Effect of "black carbon" on antimony accumulation in traffic-loaded topsoil.

Traffic-loaded areas have been of increasing concern due to the potential risk of carcinogenic pollutants, including antimony (Sb), which accumulates mostly in atmospheric particles (PM) and can interact with soil organic matter (Corg). The stability of Sb in topsoils was studied via the adsorption mechanism using standard soils and Corg-reach vehicle-produced particles as the unique source of "traffic" Sb. The mixed adsorbents were prepared from loamy sand and clay standard soils, and braking abrasion dust and diesel engine soot as Sb sources in atmospheric PM. Whereas the black carbon (BC), as part of Corg, disposes of exceptional adsorption properties compared to the other Corg, all adsorption experiments were performed identically on the adsorbents prepared from the original standard soils and Sb source materials and on the adsorbents prepared from the same materials annealed at 375 °C to ensure only BC participation in adsorption processes. The concentration of the Sb model solution corresponded to the average Sb content in rainwater from traffic-loaded localities. In addition to Sb, the Corg and iron (Fe) were monitored. The sorbability of Sb on the loamy sand soil mixtures increased up to 90% compared with the pure soil due to new active surface sites for Sb binding created due to the Corg added with the source material. The clay soil mixture containing 10 times more Corg compared with the loamy sand soil accumulated the Corg from the source material, which resulted in blocking active sites and a decline in Sb sorbability by up to 20%. The processes performed identically with original and annealed materials showed the same trends and confirmed the key role of BC and soil quality in the accumulation and stability of Sb in traffic-loaded topsoils. The participation of Fe in Sb surface interactions was not observed.

Photocatalytic degradation of gaseous pollutants on nanostructured TiO2 films of various thickness and surface area.

This work deals with the preparation of TiO2 nanoparticulate layers of various mass (0.05 mg/cm2 to 2 mg/cm2) from three commercial nanopowder materials, P90, P25 and CG 300, their characterisation (profilometry, BET and SEM) and evaluation of their photocatalytic activity in the gaseous phase in a flow-through photoreactor according to the ISO standard (ISO 22197-2). Hexane was chosen as a single model pollutant and a mixture of four compounds, namely acetaldehyde, acetone, heptane and toluene was used for the evaluation of the efficiency of simultaneous removal of several pollutants. A linear dependence between the layer mass and the layer thickness for all materials was found. Up to a layer mass 0.5 mg/cm2, the immobilisation P90 and P25 powder did not result in a decrease in BET surface area, whereas with an increase in layer mass to 1 mg/cm2, a decrease of the BET surface was observed, being more significant in the case of P90. The photocatalytic conversion of hexane was comparable for all immobilised powders up to a layer mass of 0.5 mg/cm2. For higher layer mass, the photocatalytic conversion of hexane on P25 and P90 differ; the latter achieved about 30% higher conversion. In the case of the simultaneous degradation of four compounds, acetaldehyde was degraded best, followed by acetone and toluene; the least degraded compound was heptane. The measurement of released CO2 revealed that 90% of degraded hexane was mineralised to CO2 and water while for a mixture of 4 VOCs, the level of mineralisation was 83%.

Polypyrrole-Barium Ferrite Magnetic Cryogels for Water Purification.

Magnetic polypyrrole-gelatin-barium ferrite (PPy-G-BaFe) cryogels/aerogels were synthesized by one-step oxidative cryopolymerization of pyrrole in the presence of various fractions of barium ferrite (BaFe) nanoparticles, dispersed in aqueous gelatin solution. The successful incorporation of BaFe into the composites was confirmed by elemental analysis and scanning electron microscopy paired with an energy-dispersive X-ray detector. The maximum achieved content of BaFe in the resulting material was 3.9 wt%. The aerogels with incorporated BaFe had significantly higher specific surface area and conductivity, reaching 19.3 m2 g-1 and 4 × 10-4 S cm-1, respectively, compared to PPy-G aerogel, prepared in the absence of BaFe (7.3 m2 g-1 and 1 × 10-5 S cm-1). The model adsorption experiment using an anionic dye, Reactive Black 5, showed that magnetic PPy-G-BaFe aerogel, prepared at 10 wt% BaFe fraction, had significantly higher adsorption rate and higher adsorption capacity, compared to PPy-G (dye removal fraction 99.6% and 89.1%, respectively, after 23 h). Therefore, the prepared PPy-G-BaFe aerogels are attractive adsorbents for water purification due to their enhanced adsorption performance and the possibility of facilitated separation from solution by a magnetic field.

Investigation of tadalafil molecular arrangement in solid dispersions using inverse gas chromatography and Raman mapping.

The aim of this study was to investigate the molecular structures of tadalafil solid dispersions prepared by different techniques and further to relate them to surface free energy information indicating the final amorphousness of the product. Thus, we tried to complement the existing knowledge of solid dispersion formation. Poorly water-soluble tadalafil was combined with different polymers, i.e. Kollidon® 12 PF, Kollidon® VA 64 and Soluplus®, to form model systems. To assess the extent of drug-polymer miscibility, we studied model solid dispersion surface energy using inverse gas chromatography and phase micro-structure using confocal Raman microscopy. The selection of the preparation method was found to play a crucial role in the molecular arrangement of the incorporated drug and the polymer in resulting solid dispersion. Our results showed that a lower surface free energy indicated the formation of a more homogeneous solid dispersion. Conversely, a higher surface free energy corresponded to the heterogeneous systems containing tadalafil amorphous clusters that were captured by Raman mapping. Thus, we successfully introduced a novel evaluation approach of the drug molecular arrangement in solid dispersions that is especially useful for examining the miscibility of the components when the conventional characterizing techniques are inconclusive or yield variable results.

Secreted Enzyme-Responsive System for Controlled Antifungal Agent Release.

Essential oil components (EOCs) such as eugenol play a significant role in plant antimicrobial defense. Due to the volatility and general reactivity of these molecules, plants have evolved smart systems for their storage and release, which are key prerequisites for their efficient use. In this study, biomimetic systems for the controlled release of eugenol, inspired by natural plant defense mechanisms, were prepared and their antifungal activity is described. Delivery and antifungal studies of mesoporous silica nanoparticles (MSN) loaded with eugenol and capped with different saccharide gates-starch, maltodextrin, maltose and glucose-against fungus Aspergillus niger-were performed. The maltodextrin- and maltose-capped systems show very low eugenol release in the absence of the fungus Aspergillus niger but high cargo delivery in its presence. The anchored saccharides are degraded by exogenous enzymes, resulting in eugenol release and efficient inhibition of fungal growth.

Environmental interaction of antimony and arsenic near busy traffic nodes.

Antimony (Sb) and arsenic (As) are elements with similar chemistry, toxicity and binding properties, but different environmental risks and prevailing anthropogenic sources. A significant source of Sb contamination is associated with braking in extremely loaded traffic areas, where the produced abrasion dust contains up to 5% wt. of Sb2S3. In these same exposure areas, As still originates mostly from the combustion of fossil fuels. Heavily loaded crossroads from three different regions of the Czech Republic (Central Europe) were monitored for Sb content in road dusts, topsoils and reference soils during a two-year season (2016-2017). The same samples were also tested for As content to evaluate current contamination trends of both elements in exposed urban areas. The concentration of Sb varied from 5 to 70 µg g-1 in topsoils, and from 20 to 350 µg g-1 in road dusts with the preference for binding to the fine particle fraction (<0.1 mm). The average Sb concentration was up to 60 times the background value and decreased in the order: brake abrasion (103 µg g-1) > road dust (102 µg g-1)> topsoils (101 µg g-1) >> reference soils (<1 µg g-1). The concentration of As in road dust, topsoils and reference soils had about the same level, 101 µg g-1 indicating a more regional character of As pollution. Correlation factors for Sb/As versus iron (Fe)/organic matter (OM) indicated a more robust correlations in soils compared to road dusts and generally better correlations of Sb compared to As. While arsenic contamination has recently decreased thanks to a massive decline of arsenic emissions, antimony contamination indicates a dangerous trend due to growing automotive traffic.

Waste Brick Dust as Potential Sorbent of Lead and Cesium from Contaminated Water.

Adsorption properties of waste brick dust (WBD) were studied by the removing of PbII and CsI from an aqueous system. For adsorption experiments, 0.1 M and 0.5 M aqueous solutions of Cs+ and Pb2+ and two WBD (Libochovice-LB, and Tyn nad Vltavou-TN) in the fraction below 125 µm were used. The structural and surface properties of WBD were characterized by X-ray diffraction (XRD) in combination with solid-state nuclear magnetic resonance (NMR), supplemented by scanning electron microscopy (SEM), specific surface area (SBET), total pore volume and zero point of charge (pHZPC). LB was a more amorphous material showing a better adsorption condition than that of TN. The adsorption process indicated better results for Pb2+, due to the inner-sphere surface complexation in all Pb2+ systems, supported by the formation of insoluble Pb(OH)2 precipitation on the sorbent surface. A weak adsorption of Cs+ on WBD corresponded to the non-Langmuir adsorption run followed by the outer-sphere surface complexation. The leachability of Pb2+ from saturated WBDs varied from 0.001% to 0.3%, while in the case of Cs+, 4% to 12% of the initial amount was leached. Both LB and TN met the standards for PbII adsorption, yet completely failed for any CsI removal from water systems.

Poly(d,l-lactide)/polyethylene glycol micro/nanofiber mats as paclitaxel-eluting carriers: preparation and characterization of fibers, in vitro drug release, antiangiogenic activity and tumor recurrence prevention.

Poly(d,l-lactide)/polyethylene glycol (PLA/PEG) micro/nanofibers loaded with paclitaxel (PTX, 10 wt%) were prepared by needless electrospinning technology, which allows large scale production for real medicinal practice. The fiber structure and properties were investigated by several methods including scanning electron microscopy, nitrogen adsorption/desorption isotherm measurements, differential scanning calorimetry, and X-ray diffraction measurements to examine their morphology (fiber diameter distribution, specific surface area, and total pore volume), composition, drug-loading efficiency, and physical state. An HPLC-UV method was optimized and validated to quantify in vitro PTX release into PBS. The results showed that the addition of PEG into PLA fibers promoted the release of higher amounts of hydrophobic PTX over prolonged time periods compared to fibers without PEG. An in vitro cell assay demonstrated the biocompatibility of PLA/PEG fibrous materials and showed significant cytotoxicity of PTX-loaded PLA/PEG fibers against a human fibrosarcoma HT1080 cell line. The chick chorioallantoic membrane assay proved that PTX-loaded fibers exhibited antiangiogenic activity, with a pronounced effect in the case of the PEG-containing fibers. In vivo evaluation of PTX-loaded PLA/PEG fibers in a human fibrosarcoma recurrence model showed statistically significant inhibition in tumor incidence and growth after primary tumor resection compared to other treatment groups.

Hyper-Cross-Linked Polyacetylene-Type Microporous Networks Decorated with Terminal Ethynyl Groups as Heterogeneous Acid Catalysts for Acetalization and Esterification Reactions.

Heterogeneous catalysts based on materials with permanent porosity are of great interest owing to their high specific surface area, easy separation, recovery, and recycling ability. Additionally, porous polymer catalysts (PPCs) allow us to tune catalytic activity by introducing various functional centres. This study reports the preparation of PPCs with a permanent micro/mesoporous texture and a specific surface area SBET of up to 1000 m2 g-1 active in acid-catalyzed reactions, namely aldehyde and ketone acetalization and carboxylic acid esterification. These PPC-type conjugated hyper-cross-linked polyarylacetylene networks were prepared by chain-growth homopolymerization of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane. However, only some ethynyl groups of the monomers (from 58 to 80 %) were polymerized into the polyacetylene network segments while the other ethynyl groups remained unreacted. Depending on the number of ethynyl groups per monomer molecule and the covalent structure of the monomer, PPCs were decorated with unreacted ethynyl groups from 3.2 to 6.7 mmol g-1 . The hydrogen atoms of the unreacted ethynyl groups served as acid catalytic centres of the aforementioned organic reactions. To the best of our knowledge, this is first study describing the high activity of hydrogen atoms of ethynyl groups in acid-catalyzed reactions.

Removal of arsenate and antimonate by acid-treated Fe-rich clays.

Iron impurities in clays degrade the quality in many aspects, but available Fe oxides can significantly improve adsorption affinity of clays to anionic particles. Two natural Fe-rich clays (kaolin and bentonite) were treated in 0.5 M HCl (pH = 1.1) and 0.15 M (COOH)2 (pH = 1.2), and then used to adsorb AsV/SbV oxyanions from model solutions. After acid leaching, the equilibrium sorption capacities (qmax) increased from 2.3 × 10-3 to 39.2 × 10-3 mmol g-1 for AsV and from 2.4 × 10-3 to 40.1 × 10-3 mmol g-1 for SbV, more than doubling the adsorption yields (≈95%) of both oxyanions. Leaching in 0.5 M HCl enhanced both AsV and SbV adsorption, whereas leaching in 0.15 M (COOH)2 mainly improved the adsorption of SbV. Bentonite, which contained fewer crystalline forms of Fe, exhibited better sorption properties for both oxyanions. The leaching of Fe followed first-order kinetics, whereas the adsorption of AsV/SbV followed second-order kinetics. Acid leaching of Fe-rich clays can be used for the preparation of highly selective anionactive sorbents.

Biochar physicochemical parameters as a result of feedstock material and pyrolysis temperature: predictable for the fate of biochar in soil?

Biochar application is a widely investigated topic nowadays, and precisely described biochar parameters are key information for the understanding of its behaviour in soil and other media. Pore structure and surface properties determine biochar fate. However, there is lack of complex, investigative studies describing the influence of biomass properties and pyrolysis conditions on the pore structure of biochars. The aim of our study was to evaluate a wide range of gathered agriculture residues and elevated pyrolysis temperature on the biochar surface properties and pore composition, predicting biochar behaviour in the soil. The biomass of herbaceous and wood plants was treated by slow pyrolysis, with the final temperature ranging from 400 to 600 °C. Specific surface ranged from 124 to 511 cm2 g-1 at wood biochar and from 3.19 to 192 cm2 g-1 at herbaceous biochar. The main properties influencing biochar pore composition were increasing pyrolysis temperatures and lignin (logarithmically) and ash contents (linearly) of biomass. Increasing lignin contents and pyrolysis temperatures caused the highest biochar micropore volume. The total biochar pore volume was higher of wood biomass (0.08-0.3 cm-3 g-1). Biochars of wood origin were characterised by skeletal density ranging from 1.479 to 2.015 cm3 g-1 and herbaceous ones 1.506-1.943 cm3 g-1, and the envelope density reached 0.982 cm3 g-1 at biochar of wheat grain origin and was generally higher at biochars of herbaceous origin. Density was not pyrolysis temperature dependent.

Interface Induced Growth and Transformation of Polymer-Conjugated Proto-Crystalline Phases in Aluminosilicate Hybrids: A Multiple-Quantum (23)Na-(23)Na MAS NMR Correlation Spectroscopy Study.

Nanostructured materials typically offer enhanced physicochemical properties because of their large interfacial area. In this contribution, we present a comprehensive structural characterization of aluminosilicate hybrids with polymer-conjugated nanosized zeolites specifically grown at the organic-inorganic interface. The inorganic amorphous Al-O-Si framework is formed by alkali-activated low-temperature transformation of metakaoline, whereas simultaneous copolymerization of organic comonomers creates a secondary epoxide network covalently bound to the aluminosilicate matrix. This secondary epoxide phase not only enhances the mechanical integrity of the resulting hybrids but also introduces additional binding sites accessible for compensating negative charge on the aluminosilicate framework. This way, the polymer network initiates growth and subsequent transformation of protocrystalline short-range ordered zeolite domains that are located at the organic-inorganic interface. By applying an experimental approach based on 2D (23)Na-(23)Na double-quantum (DQ) MAS NMR spectroscopy, we discovered multiple sodium binding sites in these protocrystalline domains, in which immobilized Na(+) ions form pairs or small clusters. It is further demonstrated that these sites, the local geometry of which allows for the pairing of sodium ions, are preferentially occupied by Pb(2+) ions during the ion exchange. The proposed synthesis protocol thus allows for the preparation of a novel type of geopolymer hybrids with polymer-conjugated zeolite phases suitable for capturing and storage of metal cations. The demonstrated (23)Na-(23)Na DQ MAS NMR combined with DFT calculations represents a suitable approach for understanding the role of Na(+) ions in aluminositicate solids and related inorganic-organic hybrids, particularly their specific arrangement and clustering at interfacial areas.

Leaching effect on arsenic mobility in agricultural soils.

The stability of soil arsenic during long-term leaching was studied in four soils from an agricultural area. Two identical columns simulating soil profiles of three layers were leached with As-free natural rainwater (<3.10(-3)mgL(-1) As) to test As mobility and the same rainwater enriched with As(V) (2.5mgL(-1) As) for the study of As accumulation. The relative As flow (µgg(-1)day(-1)) showed a comparable run for all soils, with the peak corresponding to maximum As release in the first leaching stage, and then with a tendency to equilibrate. The amount of released As was controlled by the saturated hydraulic conductivity Ksat and free Fe oxides, and the kinetics of the leaching process correlated with the content of organic matter (OM). An overall stability and accumulation of soil arsenic were mostly affected by soil properties (Ksat, particle size, clay fraction), while the chemical composition (Fe, OM content) and surface properties (specific surface area SBET, theoretical adsorption capacity Qt) were of marginal significance. The distribution of As forms was performed by sequential extraction (SEP), which indicated negligible transformation (<12%) of As species in upper soil layers.

Antifungal effect of essential oil components against Aspergillus niger when loaded into silica mesoporous supports.

BACKGROUND: Essential oil components (EOCs) are known for their antifungal properties; however, their high volatility limits their application as antimicrobial agents. Strategies used for controlling the volatility of EOCs include encapsulation or loading into porous materials. This study evaluated the in vitro antifungal activity of selected EOCs (carvacrol, cinnamaldehyde, eugenol and thymol) against the fungus Aspergillus niger when loaded into MCM-41 and ß-cyclodextrin (ß-CD). RESULTS: Carvacrol and thymol in Mobil Composition of Matter No. 41 (MCM-41) displayed remarkable enhanced antifungal properties in comparison to the pure or ß-CD-encapsulated EOCs. In fact, carvacrol and thymol were able to maintain antifungal activity and inhibit fungal growth for 30 days, suggesting better applicability of these EOCs as natural preservatives. CONCLUSIONS: The sustained antifungal effect of EOCs encapsulated into silica mesoporous supports was described.

Adsorption behavior of arsenic relating to different natural solids: soils, stream sediments and peats.

The sorption of anthropogenically derived arsenic to natural solids plays an important role in the mobility and fate of this toxic metalloid in the environment. The adsorption affinity of dissolved As(V) and As(III) to contrasting natural solids was investigated using model solutions of As(V)/As(III) and homogenized samples of soils, stream sediments and peat cores. The adsorption of As(III) and As(V) on investigated sorbents ran mostly according to the Langmuir model, with high correlation factors (>0.7). Sorption capacities varied from 3.5×10(-3) to 2.0×10(-1) mmol/g of As, whereas As(III) achieved a higher adsorption affinity due to the presence of Fe ions in the model solution. The lower horizons of soils and the intact peat, characterized by high enrichment factors of As content (R>1), represented a more stable system with decreased adsorption/desorption dynamics of As transport. A higher surface activity of solids associated with R<1, and an increased As mobility in the solid-water interface, prevailed in upper horizons of the soil and intact peat, where the contact with atmospheric deposition was expected. Stream sediments proved to be a well-balanced system with R≈1. A strong As-Fe correlation in the natural solids confirmed As affinity to Fe particles.

Modified aluminosilicates as low-cost sorbents of As(III) from anoxic groundwater.

The utilization of low-grade clay materials as selective sorbents represents one of the most effective possibilities of As removal from contaminated water reservoirs. The simple pre-treatment of these materials with Fe (Al, Mn) salts can significantly improve their sorption affinity to As oxyanions. The natural kaolin calcined at 550 degrees C (mostly metakaolin) and raw bentonite (mostly montmorillonite) pre-treated with Fe(II), Fe(III), Al(III) and Mn(II) salts were used to remove of As from the model anoxic groundwater with As(III) concentration about 0.5 and 10 mg L(-1). All the pre-treating methods were appropriate for bentonite; the efficiency of As(III) sorption varied from 92 to >99%, by the sorption capacity higher than 4.5 mg g(-1). In the case of metakaolin, Fe(II)- and Mn(II)-treatments proved the high sorption efficiency (>97%), while only <50% of As was removed after Fe(III) and Al(III) pre-treatment. The sorption capacities of treated metakaolin ranged from 0.1 to 2.0 mg g(-1).