Effect of Nb doping on structural, optical and photocatalytic properties of flame-made TiO2 nanopowder

TiO₂:Nb nanopowders within a dopant concentration in the range of 0.1?C15?at.% were prepared by one-step flame spray synthesis. Effect of niobium doping on structural, optical and photocatalytic properties of titanium dioxide nanopowders was studied. Morphology and structure were investigated by means of Brunauer?CEmmett?CTeller isotherm, X-ray diffraction and transmission electron microscopy. Diffuse reflectance and the resulting band gap energy were determined by diffuse reflectance spectroscopy. Photocatalytic activity of the investigated nanopowders was revised for the photodecomposition of methylene blue (MB), methyl orange (MO) and 4-chlorophenol under UVA and VIS light irradiation. Commercial TiO₂-P25 nanopowder was used as a reference. The specific surface area of the powders was ranging from 42.9?m²/g for TiO₂:0.1?at.% Nb to 90.0?m²/g for TiO₂:15?at.% Nb. TiO₂:Nb particles were nanosized, spherically shaped and polycrystalline. Anatase was the predominant phase in all samples. The anatase-related transition was at 3.31?eV and rutile-related one at 3.14?eV. TiO₂:Nb nanopowders exhibited additional absorption in the visible range. In comparison to TiO₂-P25, improved photocatalytic activity of TiO₂:Nb was observed for the degradation of MB and MO under both UVA and VIS irradiation, where low doping level (Nb?<?1?at.%) was the most effective. Niobium doping affected structural, optical and photocatalytic properties of TiO₂. Low dopant level enhanced photocatalytic performance under UVA and VIS irradiation. Therefore, TiO₂:Nb (Nb?<?1?at.%) can be proposed as an efficient selective solar light photocatalyst.     

Lead accumulation and elimination in tissues of Prussian carp, Carassius gibelio (Bloch, 1782), after long-term dietary exposure, and depuration periods

We studied the bioaccumulation of lead in selected tissues of Prussian carp Carassius gibelio (Bloch, 1782) during 12 and 24 months exposure to different doses of this metal in feed and the elimination of lead from tissues during the following 12-month depuration period. Lead concentration was determined using atomic absorption spectrometry method. The highest lead concentrations were observed at 2.0?±?0.54 to 7.4?±?1.1 mg?kg^?1 in the kidney, 3.0?±?0.13 to 5.2?±?0.17 mg?kg^?1 in the bone, and 4.5 (±0.4)?mg?kg^?1 in the hepatopancreas of fish from groups exposed to lead dietary concentration from 8 to 49 mg?kg^?1 for 24 months. The rate of accumulation were generally the highest at the beginning of exposure as evidenced by the highest monthly increments of bioaccumulation observed after 3 months of contamination for muscles, hepatopancreatic gland, intestine, and gills. Also analysis of the monthly increments of lead bioaccumulation in bone tissue and the highly significant coefficients of correlation indicate that the dynamics of accumulation are clearly dependent on dose of exposure. Depuration of accumulated lead from the organs depended mainly on tissue and duration of elimination period. Very rapid depuration was observed in soft tissues such as the intestine or muscles. Very low elimination was observed for scales and bones where until the end of the experiment highly significant lead concentration differences were observed in all groups in relation to the control group. Chronic dietary exposure in the range of 8–49 mg Pb?kg^?1 resulted in no significant effects on the growth and survival of Prussian carp females.     

Particulate Matter in California: Part 1—Intercomparison of Several PM2.5, PM10–2.5, and PM10 Monitoring Networks

Abstract

It will be many years before the recently deployed network of fine particulate matter with an aerodynamic diameter less than 2.5 [H9262]m (PM_2.5) Federal Reference Method (FRM) samplers produces information on nonattainment areas, trends, and source impacts. However, data on PM_2.5 and its major constituents have been routinely collected in California for the past 20 years. The California Air Resources Board operated as many as 20 dichotomous (dichot) samplers for PM_2.5 and coarse PM (PM_10–2.5). The California Acid Deposition Monitoring Program (CADMP) collected 12-h-average PM_2.5 and PM₁₀ from 1988 to 1995 at ten urban and rural sites and 24-h-average PM_2.5 at five urban sites since 1995. Beginning in 1994, the Children’s Health Study collected 2-week averages of PM_2.5 in 12 communities in southern California using the Two-Week Sampler (TWS). Comparisons of collocated samples establish relationships between the dichot, CADMP, and TWS samplers and the 82-site network of PM_2.5 FRM samplers deployed since 1999 in California. PM mass data from the different monitoring programs have modest to high correlation to FRM mass data, fairly small systematic biases and negative proportional biases ranging from 7 to 22%. If the biases are taken into account, all of the programs should be considered comparable with the FRM program. Thus, historical data can be used to develop long-term PM trends in California.     

Assessment of microbial contamination within working environments of different types of composting plants

The objective of the study was to determine the degree of microbiological contamination, type of microflora, bioaerosol particle size distribution, and concentration of endotoxins in dust in different types of composting plants. In addition, this study provides a list of indicator microorganisms that pose a biological threat in composting facilities, based on their prevalence within the workplace, source of isolation, and health hazards. We undertook microbiological analysis of the air, work surfaces, and compost, and assessed the particle size distribution of bioaerosols using a six-stage Andersen sampler. Endotoxins were determined using gas chromatography–mass spectrometry (GC-MS). Microbial identification was undertaken both microscopically and using biochemical tests. The predominant bacterial and fungal species were identified using 16S rRNA and ITS1/2 analysis, respectively.?The number of mesophilic microorganisms in composting plants amounted to 6.9 × 10²–2.5 × 10⁴ CFU/m³ in the air, 2.9 × 10²–3.3 × 10³ CFU/100 cm² on surfaces, and 2.2 × 10⁵–2.4 × 10⁷ CFU/g in compost. Qualitative analysis revealed 75 microbial strains in composting plants, with filamentous fungi being the largest group of microorganisms, accounting for as many as 38 isolates. The total amount of endotoxins was 0.0062–0.0140 nmol/mg of dust. The dust fraction with aerodynamic particle diameter of 0.65–1.1 μm accounted for 28–39% of bacterial aerosols and 4–13% of fungal aerosols. We propose the following strains as indicators of harmful biological agent contamination: Bacillus cereus, Aspergillus fumigatus, Cladosporium cladosporioides, C. herbarum, Mucor hiemalis, and Rhizopus oryzae for both types of composting plants, and Bacillus pumilus, Mucor fragilis, Penicillium svalbardense, and P. crustosum for green waste composting plants. The biological hazards posed within these plants are due to the presence of potentially pathogenic microorganisms and the inhalation of respirable bioaerosol. Depending on the type of microorganism, these hazards may be aggravated or reduced after cleaning procedures.

Implications:?This study assessed the microbial contamination in two categories of composting plants: (1) facilities producing substrates for industrial cultivation of button mushrooms, and (2) facilities for processing biodegradable waste. Both workplaces showed potentially pathogenic microorganisms, respirable bioaerosol, and endotoxin. These results are useful to determine the procedures to control harmful biological agents, and to disinfect workplaces in composting plants.     

Environmental Degradation of Blends of Atactic Poly[(R,S)-3-hydroxybutyrate] with Natural PHBV in Baltic Sea Water and Compost with Activated Sludge

Degradation of atactic poly[(R,S)-3-hydroxybutyrate] (a-PHB) binary blends with natural poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV, 12 mol% of 3HV units), has been investigated and compared with plain PHBV in the compost containing activated sludge and under marine exposure conditions in the dynamic water of the Baltic Sea. Characteristic parameters of compost and the Baltic Sea water were monitored during the incubation period (6 weeks) and their influence on the degree of biodegradation is discussed. After specified degradation times of the experiments the weight loss of the samples, surface changes, changes in molecular weight and polydispersity as well as changes of the composition and thermo-mechanical properties of the blends have been evaluated. Macroscopic observations of the samples were accompanied by investigations using optical microscopy, size-exclusion chromatography (SEC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and tensile testing. The degree of degradation of blends of a-PHB with PHBV depends on the blend composition and environmental conditions. In both environments studied the weight loss of plain PHBV was more significant than changes the molecular weight. In both environments only enzymatic degradation of the blends, which proceeds via surface erosion mechanisms, was observed during the incubation period.     

Differences in Cu content in selected mushroom species growing in the same unpolluted areas in Poland

The aim of the study was to estimate copper (Cu) accumulation efficiency in whole-fruiting bodies of 18 edible and non-edible wild growing mushrooms collected from 27 places in the Wielkopolska Voivodeship. Mushrooms were collected each time from the same places to estimate the diversity in Cu accumulation between tested mushroom species within 3 consecutive years of study (2011–2013). The study results revealed various accumulation of Cu in the whole-tested mushroom fruiting bodies. The highest mean accumulation of Cu was observed in Macrolepiota procera (119.4 ± 20.0 mg kg^?1 dm), while the lowest was in Suillus luteus and Russula fellea fruiting bodies (16.1 ± 3.0 and 18.8 ± 4.6 mg kg^?1 dm, respectively). Significant differences in Cu accumulation between mushroom species collected in 2011 and in the two following years (2012 and 2013) were observed. The results indicated that sporadic consumption of these mushrooms was not related to excessive intake of Cu for the human body (no toxic influence on health).     

Water-Soluble Pressure-Sensitive Adhesives Containing Carboxymethyl Starch with Improved Adhesion to Paper

Water-soluble pressure-sensitive adhesives (PSA) based on acrylic acid and carboxymethyl starch (CMS) have been prepared. The tack and peel adhesion to various paper types (newsprint, hygienic, packing, fax and art paper) as well as dynamic shear adhesion at higher temperatures (70–240?°C) have been tested with the aim of applying such PSA in a form of double-sided splicing tapes for paper industry. For all paper types tested tack and peel adhesion values increased with CMS content (0.1–10 wt% in PSA). The highest tack and peel adhesion values (for the system containing 10 wt% CMS) were noted for fax paper ca. 19.5 N/2.5 cm and 18.3 N/2.5 cm, respectively and the lowest ones for art paper: 14.7 N/2.5 cm and 13.5 N/2.5 cm, respectively. Obtained PSA were completely soluble in water, and the time of water-solubility depended on CMS content, as well as pH value, however it did not exceed 5 min.     

Particulate matter on two Prunus spp. decreases survival and performance of the folivorous beetle Gonioctena quinquepunctata

Woody plants growing along streets and construction sites play an important role in removing harmful particulate matter (PM). Researchers rarely consider the impact of different types and size fractions of PM deposited on the leaves on insect folivores. We determined differences in the accumulation of cement and roadside PM on the leaves of two Prunus species (P. padus and P. serotina) with different leaf surface structures. We also determined the effect of PM on the beetle Gonioctena quinquepunctata, the main pest of these plants. Saplings were artificially dusted in greenhouses and leaves were utilised for larval and adult insect stages feeding in laboratory conditions. Road PM accumulated in greater amounts than did cement PM, regardless of plant species. For both PM sources, P. padus accumulated twofold more than did P. serotina. Insect survival was negatively affected by PM pollution; however, neither Prunus species nor PM source variant significantly affected masses of larvae and pupae, duration of larval and pupal development or relative growth rates. The experiment showed strong negative influences of PM were noted only for adult insects, due to the grazing period being longer than that in larvae. The mass of adult insects and the efficiency of conversion of ingested food (ECI) were lower for insects exposed to PM than those for control insects. Insects compensated for lower ECI by eating a greater total amount of food (TFE). Adult insects gained significantly higher mass when fed with P. serotina than with P. padus. The effect of PM on analysed plant metabolites was insignificant. Only Prunus sp. and date of collection affected the level of condensed tannins and total phenols. Our results indicate that, when investigating the effect of the host plant on folivore performance, the accumulation of PM, as well as its type and quantity, should be taken into account.

     

Simulation study of the Lower Cretaceous geothermal reservoir for aquifer thermal energy storage

Environmental Geochemistry and Health - The aquifer thermal energy storage (ATES) has gained attention in several countries as an installation for increasing the energy efficiency of geothermal...     

Environmental benefits from geothermal energy use with a well doublet located in the Szczecin Trough (NW Poland)

Environmental Geochemistry and Health - The article presents environmental aspects related to the use of geothermal waters of the Lower Jurassic in the area of the Szczecin Trough. The research...