The Effects of Nature-Inspired Synthesis on Silver Nanoparticle Generation.

A wide range of methods can be used for nature-inspired metallic nanoparticle (NP) synthesis. These syntheses, however, are ongoing in the presence of diverse mixtures of different chemical compounds, and all or only a few of these contribute to resultant particle properties. Herein, the linden (Tilia sp.) inflorescence leachate and pure citric and protocatechuic acids were chosen for Ag-AgCl nanoparticle (NP) synthesis, and the resultant particles were then compared. We focused on the following four issues: (1) preparation of Ag-AgCl NPs using the Tilia sp.-based phytosynthetic protocol, (2) analytical determination of the common phenolic, nonphenolic, and inorganic profiles of three Tilia sp. types from different harvesting locations, (3) preparation of Ag-AgCl NPs using a mixture of citric and protocatechuic acids based on chromatographic evaluation, and (4) comparison of Tilia-based and organic acid-based syntheses. Our research confirms that the Tilia organic and inorganic profiles in biomasses are influenced by the harvesting location, and the three sites influenced both the morphology and final NP size. Our processing method was uniform, and this enabled great Ag-AgCl NP reproducibility for each specific biomass. We were then able to prove that the simplified organic acid-based synthesis produced even smaller NPs than Tilia-based synthesis. These findings provide better understanding of the significant influence on NP final properties resulting from other organic acids contained in the linden.

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 qmax 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.

Ag-AgCl Nanoparticles Fixation on Electrospun PVA Fibres: Technological Concept and Progress.

Polymer-metal based material with unique 3D structure is an attractive substrate for the development of biomedical applications. A novel preparation of the composite from polymer fibres and silver nanoparticles has been designed through: (1) preparation of silver nanoparticles by phytosynthesis and (2) incorporation of these nanoparticles in a fibrous membrane prepared by electrospinning. The nanoparticle biosynthesis was performed in a pure environmental-friendly, easy, static, bottom-up in vitro regime using Tilia sp. leachate. TEM and XRD depict the formation, stabilisation and encapsulation of crystalline silver (14 ± 9 nm) nanoparticles (NPs) in one simple step with low tendency to aggregate. We achieved successful incorporation in the uniform electrospun 221 ± 24 nm poly(vinylalcohol) fibres, and this confirms the possibility of its use in the biomedical field. Both SEM with EDX and TEM analysis determined fibre uniformity with the presence of silver NPs, and ICP-AES confirmed the relatively similar metal concentration throughout the triplicate measurement of fibre structures on the 2 × 2 cm area in the following manner: 0.303 ± 0.018 wt. %, 0.282 ± 0.017 wt. %, and 0.281 ± 0.017 wt. %. Our hypothesis is based on previously verified preparation of active silver NPs and the easily prepared PVA electrospun fibres which act as a water soluble matrix. The simple methodology of incorporating biosynthetically prepared NPs in the PVA fibers highlights the effectiveness of this material, with simple release from water-soluble PVA and final activation of the prepared NPs.

Phytosynthesis of Ag, ZnO and ZrO2 Nanoparticles Using Linden: Changes in Their Physical-Chemical Nature Over Time.

Bionanotechnology provides many new methods and protocols in nanomaterial preparation. One of these special new chemical methods is phytosynthesis. The application of biological processes in living organisms such as bacteria, fungi and higher plants contributes to rapid and easy formation of metallic nanoparticles. These nanoparticles present a promising future in heterogeneous catalysis and medicine, and here we focus on phytosynthesis of Ag, ZnO and ZrO2 nanoparticles using leachate from the linden plant. Nanoparticle activity in liquid is an important aspect of their behavior, and we investigated nanoparticles ζ-potential and monitored their particle size by dynamic light scattering during the period of three months. Transmission electron microscopy then determined shape and morphology, with results confirming their spherical shape and average size in tens and hundreds of nanometers. The amount of metals was estimated in tens of mg L-1 and the different nanoparticle sizes obtained by dynamic light scattering and transmission electron microscopy are discussed. The nanoparticles were tested against 4 human pathogens using minimum inhibitory concentration to investigate their antimicrobial potential. Only Ag nanoparticles provided antibacterial properties against Escherichia coli and Pseudomonas aeruginosa; with the remaining nanoparticles having no antibacterial effect on the four tested pathogens. All studied phenomena are related to nanoparticle concentration and their surface charge, and therefore ζ-potential and other physical and chemical properties are important in ascertaining positive and negative aspects of metallic nanoparticles in future applications and related research.

Ti and Zn Content in Moss Shoots After Exposure to TiO2 and ZnO Nanoparticles: Biomonitoring Possibilities.

To assess the uptake of nanoparticles by moss shoots and the possibility of biomonitoring the moss of nanoparticle pollution, two moss species frequently used in biomonitoring surveys [Hylocomium splendens (Hedw.) Schimp. and Pleurozium schreberi (Brid.) Mitt.] were repeatedly exposed to known concentrations of either nano-TiO2 or nano-ZnO suspensions. The interspecies differences were assessed by exposing both the species to 1 g L-1 nano-ZnO suspension, H. splendens samples were also exposed to either 0.1 g L-1 or 1 g L-1 suspension of nano TiO2. The exposed samples were analysed for Zn or Ti content using Inductively Coupled Plasma-Atomic Emission Spectroscopy. Both species showed a similar accumulation pattern, H. splendens being a slightly better accumulator. The washing suggests that Ti successfully penetrated the interior of the gametophyte. Since the relationship between the exposure and accumulation is linear, moss biomonitoring is, hereby, considered to be a viable, novel technique in nanoparticle pollution assessment.

Influence of Microwave Treatment on Ghassoul Stability.

Moroccan clay with a significant portion of stevensite, locally known as Ghassoul, is a very good sorbent. For the facilitation of the sorbent separation, it is convenient to use its magnetically modified form. Recently, the composites of FexOy/Ghassoul have been prepared using simple microwave assisted synthesis and the effect of method preparation on composite composition has been proven. The aim of the presented work was to evaluate the effect of the microwave radiation on the structure and stability of native Ghassoul. Water extracts were prepared by batch method using deionized water. The leachate was prepared for 1, 6 and 24 hours in 1:1000 ratio of solid and liquid phase from the original material and the material after interaction with microwave radiation. In the filtrate, pH was determined as well as concentrations of Al, Ca, K, Mg, Na and Si using Atomic emission spectrometry with inductively coupled plasma. The results imply that microwave treatment of the material changes the pH of the leachates to more acidic compared to the original material in which the pH increases. Even the microwave treatment of Ghassoul did not cause changes in Al, in contrast with Si which was leached considerably more in the case of the microwave-treated sample. Opposite result was observed in the case of Na and Mg. Leached amounts of Ca were comparable in both the treatments, leached amounts K were not affected by the treatment and leaching time.

Stability of Calcium Deficient Hydroxyapatite/Clay Mineral Nanocomposite in Solutions with Different pH.

Hydroxyapatite is one of the building blocks of hard tissues of living organisms. Therefore stability of nanoparticles in experimental solutions of different pH similar to one in human body is important issue for precise tailoring of the synthesis of hydroxyapatite particles on clay mineral substrate. In this study, the stability (amount of CaII and PV released into the water) of calcium deficient hydroxyapatite/clay mineral nanocomposites was investigated. The calcium deficient hydroxyapatite/clay mineral nanocomposites with montmorillonite and two vermiculites (Brazil and Bulgaria) were compared with pure calcium deficient hydroxyapatite. The stability was investigated for 24 h where calcium deficient hydroxyapatite/clay mineral nanocomposites and pure calcium deficient hydroxyapatite were placed into the water solutions with different pH values (pH= 5, 7, and 9). The presence of CaII and PV ions at solutions were determined using atomic emission spectrometry. The calcium deficient hydroxyapatite/clay mineral nanocomposites after stability testing were characterized by X-ray powder diffraction and infrared spectroscopy with Fourier transformation.

Influence of Nano-ZnO Exposure to Plants on L-Ascorbic Acid Levels: Indication of Nanoparticle-Induced Oxidative Stress.

With the continuously growing production of nanomaterials, their presence in the environment increases. The effects of nanoparticle exposure on plants are yet not fully understood. This study aimed to provide new insights into the stress induced by the exposure of plants to nanoparticles via the determination of the content of L-ascorbic acid, known antioxidant, in the samples of bryophyte species Pleurozium schreberi (Brid.) Mitt. Bryophyte samples, collected from a pristine environment, were exposed to 0.1 g·L-1 suspensions of nano-ZnO for five weeks. Prior to the exposure, the samples were subjected to the combination of treatments-washing or not washing as well as drying or irrigation. In order to assess the level of oxidative stress caused by the exposure to the ZnO nanoparticles under various pre-treatment conditions, the content of the L-ascorbic acid in the samples was determined by titration with dichlorophenolindophenol. Effect of both nano-ZnO exposure and pre-treatment was observed; nano-ZnO exposure significantly reduced the content of L-ascorbic acid in the bryophyte samples indicating it being consumed in the repair processes following the exposure-related physiological stress.

Settled Dust from Urban and Suburban Roads in an Industrial City Area: Location and Seasonal Differences in Metal Content.

Settled road dust, present on all roads surfaces in a relatively high abundance, is a complex of particles-ranging from nanosized to microsized-from both natural and anthropogenic sources and may pose possible risk to the biosphere as well as influence the atmosphere because of the road dust resuspension. Geographical and seasonal differences in heavy metal content of the settled road dust were studied at two sites: urban site with a heavy traffic in the industrial city of Ostrava, Czech Republic and suburban site of Ostrava with a negligible traffic load in settlement Ludgerovice. Dust samples were collected monthly during the period from March to October 2015. Obtained dust samples were homogenized and subsequently analyzed by Inductively Coupled Plasma Atomic Emission Spectroscopy; the results were then assessed by multivariate statistical methods (Principal components analysis, Factorial analysis on mixed data). The difference in the content of Ba, Cr, Cu, Mn, Ni, Pb, Sb, Sn, V, and Zn was explainable mainly by the factor of the site only the content of Fe was significantly dependent on the month of sampling. The contents of the particular elements and the correlations found among them confirm the assumption that heavy metals detected in the road dust samples from the urban site most likely originated primarily from the traffic-and particularly from the non-combustion processes.

Effects of binder choice in converter and blast furnace sludge briquette preparation: Environmental and practical implications.

Blast furnace and converter sludges are fine-grained waste materials characterized as dangerous waste with a negative impact on the environment. One way of recycling of such materials is briquetting followed by reuse of the material in the blast furnace. In the briquetting process, an important step is the choice of the binder suitable for manufacturing the briquettes with suitable mechanical properties. In this work, the effect of the binder choice (laundry starch UNIPRET, Portland cement) on the reduction of iron oxides in the assessed waste materials during thermal treatment (900, 1000, 1100 °C) is evaluated. Simultaneously, the effect of the binder choice on the amount and composition of the resulting waste gas was evaluated as well as its possible impact on the environment. The performed experiments proved the mutual relationship between the level of iron oxides to metal iron conversion, the binder content and retention temperature. Type of binder also affected the volume of the resulting waste gas. Factor analysis for mixed data (FAMD) proved that the resulting concentrations of the assessed hydrocarbons were correlated (apart from ethyne) and that they are closely associated with the binder applied. Conversely, the concentrations of ethyne, carbon monoxide and carbon dioxide were not associated with the binder but with the retention temperature. FAMD did not show any direct effect of final retention temperature on the amount of the rest of the resulting hydrocarbons. In comparison with the starch-containing briquettes, the cement-containing briquettes were also proved to lead to lower resulting concentrations of PAHs in the waste gas.

Residues from the thermal conversion of waste from the meat industry as a source of valuable macro- and micronutrients.

The increased consumption of meat (including poultry) observed over the last decade has led to the intensification of its production. With the production increase, the amount of generated waste also increases. Appropriate disposal of waste from the meat industry will significantly reduce the amount of such waste and its negative impact on the environment. The paper presents a method for the thermal neutralisation of feathers, poultry litter and meat and bone meal (MBM). Waste incineration was carried out in a stationary electric furnace, at a temperature varying in the range of 600-900°C. The resulting ashes were characterised by a high percentage of phosphorus (30-170 g/kg ash), calcium (20-360 g/kg ash) and other valuable macro- and micronutrients like copper, iron, manganese and zinc. The ashes produced during the thermal treatment are safe in terms of sanitary and can be used as additives enriching the fertilisers and soil improvers.

Recycling of blast furnace sludge by briquetting with starch binder: Waste gas from thermal treatment utilizable as a fuel.

Steel plants generate significant amounts of wastes such as sludge, slag, and dust. Blast furnace sludge is a fine-grained waste characterized as hazardous and affecting the environment negatively. Briquetting is one of the possible ways of recycling of this waste while the formed briquettes serve as a feed material to the blast furnace. Several binders, both organic and inorganic, had been assessed, however, only the solid product had been analysed. The aim of this study was to assess the possibilities of briquetting using commonly available laundry starch as a binder while evaluating the possible utilization of the waste gas originating from the thermal treatment of the briquettes. Briquettes (100g) were formed with the admixture of starch (UNIPRET) and their mechanical properties were analysed. Consequently, they were subjected to thermal treatment of 900, 1000 and 1100°C with retention period of 40min during which was the waste gas collected and its content analysed using gas chromatography. Dependency of the concentration of the compounds forming the waste gas on the temperature used was determined using Principal component analysis (PCA) and correlation matrix. Starch was found to be a very good binder and reduction agent, it was confirmed that metallic iron was formed during the thermal treatment. Approximately 20l of waste gas was obtained from the treatment of one briquette; main compounds were methane and hydrogen rendering the waste gas utilizable as a fuel while the greatest yield was during the lowest temperatures. Preparation of blast furnace sludge briquettes using starch as a binder and their thermal treatment represents a suitable method for recycling of this type of metallurgical waste. Moreover, the composition of the resulting gas is favourable for its use as a fuel.

Adaptation of Acidithiobacillus bacteria to metallurgical wastes and its potential environmental risks.

Metallurgical wastes--oxygen converter sludge, dust from cast iron production, lead matte, and slag from recycling of used lead batteries--were treated with Acidithiobacillus bacteria. Bacterial activity and adaptability on waste and some waste mixtures were investigated. Acidithiobacillus bacteria may easily attack oxygen converter sludge, lead matte and slag and affect the mobility of metals. Cast iron dust is not a suitable substrate for applied bacteria due to the absence of reduced sulfur and reduced iron in its mineralogical composition. Nevertheless, the pure culture was able to adapt to the mixture of this waste with slag. Disposal of these metallurgical wastes deserves special attention due to potential attack by microorganisms and consequent pH changes. According to subsequent release of hazardous substances to the environment, this phenomenon can lead to evident environmental risks.

On airborne nano/micro-sized wear particles released from low-metallic automotive brakes.

The paper addresses the wear particles released from commercially available "low-metallic" automotive brake pads subjected to brake dynamometer tests. Particle size distribution was measured in situ and the generated particles were collected. The collected fractions and the original bulk material were analyzed using several chemical and microscopic techniques. The experiments demonstrated that airborne wear particles with sizes between 10 nm and 20 µm were released into the air. The numbers of nanoparticles (< 100 nm) were by three orders of magnitude larger when compared to the microparticles. A significant release of nanoparticles was measured when the average temperature of the rotor reached 300°C, the combustion initiation temperature of organics present in brakes. In contrast to particle size distribution data, the microscopic analysis revealed the presence of nanoparticles, mostly in the form of agglomerates, in all captured fractions. The majority of elements present in the bulk material were also detected in the ultra-fine fraction of the wear particles.

Preparation of vermiculite nanoparticles using thermal hydrogen peroxide treatment.

Powdered natural Mg-vermiculite (Letovice, Czech Republic), with the formula (Mg0.35K0.02Ca0.01) (Mg2.39Fe0.51(3+)Fe0.02(2+)Al0.08) (Si2.64Al1.33Ti0.03) O10(OH)2 x 4.97H2O and particle size < 5 microm, was used for the investigation of exfoliation after hydrogen peroxide and/or microwave treatment (600 W). A sample heated in the microwave oven for 40 min exhibits a 11% mass loss and reduction of the 001 peak intensity in the X-ray diffraction pattern. The basal 001 peak intensity of untreated Mg-vermiculite sample (/001 = 100%) drops to 35% in the microwave treated sample. Only the sample treated for 5 h at 80 degrees C fully rehydrated after 120 min at room temperature. A more pronounced reduction of the 001 peak intensity (to 8%) was observed after hydrogen peroxide treatment of the sample at 25 degrees C. The combination of a five-hour hydrogen peroxide treatment at 80 degrees C and subsequent microwave heating leads to an effective extinction of the 001 diffraction in the XRD pattern. The 001 diffraction profile becomes very diffuse with peak intensity less than 1%. The degree of reduction of the 001 diffraction intensity also depends on the time and temperature of hydrogen peroxide treatment and on the peroxide concentration. An even more pronounced reduction of the peak intensity is caused by exfoliation of particles to nano-domains coupled with a randomization of the c-axes.