Emise nanometrických částic na bázi kovů z pyrometalurgie a dopravy

Import 06/11/2014Antropogenní činnosti, jako je pyrometalurgie a pozemní doprava jsou přínosem pro společnost, avšak přinášejí s sebou také jistá rizika pro životní prostředí a zdraví člověka. S těmito riziky je spojen například vznik odpadních produktů těchto procesů, které se uvolňují do životního prostředí. S výrobou železa a oceli je spojena produkce a akumulace jemnozrnných tuhých odpadů, které jsou částečně recyklovány a částečně skládkovány. Potenciální rizika těchto odpadů jsou závislá nejen na množství ale také na formě potenciálně rizikových kovů. Výskyt těchto kovů v životním prostředí představuje dlouhodobé riziko a může mít významný negativní vliv na živé organismy. Nespalovací procesy, jako je brzdění automobilů, také hojně přispívají ke znečištění životního prostředí. Brzdný otěr vzniká při tření mezi komponenty brzdné soustavy a může být rozdělen na dvě frakce, a to „nonairborne“ a „airborne“. „Nonairborne“ frakce obecně může spadat na povrchy cest, nebo být zachycena na součástech automobilu. Tyto částice jsou považovány za „velké“, ale na jejich povrchu mohou být zachyceny nanometrické částice, které mohou být uvolňovány dále do prostředí. Hlavním cílem této práce bylo určit mobilitu nanometrických částic ve vodném prostředí, jejich morfologii a složení v pěti vybraných pyrometalurgických kalech (kal z kyslíkového konvertoru, tandemové pece a vysoké pece, vysokopecní kal také po rozdružování na hydrocyklonu - výtok a přepad) a v brzdném otěru ze dvou modelových brzdových destiček (G6C a G6C/KATI) a dvou komerčních brzdových destiček (SMP1 a SMP2). Skenovací elektronová mikroskopie, rentgenová prášková difrakce, FTIR spektroskopie a Ramanova mikrospektroskopie byly použity pro charakterizaci všech původních vzorků. Podle evropské směrnice byly ze vzorků pyrometalurgických kalů připraveny vodné výluhy. Vodné suspenze byly také připraveny sedimentačním procesem pro oba typy vzorků. Připravené vodné suspenze byly nakápnuty na podložní sklíčko a nechány zaschnout pro analýzy skenovací elektronovou mikroskopií a Ramanovou mikrospektroskopií. Transmisní elektronová mikroskopie byla provedena přímo na připravených vodných suspenzích. Těmito technikami byly nalezeny nanometrické částice, některé i krystalického charakteru na bázi kovů. Připravené vodné suspenze podle normy jsou tudíž nesprávně považovány za homogenní výluh.Anthropogenic activities, as pyrometallurgy and road traffic have plenty of benefits for the society; however they may also pose risks to the environment and human health as well. These risks are mainly connected to the production of wastes during these processes. With iron and steel production the generation and accumulation of fine-grained solid wastes are connected. These solid wastes are partially being recycled and partially they are landfilled. Potential risk of these wastes depends on amounts, chemistry and bioavailability of potentially hazardous metals present in wastes. These metals are persistent and may havesignificant negative impact on living organisms, so their long term presence in the environment may pose significant risks. Non-combustion anthropogenic processes associated with road traffic, such as braking are also known to contribute to the environmental pollution. The friction contact between pad and disc during forced deceleration creates wear debris, which could be divided to the nonairborne and airborne fraction. The non-airborne fraction may settle on brake hardware, road surfaces, and in the vicinity of roads. These particles are considered to be large, but their surface may be “covered” with attached ano-sized particles, which can be potentially released to the environment. Aim of the thesis was to evaluate the mobility of the nano-sized particles in the water environment and their morphology and chemistry characterization from five selected pyrometallurgical sludges (blast furnace sludge, blast furnace sludge treated in hydrocyclone overflow and underflow, tandem furnace sludge, and oxygen converter sludge), and nonairborne wear debris from two model brake pads (G6C and G6C/KATI), and two commercial brake pads (SMP1 and SMP2). Scanning electron microscopy, X-ray powder diffraction, FTIR spectroscopy, and Raman microspectroscopy were used for characterization of initial samples. According to European standard the suspensions were prepared from pyrometallurgical sludges. Also the sedimentation technique was used for suspension preparation of pyrometallurgical sludges and brake wear debris. Prepared suspensions were dried on a glass slide and characterized by scanning electron microscopy and Raman microspectroscopy. Transmission electron microscopy measurements were evaluated with liquid suspensions. These analytical techniques revealed presence of nano-sized metal based and some crystalline particles. Filtered aqueous leachate is inaccurately considered homogenous.Prezenční9360 - Centrum nanotechnologiívyhově

Functional and eco-friendly nanocomposite kaolinite/ZnO with high photocatalytic activity

Highly photoactive nanocomposites kaolinite/ZnO with various amounts of ZnO nanoparticles (10 wt.%, 30 wt.%, and 50 wt.%) were prepared using simple hydrothermal method. Calcination of the nanocomposites at 600 °C led to the kaolinite–metakaolinite phase transformation, to further growth of ZnO crystallites, and to significant increase of photodegradation activity. The nanocomposites were studied using X-ray fluorescence spectroscopy, X-ray powder diffraction, Fourier transform infrared, diffuse reflectance and photoluminiscence spectroscopies, scanning and transmission electron microscopies, BET analysis, and molecular modeling using empirical force field. Photodegradation activity was evaluated by the discoloration of Acid Orange 7 aqueous solution under UV irradiation. Leaching tests confirmed strong interaction between kaolinite matrix and ZnO nanoparticles, and, therefore, high stability of prepared nanocomposites.Web of Science16240039

Microstructure and properties of nanostructured coating on Ti6Al4V

Implant surface properties of Ti6Al4V alloy that is currently used as a biocompatible material because of a variety of unique properties can be improved by a self-organized TiO2 layer. The TiO2 nanotubes forming on the titanium-based materials is a relatively recent technology for the surface properties modification and represents pronounced potential in promoting cell adhesion, proliferation, and differentiation that facilitate an implant osseointegration. This work focuses on the influence of surface treatment quality and anodic oxidation parameters on the structure features and properties of TiO2 nanotube coatings. The nanotubes were formed on Ti6Al4V alloy substrates by simultaneous surface oxidation and controlled dissolving of an oxide film in the presence of fluorine ions. The anodization process on ground or polished samples was performed at experimental condition of 30 V for 1 h. The selected anodized samples were heat treated for 2 h at 500 degrees C under flowing argon. All samples were characterized by scanning electron microscopy, X-ray diffraction analysis, and Raman spectroscopy. The corrosion rate in physiological solution reached 0.0043, 0.0182, and 0.0998 mm per year for the samples in polished and not-anodized, as-anodized, and anodized-heat treated conditions, respectively.Web of Science133art. no. 70

Biosilica-nanogold composite: Easy-to-prepare catalyst for soman degradation

A very fast single-step biosynthesis of gold nanoparticles (AuNPs) using algal cells of Mallomonas kalinae (MK) is introduced. The average particle size of crystalline AuNPs was approximately 10 nm. Subsequently, the catalytic activity of two systems - MK-biosilica scales and MK-biosilica scales with AuNPs - was compared with a control hydrolysis of soman (GD) performed in demineralized water. The kinetics of GD degradation was studied using a gas chromatography with mass detector (GC-MS) and solid-phase microextraction. The residual content of GD was 3.8% and 3.5% for both initial concentrations of GD (68 mu g mL(-1) and 340 mu g L-1, respectively) after 48 h of testing when nanogold was used as a catalyst. Experimental results confirmed the catalytic activity of biosynthesized AuNPs, as well as the role of biosilica itself in the degradation of GD.Web of Science12227126

Influence of thermal and UV treatment on the polypropylene/graphite composite

Electrically conductive polypropylene/graphite (PP/graphite) composites were prepared via blending granulated PP with maleic anhydride grafted PP and natural graphite. Electrical conductivity of prepared samples containing either 65, 70, or 75 wt% of graphite was measured and the most conductive sample containing 75 wt% of graphite was exposed to UV irradiation for 1 and 24 h or thermally treated at 170 °C for 1 h. The influence of thermal and UV exposure on the structural and electrical changes in such treated samples was studied. Local current measurements on the surface were made using scanning spreading resistance microscopy and morphology of the surface was studied by atomic force microscopy. X-ray diffraction analysis, infrared and Raman spectroscopy were also used for the structural characterization. Properties of treated and untreated samples are compared and differences are discussed.Web of Science52534

Preparation of risedronate nanoparticles by solvent evaporation technique

One approach for the enhancement of oral drug bioavailability is the technique of nanoparticle preparation. Risedronate sodium (Biopharmaceutical Classification System Class III) was chosen as a model compound with high water solubility and low intestinal permeability. Eighteen samples of risedronate sodium were prepared by the solvent evaporation technique with sodium dodecyl sulfate, polysorbate, macrogol, sodium carboxymethyl cellulose and sodium carboxymethyl dextran as nanoparticle stabilizers applied in three concentrations. The prepared samples were characterized by dynamic light scattering and scanning electron microscopy. Fourier transform mid-infrared spectroscopy was used for verification of the composition of the samples. The particle size of sixteen samples was less than 200 nm. Polysorbate, sodium carboxymethyl dextran and macrogol were determined as the most favourable excipients; the particle size of the samples of risedronate with these excipients ranged from 2.8 to 10.5 nm.Web of Science1911178611784

Magnetically modified biosorbent for rapid beryllium elimination from the aqueous environment

Although both beryllium and its compounds display high toxicity, little attention has been focused on the removal of beryllium from wastewaters. In this research, magnetically modified biochar obtained from poor-quality wheat with two distinct FexOy contents was studied as a sorbent for the elimination of beryllium from an aqueous solution. The determined elimination efficiency was higher than 80% in both prepared composites, and the presence of FexOy did not affect the sorption properties. The experimental q(max) values were determined to be 1.44 mg/g for original biochar and biochar with lower content of iron and 1.45 mg/g for the biochar with higher iron content. The optimum pH values favorable for sorption were determined to be 6. After the sorption procedure, the sorbent was still magnetically active enough to be removed from the solution by a magnet. Using magnetically modified sorbents proved to be an easy to apply, low-cost, and effective technique.Web of Science1421art. no. 661

Polyaniline/TiO2/kaolinite: The composite material with high electrical anisotropy

Kaolinite–TiO2 nanocomposite matrix (KATI) coated with polyaniline (PANI) layer has been prepared in powder form and pressed into tablets. The conductivity was studied in dependence on (1) wt.% of TiO2 in KATI matrix and (2) thermal pre-treatment of KATI matrix. The anisotropy factor α, i.e. the ratio of in-plane conductivity and conductivity in the direction perpendicular to the tablet plane, was found to be very high for PANI/KATI tablet (α is of the order of 103–104) in comparison with pure PANI tablet (α is of the order of 102). Structure has been studied using Raman spectroscopy, X-ray diffraction analysis, scanning electron microscopy and molecular modeling. The possibility of using the tablets as a load sensors have been tested and tablets pressed from composites containing calcined KATI seem to be promising material for this purpose.Web of Science1461-215214

Electrically conductive aluminosilicate/graphene nanocomposite

Highly electrically conductive ceramic material based on aluminosilicate/graphene nanocomposite has been prepared by high pressure (400 MPa) compaction of montmorillonite intercalated with polyaniline followed with the high temperature (1400 °C) treatment in argon atmosphere. Tablets pressed from polyaniline/montmorillonite intercalate exhibits strong texture due to the disk-shaped montmorillonite particles and, consequently, the high anisotropy in conductivity. The high temperature induced phase transformation of montmorillonite into cristobalite and mullite preserved the aluminosilicate layered structure and created good conditions for formation of graphene sheets from polyaniline layers intercalated in montmorillonite. Therefore, the texture and anisotropy in conductivity remain preserved in resulting aluminosilicate/graphene tablets, while the in-plane conductivity in aluminosilicate/graphene tablets is 23,000× higher than the conductivity of uncalcined polyaniline/montmorillonite tablets. Simple fabrication method of aluminosilicate/graphene tablets is very promising for the manufacturing of the electrically conductive and tough ceramic material, which can be exposed to corrosive environment as well as to high temperatures.Web of Science34123117311

Preparation of hydrochlorothiazide nanoparticles for solubility enhancement

Nanoparticles can be considered as a useful tool for improving properties of poorly soluble active ingredients. Hydrochlorothiazide (Class IV of the Biopharmaceutical Classification System) was chosen as a model compound. Antisolvent precipitation-solvent evaporation and emulsion solvent evaporation methods were used for preparation of 18 samples containing hydrochlorothiazide nanoparticles. Water solutions of surfactants sodium dodecyl sulfate, Tween 80 and carboxymethyl dextran were used in mass concentrations of 1%, 3% and 5%. Acetone and dichloromethane were used as solvents of the model compound. The particle size of the prepared samples was measured by dynamic light scattering. The selected sample of hydrochlorothiazide nanoparticles stabilized with carboxymethyl dextran sodium salt with particle size 2.6 nm was characterized additionally by Fourier transform mid-infrared spectroscopy and scanning electron microscopy. It was found that the solubility of this sample was 6.5-fold higher than that of bulk hydrochlorothiazide.Web of Science218art. no. 100