In this work, we present an advanced preparation method of photoactive layered graphitic carbon nitride (g-C3N4) incorporated into silica structure containing zinc ions, that enhance the sorption properties and photocatalytic activity of said material. Samples with 20 wt% and 10 wt% of g-C3N4 were prepared. Specific surface area of nanocomposites was raised from 36 m2/g of pure g-C3N4 to 366 and 320 m2/g respectively. Material was prepared by vigorous stirring of aqueous solution of zinc acetate and g-C3N4 within strong ultrasonic field. During the sonication, sodium water glass was added at once to synthesize ZnO-m·SiO2 nanoparticles. The dispersion was then rapidly frozen and subjected to vacuum freeze drying process to obtain powder material, which is easier to handle and more suitable for tests. Prepared nanocomposites were subjected to tests of sorption and photocatalytic degradation of methylene blue and indigo carmine dyes. Furthermore, samples did undergo successful process of repeated sorption followed by photocatalytic regeneration.
Graphitic carbon nitride (g-C3N4) is intensively studied material for photocatalytic application, mainly for the photocatalytic degradation of pollutants in water and air. Several methods for g-C3N4 preparation exist, whereas thermal polymerization of suitable precursors (urea, melamine, dicyanamide etc.) is the most often used. In this research, g-C3N4 was prepared by the thermal polymerization of melamine and tuning of the calcination conditions was performed using Design Of Experiment approach (DOE). Five factors, such as temperature ramp rate, final temperature, hold time, cooling rate and amount of initial melamine, were selected and tested on two levels: 3 and 10 °C/min, 500 and 550°C, 0 and 1h, shock and slow cooling, 2.5 and 10 g. A half testing plan including 16 calcination experiments was set using fractional factorial design. Yield of g-C3N4 and its photogeradation activity against model dye acid orange 7 were used as the measured output of the experiments.
Nano structuring and morphological engineering are the two important aspects of the control of the performance of functional materials. In the present work, we report on the fabrication of high aspect discrete TiO2 nanotubes possessing two or multi-legs via electrochemical anodization of titanium foils the effect of applied voltage and anodization time with appropriate optimization of electrolyte containing (NH4) HF2 in diethylene glycol-based electrolyte were investigated. Scanning electron microscopy was employed to examine the morphology of the synthesized TiO2 nanotubes. We observed that prolonged anodization times from 2 hrs to 6 hours, results in the formation of dense and high aspect nanotubes with improved lengths compared to the sample synthesized with 2 hours of anodization time.
Many paints contain special additives such as biocides which act as a prevention against biodeterioration. Presence of nanoparticles of silver and copper may inhibit the grow of microorganism. Self cleaning facade paints containing photocatalytic particles (mostly TiO2) appear also on the market. Such paints are after irradiation of sunlight no to susceptible to soiling and thus help to keep exterior of building clean. Another type of paints is prepared with aim to improve air quality in exterior via photocatalytic oxidation organics compounds such as acetaldehyde, formaldehyde etc.
This contribution deals with the application of ZnO particles to water based acrylic paints. The objective is to determined antifungal capability against A. niger. Attention will be also paid to determination of photocatalytic activity. Photocatalytic activity will be determined using indicator ink containing Resazurin dye. This method is based on observation of color change from pink to blue which occurs on photocatalytic surface.
The use of recyclable Pd-catalysts is already widely described for a lot of Pd-catalyzed coupling reactions. Nevertheless a lot of improvement is still possible. The main improvement potential for presently used heterogeneous Pd-catalysts are (I) increasing the solubility of the catalyst in the reaction mixture, (II) reducing the large energy costs due to heating of the whole reaction vessel, (III) reducing the reaction time, due to the warm-up/cool-down cycle of the whole reactor, and (IV) increasing the control and safety of the reaction. The general concept is to use a two-component nanoparticle platform, which consists of a magnetically responsive nanoparticle, surrounded by the Pd-catalyst.
The recyclable Pd-catalyst is synthesized by reducing a palladium salt onto a magnetite nanoparticle and are used in the Sonogashira- and the Stille-reaction. Both of these reactions are first optimized using thermal heating. In previous research a magnetical induced Suzuki-reaction was already performed. Therefore, the same was tried using a Sonogashira- and Stille-reaction. The influence of the amount of catalyst, the temperature and the recuperation is presented.
Silver nanoparticles, AgNPs, take important part of modern nanotechnology - catalysis, microbiology, electronics, environmental protection - due to their stability and unique physical and optical properties. A lot of these applications involve immobilization of AgNPs onto some support - natural (zeolite, clay, silica) or synthetic (polymers matrix, beads and fibres), thus forming a nanocomposite material. This approach makes the application of AgNPs in environmental protection much more convenient and cost effective.
In this study we present an amine mediated method for synthesis of silver nanoparticles at room temperature. We have used modified citrate method for reduction of silver ions, where the synthesis has been catalysed by amine. The effect of amine nature and three surfactants (sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromibe (CTAB) and polyvinylpyrrolidone (PVP)) on the process of AgNPs formation and crystal growth has been studied. The TEM analysis revealed that in the presence of primary amine, monoethanolamine (MEA) smaller AgNPs with more uniform size distribution were formed then that from triethanolamine (TEA)-catalyzed reaction. It has been shown that the surfactant not only prevents from NPs aggregation but also facilitates the synthesis due to complexation with the silver ions.
This modified citrate method for AgNPs formation at room temperature is very convenient way for preparation of hybrid nanocomposite materials. It was applied for fabrication of AgNPs/zeolite nanocomposites by loading natural zeolite with silver ions and their reduction to AgNPs. Such type of nanomaterials can be tested in reactions for environmental protection.
Sustainable oxygen evolution reaction (OER) is an essential prerequisite in hydrogen production from electrochemical water splitting. In the past few years, many research efforts have been directed towards the development of electrocatalysts for OER, which are based on noble metals and transition metal oxides. Recently, it has been found that, transition metal chalcogenide materials, especially Ni- and Co- based compounds, can catalyze OER efficiently. However, there are very few reports about the colloidal synthesis of Ni and Co based metal chalcogenides and their applications in electrocatalysis, despite that colloidal synthesis is one of the most successful methods in synthesizing nanocrystals.
Therefore, we decided here to develop a colloidal approach to synthesize quaternary Ni-Co-S-Se nanocrystals in order to study their OER activity and to correlate it with their specific composition, which was systematically varied. We devised a new colloidal synthesis, which allows to control the composition of the resulting NCs by tuning the reaction parameters, with a control over their size distribution. X-ray diffraction (XRD), transmission electron microscopy (TEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurements were performed to characterize the crystal structure, morphology, size and composition of the NCs, respectively. The samples were eventually used to test the OER properties.
Nanocatalysis is a modern approach to classical homogeneous degradation processes, because nanocatalysis have advantages of homogeneous and heterogeneous catalysis. The catalytic degradation of organic dyes is already described by Fenton's and photo-Fenton's reaction schemes. Both Fenton's schemes are transformation of peroxide into radicals with presence of iron ions. Fe(II) is basic catalyst, but role of Fe(III) is in reaction scheme described as well. Synthetic magnetite and ferrites serves as sources of both iron ions and they can be removed directly from a solution by a magnetic field. Catalytic degradation of methylene blue was performed by peroxide radicals. Degradation of peroxide into radicals was performed by synthetic magnetite nanoparticles and magnesium ferrite nanoparticles. The results were compared with catalysis by Fe(II) ions, which has higher catalytic activity then prepared samples. Higher catalytic activity was observed in case of magnesium ferrite, then by synthetic magnetite nanoparticles. Fast removal by magnetic field was proved in case of synthetic magnetite and magnesium ferrite. Research was supported by University Palacky internal grant IGA_PrF_2018_015.
This study is focused on preparation of pristine zinc sulphide (ZnS) and zinc sulphide/kaolinite (ZnS/K) nanocomposite using one-pot hydrothermal synthesis under atmospheric pressure and without any surfactant. Together with finding a simple preparation method, the aim was to achieve a high photocatalytic activity, and also reduce the environmental risk of ZnS (in the case of ZnS/K). Pristine ZnS was synthesized from aqueous solutions of zinc chloride and sodium sulphide in various ratios. ZnS/K nanocomposite was prepared similarly by addition of kaolin KKAF into the mixture of zinc chloride and sodium sulphide solutions. Reaction mixtures were continuously stirred at 100°C for several hours, resulting white solids were separated by centrifugation, washed with distilled water, and dried at 105°C overnight. X-ray powder diffraction analysis revealed the presence of cubic modification sphalerite both in ZnS and ZnS/K samples. Amount of ZnS in ZnS/K (~32 wt.%) was determined by Rietveld method which also confirmed the sphalerite structure. Morphology of the samples was observed using scanning electron microscopy. In the case of ZnS/K, the ZnS nanoparticles anchored on the kaolinite surface were observed. Photocatalytic activity evaluated using discoloration of Acid Orange 7 (AO7) in a liquid phase was found very high for ZnS samples. After 1 h of UV irradiation, ~99% of AO7 was degraded by ZnS. Photodegradation efficiency reached 96% in the case of ZnS/K. Taking into account that only ~32 wt.% of ZnS is present in ZnS/K, the photocatalytic activity of the nanocomposite can be considered three times higher compared to pristine ZnS.
Photocatalytic degradation of the hazardous substances in water and air is widely studied and the suitability of the different photocatalysts for this purpose is evaluated usually by the degradation of the model pollutants. Titanium dioxide (TiO2) especially in its anatase form undoubtedly belongs to the most studied photocatalysts. The searching for other compounds for photocatalytic purposes mainly reflects the demand for higher photodegradation efficiency. Bismuth iodate belongs to the promising material which exhibit the photoactivity in UV region. In this research bismuth iodate was prepared hydrothermal treatment of Bi(NO3)3×5H2O and I2O5 reaction mixture. The effect of the duration of hydrothermal synthesis on structure and photodegradation activity of the prepared samples was also tested. Prepared samples were characterized using XRPD, UV-VIS DRS, SEM and SSA methods. The photocatalytic performance of the prepared samples was evaluated by the photodegradation of model organic dye acid orange 7 (AO7).
ACKNOWLEDGEMENTS: This work was supported by the Grant Agency of the Czech Republic (reg. No. 16-10527S) and by the student projects and SP2018/79 of VSB-Technical University of Ostrava.
Nano-hollow spheres (NHSs) are the new drift in magnetic nanostructures as they provide more surface area at nano length scale with enhanced magnetic properties compared to their nanoparticle counterpart. Here we reported the synthesis of biocompatible CoFe2O4 NHSs of diameter around 250 nm and emergence of intrinsic multiple photoluminescence from blue, green to red on modifying their surface with small organic ligands like tartrate. The surface modified NHSs also showed notable photocatalytic activity towards the degradation of environmentally malefic dyes like Methylene Blue and Rhodamine B. The surface modified NHSs are found to exhibit superior magnetic properties.
In the present work co-precipitated Fe-Co-Mn/MgO nanocatalysts were tested for production of light olefins via CO hydrogenation reaction. The effect of a range of drying conditions including drying temperature and drying time on the structure and catalytic performance of Fe-Co-Mn/MgO nanocatalyst for FTS was investigated in a fixed bed micro-reactor under the same operational conditions of T=350°C, P=1bar, H2/CO=2/1 and GHSV=4500h-1. It was found that the nanocatalyst dried at 120°C for 16h has shown the best catalytic performance for CO hydrogenation. Furthermore the effect of drying conditions on different surface reaction rates was also investigated and it was found that the precursors drying conditions influenced the rates of different surface reactions (Figure 1). Characterization of nanocatalyst precursors and calcined samples (fresh and used) using XRD, SEM, TEM, BET, TPR, TGA and DSC showed that different investigated variables (drying conditions) influenced the structure, porosity, morphology and catalytic performance of the ternary nanocatalysts.
Development of bioplastic fibers from natural renewable polymers are crucial for most important way to reduce the non-renewable energy consumption and carbon dioxide emission thereby curtailing global warming, the human toxicity, the abiotic depletion, the eutrophication and the acidification. The present research focuses on the fabrication and characterization of bioplastic fibers based on natural polymers via self-assembly or electrospinning method. The morphology, structural and physicochemical characterizations were further studied by SEM, AFM, XRD, FTIR, TGA, BET surface area, water contact angle, and tensile strength measurements. Moreover, the comparisons of various functionalities (specific surface area, water contact angle, surface porosity, roughness and hydrophilic and hydrophobic properties) of the untreated and treated (both γ - ray irradiated and plasma treated) fibers were assessed. The bioplastic fibers produced from bio-based materials played a significant role in many important sectors, such as water treatment, food packaging, environmental remediation and biomedical research were appraised.
Geosilicates are one of the modern materials. In composites, they represent the matrix function. Their properties with other reinforcements are already known. Composite reinforcement from nanomaterials is less well known. This paper deals with the application of nanometric reinforcements in geosilicate composites. SiO2 nanotubes were used at different concentrations. Samples were subjected to thermal exposure at different levels. The mechanical properties of these composites have been determined.
The surface of the polyester nonwoven fabric was covered with a layer of silver and copper-based nanoparticles obtained from their salts and reduced using tannic acid. Polyester nonwoven MILIFE® without surface modification was used as a carrier of the metallic layer. The repetitive technological steps of preparing the conductive layer have led to an increasing color intensity of fabric with bronzing effect, which has also been manifested in their decreasing electric resistance. Simultaneously all the samples were tested for resistance to selected G+ and G- bacteria.
Nanodiamond in combination with polypyrrole (PPy) leads to enhanced free charge generation. The stability and persistent effect of composites are expected for beneficial use of organic photovoltaics. In this work, we characterize stability of surface photovoltage under dark and illumination by time-resolved analysis. The polyfunctional-detonation nanodiamond (poly-DND), polypyrrole (PPy), and poly-DND/PPy composites were respectively deposited on p-type silicon. Their photovoltage properties were detected by macroscopic Kelvin Probe Method.
The surface potential was detected at similar location on the sample. For evaluation of short-term stability, the illumination (white cold light source with halogen lamp) was switched on and off repeatedly every 100 seconds for 12 min. We repeated the short-term measurements for 9 weeks to investigate long-term stability. We averaged short-term Kelvin probe data in dark and under illumination and plotted them as function of time in the long-term.
In the short-term, the potentials were stable. However, in the long-term the potentials as well as photovoltages were fluctuating. The potential fluctuations were qualitatively very similar for all the materials, thus it may be related with some external factors. On the other hand, surface photovoltage (SPV) were the most stable on the poly-DND/PPy composite (119 ± 26 mV) compared with the components: pSi (-94 ± 52 mV), PPy (-166 ± 55 mV), poly-DND (-132 ± 32 mV). Noticeable is also opposite sign of SPV, where positive charging of the composite is in agreement with theoretical calculations. The material interaction in poly-DND/PPy composites thus contributes to photovoltage stability.
In recent years atomic layer deposition has proved to be a successful method of fabrication and modification of electrodes for lithium-ion batteries and thin film power sources. Tin oxide demonstrated considerable excellence over currently used materials for thin film batteries anodes, however, lithiated tin oxides are expected to show even better performance. In this research nanofilms of LiOx, SnO2 and lithiated tin oxide were deposited by atomic layer deposition (ALD) using lithium hexamethyldisilylazide (LiN[Si(CH3)2]2, LiHMDS), tetraethyl tin (Sn(C2H5)4, TET) as the metal-containing reagents and water or ozone or oxygen plasma as co-reagents. The monocrystalline silicon (100) and stainless steel (316SS) were used as supports. The thickness of the films was measured with spectral ellipsometry. The composition was studied by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Regardless of the type of co-reagent, the resulting films are unstable under long-term storage in air, but their stability is significantly improved by ALD of aluminum oxide with a thickness of several nanometers. The optimal temperature range was about 250-300 C for deposition of lithium oxide, tin oxide, and lithium-tin oxide nanofilms. It was observed the remarkable influence of the type of co-reactant on the properties of the prepared nanofilms.
ACKNOWLEDGEMENTS: The research was conducted under the financial support from the grant of the President of the Russian Federation, Grant No. MK-2961.2018.3.
Anodizing is a simple and effective method to synthesize self-organized titanium nanotubes. But depending on the electrolyte used for anodizing, there is a disorder “nano grass” or an “initiation layer” on top of the nano tubes. Additionally peeling off the nanotubes from substrate might happen during the anodizing of titanium which is sputtered on the fluorine doped tin oxide (FTO). Removing this unwanted layer (without delamination), especially in high length TiO2 nanotubes could increase the photo electrochemical performance. Here we report a novel method to anodize the titanium layer homogeneously and to produce open top nano tubes. Results show that the photo current density of samples will be increase up to 15% after opening the top surface of nanotubes.
The study reports on technological possibilities of magnetron sputtering systems to high-rate deposition of aluminum films and its structure. There is shown the comparison of deposition rates of magnetron sputtering systems with direct current (DC), middle-frequency (MF) and high power pulsed (HiPIMS) supplies. This article presents the using of the combination of middle-frequency (MF) and high impulse power (HiPIMS) supply is a way to significant increase of deposition rates of Al films. The composition of discharge plasma in dependence of parameters of pulse is considered by optical emission spectroscopy. XRD survey shows the role of deposition mode on crystal structure and grain size of Al films. It can be interested to thermal-control and radio-technical coatings.
In this contribution, the deposition of tin oxide thin films and the resulting layer properties are investigated. An atmospheric pressure PECVD process using a non-thermal plasma jet was applied, creating the coatings on silicon and glass slides. For a highly reactive oxygen atmosphere, the plasma process was driven with air as working gas. The precursor substance tetra-n-butyltin was provided as an aerosol towards the active plasma zone and is further converted to form the ~100 nm thin layers. Structural, electrical and gas sensing properties were determined of the undoped SnOx layers, deposited at substrate temperatures between 300°C and 500°C.
With increasing substrate temperature a decrease in film thickness and roughness of the films could be observed. In general, the films consists of a dense part near the substrate surface and a more porous structure on top. At 300°C the lowest electrical resistivity with about 7.2 × 10-2 Ωcm occurs in 4-point probe measurements. Experiments for the gas sensing characteristics revealed an electrical response to different atmospheres (water vapour, aqueous ammonia solution) already at elevated measuring temperatures of 150°C. Ammonia concentrations until 25% were tested. The thin films are showing distinct properties in gas selectivity between the changing atmospheres, gas sensitivity during ammonia interaction as well as recurring reversibility after a surface recovery step with pressurized air. So, tin oxide coatings created by atmospheric pressure PECVD are showing already in its undoped state and without further layer post-treatments high application potential.
The occurrence of static electricity on the surface of dielectric polymers can be dangerous in various areas of human life. The resulting electrical discharge can cause fire and explosion of flammable substances, lead to breakdown of various electronic devices, etc. It is known that electrization of polymers can be reduced by adding of additives that improve their surface conductivity. Special nanomodifiers creating conductive bridges in polymers with low electrical conductivity are proposed to be used as such additives. However, the introduction of additives in a large volume leads to a deterioration in the physico-mechanical properties of the modified polymers. Modification of a thin surface layer of polymers is promising. In the present work, an ultrathin layer of a conducting polymer, polyaniline (PANi), was used to modify the surface of polyethylene films in order to obtain elastic antistatic films. For this purpose, before the synthesis of PANi, fragments of polyacrylic, polystyrenesulfonic acids, and their mixture were grafted onto the surface of polyethylene films. Synthesis of PANi on the modified polyethylene films was studied by optical spectroscopy. The autocatalytic character of this process was proved. It is established that in the case of grafted polyacrylic acid, the synthesis of PANi occurs only with the addition of hydrochloric acid. It is shown that partial or complete replacement of grafted polyacrylic acid by polystyrenesulfonic acid in polyethylene films leads to an increase in the PANi synthesis rate. Optimal synthesis conditions for obtaining homogeneous films were defined. The electrical characteristics of the obtained materials were measured. The applicability of the proposed method to create antistatic coatings stable to chemical and mechanical influence was shown. The proposed method is also suitable for application of antistatic coatings on the inner surface of polymer containers of complex shape
Pavement structures often fail due to insufficient interphase interaction between bituminous binder and mineral aggregate. A thin bituminous film covering aggregate grains is often replaced by water, resulting in bitumen-water-aggregate system, which is firmly linked to adhesion failure between these materials. This paper describes how to avoid this phenomenon using nanomaterial admixtures - adhesion promoters maximizing the formation of intermolecular interactions between bitumen and aggregate surfaces. Physicochemical and topological principles about interaction between the two materials were described. Paving grade bitumen 50/70 was modified by additives based on: (i) alkylsilanes; (ii) phosphorus; and (iii) amines. Mineral aggregate grains (maximal size of 16 mm, pre-heated on 160±5 °C) were covered by the thin film of reference and such modified binders (170±5 °C). Such prepared samples were exposed to water (60 °C) for 60 minutes. After samples removing from water, their digital images were obtained and then an area of aggregate grains covered by the bituminous thin film was assessed using: (i) bitumen adhesion test, following relevant technical standards; and (ii) digital image analysis based on both gray level thresholding and entropy-based segmentation. It was shown that adhesion of the bitumen to aggregate, expressed by aggregate particle coating area, was increased by almost 18 %, if adhesion promoters were used.
The magnetically modified composites for Cd(II), Pb(II) and Zn(II) ions removal from aqueous solution were synthetized. Montmorillonite/FexOy (MMT) and bentonite/FexOy (MB) composites were successfully prepared using ferrofluid. The presence of FexOy nanopraticles (NPs) on the clay surface did not influence its chemical composition and did not lead to the release of clay elements to the solution. Moreover, the FexOy NPs enhanced the sorption properties of the clays and - due to the magnetically properties of MMT and BT composites - they could be easily removed by external magnetic field after the sorption. The influence of initial pH of aqueous solution containing Cd(II), Pb(II) and Zn(II) ions on sorption capacity of MMT and BT was studied. The accompanying elements released from clays to final extracts were observed as well. Results show that the initial pH of aqueous solution affected the sorption capacity of the observed elements and the release of the elements from original bentonite and MB. The maximum sorption capacity was determined in acid area of pH (3-4). After the sorption, FexOy NPs were determined in final extracts at low concentrations and are, therefore, fixed onto MMT strongly. However, FexOy are not fixed onto MB as strongly as onto MMT because they leached to the final extracts more than from MMT. Due to the aforementioned results of FexOy leaching, both studied composites were still magnetic after sorption experiments. The prepared composites are functional sorbents and are stable in pH 3-7.
The topic of emission reduction and recycling in civil engineering is highly discussed topic over last years. With respect to construction waste production, it is obvious to reuse materials such as concrete. Coarse aggregate recycling and reinforcement rebars separation are the most used procedure in this field so far. Recently, methods including recycling of concrete cementitious matrix were introduced to the market. As such, the concrete matrix consists of matured hydration products of the cement (calcium hydroxide, calcium silica hydrate, etc.) as well as non-hydrated Portland cement particles (clinker), which can represent up to 5 percent of the matrix.
The focus of this article is placed on microscopic level of cementitious composite with admixture of finely grounded recycled concrete. The impact of recycled addition on micro-structure of the composite, the percentage representation of individual material phases in particular, is investigated by image analysis of micro-graphs obtained with scanning electron microscopy. The micro-mechanical performance of each composite is examined with displacement driven grid indentation on several levels of the sample. In consideration of the complexity of the cementitious composite with addition of finely grounded concrete, additional testing of input materials and referential cement paste sample is indispensable to properly distinguish mechanical properties of each composite phase. Young’s modulus of individual phases is thus determined from spectral deconvolution of obtained indentation data with respect to the composite structure.
In this paper, we report the optimal conditions for the isolation of amino acid arginine from different types of matrix, such as blood, plasma or tissue and their characterization using ion-exchange liquid chromatography with VIS detector. Paramagnetic microparticles able to isolate and immobilize amino acid arginine from blood or plasma and thus preconcentrate for subsequent analysis on ion-exchange liquid chromatography with VIS detector. We modified nanomaghemite (γ-Fe2O3) by comercially available Dowex was covered by maghemite nanoparticles and the composite showed excellent binding and superparamagnetic properties. It was found that the paramagnetic microparticles were able to bind specifically amino acid arginine. Therefore, these paramagnetic microparticles have potential for better isolation of arginine and in future can use for application as a platform of delivery system.
Heavy metals are widely used in a range of materials including paints, motor vehicles, guns, and electrical components. After discarding such materials, the metal ions after dissolution can penetrate to the environment and are toxic to plants, organisms, and humans. Among such dangereous hevy metals belongs antimony. The aim of presented work was to study removal efficiency of antimony from waters using ferrate (VI). The experiments were performed for antimony in oxidation state III and V and the influence of ferrate(VI) to antimony ratio on antimony removal efficiency was studied. The experiments were performed under neutral pH value of the reaction mixture. The antimony concentration was determined using AAS method and residual concentration of antimony in reaction mixture was traced within two weeks. With increasing ferrate (VI) to antimony ratio from 10:1 to 60:1, the removal antimony efficiency slightly increased. However, even for ferrate(VI)to antimony equal to 10:1, the removal efficiency was after 30 minutes and after two weeks was even 80%. This means that the effectiveness of removal improve with prolonged contact time of components and no leaching of antimony back to aqueous solution proceed. The impact of concentration of some inorganic ions (nitrates, phosphates, sulfates, carbonates, and chlorides) usually present in real waters on antimony removal efficiency was also studied.
This work studies the properties of low density polyethylene (LDPE) nanocomposites prepared with various types of metal oxides. LDPE nanocomposites were prepared with titanium dioxide (TiO2), zinc oxide (ZnO) or silicon dioxide (SiO2). The second group of nanocomposites included addition of nanocellulose to LDPE/metal oxide composites in order to study its possible influence on mechanical reinforcement in nanocomposites. The isolation of nanocellulose was made by degradation of pine fluor. Nanocomposites preparation procedure included extrusion and pressing into foils.
Prepared LDPE nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV-Vis spectroscopy and scanning electron microscopy (SEM). The mechanical properties were also studied.
The results show that the thermal stability of LDPE nanocomposites with metal oxides is changed in relation to the pure LDPE polymer. The samples with homogeneous nanoparticles' dispersion in the polymer matrix show improved mechanical properties. The results reveal that adding the active metal oxide component to LDPE matrix improves the UV protection property of nanocomposite materials.
Natural phyllosilicate montmorillonite (MMT) was intercalated by electrically conducting polymer polypyrrole in order to obtain nanocomposites with enhanced electrical conductivity and stability in comparison with pristine polypyrrole (PPYR_100). Samples in powder form were prepared in absence of MMT (PPYR_100) or presence of MMT (the nanocomposites) via oxidative polymerization of pyrrole in aqueous solution using FeCl3 as oxidizing agent. After several hours of polymerization, resulting black solids were washed with distilled water and kiln-dried for 24 h. Two nanocomposites MMT/PPYR_32 and MMT/PPYR_45 containing 32 wt.% and 45 wt.% of PPYR, respectively, were prepared and characterized. In order to reveal composition of the samples, elemental analysis and X-ray fluorescence spectroscopy were used. Amount of polypyrrole in each nanocomposite was calculated from results of thermogravimetric analyses. Intercalation rate was monitored by X-ray powder diffraction by measuring changes in position of MMT(001) basal reflection. Raman spectroscopy was used to characterize the polypyrrole in the samples. Electrical measurements performed over 700 days revealed the course of changes in conductivity. Comparison of electrical conductivities of fresh samples, 22 S/m (PPYR_100), 49 S/m (MMT/PPYR_32), 41 S/m (MMT/PPYR_45), with conductivities after 700 days, 0.7 S/m (PPYR_100), 21 S/m (MMT/PPYR_32), 24 S/m (MMT/PPYR_45), showed enhancement of the conductivity and its preservation in the case of nanocomposites. The enhancement was observed throughout the whole testing period, the nanocomposites constantly exhibited higher conductivity compared to PPYR_100. Concerning the preservation, while PPYR_100 exhibits only 3% of the original conductivity value after 700 days, MMT/PPYR_32 and MMT/PPYR_45 samples exhibit 45% and 54%, respectively.
Increasing needs in the energy and control of climate change have raised concerns for new strategies to be adopted to shift from fossil fuels to renewable energy. Due to the rarity of fossil fuels and noble metals, it is important to find low-cost alternative materials. Zinc-air batteries, due to their high energy density and low cost of zinc have attracted much attention as replacements to their respective expensive counterpart Li-ion batteries due to its greater energy. The efficiency of zinc-air batteries is mainly limited by the stability of the catalysts in the cathode oxygen side where the oxygen reduction reaction (ORR, discharge) and oxygen evolution reactions OER (charge) occur [1]. The sluggish ORR kinetics at the cathode of zinc-air batteries limits the overall performance as well as the overpotential in the OER region. Doped reduced graphene oxide (rGO) with heteroatoms (N, S, P) has shown to be able to attain great onset potentials, current densities, high conductivity, and durability compared to the benchmark ORR catalyst, Pt/C. This is due to increase number of functionalities, defects, and porosity obtained from pyrolyzed N-doped rGO (N-rGO-800, N-rGO-900). Though metal-free heteroatom doped graphene has a reasonable ORR performance, it might lack the extra push to drive the OER reaction.
Hence, in this work a strategy to develop highly durable and efficient bifunctional electrocatalysts was adopted where a synergetic effect between CoS nanoparticles on N-doped reduced graphene oxide (CoS@N-rGO-800) allowed to obtain low voltage polarization (<0.7V, after 160 hours) in charge-discharge studies of zinc-air batteries in alkaline electrolyte. This has also been confirmed by three-electrode rotating disk electrode (RDE) studies on glassy carbon electrode (GCE) where great onset potentials, limiting current densities, chronoamperometric stability tests, and overpotentials proving the great potential to apply this catalyst as a low-cost replacement to the benchmark ORR/OER electrocatalysts Pt/C and RuO2, respectively.
The plasma enhanced chemical vapour deposition (PECVD) was combined with in situ deposition of Ge and Sn thin film by evaporation technique at surface temperature about 220°C to form tin nanoparticles (Ge or Sn NPs) on the surface of hydrogenated silicon thin films. Formation of NPs was additionally stimulated by hydrogen plasma treatment through a low pressure hydrogen glow discharge. Characterization of the prepared structures was performed by scanning electron microscopy (SEM), PIN diode structures with and without the embedded Ge or Sn NPs were characterized of I-V characteristics. ACKNOWLEDGEMENTS: This work was supported by the CSF project 16-10429J.
Investigation on Organic Light Emitting Diodes (OLEDs) is gaining utmost interest in the scientific community due to their low cost environment friendly large area processing. The main thrust is to balance charge carrier concentration within the emissive polymer layer by incorporating buffer layers to improve light emission. These layers enhance charge carrier mobility in the polymer chains and help in balancing carrier concentration in the device structure. Although, buffer layers boost light production within the emissive layer but a major portion of light remains trapped in the device structure. This is due to the drop off in refractive index values as light moves from ITO layer (µ = 2), transparent anode, to glass substrate (µ = 1.5) towards air (µ = 1). The light rays, thus, undergo total internal reflection (TIR) at the ITO/glass and glass/air interfaces. This restricts the light rays within the device structure, which are falling at angles larger than 42◦ as calculated by Snell's law. In the present work, we have demonstrated that by incorporating ZnO nanorods in the device structure the possibility of TIR can be broadly eliminated. The ZnO nanorods in conjunction with polymer material forms a single mode waveguiding structure that can extract light from the emissive layer at angles as large as 65◦ and direct them normal to the ITO layer. We have developed a MEH-PPV conjugated polymer based OLED structure that shows an enhancement in the device luminance by more than 22 times with incorporation of ZnO nanorods.
This paper deals with the analysis of the distribution of the electric field around the spinning electrodes used for the production of nanofibres by the AC-electrospinning method. Understanding the behavior of the electrostatic field around the electrodes is an important part for design a spinning device. The performed analyzes were carried out depending on the previously performed optimization of the shape of the spherical electrode, which ensures a uniform distribution of the intensity of the electric field across the functional surface of the electrode. Analyzes were performed for multiple diameters of the spherical electrode and the dependence of the intensity of the electric field on the electrode diameter was monitored. Furthermore, the electrical voltage dependence on the electrode diameter and surface was monitored at the same electric field strength.
The SDBD generating thin layers of plasma which propagate along the treated polymer surfaces was aimed to achieve uniform atmospheric pressure plasma treatment of inner and/or outer surfaces of polymeric tubes and other hollow bodies. The barrier discharge is generated from the contact line between liquid electrode, plasma gas and the wall of treated tube. Such configuration could be used for continual treatment of tubes or capillaries made from dielectric materials such as polymers, ceramics or glass. Generating the plasma and executing the plasma surface treatment at atmospheric pressures have an additional advantage in that faster surface treatment due to higher active species densities, which can lead to higher productivity. The results presented will show the possibility of such system to treat outer and inner surfaces of polymer materials in a continuous mode. Acknowledgement: This research has been supported by the project LO1411 (NPU I) funded by Ministry of Education Youth and Sports of Czech Republic
It’s well known that industries like textile, paper, cosmetics, rubber, plastics, food processing, are the important sources of dye pollution. Although the used techniques try to remove the dye from the wastewater, small quantities remain after the discharge, making these conventional systems not effective for discolouration.
Adsorption using activate carbon (powdered or granular) is widely used for dye removal from wastewater. However, it's very expensive because it need regeneration and reactive procedure. In this way our study is focused on characterisation, analysis and application of a nano activated carbon issued from the cryogenic grinding of olive stones.
The first part concerns the determination of the characteristics of nano activated carbons obtained from the olive stones, which were reduced to very small grounds by using a cryogenic grinding with liquid nitrogen. Chemical activation of this precursor at 450 °C was adopted by using the phosphoric acid as dehydration agent at 2/1 impregnation ratio. FTIR was carried out to identify the surface groups. The microscopic structure and surface were examined by a SEM/EDX and BET respectively. Results showed surface area and pore volume approaching 1000 m2/g and 1 cm3 respectively. The SEM imaging shows a Nano crystalline structure and a highly developed porosity.
In the second part, we investigate the feasibility of adsorption of Methylene Blue on the Nano activated carbon prepared from olive stones. The stock solution was prepared by dissolving Methylene Blue in 1000 ml distilled water. The experiments were carried out at ambient temperature, with the initial concentration varying from 5-50 mg/l. The absorbance of dye solution was determined by a spectrophotometer at 665 nm wavelength. The amounts of dye adsorbed were calculated from the concentrations in solutions before and after adsorption.
Nano Activated Carbon issued from the cryogenic grinding of the olive stones seems to be a promising adsorbent for removal of the cationic dye Methylene Blue from water. Indeed, 5 g of adsorbent could almost completely discolour the solution of Methylene Blue (50 mg/l).
Hexagonal mesoporous silica (HMS) supported ultra-small copper oxide nanoparticles were prepared by a one-pot sol−gel synthesis, and their physicochemical properties were determined by XRD, ICP-MS, SEM, TEM, and N2 physisorption, HR-TEM, and elemental mapping. A series of CuO/HMS catalysts was prepared with different Cu loadings (1wt % to 5 wt%). The catalytic performance of the synthesized catalysts was performed for the transformation of aldehydes to primary amides and oxidative amidation of carboxylic acids.It is noted that, under mild reaction conditions the CuO/HMS catalysts exhibited excellent activity in terms of conversions (70−95%) and selectivity (80−86%) and also catalyst reusable multiple reaction cycles. The improved catalytic performance of CuO/HMS catalysts may be attributed to the homogeneous dispersion and uniformity of the active copper species on the HMS support with a large surface area. Having investigated the functional group tolerance, the established protocol can also be extended for the synthesis of insect repellent molecules such as N,N-diethyl phenylacetamide (DEPA), N,N-diethylbenzamide (DEB), and N,N-Diethyl-m-toluamide (DEET) in good to excellent conversions with a better TON and E factor.
In this work, uniform particles of Fe3O4 are prepared by precipitation of Mohric salt (NH4)2Fe(SO4)2·6H2O with sodium hydroxide NaOH at different times and temperature of 70°C to receive earlier described appearance of 2D structured particles. Particles have narrow distribution and are suitable for further use in coating processes. Impact of reaction time is evaluated together with the controled N2 atmosphere during experiment. showing differences in size distribution and particles morphology. SEM, XRD and FTIR studies are used in this work for evaluating formed particles during synthesis.
At present, treatment of surface, underground and waste water is viewed as a high priority and many studies deal with this issue. Water can be contaminated by organic pollutants, inorganic pollutants, toxic, heavy metals and their compounds, and many other substances that do not degrade to non-toxic compounds in natural waters. Therefore, it is necessary to prevent accumulation of these substances in water and remove them from environment.
In this respect, iron compounds in the high oxidation state (IV, V and VI), called ferrates, are very promising materials to water treatment. Especially, ferrates are able to remove hormones, such as estrogen, or medicines, for example antibiotics, from water. Reactions of ferrates with pollutants occur very quickly and thus, it is difficult to monitor the course of the reaction.
This study brings a deeper insight into the mechanism of ferrate reactions with pollutants because, thanks to Mössbauer spectroscopy, we are able to in-situ observe the course of the reaction. Moreover, analyzing the input materials, intermediates and also final products of reaction is possible once this technique is employed. In this regard, the application of Mössbauer spectroscopy for monitoring the reaction of ferrate(VI) with arsenic for removal of arsenic from environment is mentioned.
Nanoscale zero-valent iron (nZVI) and iron based nanomaterials are nowadays widely used for degradation of various contaminants from the environment. In this study, the nZVI particles prepared by thermal reduction of iron oxide precursor in hydrogen atmosphere were modified via one step thermal treatment in different atmospheres including mixtures of ammonia in nitrogen and carbon dioxide in nitrogen. Morphological, structural, magnetic and stability aspects of as prepared particles were investigated by means of scanning electron microscopy, X-ray powder diffraction and Mössbauer spectroscopy. The characterization revealed that the modification took place in the whole volume of the particles rather than by creation of the surface shell. Nevertheless, such materials were suggested for evaluation of their efficiency in degradation of various contaminants including Cr(VI) and chemical warfare agents.
ACKNOWLEDGEMENTS: The authors gratefully acknowledge support from project VI20162019017 of the Ministry of Interior of Czech Republic.
The environmentally friendly preparation of silver nanoparticles was proposed for the production of antibacterial non-woven textile used in water filtration. The silver nanoparticles were prepared by chemical reduction of silver nitrate using two environmentally friendly reducing agents, such as fructose or ascorbic acid. For comparison also commonly used reducing agent - sodium borohydride was used. The silver nanoparticles in various size and yield were produced by immersion of the plasma pre-treated polypropylene (PP) non-woven textile in the colloidal solutions for different periods (35, 45 and 135 min). The morphology of the silver nanoparticles was characterized by SEM and EDX analysis. Additionally, the antibacterial activity of the silver decorated PP non-woven textile was evaluated by an agar diffusion test using both Gram-positive Staphylococcus Aureus and Gram-negative Escherichia coli. The results suggest that the type of the reducing agent has major effect both on the morphology of silver nanoparticles and the antibacterial activity.
Solid phase microextraction has been established as modern analytic method, which provides several benefits such as sensitivity, rapid and solvent free technique for sample preparation in organic analytical chemistry. Nowadays there is a scientific effort dedicated to improve analytical methods based on new and nanostructured materials. Our study follows this trend and contributes to analytical chemistry approach. Explicitly, the investigation of using nanofibrous sorbents for solid phase microextraction.
Nanofibres of polyethersulfone (PES), polyetherimide (PEI) and polysulfone (PSU) were successfully prepared by needle electrospinning and fixed on a thin stainless steel wire SPME assmebly. The geometry of sorbents plays a crucial role in the extraction kinetics of the mass transfer in SPME. The intention of using electrospun fibres geometry is to enhance the sorbent sensitivity and capacity.
The basic properties of the prepared nanofibres were determined by thermogravimetry (TGA) and scanning electron microscope (SEM). The scanning electron microscopy images of prepared nanofibers showed a diameter range from 700 to 1400 nm for polyethersulfone, 300 to 600 nm for polyetherimide and 800 to 1400 nm for polysulfone. TGA analysis proved the thermal stability of all prepared nanofibres up to 250 °C. The extraction efficiency of new lab-made SPME fibres and selected common commercial SPME fibres (PDMS and PDMS/DVB) was investigated by the headspace SPME (HS-SPME) mode of gas chromatograph coupled with tandem mass spectrometer (GC/MSMS).
Obsolete organochlorinated pesticides (OCP) as hexachlorocyclohexanes isomers (HCH) were selected as model analytes in water matrix. With these pollutants, a set of experiments was conducted to proof the effect of key SPME method conditions: extraction time and extraction temperature on MSMS response.
Chlorinated solvents such as trichloroethene (TCE) are widespread groundwater contaminants. These contaminants can be transformed by combination of abiotic and biotic methods under anaerobic conditions. Nowadays nanoscale zero-valent iron (nZVI) is used for the treatment of chlorinated compounds via its strong reducing property. Biological reductive dechlorination of CE is contributed by dehalorespiration. The influence of nZVI in combination with carboxymethyl cellulose (CMC) and molasses on the specific dehalorespiring microflora and besides the influence of biological surface modification on reactive properties of iron was tested within this study.
Groundwater contaminated with CE was collected from the chemical factory Spolchemie a.s. Batch tests (reactors) with iron and various concentrations of CMC and molasses were performed. The samples for gas chromatography (GC) analyses were taken regularly after defined period time for determination of CEs concentration and physical-chemical parameters were simultaneously monitored. DNA was extracted after filtration of the tested water and used as a template for a real-time PCR amplification. 16S rDNA gene was used as a total bacterial community marker. Specific genes were used for detection of ongoing reductive dehalogenation (vcrA, bvcA, Dre DHC-RT and Dsb) and to monitor denitrifying and sulphate reducing bacteria (nirK and apsA).
Degradation of toxic trichloroethylene (TCE) from ground water using conventional methods is very slow and expensive, so it is crucial to develop new effective methods for TCE removing. Zero-valent iron in a form of nanoparticles (nZVI) is very promising and reactive material having a capability to degrade TCE. However, nZVI particles are not very stable in water what decreases their surface reactivity. Chemical modification of nZVI nanoparticle surfaces (e.g. by sulfidization) can increase the surface stability without significant loss of reactivity with respect to TCE. We performed quantum chemical calculations (at density functional theory level, DFT) of interactions and reactions of TCE molecule with surface models of pure nZVI and mackinawite mineral (FeS), which is, according to experiments, formed on nZVI surface after the sulfidization. DFT calculations showed that nZVI can degrade TCE spontaneously with no energetic barrier. On the other hand, the calculations showed that theoretical dissociation of the first Cl atom from the TCE molecule on mackinawite (001) surface has an energetic barrier of about 54 kcal/mol and endothermic character. The barrier seems to be relatively high but it is about half less than the dissociation of the TCE in a gas phase.
Organic synthetic dyes used in textile and food industries are major sources of the environmental contaminations due to high toxicity to aquatic species and negative impact on human health. In order to decrease damage caused by organic dye pollution the use of a semiconductor/conductive polymer nanocomposite for degradation organic compounds in contaminated water or to convert them into harmless chemicals has been extensively studied. The aim of this study was to obtain the efficient photocatalytic composite material of TiO2 and conductive polymer polyaniline (PANI) active in visible light region with core-shell structure. A facile and environmentally friendly approach has been developed for the fabrication of TiO2/PANI core-shell photocatalyst. The PANI shell was formed by in-situ polymerization of monomer aniline adsorbed on the surface of TiO2 nanoparticles. The photocatalytic activity of TiO2/PANI core-shell composite was examined in the process of degradation of the Reactive Red 45 (RR45) and Acid Blue 25 (AB25) dyes under UV and visible light irradiations. Photocatalytic activity of TiO2/PANI core-shell photocatalyst was also compared with pure TiO2 nanoparticles. The TiO2/PANI core-shell photocatalyst was characterized by FTIR spectroscopy, UV/Vis spectroscopy, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Electrical conductivity was also determined by four-point probe method. Results indicated deposition of uniform PANI layer as thin as 4 nm on the surface of TiO2 nanoparticles which improved the photocatalytic activity of pure TiO2 nanoparticles.
In this proposed work, a polyelectrolyte based on Karaya gum (KG) and chitosan (Ch) sponge was fabricated via self-assembly-freeze drying method and applied for dye removal from water. The polyelectrolyte KG-Ch sponge (density = 8.67± 0.5 mg/cm³) was characterized by FTIR spectroscopy, porosity, density, contact angle, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The removal/adsorption efficiency was also determined with respect to initial dye concentration, pH, contact time, and adsorbent dosage towards toxic dyes (methylene blue (MB) and methyl orange (MO) from water using UV-VIS spectroscopy. The high absorption capacity of both dyes towards on KG-Ch sponge (efficiency of MB and MO removal were 94% and 88%, respectively) were observed. The PEC sponges showed excellent regeneration capacity and successfully used for the three cycles of adsorption-desorption. The polyelectrolytes based natural sponges could be used as an environmental friendly and efficient adsorbent for various dyes from the contaminated water.
This paper presents the synthesis and stabilization of Gold nanoparticles (Au NPs) using five different hydrocolloids [tragacanth (Tg), karaya (Kg), guar (Gg), carrageenan (Cg), and Xanthan (Xg)] via greener pathways. The particle size, morphology, stabilization characteristics and catalytic efficiencies of the synthesized Au NPs were analyzed using many spectroscopic and microscopic techniques. The Gg stabilized Au NP was extremely stable (particle size ranges from ~7.7 to 8.0 nm) for the period up to three months as compared to other Au NPs synthesized and stabilized via other polysaccharides. However, zeta potential and UV-vis analysis of Au NPs produced by Tg, Kg, Gg, Cg and Xg did not show much variation in magnitudes during the tested periods (0 to 30 days). The catalytic performance of hydrocolloid stabilized Au NPs were also evaluated and compared their kinetics reaction rates, and stability for the degradation of 4-Nitrophenol to 4-Amino phenol.
In this work we describe the electrodeposition of Ni-Fe nanostructures on polyanilyne (PAni) as templates. The conditions and parameters influence in the morphology and electrochemical activity of the electrodeposited Ni-Fe nanoparticles.
The electrocatalytic properties of Ni-Fe/polyanilyne-modified electrode toward the glucose oxidation were analyzed via cyclic voltammetry and amperometry. The studies showed that Ni-Fe /PAni electrode displayed the highest electrocatalytic activity, attributed to the high density of Ni-Fe nanoparticles deposited on the polyanilyne vibreuse nanotubes support.
Modified polymer films with metal particles incorporated into the matrix by potentiostatic deposition are known as possible electrocatalysis applications. This work presents some results concerning the electrooxidation of glucose at modified polymer thin film electrodes of copper-polyaniline (Cu-PAni) prepared on an Indium tin oxide (ITO) substrate. The response to glucose of this composite material was tested by cyclic voltammetry method in 0.1 M NaOH solution. The results show good performances and indicated a sensitive oxidation peak current of glucose on the modified electrode.
In this paper, we prepared flexible ammonia (NH3) gas sensor based on polyaniline (PANI) as an active sensing thin film layer. The sensors function was based on chemiresistive principle with a thin film deposited on top of interdigitated electrodes. We measured the change in resistance of the thin film under gas exposure. The PET based foil has been used as the substrate of the sensor. The Interdigitated electrodes (IDE) has been printed with Fujifilm Dimatix DMP 2831 inkjet printer by nanocoloid silver ink. The thin film sensing layer has been prepared from a dispersion of PANI particles by drop casting method. The morphology of the thin film surface was characterized by atomic force microscopy (AFM). The sensor response was investigated in a gas chamber, and the gas flow was controlled by mass flow meters. The sensitivity towards various gases under different concentration in the synthetic air has been tested. The tested gases were NH3, NO2, CO2, and CO. The influence of the illumination on the sensor sensitivity and response time has been analyzed. The measurement of the sensor response to the different levels of humidity was also conducted. All the measurements were performed at room temperature which is an important feature for the sensor to be able to operate in the hazardous environment and it facilitates low-power operation of the sensor as well. We also observed the long-term stability of the sensors response as well as the effect of bending the sensor on the sensor response and stability.
Fluorescence imaging is an efficient and powerful technique, which has been often utilized for tracking compounds in animals, however its application on plants or other organisms is not very common.
In this work, the fluorescence imaging was used to investigate the effect of selected nanoparticles - NPs (ZnO, CdTe, etc.) on microalgae (Scenedesmus quadricauda and Chlorella vulgaris) growth. The growth and metabolic activity of microalgae was influenced by application of nanoparticles into the growing medium (liquid and solid) and therefore the intrinsic fluorescence was affected. Microalgae pigments (chlorophylls, carotenoids) are responsible for the autofluorescence of the species and therefore, the fluorescence can be used as a tool for quick and easy evaluation of expression these compounds. These pigments have main role in light harvesting and minimize photo-oxidative damage of the cells. Such protection mechanism can be disturbed by another stress related compounds like NPs that presumably damage this protection mechanism i) indirectly (reactive oxygen species) and ii) directly (disruption of biomembranes). Owing to broad fluorescence imaging and correlation with total amount of chlorophylls and carotenoids it was possible to evaluate the influence of NPs on individual microalgae just only by in vivo imaging.
The type, number, and magnitude of environmental constraints are currently undergoing changes due to shifts in climate patterns already observed for the past and predicted for the future. These changes are already affecting grape composition with observed changes in sugar and acidity concentrations. UV sensor in vineyards is therefore needed. In this work, the ability of cadmium telluride quantum dots (CdTe QDs) to respond to UV radiation was examined. Green, yellow, orange, and red CdTe QDs were freshly prepared every day and exposed to UV daily radiation for 12 hours for seven consecutive summer days. Every day, solar irradiance was measured, reaching maximal values during the day of around 200-700 W/m2 with a UV index of 2-8. The highest solar and UV irradiances were on the third, fourth, sixth, and seventh days (700 W/m2, UV index 8). The lowest solar and UV irradiances were on the first and fifth days (600 W/m2, UV index 6). On the second day, both irradiances were average (200-500 W/m2; UV index 4-7). The physical properties of individual QDs (absorption and fluorescence maxima, electrochemical determination of cadmium concentration) were monitored. The rising dose of UV radiation led to the release of cadmium ions and the change in the size of individual QDs (a significant change of colour directed toward to the red area of the visible light spectrum). Yellow, orange, and green QDs responded most to UV radiation. This sensor will be used for detection of UV radiation in vineyards.