanochemical solid-state synthesis of ZnxCd1-xS nanoparticles from zinc acetate, cadmium acetate and sodium sulphide in a planetary laboratory mill is described. Through changing the molar ratio of the Zn and Cd precursors, ZnxCd1-xS nanoparticles of different composition were prepared. Structural, surface and morphological properties were investigated by XRD, XPS, SEM and UV-VIS. Diffusion structural diagnostics was characterised by the emanation thermal analysis (ETA) results measured on heating of the samples. The cubic phase was found to be stable under mechanochemical treatment, as determined by XRD. The mixed phases were found to have ideal solution behaviours. In addition, microstructural characterisation indicated that mechanochemical treatment resulted in a structural refinement with a surface weighted crystallite size about 2 nm. The additional information of microstructure development and transport properties of the samples on heating was obtained by ETA. The calculated lattice parameters of mixed crystals linearly depend on the composition of ZnxCd1-xS nanoparticles. The S(2p), Zn(2p) and Cd(3d) core levels of the ZnxCd1-xS nanocrystallites reveal two different types of sulphur, zinc and cadmium unlike bulk CdS and ZnS. The calculated results indicate that the quantum-size effect in the nanoparticles is not negligible. The differences in the absorption edge and the emission peak position of the nanoparticles depend not only composition. Applied high-energy milling is a facile, efficient, and scalable process that does not require a solvent and can be performed under ambient conditions. Therefore, it is a promising candidate for the production of nanocrystalline materials.

In this study, arsenic sulphide As4S4nanoparticles have been prepared, by high-energy wet milling, in the presence of sodium dodecylsulphate, which acts a surfactant. Solid state properties of the nanoparticles were characterised by XRD, Raman scattering, specific surface area and particle size distribution. Changes in surface areas of the particles, in the 0.2 - 5.4 m2g-1range, and nanosize distributions, in the 100 - 250 nm range, characterise the surface and morphological properties of nanorealgar. Raman scattering revealed various species in the milled sample that indicate a disproportionate reaction (3As4S4→ 4As2S3+ 4As) occurring as a consequence of milling. Anticancer effects, of the milled species, were confirmed for the human multiple myeloma U266 and OPM1 cell lines. Dissolution experiments in simulated gastric fluid show a possibility for the application of the realgar nanoparticles as an oral dose in future arsenic drug cancer treatments.

PbS nanocrystals using surfactant assisted mechanochemical synthesis have been prepared by co-milling of lead acetate (CH 3 COO) 2 Pb 3H 2 O and sodium sulfide Na 2 S 9H 2 O. The methods of XRD, FE-SEM, TEM (HRTEM), UV–vis, specific surface area measurements as well as reactivity in acidic FeCl 3 media were used for the nanocrystals characterization. The XRD patterns confirmed the presence of galena PbS (JCPDS 5-592) whatever treatment conditions were applied. The strong observable peaks indicate the highly crystalline nature in formation of PbS nanostructures where preferential crystal growth in the (2 0 0) direction after addition of ethylenediamine (EDA), sodiumdodecylsulphate (SDS) and ethylendiaminetetraacetic disodium salt dihydrate (EDH) surfactants has been observed. The surface weighted crystallite sizes 3, 8, 11 and 19 nm have been calculated from XRD data using the Warren–Averbach method for surfactant-free and/or EDA, SDS and EDH surfactants assisted mechanochemical synthesis. The leaching rate of galena PbS in acidic FeCl 3 solution has been studied. The dependence of PbS nanocrystals reactivity on preferential growth parameter is documented. The highest value of the specific rate constant of leaching, k 0 / S A has been obtained for the mechanochemically synthesized PbS in presence of EDH surfactant.

The mechanochemical synthesis of Cu/FeS, Pb/FeS and Sb/FeS nanoparticles was investigated with the regard to solid-state kinetics. Experiments were performed in a planetary mill and in an eccentric vibratory mill by a high-energy milling of Cu 2 S, PbS and Sb 2 S 3 , respectively with elemental iron under protective atmosphere. Cu, Pb and Sb nanometals were obtained due to the reducing power of iron. The reduction processes are very straightforward and fast and can be carried out at ambient temperature. Nanometals are embedded into FeS matrix forming metal/ceramics nanocomposites. XRD, SEM and magnetometry methods were used to characterize the ball-milled products. Solid-state kinetics has been evaluated based on magnetometry data.

PbS nanocrystals using surfactant assisted mechanochemical route has been successfully prepared. The methods of XRD, SEM, surface area and particle size measurements were used for nanocrystals characterization. The XRD patterns confirmed the presence of galena PbS (JCPDS 5–592) whatever treatment conditions were applied. The strong observable peaks indicate the highly crystalline nature in formation of PbS nanostructures where preferential crystal growth in the (200) direction after chelating agent (EDTANa2•2H2O) addition has been observed. The mean volume weighted crystallite size 4.9 nm and 35 nm has been calculated from XRD data using Williamson-Hall method for PbS synthesized without and/or with chelating agent, respectively corresponding with surface weighted crystallites sizes of 2.9 and 18.8 nm. The sample prepared without surfactant yields the smaller crystallites and the higher microstrain compared with surfactant assisted synthesis. The obtained results illustrate a possibility to manipulate crystal morphology by combining effect of milling and surfactant application.

CdxZn1-xS nanocrystals were synthesized by mechanochemical solid state route in a planetary laboratory mill. Structural, surface and morphological properties were investigated by XRD, XPS, SEM and TEM methods. Mechanochemical synthesis produced uniform particles with respect to microstructure. Surface weighted crystallite sizes approximately of 2 nm were calculated from XRD data by application of Warren-Averbach method. The observation of S(2p), Cd(3d) and Zn(2p) peaks in XPS spectra shows existence of CdZnS nanocrystals on the surface of samples. The SEM measurements show the aggregates of small nanocrystals. The TEM method confirms the aggregate formation of CdxZn1-xS nanocrystals with the sizes 5-10 nm. The CdxZn1-xS nanocrystals are obtained in the simple synthesis step, making the process attractive for industrial applications. (c) 2008 Elsevier B.V. All rights reserved.

Au-Ag noble metal wastes represent a wide range of waste types and forms with various ballast elements and components. The thiourea process of gold and silver extraction from ores, concentrates or secondary raw materials consists of gold and silver leaching into the thiourea solution and the consequent precipitation of these metals from the solution. Due to the non-toxic character of thiourea it is the perspective alternative to the up to now most frequently used cyanide method. The thiourea leaching of gold and silver from electronic waste, goldsmith’s waste and ceramic waste using crushing as the pretreatment step was investigated. For electronic waste, it was possible to achieve 97 % gold and 94 % silver recovery within 120 minutes of thiourea leaching. Up to 98 % of gold and 96 % of silver were recovered from goldsmith’s waste after 60 minutes of leaching. In the case of ceramic waste, we achieved up to 98 % gold and 97 % silver extraction efficiency after only 45 minutes of leaching. In comparison with the classical cyanide leaching, thiourea leaching acts faster and without a harmful environmental impact.

At present mechanochemistry of sulphides appears to be a science with a sound theoretical foundation exhibiting a wide range effectiveness in different areas of science and technology. For traditional application mechanochemistry is of exceptional importance in extractive metallurgy of sulphidic ores where many technological processes have been developed. Metal sulphides can be also utilized in emerging nanotechnology with application as advanced luminescence, optoelectronic, magnetic and catalytic materials.

The catalytically active solid materials were prepared by mechanochemical synthesis and impregnation. The starting material used as a support was β -zeolite with a ratio SiO 2 / Al 2 O 3 = 66 . The molybdenum precursor was 12-molybdophosphoric heteropoly acid (HPMo). The samples were characterized by TPR and IR methods. The test reaction was thiophene hydrodesulfurization at atmospheric pressure. The interaction between HPMo and β -zeolite in the catalyst sample, prepared by mechanochemical synthesis, is a weak one compared to that in the sample obtained on the basis of impregnation. The hydrodesulfurization activity of the milling sample is stabilized at a level about 50% higher than that of the sample prepared by impregnating HPMo on β -zeolite. The higher hydrogenating activity of the mechanochemically treated sample is an additional advantage.

The effect of high-energy milling of arsenic sulphide As 4 S 4 on its phase transition has been studied. The transition of α -As 4 S 4 to the high-temperature β -As 4 S 4 as well as the formation of As 4 S 4 nanosize powder (16–48 nm) has been described. The presence of β -As 4 S 4 has been proven by X-ray diffraction (XRD) and Raman spectroscopy. The fine particles were characterized by measurement of specific surface area and particle size distribution.

CdS/ZnS nanocomposites have been prepared by a two-step solid-state mechanochemical synthesis. CdS has been prepared from cadmium acetate and sodium sulfide precursors in the first step. The obtained cubic CdS (hawleyite, JCPDS 00-010-0454) was then mixed in the second step with the cubic ZnS (sphalerite, JCPDS 00-005-0566) synthesized mechanochemically from the analogous precursors. The crystallite sizes of the new type CdS/ZnS nanocomposite, calculated based on the XRD data, were 3-4 nm for both phases. The synthesized nanoparticles have been further characterized by high-resolution transmission electron microscopy (HRTEM) and micro-photoluminescence (μPL) spectroscopy. The PL emission peaks in the PL spectra are attributed to the recombination of holes/electrons in the nanocomposites occurring in depth associated with Cd, Zn vacancies and S interstitials. Their photocatalytic activity was also measured. In the photocatalytic activity tests to decolorize Methyl Orange dye aqueous solution, the process is faster and its effectivity is higher when using CdS/ZnS nanocomposite, compared to single phase CdS. Very low cytotoxic activity (high viability) of the cancer cell lines (selected as models of living cells) has been evidenced for CdS/ZnS in comparison with CdS alone. This fact is in a close relationship with Cd(II) ions dissolution tested in a physiological solution. The concentration of cadmium dissolved from CdS/ZnS nanocomposites with variable Cd:Zn ratio was 2.5-5.0 μg.mL(-1), whereas the concentration for pure CdS was much higher - 53 μg.ml(-1). The presence of ZnS in the nanocrystalline composite strongly reduced the release of cadmium into the physiological solution, which simulated the environment in the human body. The obtained CdS/ZnS quantum dots can serve as labeling media and co-agents in future anti-cancer drugs, because of their potential in theranostic applications.

In recent years nanocrystalline semiconductors (QD) have attached much attention due to their great potential in technological applications. Electronic, optical and other properties of QD with respect to corresponding bulk materials are modified considerably, offering a number of potential applications in semiconductor and other industries. Nanophases have been synthesized by a number of techniques starting from vapour phase (i. e. inert gas condensation), liquid phase (i.e. rapid sodification) and solid state. The technique starting from solid state applies mechanochemical approach where synthesis is performed by solid state reactions in high-energy mills. We have developed the mechanochemical route to produce nanocrystalline semiconductors applying high-energy milling of metal acetates with sodium sulphide. The main advantage of this route is that it is “a quantity process” permitting kilogram quantities of nanomaterials to be produced at an ambient temperatures in a very short processing time. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The bulk and surface properties of mechanochemically synthesized ZnS nanoparticles were studied. XRD, SEM, TEM (HRTEM), AFM, UV-VIS, low temperature nitrogen sorption as well as TPR characterization methods have been applied. Cubic ZnS nanocrystals (2-4 nm) with characteristic blue shift have been obtained by high-energy milling. There is an evidence of the nanocrystal aggregates formation in products of milling. The surface uniformity, homogeneity as well as enhanced uptake of hydrogen have been documented.

Arsenic sulfide compounds have a long history of application in a traditional medicine. In recent years, realgar has been studied as a promising drug in cancer treatment. In this study, the arsenic sulfide (As4S4) nanoparticles combined with zinc sulfide (ZnS) ones in different molar ratio have been prepared by a simple mechanochemical route in a planetary mill. The successful synthesis and structural properties were confirmed and followed via X-ray diffraction and high-resolution transmission electron microscopy measurements. The morphology of the particles was studied via scanning electron microscopy and transmission electron microscopy methods and the presence of nanocrystallites was verified. For biological tests, the prepared As4S4/ZnS nanoparticles were further milled in a circulation mill in a water solution of Poloxamer 407 (0.5wt%), in order to cover the particles with this biocompatible copolymer and to obtain stable nanosuspensions with unimodal distribution. The average size of the particles in the nanosuspensions (~120nm) was determined by photon cross-correlation spectroscopy method. Stability of the nanosuspensions was determined via particle size distribution and zeta potential measurements, confirming no physico-chemical changes for several months. Interestingly, with the increasing amount of ZnS in the sample, the stability was improved. The anti-cancer effects were tested on two melanoma cell lines, A375 and Bowes, with promising results, confirming increased efficiency of the samples containing both As4S4 and ZnS nanocrystals.