Many industries like textile, paper, printing, plastic, food and cosmetic are utilising dyestuff to give different colours to their goods. The waste of these industries contain a large amount of dyes which is normally discharged in the drain water without proper treatments. The photosynthetic movement of the aquatic life may affected by dyes because of the decrease in light penetration. Additionally, some dyes are toxic and carcinogenic for many aquatic species like fishes and other microbes. Moreover, these dyes are responsible for severe damage to humans in the dysfunction of the kidney, reproductive system, liver, brain and central nervous system. In recent years iron oxide nanoparticles are being studied extensively in the fields of clinical diagnosis, cancer treatment, drug delivery and removal of heavy metals and toxic materials from water. This paper presents the work for the synthesis of iron oxide nanoparticles and their application for the removal of acid red dye form water. The characterization of iron oxide nanoparticles was carried out with SEM, XRD and Vibrating sample magnetometer. The as synthesized iron oxide nanoparticles were used for the efficient removal of acid red dye from water. After adsorption of dyes, iron oxide nanoparticles can easily be separated from the water by magnetic separation. The used iron oxide nanoparticles can easily be recovered and reused many times. The results showed that iron oxide nanoparticles can successfully be employed for the wastewater treatment.
Contaminations of all water types by metals (As, Cd, Co, Ni, Cu, Al) represent a growing danger in many countries, due to the severe impact of such compounds on the population’s health. This phenomenon is clearly connected to intensification of some anthropogenic activities such as mining, use of pesticides, batteries, pigments, industrial effluents, and improper disposal of chemical wastes. Up to date, several technologies for metal ions removal have been explored including coagulation/filtration, ion exchange, reverse osmosis, membrane methods, nanofiltration, conventional iron/manganese removal processes, etc. Within these technologies, many (nano)materials of various chemical nature have been investigated/tested for metal ions removal exclusively by adsorption on a sorbent surface or into the pores of the sorbent. However, none of these primarily sorbents offer added value in terms of other process(es) (such as reduction or oxidation) which would synergically help to enhance the removal efficiency. Ferrates(VI) and metal iron nanoparticles (nZVI) represent environmentally friendly oxidants and reductants, respectively. They have been reported to be effective for the treatment of various organic and inorganic contaminants. The additional benefit of using ferrate(VI) and/or nZVI lies in the fact that resulting secondary iron oxide nanoparticles can further serve as an efficient adsorbent for oxidized/reduced pollutants. The crucial role of secondary ferric oxides/hydroxides nanoparticles is critically evaluated. Herein, we focus on identifying mechanisms by which As(III), As(V), Cd(II), Co(II), Ni(II), Cu(II) and Al(III) species are removed from the environment by ferrate(VI) and nZVI from water. The removal processes and efficiency were studied with dependence on Fe(VI)/nZVI concentration, pH value and reaction time.
The aim of this work was study dissolution and solubility of humic acids in water. Systems were studied using solution calorimetry. We used calorimeter TAM III (The Precision Titration Calorimeter with a single-position. It is a semi-adiabatic calorimeter intended for use with the TAM III Thermostat). Thermodynamics data of humic acids were determinated in aqueous solutions in the temperature range from 298.15 K to 308.15 K. We compared two types of humic acids and influence of temperature. These HAs were isolated from two different organic origin – compost and South Moravian lignite. HAs were isolated from South-Moravian lignite from the mine Mír (locality Mikulčice, Czech Republic) and compost which was obtained from the composting plant in Náměšť n. Oslavou, Czech Republic. Isolation of HAs was performed according to the procedure recommended by the International Humic Substances Society (IHSS).
Migration of zero valent iron in the subsurface is a task solved in the long term from different points of view at many workplaces. Experimental equipment in these workplaces mostly enables only one-dimensional assignments (laboratory columns) to be studied in different orders with various levels of detection of migrant substances. The 2- and 3-dimension experimental equipment from the VEGAS research facility, University of Stuttgart with large scale dimensions of approximately 1m x 0.12m x 0.7m and 8m x 1m x 3m (L x W x H) enables the migration and interaction of nanoiron particles to be studied in a homogeneous artificially created aquifer under conditions approaching the real conditions of a contaminated site. The whole experiment is linked to the international research project NANOREM, which aims to show that the application of nanoparticles is a useful and in particular reliable method for remediation of contaminated soil and groundwater.
The crawl space is a popular type of building foundations as in Europe as in Czech Republic. The most predisposed space for biodeterioration is the bottom of building and this space is often very difficult accessible for repeated protection or for repairing. For that reason, we studied the application of biocidal nanofiber textile on the material which is still used in this space - solid spruce wood. In the present paper we evaluated the antifungal efficiency of polyvinyl alcohol nanofiber textiles doped by silver ions. The polyvinyl alcohol nanofiber textile doped by silver ions was fabricated by electrospinning on Nanospider LB 500. The final theoretical concentration of silver was 1 % in nanofiber. The nanofiber textiles are applied by enveloping of timber specimens and the samples were placed on inoculated agar plate. There were used two different ways of stabilization of nanofiber textile (Glutaraldehyde vapor or leaching and heating to get insolubility in water) and the run of specimens covering (before and after stabilization). The evaluation of applied nanofiber textiles was measured as a cover of specimens by fungi. The best protection appears to be the nanotextile stabilized by glutaraldehyde vapor applied to the timber sample before the stabilization process.
Top to down fabrication of nanoparticles from micronized hematite mineral is an alternative to increase specific area and its sorbent capacity. The present work optimizes the wet milling of micronized hematite and evaluates the adsorption of As from a real contaminated groundwater (Langreo, Spain) onto the initial and milled mineral. Milling time from 6 to 20 h and concentration of sodium polyacrilate (PA) as a dispersant of PA from 0 to 10 g/l was tested. Best results were obtained for more than 10 h and PA concentration above 5 g/l. Under these conditions, average size was decreased from 2067 nm to 140-150 nm and BET surface area increased from 12,2 to 77-100 m2/g. The obtained dispersions were diluted to improve the precipitation of the mineral, extract the aqueous phase and wash the excess of PA. The obtained slurry was heated at 30-50ºC for two days to finally obtain a solid that was used for the adsorption tests. Previous batch adsorption equilibrium and kinetic tests were performed from 0 to 20 mmol/l (1,5 mg/l) of As(V) standards and initial hematite micronized mineral and were satisfactory adjusted to Freundlich isotherms with equilibrium time round 20 h. Batch experiments with milled samples were performed by mixing 0,3 grams of mineral and 20 ml of two different groundwater samples for 20 h. Results of the adsorption of the milled samples were in the range 92-164 microgram As/g mineral that were about two times the values of the initial mineral (50-80 microgram As/g mineral).
Nanofibrous layer performed as a membrane is capable of vibrating at low frequencies due to its small interfibrous spaces and planar arrangement brought into forced vibrations upon impact of sound waves of low frequency. The resonance of the nanofibrous elements allows acoustic energy to be converted into thermal energy. In this paper, a nanofibrous layer was produced by an electrospinning process from the water solution of polyvinyl alcohol PVA. The PVA nanofibrous membranes of two different fiber diameters were made and the effect of membrane resonance has been studied. For a purpose of resonance and sound absorption properties of nanofibrous membrane, the two methods have been used. The optical method containing high-speed digital camera has been used for resonant frequencies of nanofibrous membrane determination. The Two-microphone Impedance Measurement Tube Type 4206 was then used to measure the sound absorption coefficient. Moreover, the nanofiber diameter of membrane has been evaluated.
In this work, nanotechnologies including electrospun nanofibers and nanoparticles were implemented for acid dye removal from simulated wastewater. Dynamic sorption properties of Polyamide 6 nanofibrous membrane (PNM) were investigated, Titanium Dioxide (TiO2) nanoparticles deposition was applied as surface modification method for PNM, and UV light was applied during the dynamic sorption process of Acid Orange 7 (AO7) on PNM. The light absorbance of influent and effluent were measured and the sorption capacity was calculated. The result shows improvement of sorption capacity after TiO2 nanoparticles (NPs) deposition and UV light applying. Long time UV lighting can improve the sorption capacity of AO7 on PNM with NPs but destroy the material.
A novel RGO-NiWO4-ZnO ternary nanocomposite was efficiently synthesized via a facile, fast and simple microwave irradiation approach and its capability to photodegrade methylene blue (MB) dye in aqueous solution was investigated. The products were characterized through X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic activity was evaluated by estimating the extent of photodegradation of methylene blue (MB) under irradiation of visible light source and that RGO-NiWO4-ZnO nanocomposites exhibited relatively high photocatalytic activity compared to RGO-NiWO4 and pure NiWO4 on MB in aqueous solution. The outcomes reveal that the novel RGO-NiWO4-ZnO ternary nanocomposite may be a highly efficient visible light photocatalyst for the removal of organic pollutants present in wastewater.
The research is focused on water disinfection via new technological concept based on smart combination of nanostructured TiO2 layer and silver nanoparticles. The effective TiO2/Ag NPs photocatalytic system active in visible range was created via anodization of Ti thin film and UV-assisted and electrochemical pulse deposition of Ag NPs. Its efficiency was evaluated on complete inhibition of yeast Candida glabrata. A morphology of TiO2/Ag NPs system was studied via scanning electron microscopy (SEM) and composition by energy-dispersive X-ray spectroscopy (EDX).
Titanium oxide is a material majorly known for its diversified applications ranging from sunscreens, photovoltaic cells, water purification, photodegradation of dyes and pollutants, solar cells, drug delivery and gas sensing. The significance of these applications has urged a gigantic interest in the fundamental phenomenon behind the success of TiO2 as a photocatalyst. In this experimental study, the behaviour of nano titania which is photoactive is tested by depositing it on polymeric films with water dispersion. Polymers are normally sensitive to UV light. Polyamide and polyester films are selected to measure the effects of process parameters i.e. time, temperature and humidity on the photocatalytic acitivity of TiO2. Samples with and without TiO2 deposited on them are irradiated under different dosage of UV light and the changes occured in fibre surfaces are observed by comparing the samples. The adhesion of nano titania deposited on polymers films was also evaluated. Scanning electron microscopy (SEM) and other methods were utilized. We observed the effect of self-stabilization of titanium oxide nanoparticles on polyamide and polyester films by UV light.
The effect of hydrophilicity of ionic comonomers on the synthesis of silver (Ag) nanoparticles and catalytic reduction of pollutant 4NP were reported here. N-isopropylacrylamide (NIPAM)-based copolymer microgels with 5mol% acrylic acid (AA) and methacrylic acid (MAA) were synthesized by precipitation polymerization. Then spherical Ag nanoparticles were synthesized within both microgels by in-situ reduction. Pure and hybrid microgels were characterized by SEM, FTIR, DLS and UV-Visible spectroscopy. SEM images revealed that size and morphology of both microgels were almost similar. DLS analysis confirmed that the swelling ratio of P(NIPAM-AA) microgels was greater than that of P(NIPAM-MAA) microgels. UV-Visible spectroscopic analysis showed that surface plasmon resonance band of both hybrid microgels lies ~400 nm. It was investigated that value of apparent rate constant (kapp) was increased with increase in dosage of both catalysts upto a certain limit. Then the value of kapp was decreased with increase in catalyst dosage above that certain limit. The maxima was observed at 86.8 and 176 mg/mL catalyst dosage for Ag-P(NIPAM-AA) and Ag-P(NIPAM-MAA) catalyst respectively. The decrease in kapp value was due to aggregation of hybrid microgels as ionic strength of medium was high. It was also observed that kapp more rapidly increase with increase in dosage of Ag-P(NIPAM-AA) catalyst as compared to that of Ag-P(NIPAM-MAA) catalyst. This was due to the less hydrophilic nature of MAA as compared to that of AA comonomer. The effect of dosage of both catalysts on reaction completion duration and catalysis duration were also studied.
The paper deals with a change in the luminous radiation reflected by surfaces with coats with photocatalytic active particles. In the executed laboratory experiments, we used two commercially available coats with photocatalysts on the basis of TiO2 and one coat without photocatalytic active particles. As the luminous radiation source, we used two different light sources with different spectre. The used light sources provided same radiation intensity at the place of measuring of the reflection from the surface of the sample. In individual phases of the experiments, we repeatedly measured the values of impacting and reflected radiation depending on the type of the coat, its moisture and the used luminous radiation source. The coats were applied to the area of 10x10 cm according to the recommendation of the manufacturer. The weight of the coat on thus prepared samples was ascertained by weighing the sample after it dries out. With regard to the elimination of various inhomogeneities in the coat layer on the sample surface, each sample was repeatedly measured both for impacting and reflected radiation (always after having been turned by 90°). The relation between the moisture of the coat and the reflected light radiation was non-linear and the value of reflected radiation decreased with increasing moisture of the coat layer. With increasing moisture of the coat, we also recorded bigger shift in the spectre of reflected radiation towards longer wavelengths.
Optically transparent hybrid organic-inorganic copolymers of poly(titanium oxide-hydroxyethylmethacrylate) and copolymers containing Au and Ag nanoparticles (NPs) have been synthesized by two-stage method – polycondensation and polymerization. Au and Ag NPs were formed in situ by UV-reduction of corresponded ions from HAuCl4 or AgNO3. It was found out the presence of poly(titanium oxide) clusters of 4-6 nm size with the ordered anatase type structure in the materials by small-angle X-ray, X-ray phase analysis and secondary ionic mass spectroscopy. The average size of Au or Ag NPs in nanocomposites is 9 and 16 nm, respectively. Under UV-irradiation of copolymers the single-electron transition Ti(IV) + e(-) → Ti(III), accompanied by darkening of the sample, took place. The quantum yield of this transition is close to 1. The organic-inorganic copolymers with nanoparticles Au and Ag have been characterized as heterogeneous photocatalysts in the reaction of methylene orange decomposition.
A method for on-line measurement of photocatalytic activity of powdered samples by UV-Vis spectrometry was developed. It enables photocatalytic reaction to be monitored directly in the cuvette which serves as photocatalytic reactor. The cuvette is placed in a double beam UV-Vis spectrometer. Photocatalytic reaction is driven by LED diode mounted on homemade cuvette holder housing. Diodes can be easily changed, enable photocatalytic reaction to be performed under light of various wavelengths which is beneficial when evaluating visible-light photocatalytic activity. Another advantage of the method presented lies in the simultaneous degradation of model dye solution and evaluation of its photodegradation kinetics which avoid sampling during the photocatalytic reaction which is otherwise a necessary step for evaluation photocatalytic activity. Measurement of photocatalytic activity is demonstrated on Zn2TiO4 sample under the UV (λ~ 365 nm), and the visible light (λ~ 400 nm) and (λ~ 425 nm) irradiation.
The transparent dispersed suspension of SiO2-TiO2 nanocomposite was prepared to be applied on the building facades in order to prevent the biofilms formation and thus to improve urban building sustainability. The structure and the texture characterization of prepared nanocomposite were determined by electron microscopy (SEM, TEM + EDS). The photocatalytic activity of the photocatalyst was determined considering the self-cleaning surface ability and antimicrobial activity. The self-cleaning properties were evaluated according the standard ISO method, which is based on the blue methylene degradation measurement. The coatings on the different types of substrates commonly used in the building industry were prepared and tested. The antimicrobial characterization was particularly focused on the algae removing as these microorganisms are among the greatest causes of building decay. According the laboratory testing the prepared nanocomposite was applicated in the real conditions and the observation during the long time period was done. The first results indicate an ecological and noninvasive way how to qualitatively improved building surfaces. The transparent SiO2-TiO2 nanocomposite provides promising photocatalytic activity towards self-cleaning ability and algae removing. The nanocomposite may significantly reduce the aged processes of buildings caused by biological pollutants and smog exhalations.
The combination of graphene and a semiconductor for the purpose of creating a Schottky solar cell (SSC) has been found very important in the field of applied research of solar cells. An undisputable advantage of a SSC composed of graphene and a silicon semiconductor when compared to other solar cell types currently in development (organic or perovskite solar cells) is its simple manufacturing process. This simplicity and compatibility with semiconductor technologies that are already in use are, in the end, reflected in low manufacturing costs. The main issue which burdens Schottky solar cells with a graphene/silicon interface is the photocharge collection efficiency reduction due to recombination on the interface. The graphene/silicon interface was treated with 2 nm of Al2O3 to lower the recombination influence on the efficiency.
This study was focused on synthesis, characterization and analytical application of CdTe nanoparticles (QDs). QDs were prepared in aqueous medium and the most attention was paid to QDs capped by glutathion because the results of synthesis were the most reproducible ones. The analytical application was tested for behavior of QDs in the presence of metal ions (Cu, Pb) where linear decrease of the intensity of the fluorescence signal was observed and it can be used for analytical determination of metal ions.
Organic photovoltaic (PV) devices are considered promising as a renewable energy source due to their carbon-based nature, ease of fabrication, or the capability of preparation on structured or even flexible substrates. Standard device architecture is so-called bulk-heterojunction where the donor and acceptor materials are mixed together and create an interpenetrating network. Their moderate power conversion efficiency is still high enough for several specific applications (functional building designs, wearable electronics, etc.). However, if unprotected against environmental conditions their usable lifetime is still strongly limited by degradation.
In this contribution we report on characterization of a P3HT:PCBM photovoltaic system (based on P3HT from BASF) which was prepared with an Al back electrode. After the final thermal annealing (150°C, 30 min) the Al layer was partially removed. We used Kelvin Probe Force Microscopy (KPFM) to measure photovoltage response on pristine and uncovered regions as a function of time. KPFM is an atomic force microscopy (AFM) technique which detects contact potential difference (CPD) between the probe (AFM tip) and the material. CPD may vary in time or under illumination reflecting the opto-electronic processes in the material. Thus it may be used for monitoring degradation of organic PV devices [1]. Here, KPFM was repeatedly measured under a solar spectrum illumination (solar simulator via optical fiber) during 3 weeks. Comparison of the same KPFM measurement on the area where no Al was deposited and area where Al was removed after the device was completed indicates for instance a positive role of device encapsulation during thermal processing on the photovoltage stability. The data are discussed with view to reduced degradation of organic PV devices. ACKNOWLEDGEMENTS: The research was supported by the COST action MP1307 - StableNextSol, projects LD15013 (MŠMT) and 15-01809S (GAČR), and SGS16/222/OHK4/3T/13 (ČVUT). REFERENCES: [1] Čermák et al., Thin Solid Films 519 (2010) 836-840.
Organic solar cells made of polymers are attractive due to impressive possibilities not only for light-weight flexible photovoltaic (PV) devices but also for promising printable electronics due to its intrinsic compatibility with high throughput solution process. However, the efficiency of polymer solar cells is still low compare to other commercial products. To improve the efficiency needs to understand the overall mechanism of the conversion from photon energy into electric power including factors limit conversion efficiencies. Therefore, we study on the charge carrier mobility which is one of the important parameters to limit the power conversion efficiency of organic solar cells. Precise behaviors of charge carrier were estimated by means of transient photocurrent (TPC) with nano second laser pulse. And the charge carrier mobility was further analyzed as a function of active layer thickness and types of electron donor materials. Finally, correlation between active layer thickness dependent charge carrier mobility and power conversion efficiency could be figure out.
Li-ion batteries (LIBs) are widely used as portable power sources. The development of new electrode materials for LIBs is an important problem in the field of materials science. Without the use of modern methods and approaches, it will become an impossible task. One of the new methods for Li-ion batteries is an atomic layer deposition (ALD). Its main principles are based on reactions, self-controlled on the monolayer level, with functional groups of the matrix surface. The method allows deposition of films of different thickness with high precision and is actively used for preparing thin films with various chemical compositions. We have shown that the deposition of thin films of aluminum oxide with thickness 1-3 nm by ALD directly on the electrodes increases the cyclic stability at 30%. Furthermore, this method is suitable for the development of solid state batteries. Thin films of SnO2 synthesized by ALD with thickness about 80 nm showed specific capacity about 850-900 mAh/g during 600 cycles at 1C discharge current density.
The study was financed by the Ministry of Education and Science of the Russian Federation (Agreement No. 14.584.21.0004 of 16.07.2014, unique identifier RFMEFI58414X0004).
In this study, Carbon-Coated Silicon/Graphene composite anode were produced by two step process. First, silicon particles (130 nm in size) were coated with an amorphous carbon shell by pyrolysis of polyacrylonitrile (PAN). For pyrolysis process, 24 mg PAN dissolved in N-methyl-2-pyrroilidinone (NMP) solution and 200 mg silicon particles added in the solution under magnetic stirring and then the suspension was dried in vacuum oven and isothermally heated to 800oC for 4 h to decompose PAN to form amorphous carbon on the surface silicon particles. After cooling to room temperature, carbon coated silicon particles dispersed in distilled water with multilayer graphene, which is synthesized by Hummurs’ Method by ultrasonic homogenization for 1h. After then the carbon coated silicon/graphene composite powders were filtrated and dried in vacuum oven. For preparation of the electrodes, 90wt.% active composite powder was mixture with 10wt.% PVDF dissolved in NMP. Obtained slurry mixture cast on the copper foil and coated with doctor blade and then dried in vacuum oven for 12 h. Coin type CR2016 test cell were assembled in argon filled glove box, the prepared electrode was used as working electrode, Li foil used as counter electrode, 1M LiPF6 dissolved in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) (1:1 in volume) as the electrolyte. The working and counter electrodes were separated with polypropylene (PP) separator. Charge–discharge characteristics of electrodes were tested between 0.05 V and 2.0 V at a constant current of 200 mA g−1.
The ability of understanding and tailoring the interaction phenomena among nanomaterials is a prerequisite for designing new nanostructured materials with desired properties. In the current report, the self-assembly of nanostructured hybrid binary systems, coupling a new class of maghemite nanoparticles (called surface active maghemite nanoparticles, SAMNs) with three different carbon based nanomaterials, is presented. Gallic acid derived carbon dots (GA-CDs), PEG derived graphene dots (PEG-GDs) and quaternized carbon dots (Q-CDs) were successfully coupled to SAMNs by simple incubation in water, leading to hybrid nanoconjuagates. Electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometry evidenced significant differences in the charge transfer resistances, capacitive currents, electrochemical performances and reversibility among the binary nanoconjugates and with respect to bare SAMNs. Interestingly, Q-CDs oriented the electrochemical selectivity of the final Q-CDs@SAMNs hybrid nanomaterial toward polyphenol oxidation, and was further characterized by UV-Vis and Mossbauer spectroscopy, HR-TEM, SQUID magnetization measurements. Moreover, QCDs@SAMN was used to prepare an electrode able to catalyze the electro-oxidation of polyphenols, at low applied potential (+0.1V vs SCE) with a sensitivity of 81.51 nA uM-1 cm-2 and a detection limit of 7.0 uM, using hydroquinone as reference substance. Finally, the Q-CD@SAMN hybrid was applied to develop a coulometric sensor, constituted of a simple carbon paste electrode, in a low volume (1 uL) electrochemical flow cell, fabricated in-house, leading to the complete direct electro-oxidation of polyphenols in plant extracts. This report envisages the possibilities offered by the combination of metal oxide nanoparticles with carbon dots for the development of electrochemical sensors with tailored properties.
Huge scientific and technological progress observed in recent century brought up new concerns about safety of the environment. Although scientists all over the world make enormous efforts to minimize the consequences of anthropogenic pollution, there are still some pressing issues. For example: halogenated volatile compounds (HOCs) have been frequently used in the industry and disposed into wastewater and air, despite their toxicity and suspected mutagenicity. Due their refractoriness to typical oxidative water remediation techniques, HOCs became one of the most problematic group of pollutants. Over recent two decades, electrocatalytic reduction of halogenated volatile compounds was successfully employed in organic electrosynthesis and abatement of environmental pollutants by their conversion to less harmful compounds after prior phase change from water to aprotic medium.
The scope of this study was the reduction of HOCs in water environment/aqueous solutions to examine the possibility of direct elimination of HOCs without the need for phase change and direct assessment of HOCs concentration. We also reported that the nanostructured electrode with ordered array of Ag nanowires show better electrocatalytic activity toward reduction of trichloromethane than bulk electrode. To better understand this phenomena, more detailed investigation was performed. The electrocatalytic measurements were performed in various supporting electrolytes, such as NaOH, KClO4, NaClO4, NaH2PO4, to select the optimum one and assess their influence on the mechanism of electrocatalytic reduction of chloroform. The voltammetric experiments allowed determination of kinetic parameters of the reduction process. ACKNOWLEDGEMENTS: The research was financed by the Polish National Science Centre (Decision number: DEC-2015/19/N/ST4/00313).
The paper deals with the new effective design of electrode for coaxial electrospinnig process. This concept is based on the circular symmetric design enabling formation of double polymeric layer. This layer is created by overflowing of one solution over the other. Subsequently, the layer is exposed to critical voltage in the electrospinning process to create core/ shell nanofibers. Via FEM analysis of the electrospinnig process was found an appropriate distribution of the electric field linked to the shape of electrode. The suitable electrode design obtained by using FEM has been verified experimentally.
Nanofibers with magnetic properties are very specific materials that require special characterization. Important measurements such as - magnetic measurements, TGA, FTIR, etc. are performed by special methods that are described in this work. These measurements are very important for the further use in the biomedicine, industry etc.
The work also focuses on preparing nanofibres with the highest possible content of magnetic nanoparticles and it turns out that can be reach very high volume percent of nanoparticles in these nanofibers. The dimensions and properties of these materials allow for variable use.
Solid phase microextraction (SPME) has been established as a modern, simple, sensitive, rapid and solvent free technique for sample preparation in organic analytical chemistry. Since SPME was first introduced by Pawliszyn in the early 1990's, several modifications of sorbent geometry were introduced. The main goal of using electrospun fibers geometry is to enhance the sorbent sensitivity and capacity. In the present work, electrospun polyetherimide (PEI) nanofibers were prepared from 12.5 % solution (80/20 – DMF/THF) fixed on a steel wire solid phase microextraction (SPME) assembly. Electrospinning conditions were optimized to get compact and stabile PEI assemblies whereby SEM, TGA and BET characterization was employed. Analytical performance of prepared fibres was compared with common commercial available SPME fibres (100 µm polydimethylsiloxane (PDMS) and DVB/Carboxene/PDMS) in the headspace SPME (HS-SPME) mode of gas chromatograph coupled with mass spectrometer (GC/MS/MS). The chlorophenols were chosen as model water pollutants. To solve instability, tailing peaks, detectability and adsorption problems, chlorophenols were acetylated before GC step of the analysis. Lab-made PEI nanofiber assemblies appeared to have sensitivity comparable to commercial SPME fibres.
Properties related to water vapour diffusion of membrane are important in many branches also in building constructions. This article deals with comparison two methods of measurement water vapour diffusion through nanofibre textiles. One of the parameters for comparison of different sheet materials for its ability to brake the water vapour is an equivalent air layer thickness value Sd. The equivalent air layer thickness Sd [m] expresses the thickness of the air layer, which would have the same diffusion resistance as the measured material in certain thickness. It is necessary to choose the appropriate measurement method for determining the value Sd with diffusion open materials such as nanofibre materials. This article compares the outcomes of two measurement methods – Dry Cup Method according to EN ISO 12 572 and Tube Method. The measurements were carried out on a sample from nanofibre textiles based on PUR.
Ceramic fibers have gained much attention due to their diverse potential applications including catalysis, electrode and membrane materials, filters, sensors, biomedical materials etc. As compared to bulk, the fibers exhibit novel physical and chemical properties arising from their unique features such as high surface area, high surface area to volume ratio and small fiber diameter.
Fabrication of nanosized doped zirconia fibers by electrospinning from alkoxide based precursors and physical-chemical characterization of the ceramic fibers for energy applications is the main objective of the work.
Nanofibers of cubic zirconia with different microstructure were prepared by electrospinning of zirconium propoxide/polyvinylpyrrolidone (PVP) based precursors with a various composition. Fully crystalline composition of cubic zirconia was detected after fiber heat treatment at 700°C. No significant effect of precursor composition on the fiber morphology and phase composition was observed.
The fiber morphology was changed with increasing temperature of the heat treatment from flexible smooth dense structure at 700°C through porous nanograin structure at 900°C and nonporous structure with coarser nanograins at 1100°C to brittle chain-like fiber formed of submicrometer grains at 1300-1450°C. The sintering behavior was described.
Nanofiltration with additional antibacterial effect is still a big challenge in applied nanotechnology. The main requirements for innovative nanofibre filters are: the antibacterial activity and structural stability guaranteeing long-lasting effect. The aim of this work is to study these characteristics for three different types of antibacterial molecules: Chlorhexidine (CHX), dodecylthrimethylammonium (DTMA) and benzyltrimethylammonium (BTMA). Nylon6 nanofiber textile modified with antibacterial agent has been prepared by Nanospider technology. Interaction of nylon 6 with antibacterial substance and the subsequent effect on the structure of the nanofibers was studied using combination of X-ray diffraction (XRD) and molecular modeling (empirical force field calculations). Based on our previous XRD study (J Polym Res (2015) 22: 101) we suggested core-shell structure model for nylon 6 electrospun nanofibers with core alpha-phase and shell gamma-phase. Present result revealed following effects of modifying antibacterial molecules: Low binding energy of nylon 6 with antibacterial molecules preserve the phase composition of modified nylon 6 nanofibers (i.e. the volume fraction of alpha and gamma phase) the same as for pure nylon 6. This is the case of BTMA molecules. On the other hand the highest binding energy to nylon 6 in case of CHX significantly changed the phase composition of modified nylon 6 nanofibers. Nylon6/CHX nanofibers exhibit lower crystallinity in shell structure of gamma-phase and increases the fraction of amorphous phase. Combination of transmission and reflection mode in XRD measurements revealed the strong texture of nanofiber textile, i.e. the strong preferred orientation of polymer chains in plane of nanotextile. This texture is not significantly affected by modifying molecules.
Nanofiltration with additional antibacterial effect is still a big challenge in applied nanotechnology. The main requirements for innovative nanofibre filters are: antibacterial activity and structural stability guaranteeing long-lasting effect. The aim of this work is to study those characteristics for three different types of antibacterial molecules: Chlorhexidine (CHX), dodecylthrimethylammonium (DTMA) and benzyltrimethylammonium (BTMA). Nylon6 nanofiber textile modified with antibacterial agent has been prepared by Nanospider technology. Interaction of nylon 6 with antibacterial substance and the subsequent effect on the structure of the nanofibers was studied using combination of X-ray diffraction (XRD) and molecular modeling (empirical force field calculations). Based on our previous XRD study (J Polym Res (2015) 22: 101) we suggested core-shell structure model for nylon 6 electrospun nanofibers with core -phase and shell -phase. Present result revealed following effects of modifying antibacterial molecules: Low binding energy of nylon 6 with antibacterial molecules preserve the phase composition of modified nylon 6 nanofibers (i.e. the volume fraction of and phase) the same as for pure nylon 6. This is the case of BTMA molecules. On the other hand the highest binding energy to nylon 6 in case of CHX significantly changed the phase composition of modified nylon 6 nanofibers. Nylon6/CHX nanofibers exhibit lower crystallinity in shell structure of -phase and increases the fraction of amorphous phase. Combination of transmission and reflection mode in XRD measurements revealed the strong texture of nanofiber textile, i.e. the strong preferred orientation of polymer chains in plane of nanotextile. This texture is not significantly affected by modifying molecules.
Nanofiltration with additional antibacterial effect is still a big challenge in applied nanotechnology. The main requirements for innovative nanofibre filters are: antibacterial activity and structural stability guaranteeing long-lasting effect. The aim of this work is to study those characteristics for three different types of antibacterial molecules: Chlorhexidine (CHX), dodecylthrimethylammonium (DTMA) and benzyltrimethylammonium (BTMA). Nylon6 nanofiber textile modified with antibacterial agent has been prepared by Nanospider technology. Interaction of nylon6 with antibacterial substance and the subsequent effect on the structure of the nanofibers was studied using combination of X-ray diffraction (XRD) and molecular modeling (empirical force field calculations). Based on our previous XRD study (J Polym Res (2015) 22: 101) we suggested core-shell structure model for nylon6 electrospun nanofibers with core -phase and shell -phase. Present result revealed following effects of modifying antibacterial molecules: Low binding energy of nylon6 with antibacterial molecules preserve the phase composition of modified nylon6 nanofibers (i.e. the volume fraction of and phase) the same as for pure nylon 6. This is the case of BTMA molecules. On the other hand the highest binding energy to nylon6 in case of CHX significantly changed the phase composition of modified nylon6 nanofibers. Nylon6/CHX nanofibers exhibit lower crystallinity in shell structure of -phase and increases the fraction of amorphous phase. Combination of transmission and reflection mode in XRD measurements revealed the strong texture of nanofiber textile, i.e. the strong preferred orientation of polymer chains in plane of nanotextile. This texture is not significantly affected by modifying molecules.
Nanotechnology plays an important role in the textile enabling the production of innovative materials. The development of textiles nanotechnology allows to create multifunctional materials, called smart textiles, with different properties such as electrically conductive and antibacterial textiles obtained by modification with silver nanowires (AgNWs). Additionally application of titanium dioxide (TiO2) can extend their functionality into photocatalytic properties or protection against UV.
The silver nanowires (AgNWs) synthesized by polyol process and titanium dioxide (TiO2) prepared in sol-gel technique to modification of cotton fabric were applied. The results of microscopic SEM/EDS analysis showed the both nanomodifiers on the fabric surface. Raman and XRD analysis confirmed the presence of Ag and TiO2 in the most active photocatalytically form – anatase. The photocatalytic properties of modified cotton on the basis of nicotine decomposition experiment using FTIR technique was evaluated. A faster decrease in nicotine concentration adsorbed on modified fabrics was observed. It was found that the surface resistance for modified cotton was 20Ω and antibacterial activity against S.aureus (gram-positive) and K. pneumoniae (gram-negative) amounted 99.8 and 99.9%, respectively.
In these research multifunctional cotton fabric with three features - photocatalytic, electrically conductive and antibacterial was developed.
ACKNOWLEDGEMENTS: The study has been carried out within the Ministry of Science and Higher Education, Poland [grant number N N508 440736] and by the Key Project – POIG.01.03.01-00-004/08 Functional nano- and micro textile materials – NANOMITEX.
Nanotechnology enables the production of innovative textiles with targeted functions without compromising the basic properties of textile materials. Oxidising and reducing properties of titanium dioxide (TiO2) and the ability to obtain TiO2 and Ag in the nanometric form, cause the dynamic development of their use as photocatalityc modifiers. Modification of textile materials requires the selection of a suitable raw materials, structures and the effective conditions of application. Functional oriented design can change other basic properties of the modified textiles, e.g. thermal properties. The aim of presented work was to assess the impact of nano-Ag and TiO2 modification on thermal properties of polypropylene, cotton and viscose textile material under the study. The technique of differential scanning calorimetry (DSC) with the use of the thermal analyzer DSC 204 F1 Phoenix and thermogravimetric analysis (TG/DTG) with the use of the thermobalance TG 209 F1 Libra (Netzsch, Germany) were applied. The TiO2 and Ag nanomodification affected the thermal properties of studied materials. For TiO2 modified polypropylene fibers a slight decrease of ΔHm, ΔHc and for TiO2/Ag modified polypropylene fibers increase of ΔHm, ΔHc was observed relative to unmodified fibers. The degradation temperatures rose. For Ag-modified cotton and viscose fabrics decrease in degradation heat and weight loss values were found compared to raw fabrics. The degradation temperature increase for both modified fabrics.
ACKNOWLEDGEMENTS: The study has been carried out within the Ministry of Science and Higher Education, Poland [grant number N N508 440736] and by the Key Project – POIG.01.03.01-00-004/08 Functional nano- and micro textile materials – NANOMITEX.
Laboratory-prepared particles of the nanocellulose were added to the acrylate coating material in order to increase the strength of cotton canvas. The size of the cellulose nanoparticles was determined with the Zetasizer device and changes in tensile strength were experimentally observed, depending on the amount of added nanocellulose. The cotton canvas coated with acrylate coating with the optimum of nanocellulose added showed increased strength, which can be used eg. to prolong the life of bookbinding canvases.
Endocrine disrupting chemicals (EDCs), such as bisphenol A (BPA) and 17α-ethinylestradiol (EE2), mimic the effect of hormones which negatively influence human and animal health. EDCs are not easily removed from water, therefore their concentration in wastewater increases. One way to effectively eliminate these pollutants is to use enzymatically activated materials.
Laccase from the white rot fungus Trametes versicolor was immobilized onto modified polyamide 6/chitosan (PA6/CHIT) nanofibers and tested for elimination of a mixture containing 50µM EE2 and BPA. The PA6/CHIT nanofiber matrix proved to be a suitable carrier for laccase immobilization with efficient removal of a mixture of endocrine disrupting chemicals in three treatment cycles.
The reinforcement carbon fibers can be efficiently modified using low pressure cool coupled oxygen plasma treatment to attain the better adhesion between their surfaces and the matrix of any fibrous composites. The aim of this article was to determine the influence of time plasma treatment on the resulting mechanical properties of carbon fibers. Four different times of plasma treatment were used: 0, 1, 2 and 4 minutes. From practical point of view any uses of carbon fibers must also pursue enough high mechanical strength. From this reason, the monitored parameters were modulus of elasticity and a tensile strength. Observed were also the fiber surface morphology changes using the scanning electron microscope. The results shown that plasma treatment had a positive effect on the surface morphology of the carbon fibers, while no effects on tensile strength was found.
Antibacterial and self-cleaning cotton fabric was prepared by coating TiO2 nanoparticles with cellulose on the surface of cotton fabric. TiO2 nanoparticles were dispersed in cellulose solution (10% cellulose in 60% sulphuric acid solution) by mechanical stirring in order to coat. Appeared white particles on the surface of fabric in SEM pictures and characteristic x-ray diffraction peak of TiO2 at 25.4° proves that TiO2 was coated successfully on the surface of cotton fabric. Significant degradation of orange 2 dye was observed after 15 minutes of UV irradiation on TiO2-cellulose coated cotton fabric. Maximum 98.2% reduction of S.aureus bacteria was observed on TiO2-cellulose coated cotton fabric whereas 81.6% reduction of Methicillin-resistant Staphylococcus aureus (MRSA) bacteria was observed. Tensile strength increased after cellulose coating. Both antibacterial and self-cleaning properties were increased with increasing concentration of TiO2.
A bubble spinning is the last few years a much discussed topic in the production of nanofibers. The technology bubble spinning is the youngest of the current known spinning methods, the result is that they are not explored all the possibilities of the method of spinning in these days. Not otherwise is the case of spinning using alternating current (AC). This study investigated the combination of methods bubble spinning and AC spinning for producing submicron fibers. The study evaluated the morphology of fibrous layers produced by this combination of technologies and consequently its comparison with fibrous layers made separately mentioned methods. By using the method of alternating spinning and novel the bubble spinning technology we could achieve (it is possible to achieve) much more efficiency productive production of the polymeric fibers. Combinations of these two methods in one time may bring promising possibilities in the future for example in technical applications.
The potential of nanotechnology in the development of new materials (nanotextiles) in the civil engineering can provide advantage of new application. On the one hand, functionality of materials can be improved using nanotextiles and on the other hand, it could make possible a manufacture of nanotextiles with new properties. The surface properties of materials are relevant in many fields of industry such as civil engineering. Testing and characterizing of surface of nanotextiles are very important for developing a new class of protective layers for building materials based on polymeric nanofibers. One of suitable methods to characterize the surface and wetting behavior of nanotextile fibers is contact angle measurements. Contact angle can be measured with optical tensiometer by placing a liquid drop onto the nanotextile fibers.
Textiles perform an important function of protecting humans from extreme conditions. For this function, the efficacy of the fabric is a very important parameter. To improve the thermal properties of textiles, different fabrics and coating materials need to be evaluated. The thermal properties of nanofibers and their potential protection against cold environments are relatively unknown. It is possible to decrease the weight and bulk of current thermal protective clothing by incorporating nanofibers in thermal insulation battings. Such a modification will also increase the mobility of the wearer. In this paper, the mechanisms of heat transfer through fibrous insulation where the fiber diameter is less than 1 micrometer (μm) was evaluated. Using electrospinning process, flexible electrospun PUR and PVDF nanofibres embedded with silica aerogel was produced. A detailed study of thermal properties of the electrospun nanofibre embedded with SiO2 aerogel was conducted. The microscopic examination confirmed presence of aerogel. The results were statistically analyzed. The samples showed enhancement of thermal insulation by increasing the number and the weight per unit area of both nanofibrous layers. The results also confirmed that embedding silica aerogel in nanofibrous layers leads to increased thermal insulation. Based on the results, nanofibers embedded with aerogel were found to be good for thermal insulation at extreme conditions.
The paper deals with the analysis and optimization of spinning electrode designed for the nanofiber spinning method using an alternating electric current. The optimization was based on the simulation of distribution of electric field according to the shape of the spinning electrode by using the finite element method. The intensity of electric field has a major influence on the electrospinning and subsequently on the resulting structure. The aim of the optimization was to reach uniform distribution of electric field on the electrode surface by changing the number of design parameters. Based on these analyzes, a new shape of the spinning electrode was designed, which offers uniformity of the electric field intensity around the whole operative surface of the spinning electrode and provide the same physical conditions which are important for the electrospinning. This leads to the electrospinning stabilization, which affects the quality of the resulting nanofiber structure. The newly designed electrode was used for experiments during the electrospinning to determine the quality of resulting nanostructure.
Development of new materials is still growing up. The relatively new materials are nanofibers membranes. These fabrics are very popular due to their properties, which primarily depend on the structure of the material. This structure may be affected by several parameters. Setting of production parameters of the spinning device have a major impact on the structure of the fabric. The analysis of this effect is the main goal of this work.
In this paper nanofiber textiles were manufactured by using the device NanospiderTM NS LAB 500 S (Elmarco, CR). As the main spinning polymer was used polyvinyl alcohol (PVA). We created 15 types of textile where technological parameters were changed. This work contains two experimental parts. In the first one, we analyzed the effect of voltage, distance of the electrodes and the solution concentration. There were not achieved fundamental changes in the structure of the fabric. In the second experiment, we tested the effect of changes of the electric field to change the structure of the resulting nanofiber membranes. The structure was analyzed using a scanning electron microscope Tescan Maia 3. In this experiment, we achieved significant changes in structure and thus we demonstrated the significant influence of adjustment of the electric field on the final fabric structure.
Commercial polymeric macro fibers Concrix ES having diameter equal to 500 µm used as randomly dispersed reinforcement in concrete composites were treated to attain their strong adhesion with cement matrix. In order to improve their wettability by water, low pressure cool coupled oxygen plasma treatment was realized. Effect of executed treatment on fiber surface properties was examined by: i) direct horizontal optical method enabling contact angle measurement on fiber submerged in any liquid and ii) scanning electron microscopy enabling morphology changes characterization on fiber surfaces. To reveal negative impacts of plasma treatments on fiber mechanical properties, the samples were investigated by tensile strength and weight loss ratio tests (realized always before and after treatment). Finally, pull out tests of selected fibers from cement paste samples (water to cement ratio 0.4) were done. It was shown that fibers plasma treated by any time from 5 to 480 s exhibited significantly better water wettability (approximately two times) while their mechanical properties were not influenced. Based on these findings, for pull out testing were selected besides reference also plasma treated fibers by 30 s. Thus treated fibers had stronger both, chemical and physical bond between its surfaces and surrounded matrix.
TiO2 nanoparticles were prepared using sol-gel technique. The prepared nanoparticles were analyzed using transmission electron microscope (TEM). Cotton fabrics were treated using the so prepared TiO2 nanoparticles in presence of citric acid and commercially flame retarding agent named Flovan to produce cotton fabrics having multi-functional properties (anti-crease, self cleaning, and flame retardant) using pad-dry-cure- method. The treated fabrics examined by several analysis methods such as crease recovery angle (CRA), tensile strength (TS), elongation at break (El), whiteness index (WI), self cleaning and flame retarding properties expressed as thermal gravimetric analysis (TGA). The data of the results reveals that the optimum condition for the preparation of multi-functional cotton fabric is by using the following formulation (6 % citric acid, 2 % TiO2, 300g/l Flovan) padded for pick-up 100%, dried at 100oC for 2 minute and cured at 160oC. The presence of TiO2 nanoparticles on the surface of the fabrics was proofed using EDX and the fabrics examined also using scanning electron microscope.
Zinc oxide (ZnO) is a wide band gap n-type semiconductor with high exciton binding energy. Due to these properties it can be used in electronics, optoelectronics and as a photocatalyst. In addition, the use of nanostructured ZnO instead of bulk material can further improve its functionality. Among many different ZnO nanomaterials, ordered arrays of 1D structures such as nanowires seem to be the most promising morphology. Therefore many promising strategies have been already employed for fabrication of ZnO nanowires. Among them simple anodic oxidation (anodization) of metallic substrate seems to be extremely simple and versatile approach.
Here we present some recent findings on electrochemical formation of ZnO nanowires via anodic oxidation of Zn foil. Anodizations were carried out in sodium bicarbonate (5-50 mM) and ammonium bicarbonate (5 mM) electrolytes at different anodizing potentials (5-20 V) for 1-30 minutes at room temperature. The effect of anodizing conditions such as: applied potential, electrolyte concentration and duration of the process on the morphology of nanowire arrays was investigated in details. After anodization, nanowires were composed of zinc hydroxycarbonate. However, the crystalline ZnO nanowires were easily obtained by simple annealing of the samples.
The morphology of the obtained ZnO layers was analyzed by using a Field Emission Scanning Electron Microscope. The crystallinity and phase composition of the obtained ZnO nanostructures were examined by XRD measurements. The mechanism of nanowires growth was also proposed. ACKNOWLEDGEMENTS: This work was partially supported by National Science Centre, Poland (Project no. 2014/13/D/ST5/02750).
Delamination is one of most common failure mechanisms for composite materials. By interleaving a nanofibrous mat between laminate plies it can be possible to control the interlaminar delamination strength. The nanofibrous mat at a laminate interface is impregnated by the resin during the curing process. Since the studies conducted for considering the behavior of nanomodified laminate under impact loading is very limited, this phenomenon is considered using FEM method. The simulation of impact is conducted by ABAQUS/Explicit and cohesive behavior which is available in this software. For applying cohesive method, three parameters are required which are: K, G, Smax. These parameters can be obtained by conducting mode-I and mode-II fracture tests. Since the results of these tests for modified and reference laminates are available in literature, therefore they are used for finding cohesive parameters.
Since some kinds of nanofibers can be financially valuable and on the other hand interleaving nanofibrous mat between all layers can be complicated, so in this paper different kinds of interleaf sequence is considered which consists of: 1- interleaving nanofibers between all layers (11 nanofibrous mats) 2- four nanofibrous mats in upper side of specimen 3- four nanofibrous mats in downer side of specimen 4- four nanofibrous mats in middle layers of specimen 5- two layers in upper side and two layers in downer part of specimen. The results prove that interleaving nanofibrous mat between all composite layers can decrease the delaminated area 75%. Surely, first method is the best, but the third method is the most effective method after first method.
Work is directed to the solution of an urgent problem of diagnostics and forecasting of functional properties of magnetic dactyloscopic powders. Important criterion of quality of powders are their adhesive properties [1]. Investigated iron oxide compounds of different composition and structure. The methods of transmission electron microscopy (TEM), X-ray diffraction (XRD), hydrolytic adsorption method (pH-meter). [2] Adhesive properties were evaluated through a hydrophobic / hydrophilic oxide compounds [3-5]. REFERENCES: [1] L. F. Ikonnikova, K. V. Ikonnikova and E. A. Koltunova, MATEC Web of Conf. 19, 01017 (2014); [2] K. V. Ikonnikova, L. F. Ikonnikova, Yu. S. Sarkisov and T. S. Minakova, Theory and Practice of pH-metry Definition of Acid-base Properties of Solid Body Surface (Publishing House TPU, Tomsk, 2011); [3] K. V. Ikonnikova, L. F. Ikonnikova and E. A. Koltunova, Procedia Chem. J. 15, 167–173 (2015); [4] K. V. Ikonnikova, L. F. Ikonnikova and E. A. Koltunova, Key Eng. Mater. 683, 301–305 (2016); [5] K. V. Ikonnikova, L. F. Ikonnikova and E. A. Koltunova, Fundamental Research J. (in Russian – Zhurnal fundamentalnye Issledovaniya) 10 (2), 2134–2137 (2015).
A goal of the contribution is to investigate mechanical properties of surface plasma treated polymer detected by technique of standard testing machine. For this purpose polyethylene foil (PE) with dimensions of 50x4x0.01 cm and with high purity of material was chosen. The samples were tested by the testing machine Shimadzu Autograph AGS-X, Japan under the extremely low tensile strength (in case of our samples the load was below 16 N) so that the foils remained always in elastic regime and plastic deformations were excluded. Every measurement consists of 10 cycles where samples were under tensile load with relaxation phase without the load in order to ensure the same length of sample in the next cycle. The samples were measured after and before surface treatment by atmospheric pressure plasma generated by dielectric barrier discharge in air. Elasticity of the material becomes higher after the treatment by plasma and results will be completed with AFM diagnostics. ACKNOWLEDGEMENTS: This research has been supported by the project CZ.1.05/2.1.00/03.0086 funded by European Regional Development Fund and project LO1411 (NPU I) funded by Ministry of Education Youth and Sports of Czech Republic.
Humic substances are inherent part of soil. They are responsible for plants nutrition as well as soil structure and composition. Their content in the land continues to decline in the past several decades. There is an effort to artificial replacement. It was found that dusting and spraying of plants are not very effective. The most of conventionally applied fertilizers are very often washed away by rainfall or blown by wind. The solution of these problems can be found in the use of humic substances as a part of the controlled release systems. There are countless possibilities how to prepare product which would be able to release humic substances to the land continuously with limited losses only. This work is focused on use of superabsorbent polymer as a vehicle of humic substances or conventional fertilizers or both together. Incorporation of humic substances into the hydrogel matrix of superabsorbent polymer is very effective for growing plants. This system facilitates the soil’s water management which is caused by structure of polymer network as well as humic substances specific properties. Nutrients are dosed to the structure of the hydrogel in an amount and combination to meet the particular needs of the certain plant. It is important to design the ideal composition of engineered products. They should contain sufficient nutrients, minimum or rather no pollutants where possible. They should undoubtedly be biocompatible and biodegradable and have enough durable mechanical properties.
Industrial branches are developing the best materials for their applications. An important part of surface engineering is represented by Physical Vapor Deposition (PVD) and Thermal Spraying techniques. The present work aims to investigate and compare the properties of multilayer coating systems obtained from PVD deposited Diamond-like Carbon (DLC) films on top of High Velocity Oxy-Fuel thermal sprayed WC-CoCr cermet interlayers to those of as-sprayed cermet coatings. In order to determine the coatings characteristics, the morphology, microstructure and chemical composition have been analyzed by means of Scanning Electron Microscopy combined with Energy-dispersive X-ray Spectroscopy (EDX). The EDX line-scan analysis confirms the existence of a gradient coating. The adhesion layer is a mixture of carbides, nitrides and carbonitrides. The presence of the cermet interlayer has several advantages like promoting adhesion to the metallic substrate and exhibiting a gradual distribution of the metal into ceramic, offering a better opportunity for the phase distribution of the top layer. Therefore, a further used method for the characterization of the cermet coating was X-ray diffraction. Several transformations in the phase content were observed and a decomposition of the ceramic phase was detected. The coefficient of friction, measured with a Pin-on-Disk Tribometer, stabilized quickly and remained constant for the WC-CoCr coating, whereas in the case of DLC/WC-CoCr it showed a lower steady state value with light fluctuations. Polarization measurements revealed a considerable dissolution of the metallic binder in the case of WC-CoCr coatings. Meanwhile, the DLC/WC-CoCr multilayer system performed significantly better under the same electrochemical testing conditions.
Modern polymer materials offer great potential due to their simple processing and possibility to tailor its properties for exact end-use. They found their applications in almost every aspect of human life, from daily use as containers and clothing to cutting edge technology and research in medicine, electronics, optics and sensors. This versatility is reason why they still attract attention as there are found new ways for modification offering new properties.
In our current work we focused on polyetherimide (PEI). PEI is an amorphous transparent thermoplastic commercially known as Ultem. This material has very favorable properties such as high glass transition temperature, good mechanical properties and resistance to liquids. Therefore it is excellent candidate for various modifications including polymer blending, thermal treatment, mechanical modifications and metal sputtering. In this paper we would like to present our current research into PEI modification by thermal treatment and AFM tip scanning. These methods caused significant changes to surface morphology which was investigated by AFM.